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TPRV - max number of turns

Mike Lamb

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I thought the, "no more than four 90 degree turns," on a TPRV discharge pipe was a code requirement but apparently not.  That said,  I cannot find the verse from Watts that goes with this remark from the ASHI reporter.  Any help?

The discharge piping should not be reduced either by fittings, kinks or in any other way. Watts® Regulator Company, a maker of numerous water safety devices, states that discharge piping in excess of 30 feet or the use of more than four 90° elbows will reduce the discharge capacity. 

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This is one rare circumstance where the ASHI Reporter article is correct.  

With Watts, it's easy. They print that information, almost verbatim, on the little yellow tag attached to every TPR valve. I usually just snap a picture of it. 

With Cash Acme, it's a bit harder. I wrote to them and they sent me a response, which I quote to anyone who cares. They gave me permission to share that response: 



Hello Mr. Katen,

 It is recommended that all drain line tube material be ¾” Type L or M copper water tube or ¾” Schedule 40 pipe.  If the heater has an input rating of 95,000 BTU/Hr or less, up to 30 ft of ¾” copper water tube or schedule 40 pipe with up to four ¾” elbows may be used.

 Properly supported CPVC may be used if permitted by the applicable codes and the CPVC tube manufacturer. Due to the smaller inside diameter, if CPVC is used, no more than 10 ft of ¾” CPVC and a single ¾” elbow can be used if the heater input is greater than 74,000 BTU/Hr but less than or equal to 95,000 BTU/Hr. If the heater has an input rating of 74,000 BTU/Hr or less, up to 30 ft of ¾” CPVC with up to four ¾” elbows may be used.

 If longer length run of pipe or more fittings are required, the drain line size can be increased (i.e., 1”, etc. near the valve outlet) to support the needed configuration.

 Let us know if you have any questions.

 Kind regards,




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