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Banging radiator

Hi Brad –

I’ve posted a few more photos…To the right of the boiler the piping is pitched towards the wet return. On the left side there’s a three-foot section that is ever so slightly pitched back towards the boiler and then it makes a turn into the left main. After the turn the main is pitched towards the wet return. The pipe leading to the banging radiator feeds off the three foot portion that pitches back to the boiler. Do you think that could be the problem?

Everything is insulated except for that three foot section, the two pipes feeding off the header, the piping leading directly into the boiler and the entire wet return line.

When I bought the house there wasn’t any insulation at all in the basement. How close to the boiler should I get with it?

Many thanks agin for all your help. I’m determined to get this operating the way it’s suppose to.


  • Sleepless in NJ
    Sleepless in NJ Member Posts: 7
    BANGING Radiator

    One radiator in my house bangs when the heat comes on. The rest of the system is peacefully quite. I’ve tried pitching the radiator and replacing the air vent with different sizes. One guy I hired disconnected the radiator and drained out a little water that had settled inside. He said that’ll do it and billed me $90.

    I’ve got one pipe steam.

    Any advise will be greatly appreciated!!!!!
  • Brad White_203
    Brad White_203 Member Posts: 506
    May not be the radiator

    but the pipe leading to it. Might it have a sag or other potential to trap water?

    If there is a collection of debris in there, sitting on the bottom of the pipe ("as opposed to where- in the top?" he asked rhetorically..), that can create an upstream puddle against which steam-forced condensate has to hurdle.

    I assume that the system runs at low pressure, say under a pound or 1.5 pounds at most? That the others are quiet is a good thing but your pressure may still be high and shows up in this one "weak spot". Worth checking that too.

    Venting and banging are not directly related usually, but glad you got the venting looked at, at least.
  • The problem is elsewhere

    but you hear it in the radiator. Find a good steam man- click on Resources above, then Find a Professional and follow the directions. There are plenty in Joisey.

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  • Sleepless in NJ
    Sleepless in NJ Member Posts: 7
    BANGING Radiator.

    Thanks! I confirmed I’m running a low pressure following directions in Dan Holchan’s book. A couple of other observations…

    1). If I shut that radiator off the banging stops. That’s why I thought the problem was within the radiator.

    2). Banging starts right about the time the radiator is halfway hot.

    3). The valve on this radiator is newer (and) different than the others in the house.

    4). The piping directly above the furnace is almost level for about 2 feet. It then makes a right turn into one of the mains, which is pitched towards the return at the other side of the basement. The piping that goes to the radiator feeds off the level section.

    I’ve posted some pics but it may be difficult to see what I’m talking about.

    Thanks for all the help!
  • Sleepless in NJ
    Sleepless in NJ Member Posts: 7
    BANGING Radiator

    Thanks Steamhead. I posted some pictures, but I think I do need to call in a pro.
  • Brad White_203
    Brad White_203 Member Posts: 506
    Isolating that radiator

    If isolating the radiator stops the banging, that would not point to the radiator as the cause necessarily. It would point out that the source of the banging is leading to that radiator at least. This is why I suspect the pipe.

    Now, you did mention, helpfully, that the banging starts when the radiator is half-way heated. This has be thinking that you may have a dip in your piping or that your lack of insulation is playing a role too.

    (Normally, bare pipe would promote banging on start-up, when the collapse of steam on the colder pipe draws a vacuum and water back to fill it. Still may contribute but does not fit with your timing of the banging you describe.)

    Is the valve fully open? If it is partially closed or if the rubber seat gasket fell loose, that can stop the backflowing of condensate, an obstacle which the incoming steam must get around.

    Some more photos of the near boiler piping would help though, it is hard to tell if the pipes pitch back to the boiler (boiler not furnace :) or if it pitches away.

    When pipes pitch back to the boiler, that is called a counterflow system and the pipe sizes, pitch and drip requirements to remove condensate become critical because steam and condensate are moving in different directions.

    Ideally and conventionally, all should pitch away and the return would come back via a wet return, in most systems. I just want to get a better handle on what you have.

  • BQ
    BQ Member Posts: 1
    Don't sleep

  • Sleepless in NJ
    Sleepless in NJ Member Posts: 7
    Banging Radiator

    Hi Brad -

    Thought I should re-post before I get kicked off. Anyhow I wanted to thank you for your help. I hope you had a nice Thanksgiving, I'm calling in a local pro to look a my problem. Just wondering if you had any more thoughts?
  • That Valve

    on your banging radiator looks like it should belong on a hot water system. It may not have not have enough internal space to allow the condensate and the steam to quietly pass each other.

    Try replacing that valve with a proper steam radiator valve.

    Also, what vents do you have on your radiators?

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  • Sleepless in NJ
    Sleepless in NJ Member Posts: 7
    BANGING Radiator

    Thank you. I've suspected the valve. The vent is a brand new Gorton #4. I've tried larger and smaller vents without any luck.

    I'm not going to mess with the valve myself. I'll be stuck up the river without heat if I crack a pipe or strip the connections.

    I really appreciate all the feedback!
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