How does this work? [i.postimg.cc]

Does that handle release air so that the closed loop is purged?

No...….the handle bypasses the regulator function of the valve and applies city/well water pressure to the system to speed up system filling and purging. You have to be careful using that function.

thanks Paul for that good info. I appreciate it.
Why do you have to be careful using that function?

I believe his system has a failed expansion tank and the PRV is fine.
His 30 Lb relief valve is leaking as it should because the system pressure is about 31 PSI.



Edited 2 times.

release some water and get the system pressure back down to 12-15 PSI.
close the valve on the cold water fill line.
fire the system and if the pressure rises up to 25-30 PSI, the tank is bad.
if the pressure stays about the same then the fill valve is letting a tiny bit of water thru and IT needs to be replaced.



Edited 1 times.

@ Packy: I am not following you on why you think the fill valve could be the culprit?

Here's a link to that valve: [i.postimg.cc]

old gate valve or new ball valve this would always be in the open position during normal operation.

Here's a link to the boiler: [i.postimg.cc]

Here's a link to the only gauge: [i.postimg.cc]

the only symptom and customer complaint is dripping relief valve.

by fill valve i mean the automatic pressure reducer that supplies water to the boiler.
i have seen them set at 12-15 PSI but they do not keep in that range.
sometimes the let water seep by which will cause the boiler pressure to increase.
by closing the cold water shutoff you will eliminate this as the problem.

as i said.. if you close the shut off, fire the system and the pressure increases then the x-tank is bad.
if you close the valve, fire the system and the pressure does not rise then the auto-fill is the culprit.

it is a PRESSURE REGULATING fill valve - if operating correctly it should NOT fill past 12-15 psi - unless 'flip' bypass is activated

If system becomes over pressurized to PRV setting of 30 psi,

either:

fill valve is kaput

OR

compression tank is kaput.



packy's method of troubleshooting will determine

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Now I'm following.

Scheduled for Thursday AM. I'll post the results here.

thanks so much.

ya'll from south carolina speak so eloquently...
hahaha...
have a good day, my friend..

for the 'amateurs':

PRV is a confusing term.

It can mean EITHER pressure regulating valve OR (safety) pressure relief valve.

IMO: better terminology would be,

(S)PRV or (S)TPRV = relief valve for safety ('pop' safety valve)

PRV = pressure regulating valve for normal operation



==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Replaced the expansion tank, the PRV and the relief valve. Before even turning the boiler back on the pressure continued to creep and eventually reached about 33 PSI before the relief valve tripped and started to relieve the pressure. I am thinking now that the storage tank's heat exchanger piping is leaking allowing the house water pressure to build pressure into the closed boiler loop through a pin-hole leak in the copper heat exchanger.

so turn off the cold water feed into the storage tank.
that will tell you if the coil has a pinhole because the pressure will remain in the normal range..

As packy says, only close the valve to the PRV and open a hot faucet. If the boiler pressure drops, you know the coil in the indirect is leaking.