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Thread: Evohome HR92s not sending demand for heat.

  1. #11
    Automated Home Legend paulockenden's Avatar
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    Quote Originally Posted by Ozzx View Post
    Care to elaborate? How far apart should they be and why? Interference?
    Min 30cm apart. And yes, interference / performance issues.

  2. #12
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    So I guess my issue is I need something to tell the zone valve actuator and the pump to start? Any ideas?

  3. #13
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    If all radiators are HR92s there is no need for zone valves actuators. As you suggest it seems to be a zone valve problem so I would start by disconnecting the zone valves and manually opening them all , and then seeing if the radiators heat when requested by the HR92s .

    You don’t actually need a zone valve for the ufh as the manifold valves will control the flow. However when I installed mine I was told it was good practice to include a ufh feed zone valve. Which is controlled by the hcc80.

    The ufh zone valve actuator and separate ufh pump should be controlled by the hcc80 pump switch output. This ufh valve / actuator obviously should feed >only< the ufh , but in your case it looks as if it feeds the upstairs radiators too !!! Hence my suggestion to disconnect it and leave it open manually.

    An alternative wiring is that the hcc80 will switch the ufh feed zone valve actuator and the actuator in turn will switch on the ufh pump. However In my system I wired both the ufh pump and ufh zone valve in parallel to the hcc80 pump output.

  4. #14
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    Quote Originally Posted by rvb99 View Post
    If all radiators are HR92s there is no need for zone valves actuators. As you suggest it seems to be a zone valve problem so I would start by disconnecting the zone valves and manually opening them all , and then seeing if the radiators heat when requested by the HR92s .

    You don’t actually need a zone valve for the ufh as the manifold valves will control the flow. However when I installed mine I was told it was good practice to include a ufh feed zone valve. Which is controlled by the hcc80.

    The ufh zone valve actuator and separate ufh pump should be controlled by the hcc80 pump switch output. This ufh valve / actuator obviously should feed >only< the ufh , but in your case it looks as if it feeds the upstairs radiators too !!! Hence my suggestion to disconnect it and leave it open manually.

    An alternative wiring is that the hcc80 will switch the ufh feed zone valve actuator and the actuator in turn will switch on the ufh pump. However In my system I wired both the ufh pump and ufh zone valve in parallel to the hcc80 pump output.
    Thanks for the detailed reply, I think I now have it sorted. I turned the heating on so the zone valve actuator opened then removed it so it will stay open. Ill check again but it seemed to work with the downstairs heating off and I turned 1 radiator on upstairs.

    Cheers again, hopefully thats it all working 100%. I might move the 2 relays further apart if I start seeing any issues later.

  5. #15
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    Looks like I was a bit hopeful, it appears the upstairs heating is still not working unless ufh is on. I guess I need some way to turn on the pump when the HR92s need heat?

  6. #16
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    Your set up seems a little confusing. The heating bdr should be bound to the evohôme which it seems it is as the ufh comes on and the boiler fires.

    Now for the upstairs .Is it that the boiler does not fire or that the pump does not run or that the zone valve for upstairs is not opening .

    Does the bdr come on when the upstairs HR92s call for heat? If yes then it seems to be a zone valve or heating pump wiring problem .

    The fact that upstairs only comes on when the ufh heating is on suggests perhaps they are sharing the same zone valve and possibly the heating pump. However, The ufh most likely will run without the heating pump as the ufh internal circulating pump will draw from the heating circuit ( mine will but I still switch the heating feed pump with the boiler) . So as you say it’s probably the heating pump not switching.

    If the zone valve for upstairs is opening then the pump should be switched , either directly from the bdr or via the relay output on the upstairs ( +ufh?) zone valve. Ie when the valve is open one of the relay wires ( orange - but check ? ) becomes live and can be used to switch the pump ( and also the boiler in the case the boiler is not directly wired to the bdr)
    Last edited by rvb99; 8th April 2018 at 12:14 PM.

  7. #17
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    Sorted now! Thanks all for the help. It was actually a faulty zone valve actuator, when I opened it up I found that some of the teeth on the motor cog were broken which stopped it from fully opening and the switch never activated to send the demand to the boiler. I replaced the zone valve actuator and all is working perfectly :-)

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