boiler pressure

walter k. willis

my boiler reaches pressures of more than 30 psi when it fires causing the pressure relief valve to open. what can cause this as i never had a problem with it before. the system is about 10 years old.

walter k. willis

high boiler pressure

my boiler reaches pressures of more than 30 psi when it fires causing the pressure relief valve to open. what can cause this as i never had a problem with it before. the system is about 10 years old.

Ron Schroeder

Check your expansion tank.

It its a bladder type you have probably lost its charge, if its the old compression style it is probably water logged.
B.S.

Brad White_27

Short answer

Insufficient expansion tank capacity is most the most likely cause, given that it happens when it fires. You probably have an older style expansion tank up between the joists in the basement. (It is probably painted green too

If anything I mentioned above is different please let me know.

Chances are the tank has become waterlogged, the air absorbed into the heating system, forced out to the radiators where you vented it, thus enabling the escape. AHA! You are an accessory. How do you plead?

The air can get out over time which is why it may have surfaced all of a sudden.

Suggest you drain the tank at least half way. Fill the system to about 12 psi when cold for a two-story house and about 17 psi for a three story house. (If something different please ask).

Long term benefit can be had by making sure that your pumps are pumping away from the expansion tank. Chances are the pumps are on the inlet side of the boiler and the expansion tank is off the boiler directly or off of the discharge pipe from the boiler. The get an air separator such as a Spirovent and lastly you can replace that air cushion tank with a sealed diaphragm type.