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Increasing Pressure for Hot Water Radiators, Gas, Crown Boiler

Hi All-

We live in a 1916 home with its original hot water radiators. We have a Crown AWR Series gas boiler which is less than ten years old (predates house purchase). There are periodic clankings in the pipes, mostly between the basement (furnace location) and first floor, and especially in association with one particular radiator. I've bled the first-floor radiators and tried bleeding the second-floor radiators. But on the second-floor ones, air comes out for a while, but then it stops and water never comes out. My understanding is that this is a sign that the pressure is too low to drive water (and so the remaining air in the system) up to them.

Is this right? And if so, is there a way to raise the boiler pressure?

Thanks for any help!

-Tyler





Comments

  • hot_rod
    hot_rod Member Posts: 16,547
    If the gauge is reading correctly you have enough pressure. Does the gauge drop when you bleed the radiators?
    It sounds like an air problem or circulator now operating some times

    what temperature does it run?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    trputman
  • Jamie Hall
    Jamie Hall Member Posts: 19,147
    The symptom you describe -- that there is no water coming out of the upstairs radiators -- does indicate that the system pressure is much too low. However, the pressure gauge in your photo indicates that it thinks the system pressure is adequate -- 18 psi should be ample -- and therefore the pressure gauge is, very likely, broken. They do. This makes it difficult, however, to assess just what the pressure in the system is, and thus to safely add enough -- but not too much -- water and, perhaps at least as important, to determine whether the expansion tank is working.

    Fortunately, if there is a handy drain somewhere, you could get a pressure gauge and rig up a connection to the drain and get more reliable readings that way.

    Now. Somewhere in that piping there should be a connection to the domestic water supply in the house, and on that pipe there should be three valves: a shutoff valve, a backflow preventer, and a pressure reducing valve.

    Once you have a pressure gauge which is believable, make sure, first, that the shutoff valve is open. Then, on the pressure reducing valve, there should be a lever which you can lift to add water to the system. Give that a try.

    And get back to us.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    trputman
  • trputman
    trputman Member Posts: 3
    Thanks, Bob and Jamie. Currently, I'm finding that if I wait a bit and return to the upstairs radiators, the pressure must be coming back up enough to drive out more air. So far two of the three up there are now putting out water instead of just air. Still working on that third one to see if I can drive out all the air.

    Even still, does this suggest that the pressure is still lower than the gauge indicates? Thanks!
  • Jamie Hall
    Jamie Hall Member Posts: 19,147
    The gauge might be OK... but there'd be no harm to checking...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • neilc
    neilc Member Posts: 1,805
    trputman said:

    Thanks, Bob and Jamie. Currently, I'm finding that if I wait a bit and return to the upstairs radiators, the pressure must be coming back up enough to drive out more air. So far two of the three up there are now putting out water instead of just air. Still working on that third one to see if I can drive out all the air.

    Even still, does this suggest that the pressure is still lower than the gauge indicates? Thanks!

    have you tried tickleing the water feeder fast fill?
    it could be sticking some,
    try operating the lever back and forth, or up and down, a few times,
    be sure to set it back to where you find it or you'll over pressure the system,
    and have more water than you want to deal with.
    known to beat dead horses
  • trputman
    trputman Member Posts: 3
    Hi All-

    An update: After bleeding the radiators daily for about a week, I increased the pressure in the boiler by adding more water, up closer to 20, which finally allowed me to push all the air out of the second-story ones. This is great, of course, but the clanking continues.... it seems to be concentrated in the pipes below the floor that lead to each radiator, and occurs either soon after the heat kicks on/off or when someone walks over those areas of the floor. I'd describe it as a loud metallic clank, neither high- or low-pitched. It's not isolated to a single radiator but does occur most often related to two on the first floor and one on the second that are all on the same side of the house and on the far side from the boiler.

    Thanks for any help!

    -Tyler
  • pecmsg
    pecmsg Member Posts: 2,954
    trputman said:

    Hi All-

    An update: After bleeding the radiators daily for about a week, I increased the pressure in the boiler by adding more water, up closer to 20, which finally allowed me to push all the air out of the second-story ones. This is great, of course, but the clanking continues.... it seems to be concentrated in the pipes below the floor that lead to each radiator, and occurs either soon after the heat kicks on/off or when someone walks over those areas of the floor. I'd describe it as a loud metallic clank, neither high- or low-pitched. It's not isolated to a single radiator but does occur most often related to two on the first floor and one on the second that are all on the same side of the house and on the far side from the boiler.

    Thanks for any help!

    -Tyler

    Sounds like the pipes expanding and rubbing on the wood its sitting on. If you can gain access, cut a plastic milk bottle and slip it between the pipe and wood.