Click here to Find a Contractor in your area.
In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Need to contact us? Visit

Boiler pressure gauge reads 0

ken Dken D Member Posts: 60
What would you do if you found boiler with 0 pressure, but had pressure (I think)?

Went to a job, boiler pressure gauge read 0 @140*. Made t-stats for both zones to call, went down and bled water fromt the drain as boiler was firing; noticed pressure rose to 7#. Don't know if it was the heated water, or if I drained water, makeup water rose pressure.

Expansion tank had air. How do I confirm whether it is the exp tank or makeup water setting? I need, but do not yet have, a gauge to put on drain valve, but will get soon.

Do I need to isolate, unlikely possibility, exp tank, drain water, put tire gauge on it and read pressure?
Or can it be done with the water in system?
What would you do if you found boiler with 0 pressure, but had pressure (I think)?

I've read many books on this, but none from a troubleshooting perspective, or that adequately tie the system together.


  • Al LetellierAl Letellier Member Posts: 781
    boiler pressure

    You answered your own question, Ken. You need an auxiliary gauge to test system pressure. Boiler Tricators are notoriously inaccurate and short-lived. RE: the expansion tank, unless there is an isolation valve in the line to the tank, you have to bring system pressure to zero to check the pressure in the bladder tank. It whould be set for normal system operating pressure.
    If I find a boiler at 0 pressure, the first thing I do is attach my test gauge, so.....

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • MichalMichal Member Posts: 213
    get a true gauge

    well next step I would do is get a gauge I know is true and put it on and see what it reads, most likely the gauge is shot

    to check air in expansion tank, it should be taken off boiler, and checked, pressure should equal what the system will be running at usually like 12 to 15 pounds

    while you have the gauge on, drain the boiler and see if the water feed valve fills the system back up

    thats my quick next steps
  • brad rutherfordbrad rutherford Member Posts: 6
    0 pressure

    1. I have seen fill valves stick
    2. I have seen bad tridicators
    3. I have seen large systems under filled. Although, I presume your fill valve was not isolated.
    4. I have seen a rubber hammer fix both.
  • ken Dken D Member Posts: 60
    Thanks for the helpful, quick responses

  • WeezboWeezbo Member Posts: 6,232
    you can make a cool gauge that threads on to a purge valve

    even the cheapest sob puts a boiler drain on the system :)did i say cheap? and itsaves a group of hassels...ingrediients....1 old washing machine hose and a band clamp and a pressure gauge :)
This discussion has been closed.


It looks like you're new here. If you want to get involved, click one of these buttons!