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pressure relief valve on oil furnace

Christina66 Member Posts: 10
I am losing about 2 gallons of water a day from the pressure relief valve at the back of my furnace. The psi is fine. This is all new to me but i know that in the past years this has never been a problem to this extent. If I forget to empty the 2 gallon container underneath the pressure relief valve then I have water spilling out onto my basement floor. any help would be fantastic but please whatever it is please spell it out for me in the simplest of ways because I am just learning. Thanks!!!


  • Jamie Hall
    Jamie Hall Member Posts: 23,323
    There are at least three possibilities. But first... is this hot water heat or steam? The first possibility is common to both-- but is the least likely -- and that is that the pressure relief valve is failed, or has some goop caught under its seat. Now if it is hot water, I have to ask -- is the pressure really fine? That is, is the pressure when cold reasonable -- say 12to 15 psi -- and then when hot also reasonable -- no more than 20 psi? If both of those are true we go back to the valve. However, it is quite possible that the cold pressure is fine -- but the hot not, in which case we'd be looking at the expansion tank. Then for steam, it is highly unlikely that you are building enough pressure to trip the pressure relief valve, so again we go back to the valve.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • MikeL_2
    MikeL_2 Member Posts: 490
    edited March 31
      Is there a tankless coil in the boiler, or an indirect water heater connected to it?
        Boiler tridicators are notoriously inaccurate.
        What type of expansion tank?
        Automatic feed valve is a suspect also.