Results 1 to 4 of 4

Thread: Evohome, 3 zone valves and partial HR92 deployment

  1. #1
    Automated Home Lurker
    Join Date
    Nov 2021
    Posts
    3

    Question Evohome, 3 zone valves and partial HR92 deployment

    I have a recently installed Evohome controller retrofitted to a pre-existing home heating system. All is working well, except that the HR91 valves cannot fire the boiler unless one or more zone valve is open. Hereís a brief summary of the system.

    1. Evohome controller (2021)
    2. There are two heating zones and one hot water, each controlled by a motor valve, 3 in total.
    3. Each motor valve is controlled by a BDR91 relay. Thereís also a further BDR91 as a boiler relay (4 in total).
    4. Each heating zone has a wireless wall stat (T87/Y87) associated which controls the relay and in turn the motor valve for the zone
    5. Almost all radiators have TRVs, but only 4 have HR92 valve actuators
    6. A wireless cylinder stat drives the hot water relay and itís associated valve
    7. The zone valve contacts are wired in parallel with each other and in series with the boiler relay such that the boiler will only fire if at least one zone valve is open AND the boiler relay is on.


    The problem with this is that the HR92s are associated only with the boiler relay but neither of the heating zone relays (valves). If the two rooms with the wall stats are hot enough (and the cylinder is full of hot water), thereís no way for an HR92 in a much cooler (slower to heat) room to fire the boiler.

    Having read other postings on this forum Iím inclined to think I need to get rid of the boiler relay and somehow associate each of the HR92s with the relevant heating zone relay. It sounds simple, but I canít find documentation of this and donít know whether the software supports it. Please advise how best to set this up and / or where I can find instructions.

  2. #2
    Automated Home Lurker
    Join Date
    Nov 2021
    Posts
    3

    Default

    Just wondering whether anyone knows where to look for an answer to this please?

  3. #3
    Automated Home Jr Member
    Join Date
    Jan 2019
    Posts
    44

    Default

    Hi Julian,

    Does canít quite work out how your system is configured, do you also have a switched live from your zone valves to your boiler?

    My rather limited understanding of an s-plan plus system is that you have to either wire all zone valves into a single BDR or simultaneous bind multiple BDRs during the configuration stage. I.e both your CH zone valves would open on any CH demand.
    Maybe someone else can confirm
    Last edited by MajorDanby; 20th December 2021 at 08:53 AM.

  4. #4
    Automated Home Legend
    Join Date
    Jul 2014
    Posts
    1,692

    Default

    I think you have used a combination of zone wiring and evohome binding that is causing the problem. What I would do is use one or the other. You can configure CH, HW and boiler relays in the Evohome.
    You have created a dependency for the boiler relay to fire, which is what is stopping any HR92 from being able to demand heat.

Posting Permissions

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