TPRV Discharge Tube
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Discharge Tube The pipe itself must be made of a material that is rated for both high temperature and pressure, which includes most rigid wall copper or iron. Also, the size of the pipe must match the opening size of the TPR valve discharge (usually ¾ inch). The drain/drip tube must extend to within 6" to 12" of a flush type floor drain. With bowl type floor drains the drain/drip tube can over hang the side of the floor drain. An air gap must be maintained between the end of the drain/drip line and the floor drain to prevent backflow. Thus, any hot water escaping from the TPR relief valve will be directed safely into the floor drain. |
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If the discharge tube is routed to the exterior, the pipe must discharge 6 to 24 inches from grade, with a downward slope to prevent the pipe from clogging or forming a trap. Blocked discharge tubes will prevent the superheated water from discharging and will burst. Though counterintuitive, it is often recommended that the discharge tube terminate next to the water heater so that any malfunction of the water heater will be more readily noticed.