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Thread: Radiator knocking

  1. #1
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    Default Radiator knocking

    Hi,

    Anyone help please, I have one radiator that seems to have a valve that sticks, I hear the HR92 adjust then the radiator knocks. If I remove the HR92 and manually turn the wheel it stops.

    I have just set the stroke to 1 on the menu, is this likely to help?

    Any other ideas?

    Thanks

    Gl3n

  2. #2
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    So still causing issues, it seems the HR92 is not closing the valve off, removing it and turning the wheel stops the knocking.

    Using new batteries and Duracell ones. The wheel does not seem stiff. I recall someone mention you can turn up the power some how!

    Any ideas?

    Thanks

    Gl3n

  3. #3
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    Quote Originally Posted by gl3n View Post
    So still causing issues, it seems the HR92 is not closing the valve off, removing it and turning the wheel stops the knocking.

    Using new batteries and Duracell ones. The wheel does not seem stiff. I recall someone mention you can turn up the power some how!

    Any ideas?

    Thanks

    Gl3n

    what TRV body do you have and is it installed on the flow or return?
    I work for Resideo, posts are personal and my own views.

  4. #4
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    Quote Originally Posted by gl3n View Post
    So still causing issues, it seems the HR92 is not closing the valve off, removing it and turning the wheel stops the knocking.

    Using new batteries and Duracell ones. The wheel does not seem stiff. I recall someone mention you can turn up the power some how!

    Any ideas?
    The valve should not be knocking with any degree of valve opening. This is not the HR92's fault - all it does is adjust the position of the valve.

    Does it start knocking again if you manually adjust the wheel to just the right location ? If so you almost certainly have water hammer caused by a directional TRV valve body being fitted to the wrong side of the radiator.

    Older TRV valve bodies were designed to only work with the water flowing in one direction, as indicated by an arrow on the body. If they are installed the wrong way around, (usually by fitting them to the wrong side of the radiator) this will cause a hammering/knocking/vibration when the valve is open to just the right amount. It may also depend on what other radiators in the house are doing as the pressure to the radiator will change as other TRV's in the house open and close. So it might not do it all the time.

    Modern TRV's are designed to be bidirectional. Check carefully the model of TRV valve body you have for any arrows - if it has only one arrow it is directional and must be installed with the arrow in the right direction.

    I had this exact problem in a flat we lived in on the bedroom radiator - the TRV was installed on the wrong side of the radiator. Swapped it over, all good.

    Assuming this is your problem you either need to swap the TRV valve body with the lockshield valve, or if it's not practical to swap them due to obstructions you'll need to replace it with a modern bi-directional TRV valve body.
    Last edited by DBMandrake; 4th April 2016 at 03:07 PM.

  5. #5
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    Hi,

    It has two arrows, one pointing in to the radiator and one down to the pipe.

    No make I can see.

    It has only just started doing it, I have had all my HR92's for a good year or so.

    Not sure why, I will swap this with another.

    Thanks

    Gl3n

  6. #6
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    Ah ok looks like the it is actually installed the wrong side.

    I set it manually and it just knocks as you say, so looks like I need someone to swap it around.

    Not sure why it has only just started doing it but it is in a room we don't use often.

    Cheers

    Gl3n

  7. #7
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    If it has two arrows pointing in opposite directions it means its a bi-directional valve, so it shouldn't matter what side of the radiator it is installed on.

    In that case I would replace it as it sounds like the valve has become faulty. Make sure to use one that is compatible with the HR92 - preferably without needing an adaptor.
    Last edited by DBMandrake; 5th April 2016 at 12:46 AM.

  8. #8
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    Hi,

    I had a similar problem with two of my TRVs, but this started only a few days after installing the Evohome system. I have 16 radiators in total, with a mix of different TRV brands and 2 of them started creating a knocking/humming noise when nearly closed, particularly when most other zones had hit their set point temperature and closed. I could re-create the noise if I removed the HR92 head and turned the knurled wheel by hand until the valve was almost closed, opening a little further or closing fully stopped the noise. These two TRVs were about 2 years old with the brand name 'Pro' and clearly labelled as bi-directional. I tried opening and closing the valves fully by hand to see if this might clear the problem, but it didn't seem to. I also tried adjusting the automatic bypass and the pump settings, but these didn't seem to help either. I've now replaced them both with Honeywell Valencia TRVs and all is working perfectly.

    Dan

  9. #9
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    Thanks Dan sounds exactly like my issue, thanks to everyone else for your help to.

    Gl3n

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