Evohome and Zone Valves

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  • mylesm
    Automated Home Guru
    • Nov 2015
    • 153

    Evohome and Zone Valves

    Hello

    I have at the moment 3 heating Zones which are supplied by 3 zone valves controlled by wireless stats simply any stat calling for heat opens its zone valve and then end position limits on Valve switch boiler on and when stat is satisfied valve closes and boiler shuts off

    I am now going to install Evo I have an Evo connected pack which includes a Controller a Internet Gateway and a BDR91 Relay

    I think I can use the controller as a temp sensor for one Zone say living room and use the BDR91 to switch the Zone valve and leave the end limits on valve to switch boiler

    I was then going to get 2 Honeywell Stats and BDR91s like these



    and use these for the other 2 Zones using the Stats as sensors and the BDRs to switch the Zone valves again leaving the end limits on valves to switch boiler

    Basically can i have multiple Stats bound to EVO Controller and switching multiple Zone valves via BDR91 relays

    Thanks for advise

    mylesm
  • DBMandrake
    Automated Home Legend
    • Sep 2014
    • 2361

    #2
    First of all, if you have the Internet Gateway you have the older non-WiFi version of the controller that has been superseded for over a year now. This old model of controller has some limitations including that Honeywell will not be releasing any firmware updates for it.

    The current WiFi model (which doesn't require the separate Internet Gateway) is capable of receiving firmware updates (although it has only received one significant update since its release a year ago) and is therefore much more future proof. If you haven't installed it yet I'd suggest sending it back and getting the current Wifi model even though its a little bit more expensive.

    What you're trying to do with your heating zone valves is a bit peculiar - if you have multiple zones the usual way to set it up is to use HR92 radiator controllers on each radiator, then you would wire all the heating zone valves together to be controlled by the heating BDR91 relay. In this case the heating zone valves are not part of any particular zone on the controller, they all open together and the HR92's control individual radiators.

    What you're suggesting should in theory work - you can choose a "zone valve" as the actuator for a zone in the Evotouch and bind it to a BDR91 that then opens a zone valve, and you do have to have a temperature sensor for the zone as well, which can be the evotouch for one of them and a wireless wall stat for the other.

    However I haven't heard of anyone doing it this way with zone valves as the actuator for an evotouch zone. One problem with this approach is that zone valves are only open or closed, therefore they will be modulated on and off every 10 minutes to control the flow to the radiators in that zone, whereas the HR92 radiator valve is a proportional controller that adjusts the valve more precisely. And you couldn't control individual rooms, only the three zones you currently have.

    I'm not sure that I'd recommend your suggested approach - but would be interested to see what others think.

    Comment

    • mylesm
      Automated Home Guru
      • Nov 2015
      • 153

      #3
      Thanks for reply I realize that evohome is best when its controlling each zone with a hr92 but in my case the three zones work well and I don't really need individual control over each room I like the honeywell Stats so was hoping to integrate them into existing zone valves using evotouch as controller I will see how I get and if it works i may upgrade to latest wifi model as to the model I have I bought it as a connected pack which included a bdr relay and it cost very little more than bdr on its own do nothing to lose really I figured that bdr would do one zone and I nearly have a free controller to mess about with so hopefully it will work😀😀
      Thanks Mylesm

      Comment

      • DBMandrake
        Automated Home Legend
        • Sep 2014
        • 2361

        #4
        Fair enough. If you got the older controller really cheap and just want to try it out then why not. Even if you updated to a Wifi controller later you can still keep all the other components like the BDR91's and wall stats and reuse them with the new system.

        I think it should work, I just don't know how well it will work compared to using the HR92 radiator controllers. You would need one BDR91 per zone valve and a temperature sensor per zone, one of which could be the evotouch controller. Keep in mind that if you use the built in sensor of the evotouch it needs to be left in a in a suitable place in the room (and left plugged into power) to measure the temperature there and that holding the unit even for a few minutes causes its built in temperature reading to sky rocket above 30 degrees (hand heat) so its best left mostly alone when using its built in sensor.

        It's possible you might need a 4th BDR91 to control the boiler directly instead of using the orange wires from the zone valves as I'm not certain whether you can bind zone valve relays to the individual zones and yet have no overall boiler relay configured. Even if it does let you I'm also not sure whether this would allow good TPI control of the boiler when it will be doing TPI on each individual zone valve and all of them will be able to call for heat from the boiler. This might result in the boiler running more frequently than is necessary but its hard to be sure.

        You'd need to try it and see, and allow for the possibility that you might need a 4th BDR91 if it doesn't work out with three. If you did need the separate boiler control BDR91 you would just disconnect the orange wires from your zone valves that currently power the boiler and power the boiler directly from the extra BDR91 and add it as "boiler control" in the configuration.
        Last edited by DBMandrake; 25 November 2016, 11:36 AM.

        Comment

        • Little Tinker
          Automated Home Jr Member
          • Nov 2016
          • 38

          #5
          The older black and white Application Guide shows a 2 zone equivalent of this in section 2.2. I'll try an post a link when properly online.

          I think it'll work based on that.

          If the current wireless kit you have is Honeywell it may be able to be reused.

          EDIT: This one - http://eolp.evohome.honeywell.com/ev..._manual_en.pdf.

          Just noticed that it also shows boiler control (relay or OpenTherm) as an option there. Depending on what your boiler has that might help smooth out the heat demand vs zone valve opening / closing behaviour.
          Last edited by Little Tinker; 25 November 2016, 04:41 PM. Reason: Added manual link

          Comment

          • mylesm
            Automated Home Guru
            • Nov 2015
            • 153

            #6
            Originally posted by DBMandrake View Post
            Fair enough. If you got the older controller really cheap and just want to try it out then why not. Even if you updated to a Wifi controller later you can still keep all the other components like the BDR91's and wall stats and reuse them with the new system.

            I think it should work, I just don't know how well it will work compared to using the HR92 radiator controllers. You would need one BDR91 per zone valve and a temperature sensor per zone, one of which could be the evotouch controller. Keep in mind that if you use the built in sensor of the evotouch it needs to be left in a in a suitable place in the room (and left plugged into power) to measure the temperature there and that holding the unit even for a few minutes causes its built in temperature reading to sky rocket above 30 degrees (hand heat) so its best left mostly alone when using its built in sensor.

            It's possible you might need a 4th BDR91 to control the boiler directly instead of using the orange wires from the zone valves as I'm not certain whether you can bind zone valve relays to the individual zones and yet have no overall boiler relay configured. Even if it does let you I'm also not sure whether this would allow good TPI control of the boiler when it will be doing TPI on each individual zone valve and all of them will be able to call for heat from the boiler. This might result in the boiler running more frequently than is necessary but its hard to be sure.

            You'd need to try it and see, and allow for the possibility that you might need a 4th BDR91 if it doesn't work out with three. If you did need the separate boiler control BDR91 you would just disconnect the orange wires from your zone valves that currently power the boiler and power the boiler directly from the extra BDR91 and add it as "boiler control" in the configuration.
            Thanks will try it and let people know how it goes

            Comment

            • mylesm
              Automated Home Guru
              • Nov 2015
              • 153

              #7
              Originally posted by Little Tinker View Post
              The older black and white Application Guide shows a 2 zone equivalent of this in section 2.2. I'll try an post a link when properly online.

              I think it'll work based on that.

              If the current wireless kit you have is Honeywell it may be able to be reused.

              EDIT: This one - http://eolp.evohome.honeywell.com/ev..._manual_en.pdf.

              Just noticed that it also shows boiler control (relay or OpenTherm) as an option there. Depending on what your boiler has that might help smooth out the heat demand vs zone valve opening / closing behaviour.
              Thanks for that it seems to be a 2 zone system with Zone Valves so I am hoping the Same applies to 3 Zones with Zone Valves

              Comment

              • Little Tinker
                Automated Home Jr Member
                • Nov 2016
                • 38

                #8
                Originally posted by mylesm View Post
                Thanks for that it seems to be a 2 zone system with Zone Valves so I am hoping the Same applies to 3 Zones with Zone Valves
                The text in that section says "In total, 8 zones can be controlled individually", which is what I based my optimistic reply on .

                Comment

                • mylesm
                  Automated Home Guru
                  • Nov 2015
                  • 153

                  #9
                  Originally posted by Little Tinker View Post
                  The text in that section says "In total, 8 zones can be controlled individually", which is what I based my optimistic reply on .
                  I have been doing a lot of reading and searching around and I now think I could replace my existing Zone valves with inline TRVs like these




                  And then put a HR92 on each one using a remote thermostat as sensor in Zone and this would give me fully modulated control on existing zones and just use one BDR91 as Boiler relay

                  mylesm

                  Comment

                  • Little Tinker
                    Automated Home Jr Member
                    • Nov 2016
                    • 38

                    #10
                    Originally posted by mylesm View Post
                    I have been doing a lot of reading and searching around and I now think I could replace my existing Zone valves with inline TRVs like these




                    And then put a HR92 on each one using a remote thermostat as sensor in Zone and this would give me fully modulated control on existing zones and just use one BDR91 as Boiler relay

                    mylesm

                    Your valves probably have 22mm pipework, and those are 15mm which will constrict flow quite a bit.

                    Comment

                    • mylesm
                      Automated Home Guru
                      • Nov 2015
                      • 153

                      #11
                      Originally posted by Little Tinker View Post
                      Your valves probably have 22mm pipework, and those are 15mm which will constrict flow quite a bit.
                      Thanks i considered that but 2 of my Zone valves at present only have 15mm as they are only feeding a big Living room and a Kitchen Extension the third one is bedrooms its 22mm

                      But replacing the present valves with Inline HR92s seems like a possible and would mean those zones would be completely integrated into EVO

                      Comment

                      • Little Tinker
                        Automated Home Jr Member
                        • Nov 2016
                        • 38

                        #12
                        Depending how inventive you want to be you could replace just the two on the 15mm legs, and wire the remaining zone valve in parallel with boiler. It then opens whenever any of the system wants heat, but the various HR91 will ensure heat only reaches where it is needed. Or with pump if that is accessible and you have pump overun.

                        EDIT: Just realised you probably aren't putting heads on the bedroom rads which undermines the design. I'll leave it there anyway.
                        Last edited by Little Tinker; 26 November 2016, 03:13 PM.

                        Comment

                        • mylesm
                          Automated Home Guru
                          • Nov 2015
                          • 153

                          #13
                          Originally posted by Little Tinker View Post
                          Depending how inventive you want to be you could replace just the two on the 15mm legs, and wire the remaining zone valve in parallel with boiler. It then opens whenever any of the system wants heat, but the various HR91 will ensure heat only reaches where it is needed. Or with pump if that is accessible and you have pump overun.

                          EDIT: Just realised you probably aren't putting heads on the bedroom rads which undermines the design. I'll leave it there anyway.
                          Yes I was thinking maybe two inline TRVs with HR92 Heads to replace the 2 15mm Zone valves existing and use two Honeywell Y87RF stats as sensors for each Zone that should take care of them

                          The other Zone I could leave the existing Zone Valve and set it up as a Zone Valve zone in Evo and use a Honeywell Y87RF again as the Sensor for that Zone but not use end limits to trigger Boiler instead use a BDR91 as a Boiler Demand Relay to switch boiler which would give better Boiler control

                          thanks again

                          Comment

                          • ojock
                            Automated Home Jr Member
                            • Jul 2018
                            • 10

                            #14
                            Originally posted by DBMandrake View Post
                            It's possible you might need a 4th BDR91 to control the boiler directly instead of using the orange wires from the zone valves as I'm not certain whether you can bind zone valve relays to the individual zones and yet have no overall boiler relay configured. Even if it does let you I'm also not sure whether this would allow good TPI control of the boiler when it will be doing TPI on each individual zone valve and all of them will be able to call for heat from the boiler. This might result in the boiler running more frequently than is necessary but its hard to be sure.

                            You'd need to try it and see, and allow for the possibility that you might need a 4th BDR91 if it doesn't work out with three. If you did need the separate boiler control BDR91 you would just disconnect the orange wires from your zone valves that currently power the boiler and power the boiler directly from the extra BDR91 and add it as "boiler control" in the configuration.
                            That's exactly the suggestion I have been given by a Evohome Connected Specialist. 4th BDR91 required as the boiler relay, with the orange wires disconnected for the 2 motorised valves (in my case, central heating + underfloor heating).

                            I have 3 motorised valves, one for HW, one for central heating (CH) and one for underfloor heating (UFH) - my original installer installed three BDR91s to power those three valves independently, all of them in turn would fire the boiler up.

                            When my UFH Zone asked for heat, it would open up the UFH valve + fire up boiler, but then it would also signal the CH BDR91 to open up the CH valve too.

                            I had the same issue too when I first installed the Evohome HW kit - it would open the HW valve + fire up boiler, but the CH BDR91 would also be called and open up the CH valve - till I eventually sussed out that I needed to unbind the BDR91 relay that came with the Evohome connected pack, then rebind the HW kit as a "2 Two Port or Three Port Valves", which then allowed me to bind the 2 BDR91s correctly.

                            However, I could not figure out how I could do that for my UFH zone valve till I contacted specialist.

                            Comment

                            • mtmcgavock
                              Automated Home Legend
                              • Mar 2017
                              • 507

                              #15
                              Originally posted by ojock View Post
                              That's exactly the suggestion I have been given by a Evohome Connected Specialist. 4th BDR91 required as the boiler relay, with the orange wires disconnected for the 2 motorised valves (in my case, central heating + underfloor heating).

                              I have 3 motorised valves, one for HW, one for central heating (CH) and one for underfloor heating (UFH) - my original installer installed three BDR91s to power those three valves independently, all of them in turn would fire the boiler up.

                              When my UFH Zone asked for heat, it would open up the UFH valve + fire up boiler, but then it would also signal the CH BDR91 to open up the CH valve too.

                              I had the same issue too when I first installed the Evohome HW kit - it would open the HW valve + fire up boiler, but the CH BDR91 would also be called and open up the CH valve - till I eventually sussed out that I needed to unbind the BDR91 relay that came with the Evohome connected pack, then rebind the HW kit as a "2 Two Port or Three Port Valves", which then allowed me to bind the 2 BDR91s correctly.

                              However, I could not figure out how I could do that for my UFH zone valve till I contacted specialist.
                              If you've configured your UFH as just an additional zone using a BDR91 adding a boiler relay won't solve your problem of the CH BDR91 coming on when your UFH calls for heat. You need to change your UFH zone to an Electric UFH zone (On the new firmware update) and this will prevent the BDR91 on the CH from coming on and if you had a boiler relay prevent this from firing. At this point you'd just use the orange wire from the zone valve to fire the boiler for the UFH.

                              Comment

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