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Thread: Hammering TRV

  1. #1
    Automated Home Jr Member
    Join Date
    Jun 2009

    Default Hammering TRV

    While not directly related to 'home automation', I wonder if any of the heating engineers on this forum might be able to help.

    I refurbished my bedroom last year and this included replacement of the old radiator in there with a smaller (and smarter) one. After this was done, I replaced the TRV head with my usual conrad FS20 actuator and noticed that the TRV was making odd hammering noises - it sounds like a jackhammer and echo's through the house. My plumber suggested it was down to my actuator.

    Having taken the actuator off and replaced it with the original TRV head, this isn't the case and is most definately down to the TRV. The plumbers came back and replaced it (although I wasn't there to witness this) but the "new one" does exactly the same. I believe it only happens when the TRV is open a little as adjusting it either way stops the hammering (for a while).

    I have an inkling that they have put the TRV on the 'return' side of the radiator. The reason I believe this is that with the TRV off and the radiator cold (but the system running), the pipe on the side of the radiator with the lockshield is hot, but the pipe on the side with the TRV is cold. Also, while I only have three radiators upstairs, the other two both have their TRV's on the left and this one is on the right (interestingly all the TRV's downstairs are on the right hand side) - one assumes the original installer would have followed some sort of pattern? I say inkling because it took me about a year to refurbish the bedroom (during which there was no radiator, the TRV head removed and the pipework capped off) and I genuinely can't remember which side it was on previously. The replacement also involved the plumbers replacing the microbore pipe with 15mm and this was done under the floor so they may have moved pipes around.

    Does it matter what side the TRV is on? My plumbers say it doesn't. I don't think the TRV is a particularly expensive one (it is branded 'Lifestyle' or something like that). With winter now approaching I am keen to get this resolved. The only long term solution at present is to either have the rad full open (i.e. '5') or fullly closed and as a result it is either 30+ degrees or bloody freezing!

    Any thoughts would be appreciated.

    Automating my home in a family friendly way - My blog:

  2. #2


    sounds to me like the valve is directional and therefore is indeed fitted on the return incorrectly. Some TRVs are universal and designed to go on either end, while others can only be fitted to either the flow or return but not both. So you either need a universal valve fitting (such as the Honeywell valve bodies) or get the plumber to swap the TRV and lockshield valve and all should be well (providing the valve chatter has not damaged the valve).
    Sensible Heat

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