new to evoHome - existing Honeywell wireless room thermostat

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  • bruce_miranda
    Automated Home Legend
    • Jul 2014
    • 2307

    #31
    Yes you cannot have a single valve bdr91 for CH only. The only single valve setup is for HW. Daft, i know.

    Comment

    • mart1711
      Automated Home Jr Member
      • Oct 2016
      • 31

      #32
      I have just found this in another thread:

      Originally posted by The EVOHOME Shop View Post
      Hi Philip,

      Sorry but Roy is incorrect - as I said to you previously there is no 'boiler relay' required on an S-Plan set-up.

      You need to go back to system devices>boiler demand and select 'none'. Then you need to go to system devices>sundial valves and select 'none'. Then you need to go to system devices>sundial valves and select 'stored hot water'. Bind in the CS92 and select '2 port valves' and bind in the hot water BDR91 and then the heating BDR91.

      Remember you will need to 'unbind' the BDR91's first (long press on grey button until you get the 'fast flash' after 15 seconds) and then bind them in with the 5 second press until 'fast flash' changes to a 'slow flash'.

      The evohome Controller without the 'boiler relay' knows there is a heating motorised zone valve as you have told it so with the hot water configuration. It will open the heating motorised zone valve every time there is demand on any HR92.

      Hope that helps, if you are stuck give me a call tomorrow.

      Richard.
      I guess the controllers have changed slightly - if I go into "system devices" there is no option for sundial valves, there is only "Boiler Control" and "Stored Hot Water". As above, I cannot activate the hot water option as I don't have the hot water kit.

      So I guess it's back to the post just one above - either I buy the hot water kit, or try my luck with setting the BDR91 up as Boiler Control?

      Comment

      • DBMandrake
        Automated Home Legend
        • Sep 2014
        • 2361

        #33
        In your situation because you have a separate timer for hot water that powers your hot water valve and evohome will only be controlling heating you should configure your existing BDR91 that is wired to your heating zone valve as BOILER CONTROL.

        Your heating zone valve will already be wired to fire the boiler using its limit switch.

        Set stored hot water to disabled if you had tried to configure that in the evohome settings.

        Before you try to bind the boiler control relay you MUST clear any previous bindings on the BDR91.

        To do this you hold down the button on the relay until it flashes slowly then keep holding it until it flashes quickly which takes at least 15 seconds. Then release the button.

        A quick flash indicates the relay is unbound. Now hold it down again until it reverts to a slow flash then release - this indicates that it is waiting for a binding signal.

        Go into the evotouch configuration and bind it under boiler control. Personally I don't use the guided config at all I just go directly into the settings.

        The light on the relay will go out when the binding is successful.

        You should now find that when you turn up your HR 92's the relay green light should come on and open your heating zone valve and after about 15 seconds the boiler should fire.
        Last edited by DBMandrake; 3 November 2016, 06:58 PM.

        Comment

        • mart1711
          Automated Home Jr Member
          • Oct 2016
          • 31

          #34
          Aha! Many thanks for confirming. So in my case with the single BDR91 I would now set this up as Boiler Control even though it's connected to the CH valve?

          Comment

          • mart1711
            Automated Home Jr Member
            • Oct 2016
            • 31

            #35
            Fabulous, thank you.

            Comment

            • DBMandrake
              Automated Home Legend
              • Sep 2014
              • 2361

              #36
              Yes that's correct.

              Comment

              • bruce_miranda
                Automated Home Legend
                • Jul 2014
                • 2307

                #37
                Like I said before, use boiler demand relay to control your ch zone valve. Yes Honeywell did remove the Sundial configuration in the wifi controllers.
                I've been through this journey and today finally taken a new turn. I unbound the ch bdr91, put the valve in the manual open lock position and rebound my system as a single HW valve configuration with a boiler demand relay (opentherm in my instance).

                Comment

                • DBMandrake
                  Automated Home Legend
                  • Sep 2014
                  • 2361

                  #38
                  Originally posted by bruce_miranda View Post
                  Like I said before, use boiler demand relay to control your ch zone valve. Yes Honeywell did remove the Sundial configuration in the wifi controllers.
                  I've been through this journey and today finally taken a new turn. I unbound the ch bdr91, put the valve in the manual open lock position and rebound my system as a single HW valve configuration with a boiler demand relay (opentherm in my instance).
                  FYI

                  If you want your CH zone valve to remain open whenever the system is running ("bypassed") you should wire it to the pump power feed - the manual fill position on many zone valves including the ubiquitous Honeywell V4043 that I use opens the valve less than half way which causes quite a flow restriction when the system is operating.

                  The manual latch position is only intended for filling and draining not for normal operation.
                  Last edited by DBMandrake; 3 November 2016, 07:15 PM.

                  Comment

                  • mart1711
                    Automated Home Jr Member
                    • Oct 2016
                    • 31

                    #39
                    I'm finally making progress and have the first two HR92s installed. One thing that I have noted is that it takes a long time (~1 minute) for the controller to operate the BDR91. If for example I switch all heating to "OFF" from the user interfae, the BDR91 only clicks off after a minute.

                    If I turn the heating back on, it equally takes around 1 minute for the BDR91 to turn on. Is this to be expected?

                    Comment

                    • bruce_miranda
                      Automated Home Legend
                      • Jul 2014
                      • 2307

                      #40
                      Originally posted by DBMandrake View Post
                      FYI

                      If you want your CH zone valve to remain open whenever the system is running ("bypassed") you should wire it to the pump power feed - the manual fill position on many zone valves including the ubiquitous Honeywell V4043 that I use opens the valve less than half way which causes quite a flow restriction when the system is operating.

                      The manual latch position is only intended for filling and draining not for normal operation.
                      Interesting and very useful. So looks like a rewiring is needed or a normally open head. Wiring from the pump is a bit difficult for me because the pump is wired directly from the boiler and not my wiring box. But will look into this. Or i could just go back to my S plan configuration. Trouble is that I witnessed several instances where the boiler fired up under the direction of the OT bridge, with no zone valve open. I didn't like all the heat simply cycling through my bypass valve.

                      Comment

                      • Bluestraw
                        Automated Home Lurker
                        • Apr 2016
                        • 1

                        #41
                        Originally posted by bruce_miranda View Post
                        Interesting and very useful. So looks like a rewiring is needed or a normally open head. Wiring from the pump is a bit difficult for me because the pump is wired directly from the boiler and not my wiring box. But will look into this. Or i could just go back to my S plan configuration. Trouble is that I witnessed several instances where the boiler fired up under the direction of the OT bridge, with no zone valve open. I didn't like all the heat simply cycling through my bypass valve.
                        I have the same 'issue' here - I had currently latched the valve open and would now prefer to connect to the pump as suggested but my pump is internal to a Vaillant system boiler and I'm not entirely sure the best way to connect it. If you figure it out please let us know! I don't want to go back to the S plan since I had the same as you - on numerous occasions the OT bridge fired the boiler with no zone valve open which inevitably resulted with the bypass overheating and the boiler cycling...

                        Comment

                        • DBMandrake
                          Automated Home Legend
                          • Sep 2014
                          • 2361

                          #42
                          Originally posted by mart1711 View Post
                          I'm finally making progress and have the first two HR92s installed. One thing that I have noted is that it takes a long time (~1 minute) for the controller to operate the BDR91. If for example I switch all heating to "OFF" from the user interfae, the BDR91 only clicks off after a minute.

                          If I turn the heating back on, it equally takes around 1 minute for the BDR91 to turn on. Is this to be expected?
                          Yes.

                          If you change the set points from the controller (or via the Phone apps) then it takes anywhere up to about 4 minutes for the set point change to be sent to the HR92's - this is because set point changes are not sent from the controller to HR92's immediately, but on a regular 4 minute repeating schedule.

                          So depending on where you currently are in that 4 minute schedule when you make a change it might take anywhere from a few seconds to 4 minutes to take effect.

                          This is done to conserve battery life on the HR92's so the batteries can last 2 years - they only wake up once every 4 minutes to receive new commands from the controller, check the room temperature, adjust the valve (if necessary) and send a new heat demand back to the controller then go to sleep for another 4 minutes.

                          If you adjust the temperature from the knob on the top of the HR92 then this up to 4 minute delay is bypassed because you are directly controlling the device and waking it up immediately by turning the knob.

                          However there is an additional delay that always applies - when you adjust the set point, if that results in the valve having to turn it will wait until after the valve has finished turning before it sends an updated heat demand back to the controller. It can take up to 30 seconds for the valve to go from fully closed to fully open so this is an additional delay that applies regardless of where you change the set point from. If the valve only has to turn a small amount due to a small set point change the delay might be only a few seconds.

                          Once a new heat demand has been sent back to the controller it forwards it on to the boiler relay within a few seconds.

                          I wouldn't worry too much about how long reaction to set point changes takes - it does take a few minutes when done from the controller, that's just the way the system works, so turning your heating off and on from the controller is not instant like a conventional wall stat or timer due to the delay sending set point changes to the HR92's and then waiting for them to adjust their valve position and send a heat demand back.
                          Last edited by DBMandrake; 4 November 2016, 01:43 AM.

                          Comment

                          • bruce_miranda
                            Automated Home Legend
                            • Jul 2014
                            • 2307

                            #43
                            Originally posted by Bluestraw View Post
                            I have the same 'issue' here - I had currently latched the valve open and would now prefer to connect to the pump as suggested but my pump is internal to a Vaillant system boiler and I'm not entirely sure the best way to connect it. If you figure it out please let us know! I don't want to go back to the S plan since I had the same as you - on numerous occasions the OT bridge fired the boiler with no zone valve open which inevitably resulted with the bypass overheating and the boiler cycling...
                            I am lucky, in that the electrician who installed the wiring used a 5 core cable for the boiler and there is one spare wire going between boiler pcb and the wiring box. I don't have a Vaillant system boiler but my external pump is driven from the Vaillant boiler pcb which will be exactly how the system boiler will be wired. I just need to use the Live feed of the pump to also open the zone valve. This is actually quite a good suggestion because now my valve also stays open for pump over run but does not stay open forever and risk getting seized.

                            Comment

                            • DBMandrake
                              Automated Home Legend
                              • Sep 2014
                              • 2361

                              #44
                              Originally posted by bruce_miranda View Post
                              I am lucky, in that the electrician who installed the wiring used a 5 core cable for the boiler and there is one spare wire going between boiler pcb and the wiring box. I don't have a Vaillant system boiler but my external pump is driven from the Vaillant boiler pcb which will be exactly how the system boiler will be wired. I just need to use the Live feed of the pump to also open the zone valve. This is actually quite a good suggestion because now my valve also stays open for pump over run but does not stay open forever and risk getting seized.
                              I didn't think of the anti-sticking benefit, I just didn't like the idea of the valve being energised 24/7 even when the heating is off, and if there is only a point to it being open if the pump is circulating it seems logical to power it from the pump supply if you want the valve "bypassed" without actually physically removing the valve.

                              It's interesting to note that with boiler relay control using TPI, since I moved from heating only control to S-Plan and added the two zone valves (I had no zone valves at all before) I've noticed quite an improvement in the ability of the system to regulate room temperatures when demand is low.

                              I have a long pump overrun time so previously when TPI cycles the boiler off the radiators all keep flowing for quite a while (under the control of individual HR92's of course) which causes the flow to be more or less constantly on but the flow temperature drops down quite low since the radiators dissipate the heat...which sounds like what you want to happen. (Poor mans Opentherm)

                              But I found that it didn't maintain a steady flow temperature under light load conditions with the flow temperature dropping really low then going back up fairly high, so room temperatures did fluctuate above and below the set points quite a bit (maybe a degree at most) during light load conditions when only a small amount of heat was needed to keep the room temperature topped up.

                              Since I added the heating zone valve TPI now also cycles the heating zone valve closed as well as cycling the boiler off in each cycle. Initially I didn't like the idea of that because that would then shunt my boilers flow entirely through the ABV in each TPI off period, so I came up with a circuit using an MRT16-REM/VF timer to effectively give me "heating zone valve overrun" that was active only when the hot water zone valve was closed. However because that's another £30 for the timer and I'd already spent a lot on my S-Plan conversion I decided to give it a chance without that to see how the system behaved with the zone valve opening and closing with TPI.

                              Much to my surprise the temperature regulation under very light loads (mild weather outside) is much better than it was without the heating zone valve. My hallway and living room zones - both which use remote sensors so are pretty accurately measured now look like almost perfect flat lines on my temperature graphs with no oscillations, with the living room maintaining the room within about +/- 0.2 degrees all evening versus about +/- 0.5 to +/- 1 degree previously depending on conditions.

                              I puzzled over this for a while and then realised what it probably is - with no zone valve the water keeps circulating and TPI tries to control the average flow temperature, but the temperature you actually get varies all over the place and isn't directly proportional to the TPI duty cycle, so it's constantly having to make corrections due to this random variability thus both the flow temperature and room temperature keep varying.

                              With the heating zone valve what seems to happen is that the zone valve closing tends to cause the boiler to come up to its regulated flow temperature (65 at the moment) even with low loads due to latent heat in the boiler and the small automatic bypass loop. So each time the heating zone valve does open the temperature is about the same regardless of how long the valve is open, because when it opens and the temperature starts to fall the boiler comes on to maintain the flow temperature. When it goes off and the heating zone valve turns off the bypass loop maintains the temperature it was just before the boiler switched off, which is pretty close to the set flow temperature.

                              So what you have is a more or less constant flow temperature available at the boiler but the actual flow time through the radiators is controlled by the heating valve and that is directly proportional to valve open time. That means the total amount of heat going into the radiators is more or less directly proportional to the heating zone valve open time in each cycle, thus it has much better control. Genius!

                              It's probably not quite as efficient as there will be some heat loss through the bypass loop in the closed periods but watching the flow temperature its not much as it barely drops 1-2 degrees during the closed part of the cycle. Also if it was a condensing boiler it might not condense as well so maybe not quite as efficient there.

                              So my conclusion is that if you use a boiler relay and TPI that a heating zone valve may reduce the total efficiency slightly but increases accuracy of room temperature control under light loads quite significantly, perhaps almost to the point you would get with OpenTherm, as I'm very impressed with just how flat my temperature graphs are in those rooms now that previously were not like that.

                              On the other hand if you use OpenTherm which does give the system precise control over flow temperature, it seems like it would better for the heating zone valve to remain open all the time that there is heating demand and let OpenTherm just modulate the flow temperature to control total heat going to the radiators, which it can do far more accurately than TPI. The only exception might be that you would want the heating zone valve TPI modulated if there was also a simultaneous hot water demand, as the hot water demand may push your flow temperature sky high while it is reheating the water which would cause a temperature overshoot in all the active rooms.

                              Something like my zone valve overrun timer which only functions when there is no hot water demand might be just right for that.
                              Last edited by DBMandrake; 4 November 2016, 10:39 AM.

                              Comment

                              • bruce_miranda
                                Automated Home Legend
                                • Jul 2014
                                • 2307

                                #45
                                Or you use a single bdr91 but with HW priority that just closes the CH valve anytime there is HW demand. But on other times it is open.
                                Apparently the normal motorised zone valve were never designed to stay open for long durations and hence many don't recommend that they are used for UFH purposes. There are other valves that are designed for that. Problem is most plumbers and electricians swear by the Honeywell valves so will only ever use that. The compromise I guess is to make sure the valves open and close regularly so that they don't seize.

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