Zurn Wilkins 1" Pressure Relief Valve question

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Gene Brink

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Sylmar, CA
Having a problem that I am uncertain of. Factors are:
1. Old galvanized plumbing replaced with copper from meter to house & through out house by a plumbing contractor in July 2013. Everything, except the pressure valve, is still working perfectly.
2. Model 600XL pressure valve failed to reduce pressure so 160# of city water pressure was going through out the house in 2018 (just over 5 years after installed). Way over what the washer, dishwasher, et al were designed for. Fortunately there were no ill effects from this.
3. Replaced the pressure valve with an exact replacement. Did this myself. New pressure valve worked perfectly until Oct 2021 so I purchased a rebuild kit (figured the brass casting should not have gone bad somehow) and installed all the kit parts, greased the rubber with supplied lubricant, reassembled and it worked perfectly after setting to 65#. Note: stainless steel mesh screen in the valve was clean - not a single bit of grit/sand/rust etc. so don't think contamination would have damaged the rubber parts.
4. Two weeks ago the pressure valve started let the pressure bleed up to 160# when no water was being used in the house. When an outlet was opened the water rushed out with high pressure and then reduced to the 65# the regulator was set for and remained at this pressure as long as the outlet was opened. When the outlet was closed the pressure built up to 160# again within 5 minutes.

My question is does anyone have any ideas why this is happening? I'm not a professional by trade but the valve does appear to be well made and am uncertain if I should get another kit or install a new valve. (Or have a different type/make pressure valve installed. If so any recommendations?) Let me know if I've not provided enough information.

Thanking any respondents for their input, Gene
 
Do you have a tank type water heater ? If so, do you have thermal expansion control ?
 
Yes and yes. 40 gal gas heater with a relief valve as well as an hot water expansion tank as required by Los Angeles Building. Relief valve is not passing water despite the high pressure which seems odd?? Thanks for asking, I did even think to mention devices on the water heater. Is it likely something is wrong with them? Still seems like the line pressure relief valve is malfunctioning though.
 
Replace the regulator and also check that your expansion tank is working.
 
40 gal tanks usually have a relief valve rating to discharge at 150 psi. It may need replacing.
Because the pressure increased to 160 within only 5 minutes I’d suspect the prv has debris on the seat. It doesn’t take much to cause pressure creep.
If creep is happening without the water heater on, that is what I’d suspect.
Any brand of prv can have this happen by the way.
If your prv was older, sometimes the metal part of seat can erode and cause the exact same problem.
 
Thanks for the replies they give me some direction in which to go.

Twowaxhack - Did not think of the expansion tank at all. How would I go about checking to see that it is working? Will replace the pressure valve on the hot water tank as it will be cheap insurance. No idea what the inside of the PRV looks like today but when I put the rebuild kit in everything was pristine. Looks like a new PRV is the way to go (drat! $$$). Easiest to purchase the same brand & model since it will fit into the line without any modification but any thoughts on whether or not it is a "good" PRV or should I replace with something else.

Molson - Have 2 inexpensive pressure gauges (RainBird & Wilkins) and for what it is worth both show the same pressure reading. Of course both could be wrong and their matching coincidental...
 
Make sure all auto valves like ice makers are off.

Run about 10-15 gallons of hot water and make sure the water heater fires up.

Have a gauge on the system as the water heats…….if you have thermal expansion the pressure will continue to climb above 80 psi.

No water can be used during this test or it will void the test. You can’t have leaks either.

Do this after you replace your PRV and set your max pressure.
 
Thanks for this info, Twowaxhack. Just to confirm I'll need to plumb a gauge into the top of the water heater - probably the same inlet as the pressure relief valve on top of the heater? Seems fairly straightforward if I am understanding.
 
Thanks for this info, Twowaxhack. Just to confirm I'll need to plumb a gauge into the top of the water heater - probably the same inlet as the pressure relief valve on top of the heater? Seems fairly straightforward if I am understanding.

connect the gauge to any hose bibb that is after your PRV. You should have one installed to set the PRV pressure anyway.
 
Thanks for the clarification. Easy as I already have a hose bibb plumbed in! Just have to take care of everything now...
 
Make sure all auto valves like ice makers are off.

Run about 10-15 gallons of hot water and make sure the water heater fires up.

Have a gauge on the system as the water heats…….if you have thermal expansion the pressure will continue to climb above 80 psi.

No water can be used during this test or it will void the test. You can’t have leaks either.

Do this after you replace your PRV and set your max pressure.
Can also simply relieve the air valve and see what comesniut. Nothing or water means it's busted.
 
Was speaking on the expansion tank.. should've clarified
Just because the expansion tank has an air charge doesn’t mean it’s correct.

You could test air pressure of the expansion tank but you have to turn the water off and relieve the pressure to do so.

When I install PRV’s I have a gauge already on the system to set the pressure. While my gauge is on the system I check for thermal expansion control by making a draw on the hot water and making the heater fire.
 
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