Evohome and S Plan Plus

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  • no8080
    Automated Home Lurker
    • Jan 2016
    • 7

    Evohome and S Plan Plus

    Hi all,

    I am after a bit of advice, aftering reading up this is what I want to do.

    I have a potterton condensing boiler, megaflow unvented hot water with three 2port valves. Valves are currently for HW, downstairs CH zone and upstairs CH zone. Currently the valves are controlled by CH thermostats, most rads have myson standard TRVs. There is a bypass valve on the system and the pump is controlled by the boiler for pump overrun.

    I want to be able to set my boiler cycle amount and run time, as there is an issue with the boiler firing after it has been left for long periods of time. Potterton don't auto cycle, neither does my thermostats.

    I want to phase the installation, so my plan is evohome controller, HW pack wiring the brd91 to the HW 2port valve. Disconnect the wiring to the two CH valves and leave them open. Another BDR91 as the boiler relay. I assume I need at least one evohome TRV to get the CH to work, then add more as I get more time.

    Is this reasonable?

    2 questions spring to my mind,

    1) do I leave the wiring for the HW 2 port valve to fire the boiler as it is now? So the contact switch in the HW valve fires the boiler for HW?

    2) do I leave the pump power supply as it is currently, running off the boiler for the pump overrun feature?

    Thanks in advance for your responses.

    Neil
  • The EVOHOME Shop
    Site Sponsor
    • Dec 2014
    • 483

    #2
    Hi Neil,

    If you do what you propose, the system will be not as well controlled as it currently is (for the short term anyway). So HR92's on all radiators is the way forwards otherwise every time you have hot water demand, the radiators will come on.

    But to answer your questions:

    1) Once Boiler Control Relay is operational, there is no need for the end switch to operate on the hot water motorised zone valve (so the grey and orange wires on this can be disconnected and made safe).

    2) Leave the pump as is.

    Hope that helps.

    Richard.

    Comment

    • no8080
      Automated Home Lurker
      • Jan 2016
      • 7

      #3
      Yes, I understand what you mean by the lack of control in the short term, but most rads are either off or on a very low TRV settings, as many rooms are unused.

      The only issue I will have is the hall rad is not on a TRV, so I will sort that one out first.

      So, from your second point, when HW or CH is needed, the controller will open the boiler relay and fire the boiler?

      At this point I assume I can remove the old room stats and disconnect their wiring? I want to plaster the hole they will leave, they are in daft places anyway.

      Thanks

      Neil

      Comment

      • The EVOHOME Shop
        Site Sponsor
        • Dec 2014
        • 483

        #4
        Originally posted by no8080 View Post
        So, from your second point, when HW or CH is needed, the controller will open the boiler relay and fire the boiler?
        Indeed, the Boiler Control Relay will fire the boiler whenever you have demand on a heating zone or hot water zone. Best valves for the HR92's are the Honeywell Valencia valves, very high quality and have balancing inserts built into them - https://theevohomeshop.co.uk/14-radiator-valve-bodies

        Comment

        • no8080
          Automated Home Lurker
          • Jan 2016
          • 7

          #5
          Thanks for the help,

          I have ordered a base pack, HW pack and 4 TRVs, this should get me started for now.

          Thanks

          Neil

          Comment

          • The EVOHOME Shop
            Site Sponsor
            • Dec 2014
            • 483

            #6
            Any help you need give me a call...

            Comment

            • Jom
              Automated Home Jr Member
              • Aug 2015
              • 23

              #7
              most rads have myson standard TRVs.

              I had older Myson TRV's before I installed Evohome and HR92's on my radiators. I was advised to change my TRV's as the HR92's don't work very well with the Myson TRV's, something to do with the pin dimensions on the particular ones that I had. Changed them to Peglar valves and had no issues. Wasnt too much of a problem in my case as system was being drained for new gas boiler at the time. Might be worth checking up on your particular valves

              Comment

              • The EVOHOME Shop
                Site Sponsor
                • Dec 2014
                • 483

                #8
                Originally posted by Jom View Post
                most rads have myson standard TRVs.
                As Danfoss invented the TRV, I would expect there to be more of these around than any other brand and this has certainly been my perosnal experience.

                Originally posted by Jom View Post
                I had older Myson TRV's before I installed Evohome and HR92's on my radiators. I was advised to change my TRV's as the HR92's don't work very well with the Myson TRV's, something to do with the pin dimensions on the particular ones that I had. Changed them to Peglar valves and had no issues. Wasnt too much of a problem in my case as system was being drained for new gas boiler at the time. Might be worth checking up on your particular valves
                Although I have not had any personal issues with the Myson and HR92's, TRV's do not last forever and it would be my recommendation that they are replaced with every boiler change (10-15 years).

                Comment

                • no8080
                  Automated Home Lurker
                  • Jan 2016
                  • 7

                  #9
                  All the bits have arrived and I have familiarised myself with the kit,

                  1 question, the BDR for the boiler relay, it states you must fit it at least 30cm from the boiler, as my boiler is in the kitchen cupboard this is really difficult, there's barely any space between the cupboard side and the boiler. So my plan was to install it to the underside of the kitchen cupboard next to the boiler.

                  The main LCD unit will be located in the next room, so about 15m away from the boiler BDR, this sound ok?

                  Thanks

                  Neil

                  Comment

                  • The EVOHOME Shop
                    Site Sponsor
                    • Dec 2014
                    • 483

                    #10
                    Originally posted by no8080 View Post
                    All the bits have arrived and I have familiarised myself with the kit,

                    1 question, the BDR for the boiler relay, it states you must fit it at least 30cm from the boiler, as my boiler is in the kitchen cupboard this is really difficult, there's barely any space between the cupboard side and the boiler. So my plan was to install it to the underside of the kitchen cupboard next to the boiler.

                    The main LCD unit will be located in the next room, so about 15m away from the boiler BDR, this sound ok?

                    Thanks

                    Neil
                    Great stuff!

                    Yep, things to bear in mind is that the BDR91 does not like being next to anything metallic or anything which can cause interference. RF line of sight between the BDR91 and the evohome Controller is crucial and if these are satisfied then 15m will be no problem.

                    Comment

                    • no8080
                      Automated Home Lurker
                      • Jan 2016
                      • 7

                      #11
                      Hmm, that raises another point for me, the bdr91 for my HW valve has a lot of copper pipework in the HW tank cupboard, pump and a lot of wires.

                      I might pop the cable through the wall and mount the bdr91 outside the HW cupboard, luckily I have a fitted wardrobe behind the HW cupboard.

                      Thanks for the help.

                      Neil

                      Comment

                      • The EVOHOME Shop
                        Site Sponsor
                        • Dec 2014
                        • 483

                        #12
                        Originally posted by no8080 View Post
                        I might pop the cable through the wall and mount the bdr91 outside the HW cupboard, luckily I have a fitted wardrobe behind the HW cupboard.
                        Just bear in mind the 30cm separation (even on the other side of a wall they still need to be 30cm away) and RF line of sight with this too, as RF will not travel well through copper pipes.

                        Comment

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