18-29-504.6 Relief valve approval.

   Temperature and pressure relief valves (or combinations thereof) and energy cutoff devices shall bear the label of an approved agency and shall have a temperature setting of not more than 200°F (93.3°C) and a pressure setting not exceeding the tank or water heater manufacturer's rated working pressure. Where a pressure rating of more than 150 psi (1034.25 kPa) is not necessary for the proper function of the domestic hot water system, the pressure rating of the relief valve shall be limited to 150 psi (1034.25 kPa). The relieving capacity of each pressure relief valve and each temperature relief valve shall equal or exceed the heat input to the water heater or storage tank, and shall have the AGA steam temperature rating clearly indicated.

18-29-504.7 Relief outlet waste.

   The outlet of a pressure, temperature or other relief valve shall not be directly connected to the drainage system.

(Amend Coun. J. 11-9-16, p. 36266, § 37)

18-29-504.7.1 Discharge.

   The discharge from the relief valve shall be piped separately to an indirect waste receptor located inside the building. The discharge shall be piped full size and installed in a manner that does not cause personal injury or property damage and that is readily observable by the building occupants. The discharge from a relief valve shall not be trapped. The diameter of the discharge piping shall not be less than the diameter of the relief valve outlet. The discharge pipe shall be installed so as to drain by gravity flow and shall terminate atmospherically not more than 6 inches (150 mm) above the floor. The end of the discharge pipe shall not be threaded.

18-29-504.7.2 Location.

   The relief outlet discharge piping shall be installed so that it does not leave the room or enclosure in which the water heater and relief valve are located.

18-29-504.7.3 Materials.

   Relief valve discharge piping shall be of those materials listed in Section 18-29-605.5 for water distribution piping or shall be tested, rated and approved for such use in accordance with ASME A112.4.1. Piping from safety pan drains shall be of those materials listed in Table 18-29-605.5.

18-29-504.8 Required pan.

   Where a storage-tank type water heater or a hot water storage tank is installed in a location where water leakage from the tank will cause damage, the tank shall be installed in a pan constructed of one of the following:

   1.   Galvanized steel or aluminum of not less than 0.0236 inch (0.6010 mm) in thickness.

   2.   Plastic not less than 0.036 inch (0.9 mm) in thickness. (A plastic pan shall not be installed beneath a gas-fired water heater.)

(Amend Coun. J. 3-27-02, p. 82090, § 3; Amend Coun. J. 10-14-21, p. 37722, Art. V, § 4)

18-29-504.8.1 Pan size and drain.

   The pan shall not be less than 1 1/2 inches (38 mm) deep and shall be of sufficient size and shape to receive all dripping or condensate from the tank or water heater. The pan shall be drained by an indirect waste pipe having a minimum diameter of 3/4 inch (19 mm) or the outlet diameter of the required relief valve, whichever is larger.

(Amend Coun. J. 10-14-21, p. 37722, Art. V, § 4)

18-29-504.8.2 Pan drain termination.

   The pan drain shall extend full-size and terminate over a suitably located indirect waste receptor or floor drain. Where a pan drain was not previously installed, a pan drain shall not be required for a replacement water heater installation.

(Amend Coun. J. 10-14-21, p. 37722, Art. V, § 4)

18-29-505 Insulation.

18-29-505.1 Unfired vessel insulation.

   Unfired hot water storage tanks shall be insulated to R-12.5 (h × ft 2 × °F) / Btu (R-2.2 m 2 × K/W).

(Amend Coun. J. 10-14-21, p. 37722, Art. V, § 5)