Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

blowing relief

markootz Member Posts: 4
Keep blowing relief valve on residential 3 zone baseboard
loop hot water boiler. Installed new relief, extrol #30,
and pressure reducing valve . Purged all 3 loops still
blowing relief. boiler pressure is around 22 psi when cold.
Any ideas are much appreciated.


  • 22 psi cold

    is gonna give you close to the relief valve setting , or more , when it heats up . Was it preset at 22 or did you set it there ? How high is the last zone of baseboard from the boiler ? We find that 12 psi cold works fine for just about every 2 story house .
  • markootz
    markootz Member Posts: 4

    It is a 2 story house iknow 12 psi is what i'm looking for
    my question is why is the pressure so high? 22psi cold.
  • Paul Mitchell
    Paul Mitchell Member Posts: 266

    the feeder..reducing valve is shot or out of adjustment. maybe another source of water getting in boiler??

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
  • What brand of feeder ?

    We use Taco , and I believe most of the other brands all come preset at 12 psi . There is a dial on top that you back out to lower the pressure going in .

    A few things to check -

    If the house cold water pressure is too high , it can actually force more pressure through the feeder than what it is set at . Do you know what the pressure is for the home ?

    And what are they using for hot water ? If they have an internal coil or an indirect heater , if either one develops an internal leak , it will increase the pressure in the boiler . But if the boiler stays at a constant 22 psi cold , I wouldn't think this is the case . Did you try leaving the feeder valve closed , and did the pressure keep going up ? If theres an internal coil or indirect , can you isolate either one from the boiler to see what happens ? Good luck Mark , and PS - don't leave the feeder valve closed when you leave unless they have a low water cutoff working on the boiler .
  • markootz
    markootz Member Posts: 4

    No internal coil for domestic. feeder is brand new .old one doing same thing. old extrol was water logged changed that.feeder is not adjustable has fast fill on top.
  • And no indirect heater ?

    And what about the house pressure ? The only other thing I can think of is check the pressure in the new expansion tank . What brand of pressure reducer do you have ? I've never seen one without a set screw .
  • John Fernandez
    John Fernandez Member Posts: 5

    it's the expansion tank.........heated water needs a place to go!
  • Bob Cat_2
    Bob Cat_2 Member Posts: 14

    It sounds like you replaced all of the componets that cause a relief to blow off. It also sounds like you have too much pressure in the system. If you feel the need to run the system this high did you match the pre-charge pressure of the expansion tank with the fill pressure? If not then do one of the following; drop the pressure to 12 psi or with NO pressure on the system increase the precharge. I would also keep the auto fill off. Heat the bolier up if it doesn't blow off on the first or second cycle then you probally had a expansion problem. If you turn the fill back on and it blows off, say the next day, then the feeder is increasing the pressure.

    good luck
  • Dale
    Dale Member Posts: 1,317
    Extol feeder

    Reading the other posts I wonder if you have on of those new extrol feeders where the feeder is built into the top of the expansion tank. That feeder matches the water in the system to the tank air setting. If you do have one of these you need to get the pressure off the system and pump the air tank up to 12 psi and then turn on the fill water, it should go to 12.
This discussion has been closed.