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relief lets go?

G Waite
G Waite Member Posts: 23
Can someone give me a couple reasons for why a pressure relief valve would let go.


  • billtwocase
    billtwocase Member Posts: 2,385

    Pressure mainly, but excessive temp can also cause it to release
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    Do you mean...

    Why did your relief valve pop on your boiler?  For starters:

    1. air is system

    2. auto water feed bad, or stuck open or partially open

    3. old style expansion tank water logged, new type-bladder failure, or undersized.

    4. relief valve bad

    5. air is system...yeah I said it twice.

    6. boiler piped wrong.

    Is this a new problem? Was something recently done to the system? Provide a little more info, and you'll receive more help.

    There was an error rendering this rich post.

  • G Waite
    G Waite Member Posts: 23
    relief valve

    Its my bosses boiler. I got my license two or three yrs agonrver did much more than clean outs no real trouble shooting. He also ran out of fuel. There is zero maintenance so that should tell part of the story. Thank you for your help.
  • lchmb
    lchmb Member Posts: 2,997

    I would guess the boiler maintains temp, when he ran out it went cold allowing the boiler pressure to drop and added water. Then it reheated, and since the expansion tank is low on air pressure it over pressurized the system and opened the Pressure relief valve. I would start by doing a full service, cool the boiler down, take pressure off the system, remove and test the expansion tank, 12 psi. If low I recommend replacing. At that time replace the pressure relief valve and test the fast fill...
  • billtwocase
    billtwocase Member Posts: 2,385
    I would also

    lookin into a possible hole in a tankless coil, or indirect coil. As my friend said previously, a cold boiler heated back up can do funny things, high pressure can be one of them. There can only be a handful of possibilities. Faulty feed valve, expansion tank-full if old style, full, or over pressurized if new one, tank isolated by zone valves and check valve be it IFC pump or flow check, and possible piping problem. Post some pics for us
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