§434.404. Building service systems and equipment.

404.1.2 Unfired Storage Tanks. The heat loss of the tank surface area Btu/(h·ft 2) shall be based on an 80 °F water-air temperature difference.

404.1.3 Storage Volume Symbols in Table 404.1. The symbol “V” is the rated storage volume in gallons as specified by the manufacturer. The symbol “VT” is the storage volume in gallons as measured during the test to determine the standby loss. VT may differ from V, but it is within tolerances allowed by the applicable Z21 and Underwriters Laboratories standards. Accordingly, for the purpose of estimating the standby loss requirement using the rated volume shown on the rating plate, VT should be considered as no less than 0.95V for gas and oil water heaters and no less than 0.90V for electric water heaters.

404.1.4 Electric Water Heaters. In applications where water temperatures not greater than 145 °F are required, an economic evaluation shall be made on the potential benefit of using an electric heat pump water heater(s) instead of an electric resistance water heater(s). The analysis shall compare the extra installed costs of the heat pump unit with the benefits in reduced energy costs (less increased maintenance costs) over the estimated service life of the heat pump water heater. Exceptions are as follows: Electric water heaters used in conjunction with site-recovered or site-solar energy sources that provide 50% or more of the water heating load or off-peak heating with thermal storage.

404.2 Service Hot Water Piping Insulation. Circulating system piping and noncirculating systems without heat traps, the first eight feet of outlet piping from a constant-temperature noncirculating storage system, and the inlet pipe between the storage tank and a heat trap in a noncirculating storage system shall meet the provisions of subsection 403.2.9.

404.2.1 Vertical risers serving storage water heaters not having an integral heat trap and serving a noncirculating system shall have heat traps on both the inlet and outlet piping as close as practical to the water heater.

404.3 Service Water Heating System Controls. Temperature controls that allow for storage temperature adjustment from 110 °F to a temperature compatible with the intended use shall be provided in systems serving residential dwelling units and from 90 °F for other systems. When designed to maintain usage temperatures in hot water pipes, such as circulating hot water systems or heat trace, the system shall be equipped with automatic time switches or other controls that can be set to turn off the system.

404.3.1 The outlet temperature of lavatory faucets in public facility restrooms shall be limited to 110 °F.

404.4 Water Conservation. Showerheads and lavatory faucets must meet the requirements of 10 CFR 430.32 (o)-(p).

404.4.1 Lavatory faucets in public facility restrooms shall be equipped with a foot switch, occupancy sensor, or similar device or, in other than lavatories for physically handicapped persons, limit water delivery to 0.25 gal/cycle.

404.5 Swimming Pools. All pool heaters shall be equipped with a readily accessible on-off switch.

404.5.1 Time switches shall be installed on electric heaters and pumps. Exceptions are as follows:

404.5.2 Heated swimming pools shall be equipped with pool covers. Exception: When over 70% of the annual energy for heating is obtained from a site-recovered or site-solar energy source.

404.6 Combined Service Water Heating and Space Heating Equipment. A single piece of equipment shall not be used to provide both space heating and service water heating. Exceptions are as follows: