Exception: When the service water heating to an addition is provided by existing service water heating systems and equipment, such systems and equipment shall not be required to comply with this standard. However, any new systems or equipment installed must comply with specific requirements applicable to those systems and equipment.
Exception: Compliance shall not be required where there is insufficient space or access to meet these requirements.
- Recirculating system piping, including the supply and return piping of a circulating tank type water heater
- The first 8 ft of outlet piping for a constant temperature nonrecirculating storage system
- The inlet piping between the storage tank and a heat trap in a nonrecirculating storage system
- Piping that is externally heated (such as heat trace or impedance heating)
- The single space-heating boiler, or the component of a modular or multiple boiler system that is heating the service water, has a standby loss in Btu/h not exceeding
(13.3 × pmd + 400)/n
where pmd is the probable maximum demand in gal/h determined in accordance with the procedures described in generally accepted engineering standards and handbooks, and n is the fraction of the year when the outdoor daily mean temperature is greater than 64.9°F.
The standby loss is to be determined for a test period of 24 hours duration while maintaining a boiler water temperature of at least 90°F above ambient, with an ambient temperature between 60°F and 90°F. For a boiler with a modulating burner, this test shall be conducted at the lowest input.
- It is demonstrated to the satisfaction of the authority having jurisdiction that the use of a single heat source will consume less energy than separate units.
- The energy input of the combined boiler and water heater system is less than 150,000 Btu/h.
The requirements of Section 7.5.3 are effective on July 30, 2015.
|Equipment Type||Size Category (Input)||Subcategory or Rating Condition||Performance Requireda||Test Procedureb,c|
|Electric table-top water heaters||≤12 kW||Resistance ≥20 gal||0.93—0.00035V EF||DOE 10 CFR Part 430|
|Electric water heaters||≤12 kW||Resistance ≥20 gal||0.97—0.00035V EF||DOE 10 CFR Part 430|
|>12 kWe||Resistance ≥20 gal||0.3 + 27/Vm %/h||Section G.2 of ANSI Z21.10.3|
|≤24 Amps and ≤250 Volts||Heat Pump||0.93—0.00035V EF||DOE 10 CFR Part 430|
|Gas storage water heaters||≤75,000 Btu/h||≥20 gal||0.67—0.0005V EF||DOE 10 CFR Part 430|
|>75,000 Btu/hf||<4000 (Btu/h)/gal||80% Et (Q/800 + 110√V) SL, Btu/h||Sections G.1 and G.2 of ANSI Z21.10.3|
|Gas instantaneous water heaters||>50,000 Btu/h and <200,000 Btu/h||≥4000 (Btu/h)/gal and <2 gal||0.62—0.0005V EF||DOE 10 CFR Part 430|
|≥200,000 Btu/hd, f
||≥4000 (Btu/h)/gal and <10 gal||80% Et||Sections G.1 and G.2 of ANSI Z21.10.3|
|≥200,000 Btu/hf||≥4000 (Btu/h)/gal and ≥10 gal||80% Et (Q/800 + 110√V) SL, Btu/h|
|Oil storage water heaters||≤105,000 Btu/h||≥20 gal||0.59—0.0005V EF||DOE 10 CFR Part 430|
|>105,000 Btu/h||<4000 (Btu/h)/gal||80% Et (Q/800 + 110√V) SL, Btu/h||Sections G.1 and G.2 of ANSI Z21.10.3|
|Oil instantaneous water heaters||≤210,000 Btu/h||≥4000 (Btu/h)/gal and <2 gal||0.59—0.0005V EF||DOE 10 CFR Part 430|
|>210,000 Btu/h||≥4000 (Btu/h)/gal and <10 gal||80% Et||Sections G.1 and G.2 of ANSI Z21.10.3|
|>210,000 Btu/h||≥4000 (Btu/h)/gal and ≥10 gal||78% Et (Q/800 + 110√V) SL, Btu/h|
|Hot-water supply boilers, gas and oilf||≥300,000 Btu/h and <12,500,000 Btu/h||≥4000 (Btu/h)/gal and <10 gal||80% Et||Sections G.1 and G.2 of ANSI Z21.10.3|
|Hot-water supply boilers, gasf||≥4000 (Btu/h)/gal and ≥10 gal||80% Et (Q/800 + 110√V) SL, Btu/h|
|Hot-water supply boilers, oil||≥4000 (Btu/h)/gal and ≥10 gal||78% Et (Q/800 + 110√V) SL, Btu/h|
|Pool heaters, oil and gas||All||78% Et||ASHRAE 146|
|Heat-pump pool heaters||All||4.0 COP||ASHRAE 146|
|Unfired storage tanks||All||R-12.5||(none)|
- Energy factor (EF) and thermal efficiency (Et) are minimum requirements, while standby loss (SL) is maximum Btu/h based on a 70°F temperature difference between stored water and ambient requirements. In the EF equation, V is the rated volume in gallons. In the SL equation, V is the rated volume in gallons and Q is the nameplate input rate in Btu/h. Vm is the measured volume in the tank
- Section 12 contains a complete specification, including the year version, of the referenced test procedure.
- Section G.1 is titled "Test Method for Measuring Thermal Efficiency" and Section G.2 is titled "Test Method for Measuring Standby Loss."
- Instantaneous water heaters with input rates below 200,000 Btu/h must comply with these requirements if the water heater is designed to heat water to temperatures of 180°F or higher.
- Electric water heaters with input rates below 12 kW must comply with these requirements if the water heater is designed to heat water to temperatures of 180°F or higher.
- Refer to Section 7.5.3 for additional requirements for gas storage and instantaneous water heaters and gas hot water supply boilers.