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Thread: All rads working with HR 92 EVOHOME bar one1!

  1. #1
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    Default All rads working with HR 92 EVOHOME bar one1!

    I've just fitted my system with the help of a good electrician. All the rads are working in harmony with the HR 92's but one rad is getting hot whenever the hot water is on! Its HR92 is set to off, but still gets hot! I've set it to full stroke, parameter 6, but no joy. Any advice welcome!!
    DW

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    Quote Originally Posted by dafydd View Post
    I've just fitted my system with the help of a good electrician. All the rads are working in harmony with the HR 92's but one rad is getting hot whenever the hot water is on! Its HR92 is set to off, but still gets hot! I've set it to full stroke, parameter 6, but no joy. Any advice welcome!!
    DW
    Check the pin in the valve moves easily. Take the HR92 off and push the pin in and out a few times. It may be stuck and the HR92 not able to depress it.

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  4. #4
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    Quote Originally Posted by G4RHL View Post
    Check the pin in the valve moves easily. Take the HR92 off and push the pin in and out a few times. It may be stuck and the HR92 not able to depress it.
    How difficult should it be to move the pin? Should I be able to move it with a finger?
    many thanks for the advice and the video!
    Dafydd

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  6. #6
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    Quote Originally Posted by dafydd View Post
    How difficult should it be to move the pin? Should I be able to move it with a finger?
    many thanks for the advice and the video!
    Dafydd
    You should be able to. When I have done I have used the flat side of a knife blade to make it easier.

    What I am not sure about advocating, and others here can certainly confirm or otherwise, is whether it is wise to use WD40 on it.

  7. #7
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    If a TRV valve body is seizing, spraying any sort of rust penetrant or lubricant in the top down the pin is unlikely to help. In ones I have removed/replaced the pin rusts down inside the body where the water flow is - this is below the o-ring that seals the pin for leakage. So this o-ring will also prevent any lubricant getting down to where it needs to be.

    If the pin can't be pressed down with a thumb against the endge of a knife blade it's probably seized. Another way to check is to try turning the black wheel on the HR92 fitting - it should turn about 2-3 turns clockwise from the top and be quite easy to turn by hand due to the leverage of the plastic screw. If it's not easy or doesn't turn far the pin is also seized. Don't force it if it feels tight as the screw is only made from plastic.

    If it's seized I'd say replacement is the only option even though that probably means calling in a plumber for most people on an already filled/pressurised system. Be careful to choose a valve body that is compatible with the HR92 - while any M30 x 1.5 body will in theory work, they all have differences in pin stroke, pin length etc which can cause issues. If the other valves around the house seem to be working properly then I'd probably try to get the exact same valve as used elsewhere in the house, provided it's of decent quality.

  8. #8
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    Quote Originally Posted by DBMandrake View Post
    If a TRV valve body is seizing, spraying any sort of rust penetrant or lubricant in the top down the pin is unlikely to help. In ones I have removed/replaced the pin rusts down inside the body where the water flow is - this is below the o-ring that seals the pin for leakage. So this o-ring will also prevent any lubricant getting down to where it needs to be.

    If the pin can't be pressed down with a thumb against the endge of a knife blade it's probably seized. Another way to check is to try turning the black wheel on the HR92 fitting - it should turn about 2-3 turns clockwise from the top and be quite easy to turn by hand due to the leverage of the plastic screw. If it's not easy or doesn't turn far the pin is also seized. Don't force it if it feels tight as the screw is only made from plastic.

    If it's seized I'd say replacement is the only option even though that probably means calling in a plumber for most people on an already filled/pressurised system. Be careful to choose a valve body that is compatible with the HR92 - while any M30 x 1.5 body will in theory work, they all have differences in pin stroke, pin length etc which can cause issues. If the other valves around the house seem to be working properly then I'd probably try to get the exact same valve as used elsewhere in the house, provided it's of decent quality.
    Many thank for all the help, it's really appreciated. I tried the pin and it moves ok. Had another think and checked some other things. I've discovered the trv is fitted to the outflow of the rad and not the flow in. So Im guessing although the valve is closed the rad' still gets hot. Does this mean I have to switch the trv and the 'stopped' valve around?

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    Quote Originally Posted by dafydd View Post
    Many thank for all the help, it's really appreciated. I tried the pin and it moves ok. Had another think and checked some other things. I've discovered the trv is fitted to the outflow of the rad and not the flow in. So Im guessing although the valve is closed the rad' still gets hot. Does this mean I have to switch the trv and the 'stopped' valve around?
    The radiator can only get hot if water flows through it. It doesn't matter whether the valve is on the input or output side, if the valve is closed water won't flow.

    In fact traditionally valves usually go onto the output side of a radiator (as older valve types would experience water hammer if used on the input side) however modern valves can go on either side.

    So it's not that.

  10. #10
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    Just goes to show, a little knowledge is a dangerous thing! Thanks for giving me that information otherwise I could have wasted a lot of time trying to switch valves. I guess the valve itself must be faulty so looks like I have to change it for another. Really appreciate all the help. Cheers

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