Relief valve leaking on boiler

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CTDIYER

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The relief valve on my boiler is leaking. I changed it and it continues to leak. I looked at the operating pressure and it's running at about 35 psi which explains why my 30 psi relief valve is leaking. I turn down the upper limit on the aquastat control to about 205°. It's still continues to leak. Any thoughts on what else can be causing this
 

johnjh2o

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If you have a expansion tank it needs to be drained and refilled. If you have a extrol tank it needs to be replaced.
 

Diehard

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John mentions one possible cause of an over pressurized boiler. Namely an expansion tank that has lost it's air cushion and has lost all or some of the space that would typically allow the heated water to expand to.

Another cause could be a faulty PRV(Pressure Reducing Valve) on the automatic water feed system, which is typically set down around 12 to 15 psi.

@John...Out of curiosity, why do you say, "If you have a extrol tank it needs to be replaced."?
 

johnjh2o

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If he has a extrol tank and the balder has failed there is no way to repair it other then replacing it. I also agree it could be the PRV valve. That can be conformed by turning the valve off on the feed.
 

Diehard

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If he has a extrol tank and the balder has failed there is no way to repair it other then replacing it. I also agree it could be the PRV valve. That can be conformed by turning the valve off on the feed.
Oh I see. You are assuming the bladder has failed but that may not be the case.
You made it sound like if they have an Extrol tank, get rid of it. Period!
Could be needing air due to an uncapped, leaky schrader valve. ???

I never had a bladder tank. I still have my original bladder less expansion tank. Well over 43 years now.:)
 

johnjh2o

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Oh I see. You are assuming the bladder has failed but that may not be the case.
You made it sound like if they have an Extrol tank, get rid of it. Period!
Could be needing air due to an uncapped, leaky schrader valve. ???

I never had a bladder tank. I still have my original bladder less expansion tank. Well over 43 years now.:)
Sorry for the misunderstanding. Extrol tanks are the new norm and they require less maintenance then expansion tanks. Although years ago I installed may expansion tank.
 

CTDIYER

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Thanks everyone for the feedback I'll check the expansion tank and the PRV.

I always thought the upper temp limit should be set at 210 or less
 

Diehard

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205F is well above the typical recommended average.
180F I believe is the average.
There are variables that could favor a slightly higher or lower setting.
 

Diehard

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Without getting into it, as I'm not that familiar with this stuff, but isn't more efficient to have it based on ambient temperatures. I believe there are system that automatically regulate based on exterior temps.
I change mind from summer to winter but I have a tankless water heater on my boiler.
I would also think that the amount of radiation you have in a house could justify a change from the average setting.
Edit: just realized you were saying that 180F should be MAX. Yeah I believe I've seen 140 to 180F as the recommended limits.
 
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nami

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If you have a expansion tank it needs to be drained and refilled. If you have a extrol tank it needs to be replaced.
If you have a expansion tank it needs to be drained and refilled. If you have a extrol tank it needs to be replaced.
After weeks of leaks, I replaced my Watts ET-30 with a Honeywell TK 300-30 expansion tank, which solved my problems. For 13 years my TriangleTube Solo 110 boiler with a Smart 60 indirect fired hot water tank has not leaked a bit. I did have to replace the internal venting fan years ago. In 2020 I needed to replace the long internal exhaust vent which drains condensate at the bottom and the top connecting to the PVC outside vent. This mid-september (2021) I had nearly a 10 gallon leak from the 150PSI/210°F 205,000BTU/hr Watts relief valve on top of the Smart 60 hot water tank. It was temporarily fixed by turning down both the boiler supply temp, and more effectively by lowering the temp on the tank itself. I then replaced the Watts relief valve on top of the Smart 60 hot water tank, with a similar Cash-Acme FVMX-8C. That fixed the big leak, but then the 30PSI/535,000BTU/hr relief valve atop the boiler started spitting out about 1gal./day. I replaced it with a Watts 30PSI/510,000 BTU/hr relief valve, but the new relief valve still leaked. That meant another few days of lukewarm showers. After I replaced the expansion tank, I found that I couldn't drain most of the water from the old ET-30 expansion tank, which convinced me that the bladder had filled with water. It does seem that the hot water tank needed a new relief valve, but perhaps not the boiler. The real fix was replacing the expansion tank. Thanks johnih2o and you other great members of this forum for your great advice. Without your recommedations and experience, it would take DIYourselfers like myself much longer (if ever!) to solve plumbing and HVAC problems.
 
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