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Thread: HELP - System running with no control?

  1. #1
    Automated Home Jr Member
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    Default HELP - System running with no control?

    We have had an Evohome installation for 3-4 years now, no big issues to speak of.

    We came home from a weekend away with the system set to 'away', my wife adjusted some of the rooms (2 x UFH zones & rest Radiators) on our way back. When home we reset the zones back to the normal schedule & ultimately cancel all demands for heat.

    As I get into bed, I hear the boiler going, and I go to check the Airing cupboard, to find both the Hot Water & Radiators BDR91 are lit up, as well as both UFH zones lit on the HCC80R (UFH manifold controller)

    I check the controller & there is no demand for heat, all Zones are set to their 'Night time' Temps. I try turning the zones on & off again and yet the system continues 'running heat'.

    At this stage I am worried, so I turn everything off at the mains and leave it 15mins. I then turn it all back on again.

    Now, this is where I am at.

    The BDR91s are unlit/turned off, but ONE Zone on the UFH is lit....but the Manifold has both loops running flow through them. The boiler is also still fired & warming up these zones.
    The Main wall controller (big touchscreen) is showing our glasses for ALL zones

    ...and I have my UFH rooms at the hottest they have ever been?

    Can anyone please advise? For now it looks like I need to turn the whole system off at the mains to kill the heating?

  2. #2
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    could it be a failed zone valve? All three seem to actuate as normal with the lever, I also don't get how a failed zone valve would cause the UFH controller +manifold to light up & engage? Though I didn't wire it/am not clued up on this sort of setup.

  3. #3
    Automated Home Legend paulockenden's Avatar
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    Could be the microswitch in one of the zone valve heads has failed.

    P.

  4. #4
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    Quote Originally Posted by paulockenden View Post
    Could be the microswitch in one of the zone valve heads has failed.

    P.

    Thanks Paul, grateful for your post!

    With mine the system is heating up though, my UFH Controller lights up, opens the flow valves and the UFH all warms up.

    Could the Zone valve have failed 'open' allowing the flow & triggering the UFH Controller + Boiler?

  5. #5
    Automated Home Legend paulockenden's Avatar
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    I guess it depends how the wiring has been 'chained'.

    Can you not get your installer back to take a look? They'll obviously know how they did it, and so would be best places to advise.

    P.

  6. #6
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    Quote Originally Posted by paulockenden View Post
    I guess it depends how the wiring has been 'chained'.

    Can you not get your installer back to take a look? They'll obviously know how they did it, and so would be best places to advise.

    P.
    Installer retired a year ago it when I last spoke to him about another job.

    I have checked out the Zone valve on the UFH loop and it looks to be working fine. Actuator, motor all seems to be functioning normally.

    Watching the system start up the HCC80R is first to switch on Zone 1 then several seconds later Zone 2 engage. This actuates the Motorised Zone valve for that loop.I therefore don't think it is the Zone valve?

    What I cant work out is what is switching on the HCC80R.... Even disconnecting the two BDR91s (one for HW & one for 'rads') one at a time make no difference to the HCC80R turning on, and after that I am not sure what else could be connected to the HCC80R to switch it on?

    Two local plumbers I have rang have said they will have a look for their call out fee (100 inc vat) but are not familiar with the Evohome in great deal.
    Last edited by Andehh; 8th October 2019 at 07:09 PM.

  7. #7
    Automated Home Legend paulockenden's Avatar
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    What area do you live in? Perhaps there might be another forum member living nearby who could try to help you.

  8. #8
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    Factory reset the HC880R. Left it - No heat demand, system stayed off.

    Tried re-binding the individual dial controllers....one seems to work fine...the other one though....!!! Within minutes of binding it in....the system starts firing up without any visual display to say it is nor heat demand asking for it!

    It is (touch wood touch wood) looking increasingly like a failed T87RF2033 / Rotary dial thermostat!

    Going to spend next 30mins proving out a few other things out, but fingers crossed!!!


    Edit1:

    Both T87RF2033 binded, system responding Normally, though one T87RF2033 is still showing the mystery 15% demand!


    Edit2: End of day 2, 8 hours in now....

    System all seems to be working, BUT - for my ''Zone 2'' - whatever the controller I use (dial or Evo Controller) I am still seeing a Phantom ''15%'' demand logged in the installers menu. I am leaving it for a few hours with the second Zone controlled via the Evohome Controller instead of the T87RF2033 Dial..... What I don't like is even with this controller, I have that bloody 15% demand.

    Ill give it a couple of hours & see if the system comes back on because of the 15% demand, or whether that is some sort of bug/glitch.


    Humph, Some progress....not quite there yet!
    Last edited by Andehh; 9th October 2019 at 08:01 PM.

  9. #9
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    Just as an update, removing the T87RF2033 from one of the UFH zones seems to have resolved the issue. Desbite it looking & working fine, when left unattended it seemed to send an errant heat demand (15% demand) which kept turning the system in without any visible indication of why. Only within the system installation menu did it show this 15% heat demand. Thank goodness it does!.. Removing the dial and replacing the thermostat for that zone with the main evohome controller seems to have resolved....

    Still utterly baffles as to why the t87rf suddenly started with these phantom signals. Guess I'll never know!

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