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Tapping / banging noise from pipes when gas heating goes on / off?

  • 01-03-2010 6:39pm
    Registered Users Posts: 362 ✭✭

    Heya Folks,

    Over the past while I've had a noise coming from the pipes in the ceiling above the ground floor - it used to come from some of the radiators too but I've bled all of them and there seems to be no more air trapped within. I'm getting a rattling / tapping noise whenever my gas heating turns on for a while which gradually dies down and the same again when the heating goes off - needless to say since the heating goes off just before I go to bed and my bed is directly above some of the offending pipes it's quite annoying!

    Would this be more trapped air in the system somewhere? I've heard that there's also a valve in most attics that can be used to vent air from the heating - I popped up into mine but couldn't see anything obvious to try. Or do you reckon this is more to do with the gas system and something I should get an installer out to look at? It's a new boiler system put in about 4 years back - admittedly I haven't had it serviced yet :o

    Cheers for any thoughts!



  • Registered Users Posts: 44,080 ✭✭✭✭Micky Dolenz

    One common cause of this is when the pipe heats it expands and moves slightly. This causes the pipe to rub or knock off joists or where it comes through a timber floor. It also happens as the pipes contract when cooling down.

    It may also be caused by Thermostatic rad valves that are opening/closing incorrectly.

  • Registered Users Posts: 362 ✭✭joconnell

    It's only started this year after 5 years living here and no recent construction that would have dislodged or otherwise caused a shift. By Thermostatic rad valves do you mean the usual valves either end of the usual wall radiators?

    Would the recent extremes of cold have been a reason for this starting?

  • Registered Users Posts: 2,526 ✭✭✭JohnnieK

    Was the house new when you bought it? If so Micky is still right. At the start there would be little noise but after time joist settle and with the heating pipes passing through them cause the joists to expand and contract with the heat.

    I have the same thing here in my house.

  • Closed Accounts Posts: 672 ✭✭✭items

    As most have said I'd go for expansion / contraction of fittings / pipe work. might never have been a problem but over time pipes in ceiling will move even sag if not supported right, ceiling joists also expand / contract over the years as they settle.

    If you can pin point the exact area prob best to lift a board or two and place some insulation or a wedge to stop any sounds.

    I would'nt be surprised if sound was coming from area you expect the least, happens a lot, sound traveling and all that.

  • Registered Users Posts: 362 ✭✭joconnell

    Getcha. The house would be about 17 years old at this stage so you reckon it's mainly settling related at this stage? The noise is centred around the floor underneath my bed (bastards!) but I'm not sure which way the system flows from it's sources. I'll get a heating person out to take a look so. Much appreciated!

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  • Closed Accounts Posts: 672 ✭✭✭items

    Their is no real way of telling without lifting boards, all you can do is base some idea of pipework direction from position of rads compared to other rads along with boiler position.

    Best of luck with it.

  • Registered Users Posts: 362 ✭✭joconnell

    Cheers for the advice - much appreciated :)