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Thread: Evohome and Zone Valves

  1. #1
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    Default 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

    https://www.amazon.co.uk/Honeywell-Y...ywords=evohome

    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

  2. #2
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    First of all, if you have the Internet Gateway you have the older non-WiFi version of the controller that has been superseded for over a year now.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.

  3. #3
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    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

  4. #4
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    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; 25th November 2016 at 10:36 AM.

  5. #5
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    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; 25th November 2016 at 03:41 PM. Reason: Added manual link

  6. #6
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    Quote 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

  7. #7
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    Quote 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

  8. #8
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    Quote 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 .

  9. #9
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    Quote 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

    http://www.ebay.ie/itm/Honeywell-Rad...-/221993390373


    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

  10. #10
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    Quote 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

    http://www.ebay.ie/itm/Honeywell-Rad...-/221993390373


    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.

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