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// CODE SNIPPET

Section C403 Building Mechanical Systems

Residential Energy Conservation Code 2018 of Utah > 4 [CE] Commercial Energy Efficiency > C403 Building Mechanical Systems
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C403.1 General

Mechanical systems and equipment serving the building heating, cooling or ventilating needs shall comply with Section C403.2 and shall comply with Sections C403.3 and C403.4 based on the equipment and systems provided.

Walk-in coolers, walk-in freezers, refrigerated warehouse coolers and refrigerated warehouse freezers shall comply with Section C403.2.15 or C403.2.16.

C403.2 Provisions applicable to all mechanical systems (Mandatory)

Mechanical systems and equipment serving the building heating, cooling or ventilating needs shall comply with Sections C403.2.1 through C403.2.16.

C403.2.1 Calculation of heating and cooling loads

Design loads associated with heating, ventilating and air conditioning of the building shall be determined in accordance with ANSI/ASHRAE/ACCA Standard 183 or by anapproved equivalent computational procedure using the design parameters specified in Chapter 3. Heating and cooling loads shall be adjusted to account for load reductions that are achieved where energy recovery systems are utilized in the HVAC system in accordance with the ASHRAE HVAC Systems and Equipment Handbook by an approved equivalent computational procedure.

C403.2.2 Equipment sizing

The output capacity of heating and cooling equipment shall be not greater than the loads calculated in accordance with Section C403.2.1. A single piece of equipment providing both heating and cooling shall satisfy this provision for one function with the capacity for the other function as small as possible, within available equipment options.

Exceptions:

  1. Required standby equipment and systems provided with controls and devices that allow such systems or equipment to operate automatically only when the primary equipment is not operating.
  2. Multiple units of the same equipment type with combined capacities exceeding the design load and provided with controls that have the capability to sequence the operation of each unit based on load.

C403.2.3 HVAC equipment performance requirements

Equipment shall meet the minimum efficiency requirements of Tables C403.2.3(1), C403.2.3(2), C403.2.3(3), C403.2.3(4), C403.2.3(5), C403.2.3(6), C403.2.3(7), C403.2.3(8) and C403.2.3(9) when tested and rated in accordance with the applicable test procedure. Plate-type liquid-to-liquid heat exchangers shall meet the minimum requirements of Table C403.2.3(10). The efficiency shall be verified through certification under an approved certification program or, where a certification program does not exist, the equipment efficiency ratings shall be supported by data furnished by the manufacturer. Where multiple rating conditions or performance requirements are provided, the equipment shall satisfy all stated requirements. Where components, such as indoor or outdoor coils, from different manufacturers are used, calculations and supporting data shall be furnished by the designer that demonstrates that the combined efficiency of the specified components meets the requirements herein.

TABLE C403.2.3(1)

MINIMUM EFFICIENCY REQUIREMENTS: ELECTRICALLY OPERATED UNITARY AIR CONDITIONERS AND CONDENSING UNITS

EQUIPMENT TYPESIZE CATEGORYHEATING
SECTION TYPE
SUBCATEGORY OR
RATING CONDITION
MINIMUM EFFICIENCYTEST
PROCEDUREa
Before 1/1/2016As of 1/1/2016
Air conditioners,
air cooled
< 65,000 Btu/hbAllSplit System13.0 SEER13.0 SEERAHRI 210/240
Single Package13.0 SEER14.0 SEERc
Through-the-wall
(air cooled)
≤ 30,000 Btu/hbAllSplit system12.0 SEER12.0 SEER
Single Package12.0 SEER12.0 SEER
Small-duct high-velocity
(air cooled)
< 65,000 Btu/hbAllSplit System11.0 SEER11.0 SEER
Air conditioners,
air cooled
≥ 65,000 Btu/h
and
< 135,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
11.2 EER
11.4 IEER
11.2 EER
12.8 IEER
AHRI 340/360
All otherSplit System and
Single Package
11.0 EER
11.2 IEER
11.0 EER
12.6 IEER
≥ 135,000 Btu/h
and
< 240,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
11.0 EER
11.2 IEER
11.0 EER
12.4 IEER
All otherSplit System and
Single Package
10.8 EER
11.0 IEER
10.8 EER
12.2 IEER
≥ 240,000 Btu/h
and
< 760,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
10.0 EER
10.1 IEER
10.0 EER
11.6 IEER
All otherSplit System and
Single Package
9.8 EER
9.9 IEER
9.8 EER
11.4 IEER
≥ 760,000 Btu/hElectric Resistance
(or None)
Split System and
Single Package
9.7 EER
9.8 IEER
9.7 EER
11.2 IEER
All otherSplit System and
Single Package
9.5 EER
9.6 IEER
9.5 EER
11.0 IEER
Air conditioners,
water cooled
< 65,000 Btu/hbAllSplit System and
Single Package
12.1 EER
12.3 IEER
12.1 EER
12.3 IEER
AHRI 210/240
≥ 65,000 Btu/h
and
< 135,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
12.1 EER
12.3 IEER
12.1 EER
13.9 IEER
AHRI 340/360
All otherSplit System and
Single Package
11.9 EER
12.1 IEER
11.9 EER
13.7 IEER
≥ 135,000 Btu/h
and
< 240,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
12.5 EER
12.5 IEER
12.5 EER
13.9 IEER
All otherSplit System and
Single Package
12.3 EER
12.5 IEER
12.3 EER
13.7 IEER
≥ 240,000 Btu/h
and
< 760,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
12.4 EER
12.6 IEER
12.4 EER
13.6 IEER
All otherSplit System and
Single Package
12.2 EER
12.4 IEER
12.2 EER
13.4 IEER
≥ 760,000 Btu/hElectric Resistance
(or None)
Split System and
Single Package
12.2 EER
12.4 IEER
12.2 EER
13.5 IEER
All otherSplit System and
Single Package
12.0 EER
12.2 IEER
12.0 EER
13.3 IEER
Air conditioners,
evaporatively cooled
< 65,000 Btu/hbAllSplit System and
Single Package
12.1 EER
12.3 IEER
12.1 EER
12.3 IEER
AHRI 210/240
≥ 65,000 Btu/h
and
< 135,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
12.1 EER
12.3 IEER
12.1 EER
12.3 IEER
AHRI 340/360
All otherSplit System and
Single Package
11.9 EER
12.1 IEER
11.9 EER
12.1 IEER
≥ 135,000 Btu/h
and
< 240,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
12.0 EER
12.2 IEER
12.0 EER
12.2 IEER
All otherSplit System and
Single Package
11.8 EER
12.0 IEER
11.8 EER
12.0 IEER
≥ 240,000 Btu/h
and
< 760,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
11.9 EER
12.1 IEER
11.9 EER
12.1 IEER
All otherSplit System and
Single Package
11.7 EER
11.9 IEER
11.7 EER
11.9 IEER
≥ 760,000 Btu/hElectric Resistance
(or None)
Split System and
Single Package
11.7 EER
11.9 IEER
11.7 EER
11.9 IEER
All otherSplit System and
Single Package
11.5 EER
11.7 IEER
11.5 EER
11.7 IEER
Condensing units,
air cooled
≥ 135,000 Btu/h10.5 EER
11.8 IEER
10.5 EER
11.8 IEER
AHRI 365
Condensing units,
water cooled
≥ 135,000 Btu/h13.5 EER
14.0 IEER
13.5 EER
14.0 IEER
Condensing units,
evaporatively cooled
≥ 135,000 Btu/h13.5 EER
14.0 IEER
13.5 EER
14.0 IEER

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. Chapter 6 contains a complete specification of the referenced test procedure, including the reference year version of the test procedure.
  2. Single-phase, air-cooled air conditioners less than 65,000 Btu/h are regulated by NAECA. SEER values are those set by NAECA.
  3. Minimum efficiency as of January 1, 2015.

TABLE C403.2.3(2)

MINIMUM EFFICIENCY REQUIREMENTS: ELECTRICALLY OPERATED UNITARY AND APPLIED HEAT PUMPS

EQUIPMENT TYPESIZE CATEGORYHEATING
SECTION TYPE
SUBCATEGORY OR
RATING CONDITION
MINIMUM
EFFICIENCY
TEST
PROCEDUREa
Before 1/1/2016As of 1/1/2016
Air cooled
(cooling mode)
< 65,000 Btu/hbAllSplit System13.0 SEERc14.0 SEERcAHRI 210/240
Single Package13.0 SEERc14.0 SEERc
Through-the-wall,
air cooled
≤ 30,000 Btu/hbAllSplit System12.0 SEER12.0 SEER
Single Package12.0 SEER12.0 SEER
Single-duct
high-velocity air cooled
< 65,000 Btu/hbAllSplit System11.0 SEER11.0 SEER
Air cooled
(cooling mode)
≥ 65,000 Btu/h and
< 135,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
11.0 EER
11.2 IEER
11.0 EER
12.0 IEER
AHRI 340/360
All otherSplit System and
Single Package
10.8 EER
11.0 IEER
10.8 EER
11.8 IEER
≥ 135,000 Btu/h and
< 240,000 Btu/h
Electric Resistance
(or None)
Split System and
Single Package
10.6 EER
10.7 IEER
10.6 EER
11.6 IEER
All otherSplit System and
Single Package
10.4 EER
10.5 IEER
10.4 EER
11.4 IEER
≥ 240,000 Btu/hElectric Resistance
(or None)
Split System and
Single Package
9.5 EER
9.6 IEER
9.5 EER
10.6 IEER
All otherSplit System and
Single Package
9.3 EER
9.4 IEER
9.3 EER
9.4 IEER
Water to Air: Water Loop
(cooling mode)
< 17,000 Btu/hAll86°F entering water12.2 EER12.2 EERISO 13256-1
≥ 17,000 Btu/h and
< 65,000 Btu/h
All86°F entering water13.0 EER13.0 EER
≥ 65,000 Btu/h and
< 135,000 Btu/h
All86°F entering water13.0 EER13.0 EER
Water to Air: Ground Water
(cooling mode)
< 135,000 Btu/hAll59°F entering water18.0 EER18.0 EERISO 13256-1
Brine to Air: Ground Loop
(cooling mode)
< 135,000 Btu/hAll77°F entering water14.1 EER14.1 EERISO 13256-1
Water to Water: Water Loop
(cooling mode)
< 135,000 Btu/hAll86°F entering water10.6 EER10.6 EERISO 13256-2
Water to Water: Ground Water
(cooling mode)
< 135,000 Btu/hAll59°F entering water16.3 EER16.3 EER
Brine to Water: Ground Loop
(cooling mode)
< 135,000 Btu/hAll77°F entering fluid12.1 EER12.1 EER
Air cooled
(heating mode)
< 65,000 Btu/hb—Split System7.7 HSPFc8.2 HSPFcAHRI 210/240
—Single Package7.7 HSPFc8.0 HSPFc
Through-the-wall,
(air cooled, heating mode)
≤ 30,000 Btu/hb (cooling capacity)—Split System7.4 HSPF7.4 HSPF
—Single Package7.4 HSPF7.4 HSPF
Small-duct high velocity
(air cooled, heating mode)
< 65,000 Btu/hb—Split System6.8 HSPF6.8 HSPF
Air cooled
(heating mode)
≥ 65,000 Btu/h and
< 135,000 Btu/h
(cooling capacity)
—47°F db/43°F wb
outdoor air
3.3 COP3.3 COPAHRI 340/360
17°Fdb/15°F wb
outdoor air
2.25 COP2.25 COP
≥ 135,000 Btu/h
(cooling capacity)
—47°F db/43°F wb
outdoor air
3.2 COP3.2 COP
17°Fdb/15°F wb
outdoor air
2.05 COP2.05 COP
Water to Air: Water Loop
(heating mode)
< 135,000 Btu/h
(cooling capacity)
—68°F entering water4.3 COP4.3 COPISO 13256-1
Water to Air: Ground Water
(heating mode)
< 135,000 Btu/h
(cooling capacity)
—50°F entering water3.7 COP3.7 COP
Brine to Air: Ground Loop
(heating mode)
< 135,000 Btu/h
(cooling capacity)
—32°F entering fluid3.2 COP3.2 COP
Water to Water: Water Loop
(heating mode)
< 135,000 Btu/h
(cooling capacity)
—68°F entering water3.7 COP3.7 COPISO 13256-2
Water to Water: Ground Water
(heating mode)
< 135,000 Btu/h
(cooling capacity)
—50°F entering water3.1 COP3.1 COP
Brine to Water: Ground Loop
(heating mode)
< 135,000 Btu/h
(cooling capacity)
—32°F entering fluid2.5 COP2.5 COP

For SI: 1 British thermal unit per hour = 0.2931 W, °C = [(°F) - 32]/1.8.

  1. Chapter 6 contains a complete specification of the referenced test procedure, including the reference year version of the test procedure.
  2. Single-phase, air-cooled air conditioners less than 65,000 Btu/h are regulated by NAECA. SEER values are those set by NAECA.
  3. Minimum efficiency as of January 1, 2015.

TABLE C403.2.3(3)

MINIMUM EFFICIENCY REQUIREMENTS: ELECTRICALLY OPERATED PACKAGED TERMINAL AIR CONDITIONERS, PACKAGED TERMINAL HEAT PUMPS, SINGLE-PACKAGE VERTICAL AIR CONDITIONERS, SINGLE VERTICAL HEAT PUMPS, ROOM AIR CONDITIONERS AND ROOM AIR-CONDITIONER HEAT PUMPS

EQUIPMENT TYPESIZE CATEGORY (INPUT)SUBCATEGORY OR
RATING CONDITION
MINIMUM EFFICIENCYTEST
PROCEDUREa
PTAC (cooling mode)
new construction
All Capacities95°F db outdoor air14.0 — (0.300 × Cap/1000) EERcAHRI 310/380
PTAC (cooling mode)
replacementsb
All Capacities95°F db outdoor air10.9 - (0.213 × Cap/1000) EER
PTHP (cooling mode)
new construction
All Capacities95°F db outdoor air14.0 - (0.300 × Cap/1000) EER
PTHP (cooling mode)
replacementsb
All Capacities95°F db outdoor air10.8 - (0.213 × Cap/1000) EER
PTHP (heating mode)
new construction
All Capacities—3.2 - (0.026 × Cap/1000) COP
PTHP (heating mode)
replacementsb
All Capacities—2.9 - (0.026 × Cap/1000) COP
SPVAC
(cooling mode)
< 65,000 Btu/h95°F db/ 75°F wb outdoor air9.0 EERAHRI 390
≥ 65,000 Btu/h and
< 135,000 Btu/h
95°F db/ 75°F wb outdoor air8.9 EER
≥ 135,000 Btu/h and
< 240,000 Btu/h
95°F db/ 75°F wb outdoor air8.6 EER
SPVHP
(cooling mode)
< 65,000 Btu/h95°F db/ 75°F wb outdoor air9.0 EER
≥ 65,000 Btu/h and
< 135,000 Btu/h
95°F db/ 75°F wb outdoor air8.9 EER
≥ 135,000 Btu/h and
< 240,000 Btu/h
95°F db/ 75°F wb outdoor air8.6 EER
SPVHP
(heating mode)
< 65,000 Btu/h47°F db/ 43°F wb outdoor air3.0 COPAHRI 390
≥ 65,000 Btu/h and
< 135,000 Btu/h
47°F db/ 43°F wb outdoor air3.0 COP
≥ 135,000 Btu/h and
< 240,000 Btu/h
47°F db/ 75°F wb outdoor air2.9 COP
Room air conditioners,
with louvered sides
< 6,000 Btu/h—9.7 SEERANSI/AHAM RAC-1
≥ 6,000 Btu/h and
< 8,000 Btu/h
—9.7 EER
≥ 8,000 Btu/h and
< 14,000 Btu/h
—9.8 EER
≥ 14,000 Btu/h and
< 20,000 Btu/h
—9.7 SEER
≥ 20,000 Btu/h—8.5 EER
Room air conditioners,
without louvered sides
< 8,000 Btu/h—9.0 EER
≥ 8,000 Btu/h and
< 20,000 Btu/h
—8.5 EER
≥ 20,000 Btu/h—8.5 EER
Room air-conditioner
heat pumps with
louvered sides
< 20,000 Btu/h—9.0 EER
≥ 20,000 Btu/h—8.5 EER
Room air-conditioner
heat pumps without
louvered sides
< 14,000 Btu/h—8.5 EER
≥ 14,000 Btu/h—8.0 EER
Room air conditioner casement onlyAll capacities—8.7 EERANSI/AHAM RAC-1
Room air conditioner casement-sliderAll capacities—9.5 EER

For SI: 1 British thermal unit per hour = 0.2931 W, °C = [(°F) - 32]/1.8, wb = wet bulb, db = dry bulb.

“Cap” = The rated cooling capacity of the project in Btu/h. Where the unit’s capacity is less than 7000 Btu/h, use 7000 Btu/h in the calculation. Where the unit’s capacity is greater than 15,000 Btu/h, use 15,000 Btu/h in the calculations.

  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. Replacement unit shall be factory labeled as follows: “MANUFACTURED FOR REPLACEMENT APPLICATIONS ONLY: NOT TO BE INSTALLED IN NEW CONSTRUCTION PROJECTS.” Replacement efficiencies apply only to units with existing sleeves less than 16 inches (406 mm) in height and less than 42 inches (1067 mm) in width.
  3. Before January 1, 2015 the minimum efficiency shall be 13.8 - (0.300 x Cap/1000) EER.

TABLE 403.2.3(4)

WARM-AIR FURNACES AND COMBINATION WARM-AIR FURNACES/AIR-CONDITIONING UNITS, WARM-AIR DUCT FURNACES AND UNIT HEATERS, MINIMUM EFFICIENCY REQUIREMENTS

EQUIPMENT TYPESIZE CATEGORY
(INPUT)
SUBCATEGORY OR
RATING CONDITION
MINIMUM
EFFICIENCYd, e
TEST PROCEDUREa
Warm-air furnaces,
gas fired
< 225,000 Btu/h—78% AFUE or
80%Etc
DOE 10 CFR Part 430 or
ANSI Z21.47
≥ 225,000 Btu/hMaximum capacityc80%EtfANSI Z21.47
Warm-air furnaces,
oil fired
< 225,000 Btu/h—78% AFUE or
80%Etc
DOE 10 CFR Part 430 or
UL 727
≥ 225,000 Btu/hMaximum capacityb81%EtgUL 727
Warm-air duct furnaces,
gas fired
All capacitiesMaximum capacityb80%EcANSI Z83.8
Warm-air unit heaters,
gas fired
All capacitiesMaximum capacityb80%EcANSI Z83.8
Warm-air unit heaters,
oil fired
All capacitiesMaximum capacityb80%EcUL 731

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. Minimum and maximum ratings as provided for and allowed by the unit’s controls.
  3. Combination units not covered by the National Appliance Energy Conservation Act of 1987 (NAECA) (3-phase power or cooling capacity greater than or equal to 65,000 Btu/h [19 kW]) shall comply with either rating.
  4. Et = Thermal efficiency. See test procedure for detailed discussion.
  5. Ec = Combustion efficiency (100% less flue losses). See test procedure for detailed discussion.
  6. Ec = Combustion efficiency. Units shall also include an IID, have jackets not exceeding 0.75 percent of the input rating, and have either power venting or a flue damper. A vent damper is an acceptable alternative to a flue damper for those furnaces where combustion air is drawn from the conditioned space.
  7. Et = Thermal efficiency. Units shall also include an IID, have jacket losses not exceeding 0.75 percent of the input rating, and have either power venting or a flue damper. A vent damper is an acceptable alternative to a flue damper for those furnaces where combustion air is drawn from the conditioned space.

TABLE C403.2.3(5)

MINIMUM EFFICIENCY REQUIREMENTS: GAS- AND OIL-FIRED BOILERS

EQUIPMENT TYPEaSUBCATEGORY OR
RATING CONDITION
SIZE CATEGORY (INPUT)MINIMUM EFFICIENCYd, eTEST PROCEDURE
Boilers, hot waterGas-fired< 300,000 Btu/h80% AFUE10 CFR Part 430
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
80% Et10 CFR Part 431
> 2,500,000 Btu/ha82% Ec
Oil-firedc< 300,000 Btu/h80% AFUE10 CFR Part 430
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
82% Et10 CFR Part 431
> 2,500,000 Btu/ha84% Ec
Boilers, steamGas-fired< 300,000 Btu/h75% AFUE10 CFR Part 430
Gas-fired- all, except natural draft≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
79% Et10 CFR Part 431
> 2,500,000 Btu/ha79% Et
Gas-fired-natural draft≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
77% Et
> 2,500,000 Btu/ha77% Et
Oil-firedc< 300,000 Btu/h80% AFUE10 CFR Part 430
≥ 300,000 Btu/h and
≤ 2,500,000 Btu/hb
81% Et10 CFR Part 431
> 2,500,000 Btu/ha81% Et

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. These requirements apply to boilers with rated input of 8,000,000 Btu/h or less that are not packaged boilers and to all packaged boilers. Minimum efficiency requirements for boilers cover all capacities of packaged boilers.
  2. Maximum capacity – minimum and maximum ratings as provided for and allowed by the unit’s controls.
  3. Includes oil-fired (residual).
  4. Ec = Combustion efficiency (100 percent less flue losses).
  5. Et = Thermal efficiency. See referenced standard for detailed information.

TABLE C403.2.3(6)

MINIMUM EFFICIENCY REQUIREMENTS: CONDENSING UNITS, ELECTRICALLY OPERATED

EQUIPMENT TYPESIZE CATEGORYMINIMUM EFFICIENCYbTEST PROCEDUREa
Condensing units, air cooled≥ 135,000 Btu/h10.1 EER
11.2 IPLV
AHRI 365
Condensing units, water or evaporatively cooled≥ 135,000 Btu/h13.1 EER
13.1 IPLV

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.
  2. IPLVs are only applicable to equipment with capacity modulation.

TABLE C403.2.3(7)

WATER CHILLING PACKAGES — EFFICIENCY REQUIREMENTSa, b, d

EQUIPMENT TYPESIZE CATEGORYUNITSBEFORE 1/1/2015AS OF 1/1/2015TEST
PROCEDUREc
Path APath BPath APath B
Air-cooled chillers< 150 TonsEER
(Btu/W)
≥ 9.562 FLNAc≥ 10.100 FL≥ 9.700 FLAHRI 550/590
≥ 12.500 IPLV≥ 13.700 IPLV≥ 15,800 IPLV
≥ 150 Tons≥ 9.562 FLNAc≥ 10.100 FL≥ 9.700 FL
≥ 12.500 IPLV≥ 14.000 IPLV≥ 16.100 IPLV
Air cooled
without condenser,
electrically operated
All capacitiesEER
(Btu/W)
Air-cooled chillers without condenser shall be rated with
matching condensers and complying with air-cooled chiller
efficiency requirements.
Water cooled, electrically
operated positive
displacement
< 75 TonskW/ton≤ 0.780 FL≤ 0.800 FL≤ 0.750 FL≤ 0.780 FL
≤ 0.630 IPLV≤ 0.600 IPLV≤ 0.600 IPLV≤ 0.500 IPLV
≥ 75 tons and < 150 tons≤ 0.775 FL≤ 0.790 FL≤ 0.720 FL≤ 0.750 FL
≤ 0.615 IPLV≤ 0.586 IPLV≤ 0.560 IPLV≤ 0.490 IPLV
≥ 150 tons and < 300 tons≥ 0.680 FL≥ 0.718 FL≥ 0.660 FL≥ 0.680 FL
≥ 0.580 IPLV≥ 0.540 IPLV≥ 0.540 IPLV≥ 0.440 IPLV
≥ 300 tons and < 600 tons≤ 0.620 FL≤ 0.639 FL≤ 0.610 FL≤ 0.625 FL
≤ 0.540 IPLV≤ 0.490 IPLV≤ 0.520 IPLV≤ 0.410 IPLV
≥ 600 tons≤ 0.620 FL≤ 0.639 FL≤ 0.560 FL≤ 0.585 FL
≤ 0.540 IPLV≤ 0.490 IPLV≤ 0.500 IPLV≤ 0.380 IPLV
Water cooled, electrically
operated centrifugal
< 150 TonskW/ton≤ 0.634 FL≤ 0.639 FL≤ 0.610 FL≤ 0.695 FL
≤ 0.596 IPLV≤ 0.450 IPLV≤ 0.550 IPLV≤ 0.440 IPLV
≥ 150 tons and < 300 tons≤ 0.634 FL≤ 0.639 FL≤ 0.610 FL≤ 0.635 FL
≤ 0.596 IPLV≤ 0.450 IPLV≤ 0.550 IPLV≤ 0.400 IPLV
≥ 300 tons and < 400 tons≤ 0.576 FL≤ 0.600 FL≤ 0.560 FL≤ 0.595 FL
≤ 0.549 IPLV≤ 0.400 IPLV≤ 0.520 IPLV≤ 0.390 IPLV
≥ 400 tons and < 600 tons≤ 0.576 FL≤ 0.600 FL≤ 0.560 FL≤ 0.585 FL
≤ 0.549 IPLV≤ 0.400 IPLV≤ 0.500 IPLV≤ 0.380 IPLV
≥ 600 Tons≤ 0.570 FL≤ 0.590 FL≤ 0.560 FL≤ 0.585 FL
≤ 0.539 IPLV≤ 0.400 IPLV≤ 0.500 IPLV≤ 0.380 IPLV
Air cooled, absorption,
single effect
All capacitiesCOP≥ 0.600 FLNAc≥ 0.600 FLNAcAHRI 560
Water cooled absorption,
single effect
All capacitiesCOP≥ 0.700 FLNAc≥ 0.700 FLNAc
Absorption, double
effect, indirect fired
All capacitiesCOP≥ 1.000 FLNAc≥ 1.000 FLNAc
≥ 1.050 IPLV≥ 1.050 IPLV
Absorption double effect
direct fired
All capacitiesCOP≥ 1.000 FLNAc≥ 1.000 FLNAc
≥ 1.000 IPLV≥ 1.050 IPLV
  1. The requirements for centrifugal chiller shall be adjusted for nonstandard rating conditions in accordance with Section C403.2.3.1 and are only applicable for the range of conditions listed in Section C403.2.3.1. The requirements for air-cooled, water-cooled positive displacement and absorption chillers are at standard rating conditions defined in the reference test procedure.
  2. Both the full-load and IPLV requirements shall be met or exceeded to comply with this standard. Where there is a Path B, compliance can be with either Path A or Path B for any application.
  3. NA means the requirements are not applicable for Path B and only Path A can be used for compliance.
  4. FL represents the full-load performance requirements and IPLV the part-load performance requirements.

TABLE C403.2.3(8)

MINIMUM EFFICIENCY REQUIREMENTS: HEAT REJECTION EQUIPMENT

EQUIPMENT TYPEaTOTAL SYSTEM
HEAT REJECTION
CAPACITY AT RATED
CONDITIONS
SUBCATEGORY OR RATING CONDITIONiPERFORMANCE
REQUIREDb, c, d, g, h
TEST PROCEDUREe, f
Propeller or axial fan
open-circuit cooling towers
All95°F entering water
85°F leaving water
75°F entering wb
≥ 40.2 gpm/hpCTI ATC-105 and
CTI STD-201
Centrifugal fan
open-circuit cooling towers
All95°F entering water
85°F leaving water
75°F entering wb
≥ 20.0 gpm/hpCTI ATC-105 and
CTI STD-201
Propeller or axial fan
closed-circuit cooling
towers
All102°F entering water
90°F leaving water
75°F entering wb
≥ 14.0 gpm/hpCTI ATC-105S and
CTI STD-201
Centrifugal fan closed-
circuit cooling towers
All102°F entering water
90°F leaving water
75°F entering wb
≥7.0 gpm/hpCTI ATC-105S and
CTI STD-201
Propeller or axial fan
evaporative condensers
AllAmmonia Test Fluid
140°F entering gas temperature
96.3°F condensing temperature
75°F entering wb
≥ 134,000 Btu/h•hpCTI ATC-106
Centrifugal fan
evaporative condensers
AllAmmonia Test Fluid
140°F entering gas temperature
96.3°F condensing temperature
75°F entering wb
>110,000 Btu/h•hpCTI ATC-106
Propeller or axial fan
evaporative condensers
AllR-507A Test Fluid
165°F entering gas temperature
105°F condensing temperature
75°F entering wb
≥ 157,000 Btu/h•hpCTI ATC-106
Centrifugal fan
evaporative condensers
AllR-507A Test Fluid
165°F entering gas temperature
105°F condensing temperature
75°F entering wb
≥ 135,000 Btu/h•hpCTI ATC-106
Air-cooled condensersAll125°F Condensing Temperature
190°F Entering Gas Temperature
15°F subcooling 95°F entering db
≥ 176,000 Btu/h•hpAHRI 460

For SI: °C = [(°F)-32]/1.8, L/s • kW = (gpm/hp)/(11.83), COP = (Btu/h • hp)/(2550.7),

db = dry bulb temperature, °F, wb = wet bulb temperature, °F.

  1. The efficiencies and test procedures for both open- and closed-circuit cooling towers are not applicable to hybrid cooling towers that contain a combination of wet and dry heat exchange sections.
  2. For purposes of this table, open circuit cooling tower performance is defined as the water flow rating of the tower at the thermal rating condition listed in Table 403.2.3(8) divided by the fan nameplate-rated motor power.
  3. For purposes of this table, closed-circuit cooling tower performance is defined as the water flow rating of the tower at the thermal rating condition listed in Table 403.2.3(8) divided by the sum of the fan nameplate-rated motor power and the spray pump nameplate-rated motor power.
  4. For purposes of this table, air-cooled condenser performance is defined as the heat rejected from the refrigerant divided by the fan nameplate-rated motor power.
  5. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure. The certification requirements do not apply to field-erected cooling towers.
  6. Where a certification program exists for a covered product and it includes provisions for verification and challenge of equipment efficiency ratings, then the product shall be listed in the certification program; or, where a certification program exists for a covered product, and it includes provisions for verification and challenge of equipment efficiency ratings, but the product is not listed in the existing certification program, the ratings shall be verified by an independent laboratory test report.
  7. Cooling towers shall comply with the minimum efficiency listed in the table for that specific type of tower with the capacity effect of any project-specific accessories and/or options included in the capacity of the cooling tower
  8. For purposes of this table, evaporative condenser performance is defined as the heat rejected at the specified rating condition in the table divided by the sum of the fan motor nameplate power and the integral spray pump nameplate power
  9. Requirements for evaporative condensers are listed with ammonia (R-717) and R-507A as test fluids in the table. Evaporative condensers intended for use with halocarbon refrigerants other than R-507A shall meet the minimum efficiency requirements listed in this table with R-507A as the test fluid.

TABLE C403.2.3(9)

MINIMUM EFFICIENCY AIR CONDITIONERS AND CONDENSING UNITS SERVING COMPUTER ROOMS

EQUIPMENT TYPENET SENSIBLE COOLING CAPACITYaMINIMUM SCOP-127b EFFICIENCY
DOWNFLOW UNITS/UPFLOW UNITS
TEST PROCEDURE
Air conditioners, air cooled< 65,000 Btu/h2.20 / 2.09ANSI/ASHRAE 127
≥ 65,000 Btu/h and < 240,000 Btu/h2.10 / 1.99
≥ 240,000 Btu/h1.90 / 1.79
Air conditioners, water cooled< 65,000 Btu/h2.60 / 2.49
≥ 65,000 Btu/h and < 240,000 Btu/h2.50 / 2.39
≥ 240,000 Btu/h2.40 / 2.29
Air conditioners, water cooled with
fluid economizer
< 65,000 Btu/h2.55 / 2.44
≥ 65,000 Btu/h and < 240,000 Btu/h2.45 / 2.34
≥ 240,000 Btu/h2.35 / 2.24
Air conditioners, glycol cooled
(rated at 40% propylene glycol)
< 65,000 Btu/h2.50 / 2.39
≥ 65,000 Btu/h and < 240,000 Btu/h2.15 / 2.04
≥ 240,000 Btu/h2.10 / 1.99
Air conditioners, glycol cooled
(rated at 40% propylene glycol)
with fluid economizer
< 65,000 Btu/h2.45 / 2.34
≥ 65,000 Btu/h and < 240,000 Btu/h2.10 / 1.99
≥ 240,000 Btu/h2.05 / 1.94

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. Net sensible cooling capacity: the total gross cooling capacity less the latent cooling less the energy to the air movement system. (Total Gross – latent – Fan Power).
  2. Sensible coefficient of performance (SCOP-127): a ratio calculated by dividing the net sensible cooling capacity in watts by the total power input in watts (excluding reheaters and humidifiers) at conditions defined in ASHRAE Standard 127. The net sensible cooling capacity is the gross sensible capacity minus the energy dissipated into the cooled space by the fan system.

TABLE C403.2.3(10)

HEAT TRANSFER EQUIPMENT

EQUIPMENT TYPESUBCATEGORYMINIMUM EFFICIENCYTEST PROCEDUREa
Liquid-to-liquid heat exchangersPlate typeNRAHRI 400

NR = No Requirement.

  1. Chapter 6 contains a complete specification of the referenced test procedure, including the referenced year version of the test procedure.

C403.2.3.1 Water-cooled centrifugal chilling packages

Equipment not designed for operation at AHRI Standard 550/590 test conditions of 44°F (7°C) leaving chilled-water temperature and 2.4 gpm/ton evaporator fluid flow and 85°F (29°C) entering condenser water temperature with 3 gpm/ton (0.054 I/s • kW) condenser water flow shall have maximum full-load kW/ton (FL) and part-load ratings requirements adjusted using Equations 4-6 and 4-7.

(Equation 4-6)

(Equation 4-7)

where:

Kadj=A × B
FL=Full-load kW/ton value as specified in Table C403.2.3(7).
FLadj=Maximum full-load kW/ton rating, adjusted for nonstandard conditions.
IPLV=Value as specified in Table C403.2.3(7).
PLVadj=Maximum NPLV rating, adjusted for nonstandard conditions.
A=0.00000014592 • (LIFT)4 – 0.0000346496 • (LIFT)3 + 0.00314196 • (LIFT)2 – 0.147199 • (LIFT) + 3.9302
B=0.0015 • Lvg Evap + 0.934
LIFT=LvgCond – Lvg Evap
LvgCond=Full-load condenser leaving fluid temperature (°F).
LvgEvap=Full-load evaporator leaving temperature (°F).

The FLadj and PLVadj values are only applicable for centrifugal chillers meeting all of the following full-load design ranges:

  1. Minimum evaporator leaving temperature: 36°F.
  2. Maximum condenser leaving temperature: 115°F.
  3. 20°F ≤ LIFT ≤ 80°F.

C403.2.3.2 Positive displacement (air- and water-cooled) chilling packages

Equipment with a leaving fluid temperature higher than 32°F (0°C) and water-cooled positive displacement chilling packages with a condenser leaving fluid temperature below 115°F (46°C) shall meet the requirements of Table C403.2.3(7) when tested or certified with water at standard rating conditions, in accordance with the referenced test procedure.

C403.2.4 HVAC system controls

Each heating and cooling system shall be provided with thermostatic controls as specified in Section C403.2.4.1, C403.2.4.1.3, C403.2.4.2, C403.2.4.3, C403.3.1, C403.4, C403.4.1 or C403.4.4.

C403.2.4.1 Thermostatic controls

The supply of heating and cooling energy to each zone shall be controlled by individual thermostatic controls capable of responding to temperature within the zone. Where humidification or dehumidification or both is provided, at least one humidity control device shall be provided for each humidity control system.

Exception: Independent perimeter systems that are designed to offset only building envelope heat losses, gains or both serving one or more perimeter zones also served by an interior system provided:

  1. The perimeter system includes at least one thermostatic control zone for each building exposure having exterior walls facing only one orientation (within +/-45 degrees) (0.8 rad) for more than 50 contiguous feet (15 240 mm); and
  2. The perimeter system heating and cooling supply is controlled by thermostats located within the zones served by the system.

C403.2.4.1.1 Heat pump supplementary heat

Heat pumps having supplementary electric resistance heat shall have controls that, except during defrost, prevent supplementary heat operation where the heat pump can provide the heating load.

C403.2.4.1.2 Deadband

Where used to control both heating and cooling, zone thermostatic controls shall be capable of providing a temperature range or deadband of at least 5°F (2.8°C) within which the supply of heating and cooling energy to the zone is capable of being shut off or reduced to a minimum.

Exceptions:

  1. Thermostats requiring manual changeover between heating and cooling modes.
  2. Occupancies or applications requiring precision in indoor temperature control as approved by the code official.

C403.2.4.1.3 Setpoint overlap restriction

Where a zone has a separate heating and a separate cooling thermostatic control located within the zone , a limit switch, mechanical stop or direct digital control system with software programming shall be provided with the capability to prevent the heating set point from exceeding the cooling set point and to maintain a deadband in accordance with Section C403.2.4.1.2.

C403.2.4.2 Off-hour controls

Each zone shall be provided with thermostatic setback controls that are controlled by either an automatic time clock or programmable control system.

Exceptions:

  1. Zones that will be operated continuously.
  2. Zones with a full HVAC load demand not exceeding 6,800 Btu/h (2 kW) and having a readily accessible manual shutoff switch.

C403.2.4.2.1 Thermostatic setback capabilities

Thermostatic setback controls shall have the capability to set back or temporarily operate the system to maintainzone temperatures down to 55°F (13°C) or up to 85°F (29°C).

C403.2.4.2.2 Automatic setback and shutdown capabilities

Automatic time clock or programmable controls shall be capable of starting and stopping the system for seven different daily schedules per week and retaining their programming and time setting during a loss of power for at least 10 hours. Additionally, the controls shall have a manual override that allows temporary operation of the system for up to 2 hours; a manually operated timer capable of being adjusted to operate the system for up to 2 hours; or an occupancy sensor.

C403.2.4.2.3 Automatic start capabilities

Automatic start controls shall be provided for each HVAC system. The controls shall be capable of automatically adjusting the daily start time of the HVAC system in order to bring each space to the desired occupied temperature immediately prior to scheduled occupancy.

C403.2.4.3 Shutoff dampers

Outdoor air intake and exhaust openings and stairway and shaft vents shall be provided with Class I motorized dampers. The dampers shall have an air leakage rate not greater than 4 cfm/ft2 (20.3 L/s • m2) of damper surface area at 1.0 inch water gauge (249 Pa) and shall be labeled by an approved agency when tested in accordance with AMCA 500D for such purpose.

Outdoor air intake and exhaust dampers shall be installed with automatic controls configured to close when the systems or spaces served are not in use or during unoccupied period warm-up and setback operation, unless the systems served require outdoor or exhaust air in accordance with the International Mechanical Code or the dampers are opened to provide intentional economizer cooling.

Stairway and shaft vent dampers shall be installed with automatic controls configured to open upon the activation of any fire alarm initiating device of the building’s fire alarm system or the interruption of power to the damper.

Exception: Gravity (nonmotorized) dampers shall be permitted to be used as follows:

  1. In buildings less than three stories in height above grade plane.
  2. In buildings of any height located in Climate Zones 1, 2 or 3.
  3. Where the design exhaust capacity is not greater than 300 cfm (142 L/s).

Gravity (nonmotorized) dampers shall have an air leakage rate not greater than 20 cfm/ft2 (101.6 L/s • m2) where not less than 24 inches (610 mm) in either dimension and 40 cfm/ft2 (203.2 L/s • m2) where less than 24 inches (610 mm) in either dimension. The rate of air leakage shall be determined at 1.0 inch water gauge (249 Pa) when tested in accordance with AMCA 500D for such purpose. The dampers shall be labeled by an approved agency.

C403.2.4.4 Zone isolation

HVAC systems serving zones that are over 25,000 square feet (2323 m2) in floor area or that span more than one floor and are designed to operate or be occupied nonsimultaneously shall be divided into isolation areas. Each isolation area shall be equipped with isolation devices and controls configured to automatically shut off the supply of conditioned air and outdoor air to and exhaust air from the isolation area. Each isolation area shall be controlled independently by a device meeting the requirements of Section C403.2.4.2.2. Central systems and plants shall be provided with controls and devices that will allow system and equipment operation for any length of time while serving only the smallest isolation area served by the system or plant.

Exceptions:

  1. Exhaust air and outdoor air connections to isolation areas where the fan system to which they connect is not greater than 5,000 cfm (2360 L/s).
  2. Exhaust airflow from a single isolation area of less than 10 percent of the design airflow of the exhaust system to which it connects.
  3. Isolation areas intended to operate continuously or intended to be inoperative only when all other isolation areas in a zone are inoperative.

C403.2.4.5 Snow- and ice-melt system controls

Snow- and ice-melting systems shall include automatic controls capable of shutting off the system when the pavement temperature is above 50°F (10°C) and no precipitation is falling and an automatic or manual control that will allow shutoff when the outdoor temperature is above 40°F (4°C).

C403.2.4.6 Freeze protection system controls

Freeze protection systems, such as heat tracing of outdoor piping and heat exchangers, including self-regulating heat tracing, shall include automatic controls configured to shut off the systems when outdoor air temperatures are above 40°F (4°C) or when the conditions of the protected fluid will prevent freezing.

C403.2.4.7 Economizer fault detection and diagnostics (FDD)

Air-cooled unitary direct-expansion units listed in Tables C403.2.3(1) through C403.2.3(3) and variable refrigerant flow (VRF) units that are equipped with an economizer in accordance with Section C403.3 shall include a fault detection and diagnostics (FDD) system complying with the following:

  1. The following temperature sensors shall be permanently installed to monitor system operation:

    1. 1.1. Outside air.
    2. 1.2. Supply air.
    3. 1.3. Return air.
  2. Temperature sensors shall have an accuracy of ±2°F (1.1°C) over the range of 40°F to 80°F (4°C to 26.7°C).
  3. Refrigerant pressure sensors, where used, shall have an accuracy of ±3 percent of full scale.
  4. The unit controller shall be capable of providing system status by indicating the following:

    1. 4.1. Free cooling available.
    2. 4.2. Economizer enabled.
    3. 4.3. Compressor enabled.
    4. 4.4. Heating enabled.
    5. 4.5. Mixed air low limit cycle active.
    6. 4.6. The current value of each sensor.
  5. The unit controller shall be capable of manually initiating each operating mode so that the operation of compressors, economizers, fans and the heating system can be independently tested and verified.
  6. The unit shall be capable of reporting faults to a fault management application accessible by dayto-day operating or service personnel, or annunciated locally on zone thermostats.
  7. The FDD system shall be capable of detecting the following faults:

    1. 7.1. Air temperature sensor failure/fault.
    2. 7.2. Not economizing when the unit should be economizing.
    3. 7.3. Economizing when the unit should not be economizing.
    4. 7.4. Damper not modulating.
    5. 7.5. Excess outdoor air.

C403.2.5 Hot water boiler outdoor temperature setback control

Hot water boilers that supply heat to the building through one- or two-pipe heating systems shall have an outdoor setback control that lowers the boiler water temperature based on the outdoor temperature.

C403.2.6 Ventilation

Ventilation, either natural or mechanical, shall be provided in accordance with Chapter 4 of theInternational Mechanical Code . Where mechanical ventilation is provided, the system shall provide the capability to reduce the outdoor air supply to the minimum required by Chapter 4 of the International Mechanical Code .

C403.2.6.1 Demand controlled ventilation

Demand control ventilation (DCV) shall be provided for spaces larger than 500 square feet (46.5 m2) and with an average occupant load of 25 people per 1,000 square feet (93 m2) of floor area (as established in Table 403.3.1.1 of the International Mechanical Code) and served by systems with one or more of the following:

  1. An air-side economizer.
  2. Automatic modulating control of the outdoor air damper.
  3. A design outdoor airflow greater than 3,000 cfm (1416 L/s).

Exception: Demand control ventilation is not required for systems and spaces as follows:

  1. Systems with energy recovery complying with Section C403.2.7.
  2. Multiple-zone systems without direct digital control of individual zones communicating with a central control panel.
  3. Systems with a design outdoor airflow less than 1,200 cfm (566 L/s).
  4. Spaces where the supply airflow rate minus any makeup or outgoing transfer air requirement is less than 1,200 cfm (566 L/s).
  5. Ventilation provided for process loads only.

C403.2.6.2 Enclosed parking garage ventilation controls

Enclosed parking garages used for storing or handling automobiles operating under their own power shall employ contamination-sensing devices and automatic controls configured to stage fans or modulate fan average airflow rates to 50 percent or less of design capacity, or intermittently operate fans less than 20 percent of the occupied time or as required to maintain acceptable contaminant levels in accordance with International Mechanical Code provisions. Failure of contamination sensing devices shall cause the exhaust fans to operate continuously at design airflow.

Exceptions:

  1. Garages with a total exhaust capacity less than 22,500 cfm (10 620 L/s) with ventilation systems that do not utilize heating or mechanical cooling.
  2. Garages that have a garage area to ventilation system motor nameplate power ratio that exceeds 1125 cfm/hp (710 L/s/kW) and do not utilize heating or mechanical cooling.

C403.2.7 Energy recovery ventilation systems

Where the supply airflow rate of a fan system exceeds the values specified in Tables C403.2.7(1) and C403.2.7(2), the system shall include an energy recovery system. The energy recovery system shall have the capability to provide a change in the enthalpy of the outdoor air supply of not less than 50 percent of the difference between the outdoor air and return air enthalpies, at design conditions. Where an air economizer is required, the energy recovery system shall include a bypass or controls which permit operation of the economizer as required by Section C403.3.

Exception: An energy recovery ventilation system shall not be required in any of the following conditions:

  1. Where energy recovery systems are prohibited by the International Mechanical Code.
  2. Laboratory fume hood systems that include at least one of the following features:

    1. 2.1. Variable-air-volume hood exhaust and room supply systems capable of reducing exhaust and makeup air volume to 50 percent or less of design values.
    2. 2.2. Direct makeup (auxiliary) air supply equal to at least 75 percent of the exhaust rate, heated not warmer than 2°F (1.1°C) above room setpoint, cooled to not cooler than 3°F (1.7°C) below room setpoint, no humidification added, and no simultaneous heating and cooling used for dehumidification control.
  3. Systems serving spaces that are heated to less than 60°F (15.5°C) and are not cooled.
  4. Where more than 60 percent of the outdoor heating energy is provided from site-recovered or site solar energy.
  5. Heating energy recovery in Climate Zones 1 and 2.
  6. Cooling energy recovery in Climate Zones 3C, 4C, 5B, 5C, 6B, 7 and 8.
  7. Systems requiring dehumidification that employ energy recovery in series with the cooling coil.
  8. Where the largest source of air exhausted at a single location at the building exterior is less than 75 percent of the design outdoor air flow rate.
  9. Systems expected to operate less than 20 hours per week at the outdoor air percentage covered by Table C403.2.7(1).
  10. Systems exhausting toxic, flammable, paint or corrosive fumes or dust.
  11. Commercial kitchen hoods used for collecting and removing grease vapors and smoke.

TABLE C403.2.7(1)

ENERGY RECOVERY REQUIREMENT (Ventilation systems operating less than 8,000 hours per year)

CLIMATE ZONEPERCENT (%) OUTDOOR AIR AT FULL DESIGN AIRFLOW RATE
≥ 10% and < 20%≥ 20% and < 30%≥ 30% and < 40%≥ 40% and <
50%
≥ 50% and <
60%
≥ 60% and <
70%
≥ 70% and <
80%
≥ 80%
DESIGN SUPPLY FAN AIRFLOW RATE (cfm)
3B, 3C, 4B, 4C, 5BNRNRNRNRNRNRNRNR
1B, 2B, 5CNRNRNRNR≥ 26,000≥ 12,000≥ 5,000≥ 4,000
6B≥ 28,000≥ 26,5000≥ 11,000≥ 5,500≥ 4,500≥ 3,500≥ 2,500≥ 1,500
1A, 2A, 3A, 4A,
5A, 6A
≥ 26,000≥ 16,000≥ 5,500≥ 4,500≥ 3,500≥ 2,000≥ 1,000>0
7,8≥ 4,500≥ 4,000≥ 2,500≥ 1,000>0>0>0>0

For SI: 1 cfm = 0.4719 L/s.

NR = Not Required.

TABLE C403.2.7(2)

ENERGY RECOVERY REQUIREMENT (Ventilation systems operating not less than 8,000 hours per year)

CLIMATE ZONEPERCENT (%) OUTDOOR AIR AT FULL DESIGN AIRFLOW RATE
≥ 10% and
< 20%
≥ 20% and
< 30%
≥ 30% and
< 40%
≥ 40% and
< 50%
≥ 50% and
< 60%
≥ 60% and
< 70%
≥ 70% and
< 80%
≥ 80%
Design Supply Fan Airflow Rate (cfm)
3CNRNRNRNRNRNRNRNR
1B, 2B, 3B, 4C, 5CNR≥ 19,500≥ 9,000≥ 5,000≥ 4,000≥ 3,000≥ 1,500> 0
1A, 2A, 3A, 4B, 5B≥ 2,500≥ 2,000≥ 1,000≥ 500> 0> 0> 0> 0
4A, 5A, 6A, 6B, 7, 8> 0> 0> 0> 0> 0> 0> 0> 0

For SI: 1 cfm = 0.4719 L/s.

NR = Not required

C403.2.8 Kitchen exhaust systems

Replacement air introduced directly into the exhaust hood cavity shall not be greater than 10 percent of the hood exhaust airflow rate. Conditioned supply air delivered to any space shall not exceed the greater of the following:

  1. The ventilation rate required to meet the space heating or cooling load.
  2. The hood exhaust flow minus the available transfer air from adjacent space where available transfer air is considered that portion of outdoor ventilation air not required to satisfy other exhaust needs, such as restrooms, and not required to maintain pressurization of adjacent spaces.

Where total kitchen hood exhaust airflow rate is greater than 5,000 cfm (2360 L/s), each hood shall be a factory-built commercial exhaust hood listed by a nationally recognized testing laboratory in compliance with UL 710. Each hood shall have a maximum exhaust rate as specified in Table C403.2.8 and shall comply with one of the following:

  1. Not less than 50 percent of all replacement air shall be transfer air that would otherwise be exhausted.
  2. Demand ventilation systems on not less than 75 percent of the exhaust air that are capable of not less than a 50-percent reduction in exhaust and replacement air system airflow rates, including controls necessary to modulate airflow in response to appliance operation and to maintain full capture and containment of smoke, effluent and combustion products during cooking and idle.
  3. Listed energy recovery devices with a sensible heat recovery effectiveness of not less than 40 percent on not less than 50 percent of the total exhaust airflow.

Where a single hood, or hood section, is installed over appliances with different duty ratings, the maximum allowable flow rate for the hood or hood section shall be based on the requirements for the highest appliance duty rating under the hood or hood section.

Exception: Where not less than 75 percent of all the replacement air is transfer air that would otherwise be exhausted

TABLE C403.2.8

MAXIMUM NET EXHAUST FLOW RATE, CFM PER LINEAR FOOT OF HOOD LENGTH

TYPE OF HOODLIGHT-DUTY
EQUIPMENT
MEDIUM-DUTY
EQUIPMENT
HEAVY-DUTY
EQUIPMENT
EXTRA-HEAVY-DUTY
EQUIPMENT
Wall-mounted canopy140210280385
Single island280350420490
Double island (per side)175210280385
Eyebrow175175NANA
Backshelf/Pass-over210210280NA

For SI: 1 cfm = 0.4719 L/s; 1 foot = 305 mm.

NA = Not Allowed.

C403.2.9 Duct and plenum insulation and sealing

Supply and return air ducts and plenums shall be insulated with a minimum of R-6 insulation where located in unconditioned spaces and where located outside the building with a minimum of R-8 insulation in Climate Zones 1 through 4 and a minimum of R-12 insulation in Climate Zones 5 through 8. Where located within a building envelope assembly, the duct or plenum shall be separated from the building exterior or unconditioned or exempt spaces by a minimum of R-8 insulation in Climate Zones 1 through 4 and a minimum of R-12 insulation in Climate Zones 5 through 8.

Exceptions:

  1. Where located within equipment.
  2. Where the design temperature difference between the interior and exterior of the duct or plenum is not greater than 15°F (8°C).

Ducts, air handlers and filter boxes shall be sealed. Joints and seams shall comply with Section 603.9 of the International Mechanical Code.

C403.2.9.1 Duct construction

Ductwork shall be constructed and erected in accordance with theInternational Mechanical Code .

C403.2.9.1.1 Low-pressure duct systems

Longitudinal and transverse joints, seams and connections of supply and return ducts operating at a static pressure less than or equal to 2 inches water gauge (w.g.) (498 Pa) shall be securely fastened and sealed with welds, gaskets, mastics (adhesives), mastic-plus-embedded-fabric systems or tapes installed in accordance with the manufacturer’s instructions. Pressure classifications specific to the duct system shall be clearly indicated on the construction documents in accordance with the International Mechanical Code.

Exception: Locking-type longitudinal joints and seams, other than the snap-lock and button-lock types, need not be sealed as specified in this section.

C403.2.9.1.2 Medium-pressure duct systems

Ducts and plenums designed to operate at a static pressure greater than 2 inches water gauge (w.g.) (498 Pa) but less than 3 inches w.g. (747 Pa) shall be insulated and sealed in accordance with Section C403.2.9. Pressure classifications specific to the duct system shall be clearly indicated on the construction documents in accordance with theInternational Mechanical Code .

C403.2.9.1.3 High-pressure duct systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.

Ducts and plenums designed to operate at static pressures greater than 3 inches water gauge (747 Pa) shall be insulated and sealed in accordance with Section C403.2.9. In addition, ducts and plenums shall be leak tested in accordance with the SMACNA HVAC Air Duct Leakage Test Manual and shown to have a rate of air leakage (CL) less than or equal to 4.0 as determined in accordance with Equation 4-8.

(Equation 4-8)

where:

F=The measured leakage rate in cfm per 100 square feet of duct surface.
SL =The static pressure of the test.

Documentation shall be furnished by the designer demonstrating that representative sections totaling at least 25 percent of the duct area have been tested and that all tested sections comply with the requirements of this section.

C403.2.10 Piping insulation

Piping serving as part of a heating or cooling system shall be thermally insulated in accordance with Table C403.2.10.

Exceptions:

  1. Factory-installed piping within HVAC equipment tested and rated in accordance with a test procedure referenced by this code.
  2. Factory-installed piping within room fan-coils and unit ventilators tested and rated according to AHRI 440 (except that the sampling and variation provisions of Section 6.5 shall not apply) and AHRI 840, respectively.
  3. Piping that conveys fluids that have a design operating temperature range between 60°F (15°C) and 105°F (41°C).
  4. Piping that conveys fluids that have not been heated or cooled through the use of fossil fuels or electric power.
  5. Strainers, control valves, and balancing valves associated with piping 1 inch (25 mm) or less in diameter.
  6. Direct buried piping that conveys fluids at or below 60°F (15°C).

TABLE C403.2.10

MINIMUM PIPE INSULATION THICKNESS (in inches)a, c

FLUID OPERATING
TEMPERATURE RANGE
AND USAGE (°F)
INSULATION CONDUCTIVITYNOMINAL PIPE OR TUBE SIZE (inches)
Conductivity
Btu • in./(h • ft2• °F)b
Mean Rating Temperature, °F< 11 to < 1 1/21 1/2 to < 44 to < 8≥ 8
> 3500.32 – 0.342504.55.05.05.05.0
251 – 3500.29 – 0.322003.04.04.54.54.5
201 – 2500.27 – 0.301502.52.52.53.03.0
141 – 2000.25 – 0.291251.51.52.02.02.0
105 – 1400.21 – 0.281001.01.01.51.51.5
40 – 600.21 – 0.27750.50.51.01.01.0
< 400.20 – 0.26500.51.01.01.01.5

For SI: 1 inch = 25.4 mm, °C = [(°F) - 32]/1.8.

  1. For piping smaller than 11/2 inches and located in partitions within conditioned spaces, reduction of these thicknesses by 1 inch shall be permitted (before thickness adjustment required in footnote b) but not to a thickness less than 1 inch.
  2. For insulation outside the stated conductivity range, the minimum thickness (T) shall be determined as follows:
  3. where:

    T=minimum insulation thickness,
    r=actual outside radius of pipe,
    t=insulation thickness listed in the table for applicable fluid temperature and pipe size,
    K=conductivity of alternate material at mean rating temperature indicated for the applicable fluid temperature (Btu • in/h • ft2 • °F) and
    k=the upper value of the conductivity range listed in the table for the applicable fluid temperature.
  4. For direct-buried heating and hot water system piping, reduction of these thicknesses by 11/2 inches (38 mm) shall be permitted (before thickness adjustment required in footnote b but not to thicknesses less than 1 inch (25 mm).

C403.2.10.1 Protection of piping insulation

Piping insulation exposed to the weather shall be protected from damage, including that due to sunlight, moisture, equipment maintenance and wind, and shall provide shielding from solar radiation that can cause degradation of the material. Adhesive tape shall not be permitted.

C403.2.11 Mechanical systems commissioning and completion requirements

Mechanical systems shall be commissioned and completed in accordance with Section C408.2.

C403.2.12 Air system design and control

Each HVAC system having a total fan system motor nameplate horsepower (hp) exceeding 5 hp (3.7 kW) shall comply with the provisions of Sections C403.2.12.1 through C403.2.12.3.

C403.2.12.1 Allowable fan motor horsepower

Each HVAC system at fan system design conditions shall not exceed the allowable fan system motor nameplate hp (Option 1) or fan system bhp (Option 2) as shown in Table C403.2.12.1(1). This includes supply fans, exhaust fans, return/relief fans, and fan-powered terminal units associated with systems providing heating or cooling capability.

Single-zone variable air volume systems shall comply with the constant volume fan power limitation.

Exceptions:

  1. Hospital, vivarium and laboratory systems that utilize flow control devices on exhaust or return to maintain space pressure relationships necessary for occupant health and safety or environmental control shall be permitted to use variable volume fan power limitation.
  2. Individual exhaust fans with motor nameplate horsepower of 1 hp (0.746 kW) or less are exempt from the allowable fan horsepower requirement.

TABLE C403.2.12.1(1)

FAN POWER LIMITATION

LIMITCONSTANT VOLUMEVARIABLE VOLUME
Option 1: Fan system motor nameplate hpAllowable nameplate motor hphp ≤ CFMs • 0.0011hp ≤ CFMs • 0.0015
Option 2: Fan system bhpAllowable fan system bhpbhp ≤ CFMS • 0.00094 + Abhp ≤CFMS • 0.0013 + A

For SI: 1 bhp = 735.5 W, 1 hp = 745.5 W, 1 cfm = 0.4719 L/s.

where:

CFMS=The maximum design supply airflow rate to conditioned spaces served by the system in cubic feet per minute.
hp=The maximum combined motor nameplate horsepower.
Bhp=The maximum combined fan brake horsepower.
A=Sum of [PD × CFMD/4131]

where:

PD=Each applicable pressure drop adjustment from Table C403.2.12.1(2) in. w.c.
CFMD=The design airflow through each applicable device from Table C403.2.12.1(2) in cubic feet per minute.

TABLE C403.2.12.1(2)

FAN POWER LIMITATION PRESSURE DROP ADJUSTMENT

DEVICEADJUSTMENT
Credits
Fully ducted return and/or exhaust air systems0.5 inch w.c. (2.15 in w.c. for laboratory and vivarium systems)
Return and/or exhaust airflow control devices0.5 inch w.c.
Exhaust filters, scrubbers or other exhaust treatmentThe pressure drop of device calculated at fan system design condition
Particulate filtration credit: MERV 9 thru 120.5 inch w.c.
Particulate filtration credit: MERV 13 thru 150.9 inch. w.c.
Particulate filtration credit: MERV 16 and greater and
electronically enhanced filters
Pressure drop calculated at 2x clean filter pressure drop at
fan system design condition.
Carbon and other gas-phase air cleanersClean filter pressure drop at fan system design condition.
Biosafety cabinetPressure drop of device at fan system design condition.
Energy recovery device, other than coil runaround loop(2.2 × energy recovery effectiveness) – 0.5 inch w.c. for each airstream.
Coil runaround loop0.6 inch w.c. for each airstream.
Evaporative humidifier/cooler in series with another
cooling coil
Pressure drop of device at fan system design conditions.
Sound attenuation section (fans serving spaces with design
background noise goals below NC35)
0.15 inch w.c.
Exhaust system serving fume hoods0.35 inch w.c.
Laboratory and vivarium exhaust systems in high-rise buildings0.25 inch w.c./100 feet of vertical duct exceeding 75 feet.
Deductions
Systems without central cooling device- 0.6 in. w.c.
Systems without central heating device- 0.3 in. w.c.
Systems with central electric resistance heat- 0.2 in. w.c.

For SI: 1 inch w.c. = 249 Pa, 1 inch = 25.4 mm.

w.c. = water column, NC = Noise criterion.

C403.2.12.2 Motor nameplate horsepower

For each fan, the fan brake horsepower shall be indicated on the construction documents and the selected motor shall be not larger than the first available motor size greater than the following:

  1. For fans less than 6 bhp (4413 W), 1.5 times the fan brake horsepower.
  2. For fans 6 bhp (4413 W) and larger, 1.3 times the fan brake horsepower.
  3. Systems complying with Section C403.2.12.1fan system motor nameplate hp (Option 1).

C403.2.12.3 Fan efficiency

Fans shall have a fan efficiency grade (FEG) of not less than 67 when determined in accordance with AMCA 205 by an approved, independent testing laboratory and labeled by the manufacturer. The total efficiency of the fan at the design point of operation shall be within 15 percentage points of the maximum total efficiency of the fan.

Exception: The following fans are not required to have a fan efficiency grade:

  1. Fans of 5 hp (3.7 kW) or less as follows:

    1. 1.1. Single fan with a motor nameplate horsepower of 5 hp (3.7 kW) or less, unless Exception 1.2 applies.
    2. 1.2. Multiple fans in series or parallel that have a combined motor nameplate horsepower of 5 hp (3.7 kW) or less and are operated as the functional equivalent of a single fan.
  2. Fans that are part of equipment covered under Section C403.2.3.
  3. Fans included in an equipment package certified by an approved agency for air or energy performance.
  4. Powered wall/roof ventilators.
  5. Fans outside the scope of AMCA 205.
  6. Fans that are intended to operate only during emergency conditions.

C403.2.13 Heating outside a building

Systems installed to provide heat outside a building shall be radiant systems.

Such heating systems shall be controlled by an occupancy sensing device or a timer switch, so that the system is automatically deenergized when no occupants are present.

C403.2.14 Refrigeration equipment performance

Refrigeration equipment shall have an energy use in kWh/day not greater than the values of Tables C403.2.14(1) and C403.2.14(2) when tested and rated in accordance with AHRI Standard 1200. The energy use shall be verified through certification under an approved certification program or, where a certification program does not exist, the energy use shall be supported by data furnished by the equipment manufacturer.

TABLE C403.2.14(1)

MINIMUM EFFICIENCY REQUIREMENTS: COMMERCIAL REFRIGERATION

EQUIPMENT TYPEAPPLICATIONENERGY USE LIMITS
(kWh per day)a
TEST PROCEDURE
Refrigerator with solid doorsHolding Temperature0.10 • V + 2.04AHRI 1200
Refrigerator with transparent doors0.12 • V + 3.34
Freezers with solid doors0.40 • V + 1.38
Freezers with transparent doors0.75 • V + 4.10
Refrigerators/freezers with solid doorsthe greater of 0.12 • V + 3.34 or 0.70
Commercial refrigeratorsPulldown0.126 • V + 3.51
  1. V = volume of the chiller or frozen compartment as defined in AHAM-HRF-1.

TABLE C403.2.14(2)

MINIMUM EFFICIENCY REQUIREMENTS: COMMERCIAL REFRIGERATORS AND FREEZERS

EQUIPMENT TYPEENERGY USE LIMITS
(kWh/day)a, b
TEST
PROCEDURE
Equipment ClasscFamily CodeOperating ModeRating Temperature
VOP.RC.MVertical openRemote condensingMedium0.82 • TDA + 4.07AHRI 1200
SVO.RC.MSemivertical openRemote condensingMedium0.83 • TDA + 3.18
HZO.RC.MHorizontal openRemote condensingMedium0.35 • TDA + 2.88
VOP.RC.LVertical openRemote condensingLow2.27 • TDA + 6.85
HZO.RC.LHorizontal openRemote condensingLow0.57 • TDA + 6.88
VCT.RC.MVertical
transparent door
Remote condensingMedium0.22 TDA + 1.95
VCT.RC.LVertical
transparent door
Remote condensingLow0.56 • TDA + 2.61
SOC.RC.MService over counterRemote condensingMedium0.51 • TDA + 0.11
VOP.SC.MVertical openSelf-containedMedium1.74 • TDA + 4.71
SVO.SC.MSemivertical openSelf-containedMedium1.73 • TDA + 4.59
HZO.SC.MHorizontal openSelf-containedMedium0.77 • TDA + 5.55
HZO.SC.LHorizontal openSelf-containedLow1.92 • TDA + 7.08
VCT.SC.IVertical
transparent door
Self-containedIce cream0.67 • TDA + 3.29
VCS.SC.IVertical solid doorSelf-containedIce cream0.38 • V + 0.88
HCT.SC.IHorizontal
transparent door
Self-containedIce cream0.56 • TDA + 0.43
SVO.RC.LSemivertical openRemote condensingLow2.27 • TDA + 6.85
VOP.RC.IVertical openRemote condensingIce cream2.89 • TDA + 8.7
SVO.RC.ISemivertical openRemote condensingIce cream2.89 • TDA + 8.7
HZO.RC.IHorizontal openRemote condensingIce cream0.72 • TDA + 8.74
VCT.RC.IVertical
transparent door
Remote condensingIce cream0.66 • TDA + 3.05
HCT.RC.MHorizontal
transparent door
Remote condensingMedium0.16 • TDA + 0.13
HCT.RC.LHorizontal
transparent door
Remote condensingLow0.34 • TDA + 0.26
HCT.RC.IHorizontal
transparent door
Remote condensingIce cream0.4 • TDA + 0.31
VCS.RC.MVertical solid doorRemote condensingMedium0.11 • V + 0.26
VCS.RC.LVertical solid doorRemote condensingLow0.23 • V + 0.54
VCS.RC.IVertical solid doorRemote condensingIce cream0.27 • V + 0.63
HCS.RC.MHorizontal solid doorRemote condensingMedium0.11 • V + 0.26
HCS.RC.LHorizontal solid doorRemote condensingLow0.23 • V + 0.54
HCS.RC.IHorizontal solid doorRemote condensingIce cream0.27 • V + 0.63
HCS.RC.IHorizontal solid doorRemote condensingIce cream0.27 • V + 0.63
SOC.RC.LService over counterRemote condensingLow1.08 • TDA + 0.22
SOC.RC.IService over counterRemote condensingIce cream1.26 • TDA + 0.26
VOP.SC.LVertical openSelf-containedLow4.37 • TDA + 11.82
VOP.SC.IVertical openSelf-containedIce cream5.55 • TDA + 15.02
SVO.SC.LSemivertical openSelf-containedLow4.34 • TDA + 11.51
SVO.SC.ISemivertical openSelf-containedIce cream5.52 • TDA + 14.63
HZO.SC.IHorizontal openSelf-containedIce cream2.44 • TDA + 9.0
SOC.SC.IService over counterSelf-containedIce cream1.76 • TDA + 0.36
HCS.SC.IHorizontal solid doorSelf-containedIce cream0.38 • V + 0.88
  1. V = Volume of the case, as measured in accordance with Appendix C of AHRI 1200.
  2. TDA = Total display area of the case, as measured in accordance with Appendix D of AHRI 1200.
  3. Equipment class designations consist of a combination [(in sequential order separated by periods (AAA).(BB).(C))] of:

    (AAA)An equipment family code where:
    VOP=vertical open
    SVO=semivertical open
    HZO=horizontal open
    VCT=vertical transparent doors
    VCS=vertical solid doors
    HCT=horizontal transparent doors
    HCS=horizontal solid doors
    SOC=service over counter
    (BB)An operating mode code:
    RC=remote condensing
    SC=self-contained
    (C)A rating temperature code:
    M=medium temperature (38°F)
    L=low temperature (0°F)
    I=ice-cream temperature (15°F)

    For example, “VOP.RC.M” refers to the “vertical-open, remote-condensing, medium-temperature” equipment class.

C403.2.15 Walk-in coolers, walk-in freezers, refrigerated warehouse coolers and refrigerated warehouse freezers

Refrigerated warehouse coolers and refrigerated warehouse freezers shall comply with this section. Walk-in coolers and walk-in freezers that are not either site assembled or site constructed shall comply with the following:

1. Be equipped with automatic door-closers that firmly close walk-in doors that have been closed to within 1 inch (25 mm) of full closure.

Exception: Automatic closers are not required for doors more than 45 inches (1143 mm) in width or more than 7 feet (2134 mm) in height.

2. Doorways shall have strip doors, curtains, spring-hinged doors or other method of minimizing infiltration when doors are open.

3. Walk-in coolers and refrigerated warehouse coolers shall contain wall, ceiling, and door insulation of not less than R-25 and walk-in freezers and refrigerated warehouse freezers shall contain wall, ceiling and door insulation of not less than R-32.

Exception: Glazed portions of doors or structural members need not be insulated.

4. Walk-in freezers shall contain floor insulation of not less than R-28.

5. Transparent reach-in doors for walk-in freezers and windows in walk-in freezer doors shall be of triple-pane glass, either filled with inert gas or with heat-reflective treated glass.

6. Windows and transparent reach-in doors for walk-in coolers doors shall be of double-pane or triple-pane, inert gas-filled, heat-reflective treated glass.

7. Evaporator fan motors that are less than 1 hp

(0.746 kW) and less than 460 volts shall use electronically commutated motors, brushless direct-current motors, or 3-phase motors.

8. Condenser fan motors that are less than 1 hp

(0.746 kW) shall use electronically commutated motors, permanent split capacitor-type motors or 3-phase motors.

9. Where antisweat heaters without antisweat heater controls are provided, they shall have a total door rail, glass and frame heater power draw of not more than 7.1 W/ft2 (76 W/m2) of door opening for walk-in freezers and 3.0 W/ft2 (32 W/m2) of door opening for walk-in coolers.

10. Where antisweat heater controls are provided, they shall reduce the energy use of the antisweat heater as a function of the relative humidity in the air outside the door or to the condensation on the inner glass pane.

11. Lights in walk-in coolers, walk-in freezers, refrigerated warehouse coolers and refrigerated warehouse freezers shall either use light sources with an efficacy of not less than 40 lumens per watt, including ballast losses, or shall use light sources with an efficacy of not less than 40 lumens per watt, including ballast losses, in conjunction with a device that turns off the lights within 15 minutes when the space is not occupied.

C403.2.16 Walk-in coolers and walk-in freezers

Site-assembled or site-constructed walk-in coolers and walk-in freezers shall comply with the following:

1. Automatic door closers shall be provided that fully close walk-in doors that have been closed to within 1 inch (25 mm) of full closure.

Exception: Closers are not required for doors more than 45 inches (1143 mm) in width or more than 7 feet (2134 mm) in height.

2. Doorways shall be provided with strip doors, curtains, spring-hinged doors or other method of minimizing infiltration when the doors are open.

3. Walls shall be provided with insulation having a thermal resistance of not less than R-25, ceilings shall be provided with insulation having a thermal resistance of not less than R-25 and doors of walk-in coolers and walk-in freezers shall be provided with insulation having a thermal resistance of not less than R-32.

Exception: Insulation is not required for glazed portions of doors or at structural members associated with the walls, ceiling or door frame.

4. The floor of walk-in freezers shall be provided with insulation having a thermal resistance of not less than R-28.

5. Transparent reach-in doors for and windows in opaque walk-in freezer doors shall be provided with triple-pane glass having the interstitial spaces filled with inert gas or provided with heat-reflective treated glass.

6. Transparent reach-in doors for and windows in opaque walk-in cooler doors shall be double-pane heat-reflective treated glass having the interstitial space gas filled.

7. Evaporator fan motors that are less than 1 hp

(0.746 kW) and less than 460 volts shall be electronically commutated motors or 3-phase motors.

8. Condenser fan motors that are less than 1 hp

(0.746 kW) in capacity shall be of the electronically commutated or permanent split capacitor-type or shall be 3-phase motors.

Exception: Fan motors in walk-in coolers and walk-in freezers combined in a single enclosure greater than 3,000 square feet (279 m2) in floor area are exempt.

9. Antisweat heaters that are not provided with anti-sweat heater controls shall have a total door rail, glass and frame heater power draw not greater than 7.1 W/ft2 (76 W/m2) of door opening for walk-in freezers, and not greater than 3.0 W/ft2 (32 W/m2) of door opening for walk-in coolers.

10. Antisweat heater controls shall be capable of reducing the energy use of the antisweat heater as a function of the relative humidity in the air outside the door or to the condensation on the inner glass pane.

11. Light sources shall have an efficacy of not less than 40 lumens per Watt, including any ballast losses, or shall be provided with a device that automatically turns off the lights within 15 minutes of when the walk-in cooler or walk-in freezer was last occupied.

C403.2.17 Refrigerated display cases

Site-assembled or site-constructed refrigerated display cases shall comply with the following:

  1. Lighting and glass doors in refrigerated display cases shall be controlled by one of the following:

    1. 1.1. Time switch controls to turn off lights during nonbusiness hours. Timed overrides for display cases shall turn the lights on for up to 1 hour and shall automatically time out to turn the lights off.
    2. 1.2. Motion sensor controls on each display case section that reduce lighting power by at least 50 percent within 3 minutes after the area within the sensor range is vacated.
  2. Low-temperature display cases shall incorporate temperature-based defrost termination control with a time-limit default. The defrost cycle shall terminate first on an upper temperature limit breach and second upon a time limit breach.
  3. Antisweat heater controls shall reduce the energy use of the antisweat heater as a function of the relative humidity in the air outside the door or to the condensation on the inner glass pane.

C403.3 Economizers (Prescriptive)

Each cooling system shall include either an air or water economizer complying with Sections C403.3.1 through C403.3.4.

Exceptions: Economizers are not required for the systems listed below.

  1. In cooling systems for buildings located in Climate Zones 1A and 1B.
  2. In climate zones other than 1A and 1B, where individual fan cooling units have a capacity of less than 54,000 Btu/h (15.8 kW) and meet one of the following:

    1. 2.1. Have direct expansion cooling coils.
    2. 2.2. The total chilled water system capacity less the capacity of fan units with air economizers is less than the minimum specified in Table C403.3(1).

    The total supply capacity of all fan-cooling units not provided with economizers shall not exceed 20 percent of the total supply capacity of all fan-cooling units in the building or 300,000 Btu/h (88 kW), whichever is greater.

  3. Where more than 25 percent of the air designed to be supplied by the system is to spaces that are designed to be humidified above 35°F (1.7°C) dew-point temperature to satisfy process needs.
  4. Systems that serve residential spaces where the system capacity is less than five times the requirement listed in Table C403.3(1).
  5. Systems expected to operate less than 20 hours per week.
  6. Where the use of outdoor air for cooling will affect supermarket open refrigerated casework systems.
  7. Where the cooling efficiency meets or exceeds the efficiency requirements in Table C403.3(2).
  8. Chilled-water cooling systems that are passive (without a fan) or use induction where the total chilled water system capacity less the capacity of fan units with air economizers is less than the minimum specified in Table C403.3(1).
  9. Systems that include a heat recovery system in accordance with Section C403.4.5.

TABLE C403.3(1)

MINIMUM CHILLED-WATER SYSTEM COOLING CAPACITY FOR DETERMINING ECONOMIZER COOLING REQUIREMENTS

CLIMATE ZONES
(COOLING)
TOTAL CHILLED-WATER SYSTEM CAPACITY LESS CAPACITY OF COOLING UNITS WITH AIR ECONOMIZERS
Local Water-cooled Chilled-water SystemsAir-cooled Chilled-water Systems or District Chilled-Water Systems
1aNo economizer requirementNo economizer requirement
1b, 2a, 2b960,000 Btu/h1,250,000 Btu/h
3a, 3b, 3c, 4a, 4b, 4c720,000 Btu/h940,000 Btu/h
5a, 5b, 5c, 6a, 6b, 7, 81,320,000 Btu/h1,720,000 Btu/h

For SI: 1 British thermal unit per hour = 0.2931 W.

TABLE C403.3(2)

EQUIPMENT EFFICIENCY PERFORMANCE EXCEPTION FOR ECONOMIZERS

CLIMATE
ZONES
COOLING EQUIPMENT PERFORMANCE
IMPROVEMENT (EER OR IPLV)
2B10% efficiency improvement
3B15% efficiency improvement
4B20% efficiency improvement

C403.3.1 Integrated economizer control

Economizer systems shall be integrated with the mechanical cooling system and be capable of providing partial cooling even where additional mechanical cooling is required to provide the remainder of the cooling load. Controls shall not be capable of creating a false load in the mechanical cooling systems by limiting or disabling the economizer or any other means, such as hot gas bypass, except at the lowest stage of mechanical cooling.

Units that include an air economizer shall comply with the following:

  1. Unit controls shall have the mechanical cooling capacity control interlocked with the air economizer controls such that the outdoor air damper is at the 100-percent open position when mechanical cooling is on and the outdoor air damper does not begin to close to prevent coil freezing due to minimum compressor run time until the leaving air temperature is less than 45°F (7°C).
  2. Direct expansion (DX) units that control 75,000 Btu/h (22 kW) or greater of rated capacity of the capacity of the mechanical cooling directly based on occupied space temperature shall have not fewer than two stages of mechanical cooling capacity
  3. Other DX units, including those that control space temperature by modulating the airflow to the space, shall be in accordance with Table C403.3.1.

TABLE C403.3.1

DX COOLING STAGE REQUIREMENTS FOR MODULATING AIRFLOW UNITS

RATING CAPACITYMINIMUM NUMBER
OF MECHANICAL COOLING STAGES
MINIMUM
COMPRESSOR DISPLACEMENTa
≥ 65,000 Btu/h and
< 240,000 Btu/h
3 stages≤ 35% of full load
≥ 240,000 Btu/h4 stages≤ 25% full load

For SI: 1 British thermal unit per hour = 0.2931 W.

  1. For mechanical cooling stage control that does not use variable compressor displacement, the percent displacement shall be equivalent to the mechanical cooling capacity reduction evaluated at the full load rating conditions for the compressor.

C403.3.2 Economizer heating system impact

HVAC system design and economizer controls shall be such that economizer operation does not increase building heating energy use during normal operation.

Exception: Economizers on variable air volume (VAV) systems that cause zone level heating to increase due to a reduction in supply air temperature.

C403.3.3 Air economizers

Air economizers shall comply with Sections C403.3.3.1 through C403.3.3.5.

C403.3.3.1 Design capacity

Air economizer systems shall be capable of modulatingoutdoor air and return air dampers to provide up to 100 percent of the design supply air quantity as outdoor air for cooling.

C403.3.3.2 Control signal

Economizer dampers shall be capable of being sequenced with the mechanical cooling equipment and shall not be controlled by only mixed-air temperature.

Exception: The use of mixed-air temperature limit control shall be permitted for systems controlled from space temperature (such as single-zone systems).

C403.3.3.3 High-limit shutoff

Air economizers shall be capable of automatically reducing outdoor air intake to the design minimum outdoor air quantity when outdoor air intake will no longer reduce cooling energy usage. High-limit shutoff control types for specific climates shall be chosen from Table C403.3.3.3. High-limit shutoff control settings for these control types shall be those specified in Table C403.3.3.3.

TABLE C403.3.3.3

HIGH-LIMIT SHUTOFF CONTROL SETTING FOR AIR ECONOMIZERSb

DEVICE TYPECLIMATE ZONEREQUIRED HIGH LIMIT
(ECONOMIZER OFF WHEN):
EquationDescription
Fixed dry bulb1B, 2B, 3B, 3C, 4B, 4C,
5B, 5C, 6B, 7, 8
TOA > 75°FOutdoor air temperature exceeds 75°F
5A, 6ATOA > 70°FOutdoor air temperature exceeds 70°F
1A, 2A, 3A, 4ATOA > 65°FOutdoor air temperature exceeds 65°F
Differential dry bulb1B, 2B, 3B, 3C, 4B, 4C, 5A,
5B, 5C, 6A, 6B, 7, 8
TOA > TRAOutdoor air temperature exceeds
return air temperature
Fixed enthalpy with fixed
dry-bulb temperatures
AllhOA > 28 Btu/lba or
TOA > 75°F
Outdoor air enthalpy exceeds
28 Btu/lb of dry aira or
Outdoor air temperature exceeds 75°F
Differential enthalpy with
fixed dry-bulb temperature
AllhOA > hRA or
TOA > 75°F
Outdoor air enthalpy exceeds
return air enthalpy or
Outdoor air temperature exceeds 75°F

For SI: 1 foot = 305 mm, °C = (°F - 32)/1.8, 1 Btu/lb = 2.33 kJ/kg.

  1. At altitudes substantially different than sea level, the fixed enthalpy limit shall be set to the enthalpy value at 75°F and 50-percent relative humidity. As an example, at approximately 6,000 feet elevation, the fixed enthalpy limit is approximately 30.7 Btu/lb.
  2. Devices with selectable setpoints shall be capable of being set to within 2°F and 2 Btu/lb of the setpoint listed.

C403.3.3.4 Relief of excess outdoor air

Systems shall be capable of relieving excessoutdoor air during air economizer operation to prevent overpressurizing the building. The relief air outlet shall be located to avoid recirculation into the building.

C403.3.3.5 Economizer dampers

Return, exhaust/relief and outdoor air dampers used in economizers shall comply with Section C403.2.4.3.

C403.3.4 Water-side economizers

Water-side economizers shall comply with Sections C403.3.4.1 and C403.3.4.2.

C403.3.4.1 Design capacity

Water economizer systems shall be capable of cooling supply air by indirect evaporation and providing up to 100 percent of the expected system cooling load at outdoor air temperatures of not greater than 50°F (10°C) dry bulb/45°F (7°C) wet bulb.

Exceptions:

  1. Systems primarily serving computer rooms in which 100 percent of the expected system cooling load at 40°F (4°C) dry bulb/35°F (1.7°C) wet bulb is met with evaporative water economizers.
  2. Systems primarily serving computer rooms with dry cooler water economizers which satisfy 100 percent of the expected system cooling load at 35°F (1.7°C) dry bulb.
  3. Systems where dehumidification requirements cannot be met using outdoor air temperatures of 50°F (10°C) dry bulb/45°F (7°C) wet bulb and where 100 percent of the expected system cooling load at 45°F (7°C) dry bulb/40°F (4°C) wet bulb is met with evaporative water economizers.

C403.3.4.2 Maximum pressure drop

Precooling coils and water-to-water heat exchangers used as part of a water economizer system shall either have a water-side pressure drop of less than 15 feet (45 kPa) of water or a secondary loop shall be created so that the coil or heat exchanger pressure drop is not seen by the circulating pumps when the system is in the normal cooling (noneconomizer) mode.

C403.4 Hydronic and multiple-zone HVAC systems controls and equipment. (Prescriptive)

Hydronic and multiple-zone HVAC system controls and equipment shall comply with this section.

C403.4.1 Fan control

Controls shall be provided for fans in accordance with Sections C403.4.1.1 through C403.4.1.3.

C403.4.1.1 Fan airflow control

Each cooling system listed in Table C403.4.1.1 shall be designed to vary the indoor fan airflow as a function of load and shall comply with the following requirements:

  1. Direct expansion (DX) and chilled water cooling units that control the capacity of the mechanical cooling directly based on space temperature shall have not fewer than two stages of fan control. Low or minimum speed shall not be greater than 66 percent of full speed. At low or minimum speed, the fan system shall draw not more than 40 percent of the fan power at full fan speed. Low or minimum speed shall be used during periods of low cooling load and ventilation-only operation.
  2. Other units including DX cooling units and chilled water units that control the space temperature by modulating the airflow to the space shall have modulating fan control. Minimum speed shall be not greater than 50 percent of full speed. At minimum speed the fan system shall draw not more than 30 percent of the power at full fan speed. Low or minimum speed shall be used during periods of low cooling load and ventilation-only operation.
  3. Units that include an airside economizer in accordance with Section C403.3 shall have not fewer than two speeds of fan control during economizer operation

Exceptions:

  1. Modulating fan control is not required for chilled water and evaporative cooling units with fan motors of less than 1 hp (0.746 kW) where the units are not used to provide ventilation air and the indoor fan cycles with the load.
  2. Where the volume of outdoor air required to comply with the ventilation requirements of the International Mechanical Code at low speed exceeds the air that would be delivered at the speed defined in Section C403.4.1, the minimum speed shall be selected to provide the required ventilation air.

TABLE C403.4.1.1

EFFECTIVE DATES FOR FAN CONTROL

COOLING
SYSTEM TYPE
FAN
MOTOR SIZE
MECHANICAL
COOLING CAPACITY
DX coolingAny≥ 75,000 Btu/h
(before 1/1/2016)
≥ 65,000 Btu/h
(after 1/1/2016)
Chilled water and
evaporative cooling
≥ 5 hpAny
≥ 1/4 hpAny

For SI: 1 British thermal unit per hour = 0.2931 W; 1 hp = 0.746 kW.

C403.4.1.2 Static pressure sensor location

Static pressure sensors used to control VAV fans shall be located such that the controller set point is not greater than 1.2 inches w.c. (299 Pa). Where this results in one or more sensors being located downstream of major duct splits, not less than one sensor shall be located on each major branch to ensure that static pressure can be maintained in each branch.

C403.4.1.3 Set points for direct digital control

For systems with direct digital control of individual zones reporting to the central control panel, the static pressure set point shall be reset based on the zone requiring the most pressure. In such case, the set point is reset lower until one zone damper is nearly wide open. The direct digital controls shall be capable of monitoring zone damper positions or shall have an alternative method of indicating the need for static pressure that is capable of all of the following:

  1. Automatically detecting any zone that excessively drives the reset logic.
  2. Generating an alarm to the system operational location.
  3. Allowing an operator to readily remove one or more zones from the reset algorithm.

C403.4.2 Hydronic systems controls

The heating of fluids that have been previously mechanically cooled and the cooling of fluids that have been previously mechanically heated shall be limited in accordance with Sections C403.4.2.1 through C403.4.2.3. Hydronic heating systems comprised of multiple-packaged boilers and designed to deliver conditioned water or steam into a common distribution system shall include automatic controls capable of sequencing operation of the boilers. Hydronic heating systems comprised of a single boiler and greater than 500,000 Btu/h (146.5 kW) input design capacity shall include either a multistaged or modulating burner.

C403.4.2.1 Three-pipe system

Hydronic systems that use a common return system for both hot water and chilled water are prohibited.

C403.4.2.2 Two-pipe changeover system

Systems that use a common distribution system to supply both heated and chilled water shall be designed to allow a dead band between changeover from one mode to the other of not less than 15°F (8.3°C) outside air temperatures; be designed to and provided with controls that will allow operation in one mode for not less than 4 hours before changing over to the other mode; and be provided with controls that allow heating and cooling supply temperatures at the changeover point to be not more than 30°F (16.7°C) apart.

C403.4.2.3 Hydronic (water loop) heat pump systems

Hydronic heat pump systems shall comply with Sections C403.4.2.3.1 through C403.4.2.3.2.

C403.4.2.3.1 Temperature dead band

Hydronic heat pumps connected to a common heat pump water loop with central devices for heat rejection and heat addition shall have controls that are capable of providing a heat pump water supply temperature dead band of not less than 20°F (11°C) between initiation of heat rejection and heat addition by the central devices.

Exception: Where a system loop temperature optimization controller is installed and can determine the most efficient operating temperature based on realtime conditions of demand and capacity, dead bands of less than 20°F (11°C) shall be permitted.

C403.4.2.3.2 Heat rejection

Heat rejection equipment shall comply with Sections C403.4.2.3.2.1 and C403.4.2.3.2.2.

Exception: Where it can be demonstrated that a heat pump system will be required to reject heat throughout the year.

C403.4.2.3.2.1 Climate zones 3 and 4

For Climate Zones 3 and 4:

  1. Where a closed-circuit cooling tower is used directly in the heat pump loop, either an automatic valve shall be installed to bypass all but a minimal flow of water around the tower, or lower leakage positive closure dampers shall be provided.
  2. Where an open-circuit tower is used directly in the heat pump loop, an automatic valve shall be installed to bypass all heat pump water flow around the tower.
  3. Where an open- or closed-circuit cooling tower is used in conjunction with a separate heat exchanger to isolate the cooling tower from the heat pump loop, then heat loss shall be controlled by shutting down the circulation pump on the cooling tower loop.

C403.4.2.3.2.2 Climate zones 5 through 8

ForClimate Zones 5 through 8, where an open- or closed-circuit cooling tower is used, a separate heat exchanger shall be provided to isolate the cooling tower from the heat pump loop, and heat loss shall be controlled by shutting down the circulation pump on the cooling tower loop and providing an automatic valve to stop the flow of fluid.

C403.4.2.3.3 Two-position valve

Each hydronic heat pump on the hydronic system having a total pump system power exceeding 10 hp (7.5 kW) shall have a two-position valve.

C403.4.2.4 Part-load controls

Hydronic systems greater than or equal to 500,000 Btu/h (146.5 kW) in design output capacity supplying heated or chilled water to comfort conditioning systems shall include controls that have the capability to do all of the following:

1. Automatically reset the supply-water temperatures in response to varying building heating and cooling demand using coil valve position, zone-return water temperature, building-return water temperature or outside air temperature. The temperature shall be capable of being reset by not less than 25 percent of the design supply-to-return water temperature difference.

2. Automatically vary fluid flow for hydronic systems with a combined motor capacity of 10 hp

(7.5 kW) or larger with three or more control valves or other devices by reducing the system design flow rate by not less than 50 percent by designed valves that modulate or step open and close, or pumps that modulate or turn on and off as a function of load.

3. Automatically vary pump flow on chilled-water systems and heat rejection loops serving water-cooled unitary air conditioners with a combined motor capacity of 10 hp (7.5 kW) or larger by reducing pump design flow by not less than 50 percent, utilizing adjustable speed drives on pumps, or multiple-staged pumps where not less than one-half of the total pump horsepower is capable of being automatically turned off. Pump flow shall be controlled to maintain one control valve nearly wide open or to satisfy the minimum differential pressure.

Exceptions:

  1. Supply-water temperature reset for chilled-water systems supplied by off-site district chilled water or chilled water from ice storage systems.
  2. Minimum flow rates other than 50 percent as required by the equipment manufacturer for proper operation of equipment where using flow bypass or end-of-line 3-way valves.
  3. Variable pump flow on dedicated equipment circulation pumps where configured in primary/secondary design to provide the minimum flow requirements of the equipment manufacturer for proper operation of equipment.

C403.4.2.5 Boiler turndown

Boiler systems with design input of greater than 1,000,000 Btu/h (293 kW) shall comply with the turndown ratio specified in Table C403.4.2.5.

The system turndown requirement shall be met through the use of multiple single input boilers, one or more modulating boilers or a combination of single input and modulating boilers.

TABLE C403.4.2.5

BOILER TURNDOWN

BOILER SYSTEM DESIGN INPUT (Btu/h)MINIMUM
TURNDOWN
RATIO
≥ 1,000,000 and less than or equal to 5,000,0003 to 1
> 5,000,000 and less than or equal to 10,000,0004 to 1
> 10,000,0005 to 1

For SI: 1 British thermal unit per hour = 0.2931 W.

C403.4.2.6 Pump isolation

Chilled water plants including more than one chiller shall have the capability to reduce flow automatically through the chiller plant when a chiller is shut down. Chillers piped in series for the purpose of increased temperature differential shall be considered as one chiller.

Boiler plants including more than one boiler shall have the capability to reduce flow automatically through the boiler plant when a boiler is shut down.

C403.4.3 Heat rejection equipment

Each fan powered by a motor of 7.5 hp (5.6 kW) or larger shall have the capability to operate that fan at two-thirds of full speed or less, and shall have controls that automatically change the fan speed to control the leaving fluid temperature or condensing temperature/pressure of the heat rejection device.

Exception: Factory-installed heat rejection devices within HVAC equipment tested and rated in accordance with Tables C403.2.3(6) and C403.2.3(7).

C403.4.3.1 General

Heat rejection equipment such as air-cooled condensers, dry coolers, open-circuit cooling towers, closed-circuit cooling towers and evaporative condensers used for comfort cooling applications shall comply with this section.

Exception: Heat rejection devices where energy usage is included in the equipment efficiency ratings listed in Tables C403.2.3(6) and C403.2.3(7).

C403.4.3.2 Fan speed control

The fan speed shall be controlled as provided in Sections C403.4.3.2.1 and C403.4.3.2.2.

C403.4.3.2.1 Fan motors not less than 7.5 hp

Each fan powered by a motor of 7.5 hp (5.6 kW) or larger shall have the capability to operate that fan at two-thirds of full speed or less, and shall have controls that automatically change the fan speed to control the leaving fluid temperature or condensing temperature/pressure of the heat rejection device.

Exception: The following fan motors over 7.5 hp (5.6 kW) are exempt:

  1. Condenser fans serving multiple refrigerant circuits.
  2. Condenser fans serving flooded condensers.
  3. Installations located in Climate Zones 1 and 2.

C403.4.3.2.2 Multiple-cell heat rejection equipment

Multiple-cell heat rejection equipment with variable speed fan drives shall be controlled in both of the following manners:

  1. To operate the maximum number of fans allowed that comply with the manufacturer’s requirements for all system components.
  2. So all fans can operate at the same fan speed required for the instantaneous cooling duty, as opposed to staged (on/off) operation.

Minimum fan speed shall be the minimum allowable speed of the fan drive system in accordance with the manufacturer’s recommendations.

C403.4.3.3 Limitation on centrifugal fan open-circuit cooling towers

Centrifugal fan open-circuit cooling towers with a combined rated capacity of 1,100 gpm (4164 L/m) or greater at 95°F (35°C) condenser water return, 85°F (29°C) condenser water supply, and 75°F (24°C) outdoor air wet-bulb temperature shall meet the energy efficiency requirement for axial fan open-circuit cooling towers listed in Table C403.2.3(8).

Exception: Centrifugal open-circuit cooling towers that are designed with inlet or discharge ducts or require external sound attenuation.

C403.4.3.4 Tower flow turndown

Open-circuit cooling towers used on water-cooled chiller systems that are configured with multiple- or variable-speed condenser water pumps shall be designed so that all open-circuit cooling tower cells can be run in parallel with the larger of the flow that is produced by the smallest pump at its minimum expected flow rate or at 50 percent of the design flow for the cell.

C403.4.4 Requirements for complex mechanical systems serving multiple zones

Sections C403.4.4.1 through C403.4.6.4 shall apply to complex mechanical systems serving multiple zones. Supply air systems serving multiple zones shall be variable air volume (VAV) systems that, during periods of occupancy, are designed and capable of being controlled to reduce primary air supply to each zone to one of the following before reheating, recooling or mixing takes place:

  1. Thirty percent of the maximum supply air to each zone.
  2. Three hundred cfm (142 L/s) or less where the maximum flow rate is less than 10 percent of the total fan system supply airflow rate.
  3. The minimum ventilation requirements of Chapter 4 of the International Mechanical Code.
  4. Any higher rate that can be demonstrated to reduce overall system annual energy use by offsetting reheat/recool energy losses through a reduction in outdoor air intake for the system, as approved by the code official.
  5. The airflow rate required to comply with applicable codes or accreditation standards, such as pressure relationships or minimum air change rates.

Exception: The following individual zones or entire air distribution systems are exempted from the requirement for VAV control:

  1. Zones or supply air systems where not less than 75 percent of the energy for reheating or for providing warm air in mixing systems is provided from a site-recovered or site-solar energy source.
  2. Zones where special humidity levels are required to satisfy process needs.
  3. Zones with a peak supply air quantity of 300 cfm (142 L/s) or less and where the flow rate is less than 10 percent of the total fan system supply airflow rate.
  4. Zones where the volume of air to be reheated, recooled or mixed is not greater than the volume of outside air required to provide the minimum ventilation requirements of Chapter 4 of the International Mechanical Code.
  5. Zones or supply air systems with thermostatic and humidistatic controls capable of operating in sequence the supply of heating and cooling energy to the zones and which are capable of preventing reheating, recooling, mixing or simultaneous supply of air that has been previously cooled, either mechanically or through the use of economizer systems, and air that has been previously mechanically heated.

C403.4.4.1 Single-duct VAV systems, terminal devices

Single-duct VAV systems shall use terminal devices capable of reducing the supply of primary supply air before reheating or recooling takes place.

C403.4.4.2 Dual-duct and mixing VAV systems, terminal devices

Systems that have one warm air duct and one cool air duct shall use terminal devices that are capable of reducing the flow from one duct to a minimum before mixing of air from the other duct takes place.

C403.4.4.3 Single-fan dual-duct and mixing VAV systems, economizers

Individual dual-duct or mixing heating and cooling systems with a single fan and with total capacities greater than 90,000 Btu/h [(26.4 kW) 7.5 tons] shall not be equipped with air economizers.

C403.4.4.4 Fractional hp fan motors

Motors for fans that are not less than 1/12 hp (0.082 kW) and less than 1 hp (0.746 kW) shall be electronically commutated motors or shall have a minimum motor efficiency of 70 percent, rated in accordance with DOE 10 CFR 431. These motors shall also have the means to adjust motor speed for either balancing or remote control. The use of belt-driven fans to sheave adjustments for airflow balancing instead of a varying motor speed shall be permitted.

Exceptions: The following motors are not required to comply with this section:

  1. Motors in the airstream within fan coils and terminal units that only provide heating to the space served.
  2. Motors in space-conditioning equipment that comply with Section 403.2.3 or C403.2.12.
  3. Motors that comply with Section C405.8.

C403.4.4.5 Supply-air temperature reset controls

Multiple-zone HVAC systems shall include controls that automatically reset the supply-air temperature in response to representative building loads, or to outdoor air temperature. The controls shall be capable of resetting the supply air temperature not less than 25 percent of the difference between the design supply-air temperature and the design room air temperature.

Exceptions:

  1. Systems that prevent reheating, recooling or mixing of heated and cooled supply air.
  2. Seventy-five percent of the energy for reheating is from site-recovered or site-solar energy sources.
  3. Zones with peak supply air quantities of 300 cfm (142 L/s) or less.

C403.4.4.6 Multiple-zone VAV system ventilation optimization control

Multiple-zone VAV systems with direct digital control of individual zone boxes reporting to a central control panel shall have automatic controls configured to reduce outdoor air intake flow below design rates in response to changes in system ventilation efficiency (Ev) as defined by the International Mechanical Code.

Exceptions:

  1. VAV systems with zonal transfer fans that recirculate air from other zones without directly mixing it with outdoor air, dual-duct dual-fan VAV systems, and VAV systems with fan-powered terminal units.
  2. Systems having exhaust air energy recovery complying with Section C403.2.7.
  3. Systems where total design exhaust airflow is more than 70 percent of total design outdoor air intake flow requirements.

C403.4.5 Heat recovery for service water heating

Condenser heat recovery shall be installed for heating or reheating of service hot water provided that the facility operates 24 hours a day, the total installed heat capacity of water-cooled systems exceeds 6,000,000 Btu/hr (1 758 kW) of heat rejection, and the design service water heating load exceeds 1,000,000 Btu/h (293 kW).

The required heat recovery system shall have the capacity to provide the smaller of the following:

  1. Sixty percent of the peak heat rejection load at design conditions.
  2. The preheating required to raise the peak service hot water draw to 85°F (29°C).

Exceptions:

  1. Facilities that employ condenser heat recovery for space heating or reheat purposes with a heat recovery design exceeding 30 percent of the peak water-cooled condenser load at design conditions.
  2. Facilities that provide 60 percent of their service water heating from site solar or site recovered energy or from other sources.

C403.4.6 Hot gas bypass limitation

Cooling systems shall not use hot gas bypass or other evaporator pressure control systems unless the system is designed with multiple steps of unloading or continuous capacity modulation. The capacity of the hot gas bypass shall be limited as indicated in Table C403.4.6, as limited by Section C403.3.1.

TABLE C403.4.6

MAXIMUM HOT GAS BYPASS CAPACITY

RATED CAPACITYMAXIMUM HOT GAS BYPASS CAPACITY
(% of total capacity)
≤ 240,000 Btu/h50
> 240,000 Btu/h25

For SI: 1 British thermal unit per hour = 0.2931 W.

C403.5 Refrigeration systems

Refrigerated display cases, walk-in coolers or walk-in freezers that are served by remote compressors and remote condensers not located in a condensing unit, shall comply with Sections C403.5.1 and C403.5.2.

Exception: Systems where the working fluid in the refrigeration cycle goes through both subcritical and supercritical states (transcritical) or that use ammonia refrigerant are exempt.

C403.5.1 Condensers serving refrigeration systems

Fan-powered condensers shall comply with the following:

  1. The design saturated condensing temperatures for air-cooled condensers shall not exceed the design dry-bulb temperature plus 10°F (5.6°C) for low-temperature refrigeration systems, and the design dry-bulb temperature plus 15°F (8°C) for medium temperature refrigeration systems where the saturated condensing temperature for blend refrigerants shall be determined using the average of liquid and vapor temperatures as converted from the condenser drain pressure.
  2. Condenser fan motors that are less than 1 hp (0.75 kW) shall use electronically commutated motors, permanent split-capacitor-type motors or 3-phase motors.
  3. Condenser fans for air-cooled condensers, evaporatively cooled condensers, air- or water-cooled fluid coolers or cooling towers shall reduce fan motor demand to not more than 30 percent of design wattage at 50 percent of design air volume, and incorporate one of the following continuous variable speed fan control approaches:

    1. 3.1. Refrigeration system condenser control for air-cooled condensers shall use variable setpoint control logic to reset the condensing temperature setpoint in response to ambient dry-bulb temperature.
    2. 3.2. Refrigeration system condenser control for evaporatively cooled condensers shall use variable setpoint control logic to reset the condensing temperature setpoint in response to ambient wet-bulb temperature.
  4. Multiple fan condensers shall be controlled in unison.
  5. The minimum condensing temperature setpoint shall be not greater than 70°F (21°C).

C403.5.2 Compressor systems

Refrigeration compressor systems shall comply with the following:

  1. Compressors and multiple-compressor system suction groups shall include control systems that use floating suction pressure control logic to reset the target suction pressure temperature based on the temperature requirements of the attached refrigeration display cases or walk-ins.

    Exception: Controls are not required for the following:

    1. Single-compressor systems that do not have variable capacity capability.
    2. Suction groups that have a design saturated suction temperature of 30°F (-1.1°C) or higher, suction groups that comprise the high stage of a two-stage or cascade system, or suction groups that primarily serve chillers for secondary cooling fluids.
  2. Liquid subcooling shall be provided for all low-temperature compressor systems with a design cooling capacity equal to or greater than 100,000 Btu/hr (29.3 kW) with a design-saturated suction temperature of -10°F (-23°C) or lower. The sub-cooled liquid temperature shall be controlled at a maximum temperature setpoint of 50°F (10°C) at the exit of the subcooler using either compressor economizer (interstage) ports or a separate compressor suction group operating at a saturated suction temperature of 18°F (-7.8°C) or higher.

    1. 2.1. Insulation for liquid lines with a fluid operating temperature less than 60°F (15.6°C) shall comply with Table C403.2.10.
  3. Compressors that incorporate internal or external crankcase heaters shall provide a means to cycle the heaters off during compressor operation.
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