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Thread: UFH - EvoHome and reluctant plumber

  1. #41
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    Any view on using the HM80 in place of my BDR91? I.e. just using the ON signal to open my current 2 port zone valve but using the HM80 to control the pump.

  2. #42
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    Quote Originally Posted by bruce_miranda View Post
    Any view on using the HM80 in place of my BDR91? I.e. just using the ON signal to open my current 2 port zone valve but using the HM80 to control the pump.
    I think that would only make sense if you could find a compatible 2-way rotary valve that the actuator could adjust to alter the flow temperature. But you would then need an auto bypass across your manifold to stop your UFH pump dead heading when the valve has limited flow.

    Hmm, in that case could you not just use an HR92 as the actuator and room thermostat as the sensor?

    Iíll think about it some more.

  3. #43
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    See how my manifold controller looks.

    The boiler flow and return goes into the bottom. This is clearly being mixed down to the required temperature by the TRV at the bottom and then fed to the manifold flow loops at the top.

    Are you saying that if the boiler flow zone valve closes the flow from the boiler, the UFH pump would dead end? How,? Won't the UFH just recycle the water within the UFH loops but without new Hot water coming in from the boiler.
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  4. #44
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    Quote Originally Posted by bruce_miranda View Post
    See how my manifold controller looks.

    The boiler flow and return goes into the bottom. This is clearly being mixed down to the required temperature by the TRV at the bottom and then fed to the manifold flow loops at the top.

    Are you saying that if the boiler flow zone valve closes the flow from the boiler, the UFH pump would dead end? How,? Won't the UFH just recycle the water within the UFH loops but without new Hot water coming in from the boiler.
    If you replaced your 3-way with a 2-way rotary valve your pump could dead head when the room is close to set point with the valve restricting boiler flow to the manifold. The same situation occurs in my new house if all manifold actuators are closed, so there’s an auto bypass bridging flow and return.

    So best to retain your 3-way setup (I went 4-way because that was my original setup). And fit a gate valve to restrict flow when the valve is diverting all flow to return. If your floor design temperature is only 35C you probably don’t need much injected flow to your UFH circuit.

  5. #45
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    Where do you see a 3 way in my set up?

  6. #46
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    Quote Originally Posted by bruce_miranda View Post
    Where do you see a 3 way in my set up?
    Iím assuming thatís a flow connection at the bottom, return at the right of the thermostatic valve and supply at the top. So you would junk your thermostatic valve for a 3-port: one port flow, one port return, one port supply to manifold.

  7. #47
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    It's actually a flow and return at the bottom from/to boiler. Then to the Top is the mixed manifold flow going into the pump, and then coming from the Right is the manifold return.
    Hence my question. Why would my UFH pump dead end if I simply shut off the boiler flow. Wouldn't the UFH just continue to circulate the water through the manifold loops, but with no new hot water coming in from the boiler flow.

  8. #48
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    Quote Originally Posted by bruce_miranda View Post
    It's actually a flow and return at the bottom from/to boiler. Then to the Top is the mixed manifold flow going into the pump, and then coming from the Right is the manifold return.
    Hence my question. Why would my UFH pump dead end if I simply shut off the boiler flow. Wouldn't the UFH just continue to circulate the water through the manifold loops, but with no new hot water coming in from the boiler flow.
    It wouldnít with your current setup but certainly in my case the motivation was to replace a thermostatic mixing valve/blender with an actuator controlled rotary valve. Is that not what you want to do?

  9. #49
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    Yes and No. I actually want the UFH pump to stop doing TPI because I do not believe it should. I am also thinking that if I can control the temperature of the water coming into the manifold TRV, then I am effectively doing away with the TRV in any case, because it would be open completely.

  10. #50
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    Kevin, I looked at your previous configuration picture again. In your case too, if you shut off the flow from the boiler completely, wouldn't your UFH pump just circulate the water round the manifold loops, especially since I note you don't the powered actuator heads arent used on the manifold returns, so they will must be fully open.

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