Tankless hot water relief valve


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Old 07-17-22, 04:07 PM
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Tankless hot water relief valve

I'm currently replacing my galvanized water lines with PEX. Everything is pretty straight forward, but after some inspection, I've realized that my hot water line coming off of my tankless Rinnai tees off with one line to the rest of the house but the other to a relief valve that is then plumbed to a drain. I'm thinking it's better to just have the relief valve connected to an open CPVC line that I can just relieve into a bucket when servicing. And NOT have a drain connected in any shape or form to my hot water potable line. Right? Am I nuts? What have I been showering in these past few years All jokes aside, thanks for any info, much appreciated!
 
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Old 07-17-22, 04:45 PM
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I'm not following..... discharge into a bucket or a drain..... depends on how it's connected.

It should be discharging into an open standpipe like a clothes washer would be doing.
It should not be hard connected into a sealed drain system.
 
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Old 07-17-22, 05:12 PM
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I'm pretty sure it's all connected directly (no air gap, pan or anything) into the drain system. Hot water line from tank tees off, one side to house then the other to a discharge that is connected to glued cpvc then shark bite connection to copper, which then runs to various assortments of upsizing adapters, etc. then connected directly to a 2" tee (vertical drain and vent). Seems a little wild to me. Everything is either glued or sweated, so I'm pretty certain it's all hard connected.

Side note: I believe this area of the house once had a washer/dryer as I found some old capped off water lines. in the wall near the drain. I can't imagine the 2" drain was installed for a water heater relief valve.
 
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Old 11-22-22, 11:13 AM
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The pressure safety valve should vent to an open drain (floor drain, laundry scupper, standpipe, or outside). The idea is that you don't want any backpressure on it at any time, and you want to be able to see the discharge and thus learn that there is a problem with the heater or plumbing circuit. The discharge pipe should be the same size or larger as the connection on the valve.
 
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Old 11-22-22, 08:20 PM
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I believe the pressure relief valve the OP is discussing is one in the hot water line.
A tankless Rinnai should have its own dedicated pressure relief valve.
 
 

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