Weil Mclain Boiler Relief Valve Dripping- Pressure High

Bostopa

Hi all,

Have a boiler 105K BTU at my sisters house that relief valve was leaking. The expansion tank was bad that changed that and the Watts 1556 pressure valve.

After new valve installed pressure still goes upo to 40 psi. I have not had a minute to go back and remove some water get it down to say 15 psi and shut the main water supply off and see what happens to pressure. One thing is when the new Watts valve went in, it pushed pressure up to around 30 psi. Watts was brand new wondering if its defective.

neilc

is the boiler making the domestic water hot also? that coil may be leaking the higher domestic pressure into the boiler system,

or you prv is leaking by, do you see isolation valves for the prv?

Alan (California Radiant) Forbes

When high pressure is the problem and the x-tank is replaced or recharged, it sometimes takes awhile for the system to shake hands and make friends with the new addition. Hard to explain to a disgruntled customer.

Bostopa

No, the boiler does not make domestic hot water. No PRV isolation valve. You ststed could be leaking by but if the pressure on the gauge is showing 40 and PRV is leaking by I assume it's not a faulty PRV since thats what its designed to do. If temp gaiuge was wrong then I would also think PRV would not be leaking by.

neilc

ok,

I'm meaning pressure reducing valve, your feed valve, and any isolation, this would be your only source of building pressure, esp with a new expansion tank, did you check the precharge?

was assuming you meant pressure relief (safety) valve

can you post pictures?

HVACNUT

Was the air side of the new extrol tested before it was installed?

Its unlikely the new relief valve is bad. Set the pressure to 12 psi, then close the valve to the feed and wait.

Bostopa

expansion tank was right at 12 psi when installed.

Bostopa

neilc

nah, look at your gage again, that's 40 foot of head(outside scale), and 15psi(inside scale), I think your ok there,

what was / is dripping? the relief, or the backflow?

Bostopa

Neilc…. Geez Louise!!! How the heck did I not see that!!!!!

thank you for pointing it out!!! I’ll get it just the pressure relief valve that needs changing!!! I’ll do that weds! We are going to get hammered here in Boston tonight and tomorrow

Alan (California Radiant) Forbes

Your pump is on the return and the expansion tank is on the supply. Every time your pump turns on, there's a drop in pressure on the suction side of the pump. If the drop is large enough, it might cause the fill valve to add water and if this happens long enough, pressure will build enough to open the relief valve.

I'm not saying that this is happening to your system. There are thousands of systems out there like yours. Some are affected, some aren't. Many would say to move the pump so it's pumping away from the x-tank.

Bostopa

Alan - Thanks understood…thats gonna have to be a summer job