The service water heating system for single-
family houses, multi-family structures of three stories or
fewer above grade, and modular houses shall comply with
Section L502.2 through Section L502.7.3. The service water
heating system of all other buildings shall comply with Section
L503.0.
Residential-type
water heaters, pool heaters, and unfired water heater storage
tanks shall comply with the minimum performance
requirements specified by federal law.
Unfired storage water heating equipment shall have a heat loss through the tank surface area of less than 6.5 British thermal units per square foot hour [Btu/(ft2•h)] (20.5 W/m2). (ASHRAE 90.2:7.1]
Unfired storage water heating equipment shall have a heat loss through the tank surface area of less than 6.5 British thermal units per square foot hour [Btu/(ft2•h)] (20.5 W/m2). (ASHRAE 90.2:7.1]
Recirculation systems
shall comply with the provisions of Section L501.3.
Service
water heating equipment (central systems) that do not fall
under the requirements for residential-type service water heating
equipment addressed in Section L502.0 shall comply
with the applicable requirements for service water-heating
equipment found in Section L503.0. [ASHRAE 90.2:7.3]
Insulation for hot water and return piping
shall comply with the provisions of Section L501.2.
Where water has hardness equal to or
exceeding 9 grains per gallon (gr/gal) (154 mg/L) measured as
total calcium carbonate equivalents, the water supply line to
water heating equipment in new one- and two-family dwellings
shall be roughed-in to allow for the installation of water treatment equipment.
The maximum
volume of water contained in hot water distribution pipes shall
be in accordance with Section L502.7.1 or Section L502.7.2.
The water volume shall be calculated using Table L502.7.
For SI units: 1 ounce = 29.573 mL
* NA: Not Applicable
| OUNCES OF WATER PER FOOT LENGTH OF PIPING | |||||||||||||
| NOMINAL SIZE (inch) |
COPPER M |
COPPER L |
COPPER K |
CPVC CTS SDR 11 |
CPVC SCH 40 |
PEX-AL- PEX |
PE-AL-PE | CPVC SCH 80 |
PEX CTS SDR 9 |
PE-RT SDR 9 |
PP SDR 6 | PP SDR 7.3 |
PP SDR 11 |
| 3/8 | 1.06 | 0.97 | 0.84 | NA | 1.17 | 0.63 | 0.63 | NA | 0.64 | 0.64 | 0.91 | 1.09 | 1.24 |
| 1/2 | 1.69 | 1.55 | 1.45 | 1.25 | 1.89 | 1.31 | 1.31 | 1.46 | 1.18 | 1.18 | 1.41 | 1.68 | 2.12 |
| 3/4 | 3.43 | 3.22 | 2.90 | 2.67 | 3.38 | 3.39 | 3.39 | 2.74 | 2.35 | 2.35 | 2.23 | 2.62 | 3.37 |
| 1 | 5.81 | 5.49 | 5.17 | 4.43 | 5.53 | 5.56 | 5.56 | 4.57 | 3.91 | 3.91 | 3.64 | 4.36 | 5.56 |
| 11/4 | 8.70 | 8.36 | 8.09 | 6.61 | 9.66 | 8.49 | 8.49 | 8.24 | 5.81 | 5.81 | 5.73 | 6.81 | 8.60 |
| 11/2 | 12.18 | 11.83 | 11.45 | 9.22 | 13.20 | 13.88 | 13.88 | 11.38 | 8.09 | 8.09 | 9.03 | 10.61 | 13.47 |
| 2 | 21.08 | 20.58 | 20.04 | 15.79 | 21.88 | 21.48 | 21.48 | 19.11 | 13.86 | 13.86 | 14.28 | 16.98 | 21.39 |
* NA: Not Applicable
The maximum volume
of water contained in hot water distribution pipe between
the water heater and any fixture fitting shall not exceed
32 ounces (oz) (946 mL). Where a fixture fitting shutoff
valve (supply stop) is installed ahead of the fixture fitting,
the maximum volume of water is permitted to be
calculated between the water heater and the fitting shutoff
valve (supply stop).
The maximum volume
of water contained in the branches between the recirculation
loop or electrically heat traced pipe, and the fixture
fitting shall not exceed 16 oz (473 mL). Where a fixture
fitting shutoff valve (supply stop) is installed ahead of
the fixture fitting, the maximum volume of water is permitted
to be calculated between the recirculation loop or
electrically, heat traced pipe and the fixture fitting shutoff
valve (supply stop).
Exception: Whirlpool bathtubs or bathtubs that are not
equipped with a shower are exempted from the requirements
of Section L502.7.
Where a hot water pipe from a circulation loop or electric heat
trace line is equipped with a submeter, the hot water distribution
system downstream of the submeter shall have
either an end-of-line hot water circulation pump or shall
be electrically heat traced. The maximum volume of
water in a branch from the circulation loop or electric
heat trace line downstream of the submeter shall not
exceed 16 oz (473 mL).
Where there is no circulation loop or electric heat traced line downstream of the submeter, the submeter shall be located within 2 feet (610 mm) of the central hot water system; or the branch line to the submeter shall be circulated or heat traced to within 2 feet (610 mm) of the submeter. The maximum volume from the submeter to each fixture shall not exceed 32 oz (946 mL).
The circulation pump controls shall comply with the provisions of Section L501.4.
Where there is no circulation loop or electric heat traced line downstream of the submeter, the submeter shall be located within 2 feet (610 mm) of the central hot water system; or the branch line to the submeter shall be circulated or heat traced to within 2 feet (610 mm) of the submeter. The maximum volume from the submeter to each fixture shall not exceed 32 oz (946 mL).
The circulation pump controls shall comply with the provisions of Section L501.4.