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Thread: Evohome and OpenTherm boiler recommendations?

  1. #11
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    Vaillant with the VR33 works fine too. And now there is a solution for the variable target flows depending on DHW heating vs CH heating too. The only bug, I have spotted is an incorrectly reported Outside Temperature sensor over OT. This has no impact now, but if ever Resideo move to using the locally connected Outside sensor for their smart weather features, then it will not work.

  2. #12
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    Quote Originally Posted by bruce_miranda View Post
    Vaillant with the VR33 works fine too. And now there is a solution for the variable target flows depending on DHW heating vs CH heating too. The only bug, I have spotted is an incorrectly reported Outside Temperature sensor over OT. This has no impact now, but if ever Resideo move to using the locally connected Outside sensor for their smart weather features, then it will not work.
    "solution for the variable target flows"? I hope you don't mean by using an OpenTherm monitor?

  3. #13
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    No, basically the Vaillants are able to handle two flow temperatures but using their own eBUS controls. However if you use the Evohome HW BDR91 to short the DHW sensor inputs, it tricks the Vaillant to think its doing a DHW reheat and so uses the DHW settings. It works well.

  4. #14
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    In my earlier post I said I could hear the pump starting up when there is no call for heat. This morning I was decorating where the boiler is and thus could listen to its antics. It is not the pump but the fan that starts up, without the pump and without the boiler firing up. The noise is a whoosh or oomph sound. It runs for a very short time and then you hear it slowing down. When the house is quiet it is quite intrusive. Bloody annoying.

  5. #15
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    Quote Originally Posted by G4RHL View Post
    In my earlier post I said I could hear the pump starting up when there is no call for heat. This morning I was decorating where the boiler is and thus could listen to its antics. It is not the pump but the fan that starts up, without the pump and without the boiler firing up. The noise is a whoosh or oomph sound. It runs for a very short time and then you hear it slowing down. When the house is quiet it is quite intrusive. Bloody annoying.


    It sounds like you have the DHW 'keep hot' function selected, so the boiler will fire occasionaly to maintain DHW temperature between demands. The boiler will also fire to maintain an adjustable minimum flow temperature in very cold conditions.

    Although these firings are audible on our system too, they have never been intrusive, even though the boiler is mounted in the bathroom on the dividing wall with our bedroom. We're very happy with the low noise levels from the boiler.

  6. #16
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    The DHW is set to ECO mode. I would understand it if it was set as you say.

  7. #17
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    Quote Originally Posted by G4RHL View Post
    The DHW is set to ECO mode. I would understand it if it was set as you say.
    My boiler is set to ECO mode too.

  8. #18
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    Quote Originally Posted by blowlamp View Post
    My boiler is set to ECO mode too.
    It is of course possible that it is still in learning mode. I did not notice it as much early this morning before any heat or hot water was needed. I assume Evohome provides the time for the Eco function to work properly. What is odd is that if you switch the power off it looses the set time. Not helpful to those who rely on the programme in the boiler. No backup battery. Which reminds me I switched it off yesterday whilst I re-routed a cable and have forgotten to reset the time clock!

  9. #19
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    Quote Originally Posted by G4RHL View Post
    It is of course possible that it is still in learning mode. I did not notice it as much early this morning before any heat or hot water was needed. I assume Evohome provides the time for the Eco function to work properly. What is odd is that if you switch the power off it looses the set time. Not helpful to those who rely on the programme in the boiler. No backup battery. Which reminds me I switched it off yesterday whilst I re-routed a cable and have forgotten to reset the time clock!
    The boiler DHW operation is completely independent from Evohome, Evohome doesn’t provide the time. The Eco learning is supposed to be based on usage, so I guess it’s essential that the boiler’s time setting is consistent.

  10. #20
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    Quote Originally Posted by kevinsmart View Post
    The boiler DHW operation is completely independent from Evohome, Evohome doesn’t provide the time. The Eco learning is supposed to be based on usage, so I guess it’s essential that the boiler’s time setting is consistent.
    But I have OpenTherm connected and the Manual says to use Eco mode with OpenTherm in order for OpenTherm to learn. I wonder if anybody has come up with an easy way t provide backup power to the clock on these boilers>?

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