Page 1 of 2 12 LastLast
Results 1 to 10 of 17

Thread: Evohome HR92s not sending demand for heat.

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. #1
    Automated Home Jr Member
    Join Date
    Oct 2017
    Posts
    10

    Default Evohome HR92s not sending demand for heat.

    Hi all,

    After months of trying to get someone to install my evohome system I finally got it in last weekend.

    Downstairs is underfloor heating with a singlezone thermostat in each room
    Upstairs are 4 radiators with HR92 TRVs.

    Downstairs heating and hot water are both working properly, however the upstairs radiators are not sending a call for heat when needed.

    The HR92s are bound to the controller and show the current temperatures and set temps, the motorised valves open and close when the set temp is changed either from the controller or on the TRVs themselves but the boiler does not fire up when needed. If the underfloor heating is on then the upstairs radiators will heat up as required but if all the zones downstairs are off then the boiler is off and there is no heat going to the radiators.

    I have done RF checks and got signal strength 5.

    Any ideas what is wrong or what checks I can do?

    Thanks

  2. #2
    Automated Home Legend
    Join Date
    Sep 2014
    Location
    Scotland
    Posts
    1,917

    Default

    We'd probably need to know a bit more about how your system is set up to help.

    What kind of boiler do you have, and how is the Evohome system configured to fire the boiler ? Are you using the OpenTherm bridge, or the BDR91 relay box ?

    You have a mix of underfloor heating, radiator valves and hot water - so how many BDR91's do you have in total ? I'm assuming the system is S-Plan - are the zone valves wired to fire the boiler ? Do you have the HCC80 underfloor mixing controller ?

    The issue it not going to be the HR92's not calling for heat, it will be how the Evohome is wired up to fire the boiler.

    One thing you could check is in the installer menu (long press on settings) go into system summary where you will see the current heat demand for each zone - take a picture of this when your upstairs radiators are turned on but your boiler is not firing.

  3. #3
    Automated Home Ninja
    Join Date
    Aug 2016
    Posts
    489

    Default

    Since you've described upstairs and downstairs operating differently, have you got separate zone values for each floor, and has your boiler been configured to fire off the orange wire from only one of the zone valves?

  4. #4
    Automated Home Jr Member
    Join Date
    Oct 2017
    Posts
    10

    Default

    Thanks for the replies, was a busy week so only just getting round replying. Below a description of my setup with some pictures to help identify where the issue is.

    The boiler is oil fired with 2 x BDR91 relays wired in (1 for heating, 1 for hot water).
    20180318_115609.jpg

    The hot water kit is installed and working fine.

    Heating upstairs is by radiators (total of 4), each with a HR92 TRV.

    The underfloor heating has 6 zones, each with a T87RF2033 single zone thermostat linked to the underfloor heating controller (HCC80R with extension module).
    20180318_120252.jpg
    20180318_115708.jpg

    You can see in the above photos that there is another pump for the heating system and 2 x zone actuators, 1 for the underfloor and 1 for the upstairs heating (I think!). Im guessing there is nothing telling this pump to go on when the upstairs radiators need heat.

    Thanks for any advice how to sort this.

  5. #5
    Automated Home Jr Member
    Join Date
    Oct 2017
    Posts
    10

    Default

    Quote Originally Posted by dty View Post
    Since you've described upstairs and downstairs operating differently, have you got separate zone values for each floor, and has your boiler been configured to fire off the orange wire from only one of the zone valves?
    dty, Im not sure about this as I didnt do the wiring. Is there an easy way to check?

  6. #6
    Automated Home Legend paulockenden's Avatar
    Join Date
    Apr 2015
    Location
    South Coast
    Posts
    1,633

    Default

    BDR91s are *much* too close together.

  7. #7
    Automated Home Jr Member
    Join Date
    Oct 2011
    Posts
    11

    Default

    Does the green light on the BDR91 relay box come on when the upstairs HR92s call for heat ?

  8. #8
    Automated Home Jr Member
    Join Date
    Oct 2017
    Posts
    10

    Default

    Quote Originally Posted by paulockenden View Post
    BDR91s are *much* too close together.
    Care to elaborate? How far apart should they be and why? Interference?

  9. #9
    Automated Home Sr Member
    Join Date
    Oct 2017
    Location
    France & UK
    Posts
    74

    Default

    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.

  10. #10
    Automated Home Jr Member
    Join Date
    Oct 2017
    Posts
    10

    Default

    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.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •