Page 2 of 2 FirstFirst 12
Results 11 to 16 of 16

Thread: Evohome DIY install check

  1. #11
    Automated Home Legend
    Join Date
    Jul 2014
    Posts
    1,542

    Default

    I too replaced a 2 channel timer with 2 BDR91s in the early days. That was almost too easy. Everything stayed the same and the microswitches inside the CH and DHW zone valves fired the boiler. Then when I moved to OT, things got a bit more convoluted.
    Now my CH zone valve is wired in parallel to my pump with no BDR control. The DHW has its own BDR91 and then finally I have another BDR now controlling an UFH zone valve. Once we get out of Lockdown, I want to try running the UFH circuit off a rotary valve rather than using the zone valve.

  2. #12
    Automated Home Lurker
    Join Date
    Jan 2021
    Posts
    7

    Default

    Iím totally confused now!
    Iíve worked out that I actually have my CH set up with the boiler relay also switching the ch zone valves in my s plan. I donít have any separate sensors other than the evohome controller and the radiators all with hr91ís. I therefore donít seem to be able to link the evohome controller to a bdr1 just for ch.

    Will this setup work? I guess I could just open the ch valves but I was hoping to be able to turn the ch off completely in summer. Otherwise, When I get any the ch off in summer I can just keep the towel rails open as a bypass when the hot water comes on or will the hw bdr1 (yet to be installed) not trigger the ch system.

    Finally - will this then be heating the hw every time the boiler fires?

    I also canít find the posts that relate to setting up an evohome with an s plan - where would I find these on the forum?

    Sorry, feeling more and more like a complete novice!
    Last edited by blobbi; 5th February 2021 at 07:34 AM.

  3. #13
    Automated Home Lurker
    Join Date
    Jan 2021
    Posts
    7

    Default

    FYI

    The Sparky has simplified the wiring (by removing most of it) and its pretty easy to work out now.
    I have set it up as per this post and EVOHOMES post half way down (ie clearing - DHW first and then CH with 2 port valves).

    https://www.automatedhome.co.uk/vbul...e-of-questions

    It seems to be working and I have no boiler relay set up - just zone valves for DHW and separate ones for CH which are triggering at the right times.

    And I even managed to flush out a radiator with help from You Tube which has got a Rad in my office going for the first time since we moved in.

    Thanks for the help.

  4. #14
    Automated Home Legend
    Join Date
    Jul 2014
    Posts
    1,542

    Default

    I have never quite worked out the reason why one would use a 3rd Boiler relay in addition to the relays on the CH and DHW zone valves and then using the micro switches within them to trigger the boiler. But I am sure Simon will come along and give us a great reason why he uses the 3 relay configuration.

  5. #15
    Automated Home Legend
    Join Date
    Sep 2014
    Location
    Scotland
    Posts
    2,303

    Default

    Quote Originally Posted by bruce_miranda View Post
    I have never quite worked out the reason why one would use a 3rd Boiler relay in addition to the relays on the CH and DHW zone valves and then using the micro switches within them to trigger the boiler. But I am sure Simon will come along and give us a great reason why he uses the 3 relay configuration.
    1) Hot water overrun only works if you have a boiler relay. (since Evohome needs to be able to control boiler and zone valves independently to achieve this)
    2) Removes the 10-15 second delay each TPI cycle between powering a zone valve until the microswitch is closed and the boiler fires.
    3) Gives access to the minimum on time and cycle rate settings
    4) Allows me to use clever wiring configurations such as my often posted circuit diagram where my heating zone valve remains continuously open when the pump is running except when hot water reheat is happening. (During hot water reheat the heating zone valve reverts to TPI) Impossible to wire up this configuration without a boiler relay.

    But for many people zone valve relays and no boiler relay will be just fine. I did actually run my system like that for a few weeks but ultimately I needed a bit more control to keep my old cranky boiler happy - like the heating zone valve wiring hack to disable TPI on the heating zone valve when it's not needed.
    Last edited by DBMandrake; 13th February 2021 at 09:32 AM.

  6. #16
    Automated Home Legend
    Join Date
    Jul 2014
    Posts
    1,542

    Default

    You never disappoint Simon and never fail to amaze me on the time you take to write out each detailed response.

Tags for this Thread

Posting Permissions

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