§ 18-29-501.1 Scope.
The provisions of this article shall govern the materials, design and installation of water heaters and the related safety devices and appurtenances.
§ 18-29-501.2 Deliberately omitted.
§ 18-29-501.3 Drain valves.
Each heated water storage tank shall be provided with a sludge drain pipe which shall be connected at the lowest level of the bottom section of the tank. This drain shall be provided with a control valve with a clear waterway equal to the area of the sludge drain pipe, and shall discharge through an indirect connection into the drainage system of the building. Drain valves shall conform to ASSE 1005.
§ 18-29-501.4 Location for access.
Water heaters and storage tanks shall be located and connected so as to provide access for observation, maintenance, servicing and replacement.
§ 18-29-501.5 Water heater labeling.
All water heaters shall bear the label of an approved agency. Listing by Underwriters Laboratories, American Gas Association (AGA), National Board of Boiler and Pressure Vessel Inspectors, or the ASME Standard to which it was constructed, shall constitute evidence of conformance with these standards.
§ 18-29-501.6 Tankless water heaters.
The temperature of water from tankless water heaters shall be a maximum of 140F (60C) when intended for domestic uses. This provision shall not supersede the requirement for protective shower valves in accordance with Section § 18-29-424.4.
§ 18-29-501.6.1 Coils.
Indirect, external, tankless or submerged coils used in heating water shall be equipped with a thermostatic mixing valve or valves when not connected to a storage tank. A pressure relief valve or expansion tank shall be installed on the cold water inlet to the heater. A temperature and pressure relief valve shall be installed on the tempered line with the temperature sensing element immersed in the tempered water pipe as close as possible to the mixing valve.
§ 18-29-501.7 Pressure marking of storage tanks.
Storage tanks and water heaters installed for domestic hot water shall have the maximum allowable working pressure clearly and indelibly stamped in the metal or marked on a plate welded thereto or otherwise permanently attached. Such markings shall be in an accessible position outside of the tank so as to make inspection or reinspection readily possible.
Water heaters of 200,000 BTU input per hour or more and storage tanks of 120 gallons (454 L) capacity or more shall be constructed in accordance with ASME Boiler and Pressure Vessel Code, Section IV.
§ 18-29-501.8 Temperature controls.
All hot water supply systems shall be equipped with automatic temperature controls capable of adjustments from the lowest to the highest acceptable temperature settings for the intended temperature operating range. Multiple temperature hot water supply systems shall be provided with thermostatic mixing valves to control the desired temperatures.
§ 18-29-501.8.1 Instantaneous water heaters.
Direct fired instantaneous water heaters shall be equipped with a thermostatic mixing valve or valves. A pressure relief valve shall be installed on or adjacent to the heater. A temperature and pressure relief valve shall be installed on the tempered line with the temperature sensing element immersed in the tempered water pipe as close as possible to the mixing valve.
§ 18-29-501.9 Heat exchangers.
Heat exchangers using a toxic transfer fluid or having conditioning chemicals in the system shall be separated from the potable water by double wall construction. There shall be an air gap open to the atmosphere between the two walls. No heat exchanger will be permitted on any boiler system operating in excess of 65 psi (448.2 kPa), or high temperature hot water system operating in excess of 250F (121C), or any steam boiler operating with a pressure in excess of 50 psi (344.75 kPa), unless:
The heat exchanger is double-walled;
The heat exchanger has an air gap open to the atmosphere between the two walls; and
The heat exchanger has a pressure gradient monitor system with a fail-safe to off switch installed to isolate the heat exchanger from the potable cold or hot water system. If pressure on the potable water side reaches less than 20 psi (137.9 kPa) above the pressure of the transfer fluid or steam, and a pressure reducing valve is installed on the inlet to the heat exchanger with a setting of 20 psi (137.9 kPa) lower than the potable water pressure at the heat exchanger, an audible alarm shall be activated and the heat exchanger shall be automatically shut off until the alarm and the heat exchanger can be reset manually. Any boiler using toxic chemicals shall have a label with a minimum size of 5 inches by 5 inches (125 mm by 125 mm) attached to the boiler in a conspicuous place. The label shall read as follows:
Chemicals and additives used to treat the boiler feed water in this boiler are not approved for potable water. The steam or hot water produced by this boiler is not potable. If the steam or hot water produced by this boiler is used to heat water, the water will not be considered potable if the steam and potable water are mixed.