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.
- Not be directly connected to the drainage system.
- Discharge through an air gap located in the same room as the water heater.
- Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air gap.
- Serve a single relief device and shall not connect to piping serving any other relief device or equipment.
- Discharge to the floor, to the pan serving the water heater or storage tank, to a waste receptor or to the outdoors.
- Discharge in a manner that does not cause personal injury or structural damage.
- Discharge to a termination point that is readily observable by the building occupants.
- Not be trapped.
- Be installed so as to flow by gravity.
- Terminate not more than 6 inches (152 mm) above and not less than two times the discharge pipe diameter above the floor or flood level rim of the waste receptor.
- Not have a threaded connection at the end of such piping.
- Not have valves or tee fittings.
- Be constructed of those materials listed in Section 605.4 or materials tested, rated and approved for such use in accordance with ASME A112.4.1.
- Be one nominal size larger than the size of the relief valve outlet, where the relief valve discharge piping is installed with insert fittings. The outlet end of such tubing shall be fastened in place.
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:
- Galvanized steel or aluminum of not less than 0.0236 inch (0.6010 mm) in thickness.
- Plastic not less than 0.036 inch (0.9 mm) in thickness.
- Other approved materials.
A plastic pan shall not be installed beneath a gas-fired water heater.
Unless the pan is constructed of material having a flame spread index of 25 or less and a smoke-developed index of 450 or less when tested in accordance with ASTM E84 or UL 723.