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Troubleshooting Boiler pressure increase

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mrscoular
mrscoular Member Posts: 5
in Gas Heating

Hi there, have a gas heat boiler in our basement that heats a third floor finished attic space. I noticed the boiler is sitting at 35 PSI and it’s July so it’s not currently heating the space. The 30 PSI watts pressure relief valve on the boiler has a slow leak. Wondering if I should shut the power off and release water from the drain valve on the side of the boiler or bleed that air valves on the baseboard radiators in the attic to reduce the pressure? Also the accumulation tank feels like it’s empty right now. Second question is what most likely causes the pressure increase since this seemed to happen during the summer when the boiler isn’t running? Appreciate any feedback.

Comments

  • mattmia2
    mattmia2 Member Posts: 13,517

    Does the boiler make domestic hot water or is it only for space heating?

    Can you show us some pictures of the boiler, especially the feed from the potable water in to the boiler for make up water and of the expansion tank?

  • Big Ed_4
    Big Ed_4 Member Posts: 3,241

    I would check the pressure reducing valve ( bell shape) . Shut if off see if the pressure drops…

    There was an error rendering this rich post.

  • mrscoular
    mrscoular Member Posts: 5

    @mattmia2 this is for space hearing only. Pics posted below. The system is reading 30 PSI today.

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  • mrscoular
    mrscoular Member Posts: 5

    @Big Ed_4 can you let me know if you see the pressure reducing valve in the pics posted.

  • mattmia2
    mattmia2 Member Posts: 13,517

    Where does this pipe go? The prv or manual fill valve will be on this pipe.

    image.png
  • HydronicMike
    HydronicMike Member Posts: 84
    edited July 23

    The boiler says 3rd floor on it. What is the height from the boiler gauge to the top of the heights t radiation? That will tell you what your expansion tank, boiler feed, and system pressure.

    What is the volume of water in the piping and boiler (and starting and ending boiler temps)? That will tell you what size expansion tank is needed.

    I’d suspect the boiler getting cold may have allowed the boiler to feed to open a little (or there is a small leak), and maybe it didn’t fully seat.
    And/or there is air in the system.
    And/or your expansion tank has lost charge/failed, or simply isn’t big enough.

    The air scoop with the coin vent is pretty much ancient technology.

    Is the yellow handled valve closed or not fully open?

  • mrscoular
    mrscoular Member Posts: 5

    @mattmia2 that is the incoming water pipe. All is see is a shutoff valve down the line from what you’re seeing here.

  • mrscoular
    mrscoular Member Posts: 5

    @HydronicMike i have hoses to hook up to run water through the system to remove any air build up. Should I do that or bleed the air vents? There’s an air vent on the boiler itself and the baseboard radiators.

  • MattinIndy
    MattinIndy Member Posts: 19

    Personally, if I were involved I'd get and new expansion tank. Then the "fill-a-trol valve that your expansion tank is currently hanging from would go in the garbage. I would replace that with a convention PRV of your choosing. There will be some minor repiping involved with this. While you are at it, it probably wouldn't be a bad idea to replace the relief valve on the boiler as well. Then I'd refill and purge air and see where you stand.

    In my experience the fill-a-trol valves do no work very well, or last long.

    mattmia2mrscoularEurora
  • mattmia2
    mattmia2 Member Posts: 13,517
    edited July 23

    If it is it cold and it has a manual fill valve and it doesn't have a DHW coil of some sort then the fill valve probably isn't holding, either that or it was overfilled.

    Drain some water from one of the boiler drains until it gets to around 12 psig and let it sit off a few days and see if the pressure creeps up. If it does the only option is that the fill valve isn't holding. The amount of water you will have to reduce the pressure will probably be something like under a cup to a quart or so.

    Those gauges are also very easily damaged so that they become inaccurate but since the relief valve is weeping I don't think the gauge is wrong.

    mrscoular

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