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callterrence · Mar 15, 2009, 03:37 PM

Have boiler that drips water from pressure relief valve when gauge reaches approx.32 psi.. Same gauge also has water temp where boiler turns off at aprox. 172 degrees. As boiler haeats up to 172 degrees, water pressure also goes up and begins to drip water at approx. 32 psi.. Unknown as to why and looking forsome insight as to where to start to resolve problem. Have feeling has something to do with expansion tank. Expansion tank has a valve to pump air into it, what pressure should be within expansion tank? If I have to remove expansion tank, should it have water in it? Should I remove expansion tank to add air to it.I'm hoping system doesn't empty out of all water to where I end up with no heat or do major damage to boiler. Please advise if you can, getting concerned about this problem ,as I have to empty bucket on daily basis. Thank You!

hvac1000 · Mar 15, 2009, 04:21 PM

Usually the expansion tank is set at the factory at 12 to 15 pounds. If you go to pressurize it and water comes out the air fill valve then the bladder in the tank is shot and the tank will have to be replaced. Usually the boiler should have no more than 12 PSI when cold and 18 to 24 when hot. But this also depends upon how many storys or floors the home has. The relief valve is factory set at 30 PSI so anything over that will cause it to drip oropen up. Many times if the valve leaks it will not close off tight again. If that is the case open it up with the lever and let a bit of water flow out then let it close. That will sometimes wash the dirt off the seat allowing it to close.

callterrence · Mar 15, 2009, 04:48 PM

Originally Posted by hvac1000

Usually the expansion tank is set at the factory at 12 to 15 pounds. If you go to pressurize it and water comes out the air fill valve then the bladder in the tank is shot and the tank will have to be replaced. Usually the boiler should have no more than 12 PSI when cold and 18 to 24 when hot. But this also depends upon how many storys or floors the home has. The relief valve is factory set at 30 PSI so anything over that will cause it to drip oropen up. Many times if the valve leaks it will not close off tight again. if that is the case open it up with the lever and let a bit of water flow out then let it close. That will sometimes wash the dirt off the seat allowing it to close.

My home has baseboard in the basement which is a finished basement and baseboard on main floor. To remove expansion tank I should shut off all water supply before removing tank? A sequence of events that you could provide would greatly be appreciated! Thank You So far for Your Input!
callterrence

hvac1000 · Mar 15, 2009, 11:15 PM

To remove expansion tank I should shut off all water supply before removing tank?

Yes

Let boiler cool. Turn off water supply, Remove expansion tank,replace expansion tank with the same size tank using pipe dope on threads. Reopen water supply valve to boiler. Check gauge pressure and you might have to bleed the system if any air was taken in while changing the expansion tank.

All boiler work requires the skills of a mechanical contractor/HVAC person. I have no idea of your qualifications or skill level. Removing and replacing a tank is not difficult if you have some minimum skills and the proper tools.