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Drippy Relief

NYplumber Member Posts: 503
Drippy Relief 

Details and issue: Six months ago we installed an eighty gallon indirect to replace a non performing reverse indirect. The past few weeks the relief valve has been dripping on the brand name indirect. Thought it was faulty and replaced with a 175psi relief valve (used an extension coupling, not that that should matter). Two days later, the new relief is dripping.

Tank temp is set to 155*f since day one of install. Tank pressure measured at the bottom of the tank is 60psi. There is a Honeywell mixing valve on the output to mix down to a safe temperature, as well as a recirc pump from when the house was built.

One other issue, there are Grohe shower bodies all over the home. The home owner says that the first few minute of the shower he has to hunt with the temp setting to stabalize it. After a few minutes it all settles, or if a shower was taken shortly before, it is stable.

My guess is an expansion tank is needed (unsure what size).

The recirc pump has to be piped as per the dotted line. (This should help with the shower hunting issue.) 

OR, maybe the relief is going off on temp, and that's due to "stacking".

Comment away....Thanks


  • STEVEusaPA
    STEVEusaPA Member Posts: 4,970
    edited May 2012

    I think you definately need an expansion tank.

    Look at page 9.

    Regarding the shower issues, how is the recirc line, and pump controlled?

    edit:  Also you'll need another check in the cold domestic side.
  • NYplumber
    NYplumber Member Posts: 503

    Thanks Steve. Where do you see a check valve missing? This drawing is off memory since the job is a nice distance away.

    As for the recirc line, its controlled via aquastat set to 120*f.

    Thanks again.
  • NYplumber
    NYplumber Member Posts: 503
    All good

    Expansion tank added, and now all is good.

    What took it a few months to start dripping if the expansion (water/heat expansion, not expansion tank) was always present is beyond me. Cant blame a weakened relief spring, because the new valve dripped from the first moment.
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