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Thread: Very noisy CH when TRVs are turned down

  1. #1
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    Default Very noisy CH when TRVs are turned down

    Hi

    My CH is unusually noisy and I'm wondering if anyone else has had a similar experience. I've had a couple of plumbers come and have a look with no joy.

    All the radiators in the house have TRVs. The Worcester combi boiler supposedly has an automatic bypass fitted. There are no separate wall/room thermostats.

    When all of the TRVs are turned on full, the noise from the CH is acceptably ambient.

    However, when I turn down one of the TRVs to a lower setting (in the kitchen, for example), this seems to create a blockage for the entire system.

    The gush of circulating water in all of the radiators gets (and stays) very, very loud and is accompanied by a high-pitched whine. This reverberates throughout the entire house and sounds like a huge strain on the system. The only cure is to turn all the TRVs on full.

    Any ideas?

    Thanks for your suggestions.

    Les

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    Moderator toscal's Avatar
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    Default Re: Very noisy CH when TRVs are turned down

    What type of noise is it.
    Banging type this could be a faulty vavle, or the water flow is too fast. See if there is a switch on the side of the pump, they are usually marked 1,2 and sometime even a 3. This could also be marked as I, II, or III. Try a lower number.
    If the pipes are humming this could be vibrational noise from the pump, you can get anti-vibration pump brackets and fit these. This may help. Also check the pump speed. And lastly the actual diameter of the pipes may be too small for the amount of water they have to carry arround the system.
    If its creaking noises then the pipes could be expanding and if they gom through floor boards or walls. The holes may be too small to alow for expansion.
    Lastly and the easiest one to try first is that banging, howling or whistling pipes can sometimes be caused by air in the system. So try bleeding the rads first and see if this improves the situation.
    Something else to try if you have a pressure relief valve or vent pipe then check its not leaking, or corroded, it could be letting air into the system.

  3. #3
    Moderator sunbeam's Avatar
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    Default Re: Very noisy CH when TRVs are turned down

    do you know what model of Worcester.

    how hot are your rads?

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    Default Re: Very noisy CH when TRVs are turned down

    Never turn the pump speed down on a combi. Not if you want hot water.

    Try leaving one TRV off. Remove the head.

  5. #5
    Moderator toscal's Avatar
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    Default Re: Very noisy CH when TRVs are turned down

    "Never turn the pump speed down on a combi. Not if you want hot water." Botmission how do you know this. On my combi boiler the pump is only used for the central heating. I have just turned the pump speed down and I still get hot water. I have Junkers Bosch combi boiler. And also I had a problem with my boiler and it was to do with the pump. It wouldn't work but I still got hot water as normal. So where are you getting this information about the pump and hot water.

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    Default Re: Very noisy CH when TRVs are turned down

    On every combi I've worked on, the pump is part of the operation of the boiler, heat or hot water. Also they have high head pumps which are basically faster than the ones in a non combi system.

    A valve or dual heat exchanger determines heating of hot water.

    Wouldn't know about the ones in Spain though...

  7. #7
    Moderator sunbeam's Avatar
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    Default Re: Very noisy CH when TRVs are turned down

    some Worcesters ,same as alpha c range combis don't use the pump for hot water, they work like a normal multipiont.

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    Default Re: Very noisy CH when TRVs are turned down

    I had an identical problem a few years back with noise on a combi boiler, the pump needed to be reduced in speed and all was fine after that.

    Before the speed was reduced the vales, both lock sheld and the TVR had to be left fully open on most of the rads to cure the noise.

    And....

    Some idiot had wired the pump straight into the mains, so it ran 24/7

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    Default Re: Very noisy CH when TRVs are turned down

    Hi

    Many thanks for your replies. They've given me a few things to troubleshoot.

    Curiously, one of the plumbers mentioned in passing that the pump was a bit noisy, though stopped short of investigating as it's not much more than a year old.

    To answer those unanswered questions:

    The best way to describe the radiator noise is like the loud hissing of open gas taps on a cooker top. Times infinity.

    The radiators get appropriately hot and the model is a Worcester 24 or 28 (can't remember exactly which at the moment).

    Thanks again for the suggestions.

    Les

  10. #10
    Moderator sunbeam's Avatar
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    Default Re: Very noisy CH when TRVs are turned down

    With Worcester 24 i & 28 i the pump doesn't run on hot water,
    but I'm sure you can't turn the pump down,
    I concure with botmission take off a t.r.v head.
    failing that put some cleanser in the system for a few days via a rad, drain down and re-fill.

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