To read more about it, see our blog post What is an indirect waste receptor?Ģ) The pipe should not be smaller than the outlet of the valve and must run full-size (no reductions) to the termination.ģ) Each TPR valve must have its own discharge piping, not shared with any other devices or equipment. In the example below, an upper pressure relief valve drain (not visible behind vent connector) has been tied into the drain for the lower one.Ĥ) Termination of the discharge piping can be to any of the following: The photo below shows TPR and catch pan drains that dump into a laundry sink without necessary minimum 1-inch air gap above rim of sink. An air gap eliminates the possibility of backflow from the drain into the discharge piping. And, unfortunately, we have an abundance of examples of how not to do it.ġ) The discharge pipe cannot be directly connected to the home’s plumbing drainage system, but an air gap located in the same room as the water heater can used to connect to the drainage system. So, both the International Residential Code (IRC) and the Residential Edition of the Florida Building Code (FBC P2804.6.1) have the following requirements to make sure that there are no obstructions or the possiblity of injury from the scalding water if the valve opens. Super-hot and high-pressure water gets released to keep the tank from exploding like a bomb. Temperature-Pressure Relief (TPR) valves rarely go off but, if one does, it’s a big deal.

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