Boiler pressure

Discussion in 'Boiler Forum' started by my88r, Apr 17, 2011.

  1. my88r

    my88r New Member

    Messages:
    1
    Location:
    Horseheads, NY
    I have a boiler in my basement. That does the apartment upstairs it goes up the wall to there ceiling. The building is 2 store and the boiler goes up to the apartment. There's a pressure difference is goes to about 30 psi. When running the thermostat at 70 degrees. Is that cause it goes upstair and goes along distance. Will this hurt anything.??
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,183
    Location:
    New England
    Depending on the boiler, 30# might be normal, but that seems high for just two stories. To keep the pressure semi-constant, the expansion tank needs to be working. This could be an older style air over water tank, or a newer bladder tank. You may need to replace the bladder tank or purge the old tank to get it to regulate properly. Also, if you have an autofill valve, it could be worn out and letting new water into the system. And, if you have a tankless coil, it could have a leak in it, raising the pressure.
  3. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,236
    Location:
    Maine
    30 lbs is where the relief valve does it's thing so no, the system pressure should not be any higher than 15 lbs. Drain or replace the expansion tank. If the pressure still climbs test the auto fill or for a leak in the hot water coil if you have one.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,183
    Location:
    New England
    Most residential boilers use 30# relief valves, but there could be a higher pressure one there in an unusual circumstance. Normal operating pressure is typically in the 15# range. A failed expansion tank will cause the pressure to rise, often enough to cause the relief valve to open.
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