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Thread: EvoHome self install

  1. #1
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    Default EvoHome self install

    I'm planning on getting an EvoHome system to control my combi boiler CH and five radiators which have TRVs already fitted. I've got an electrician coming to wire up the boiler controller end of things and after that I'll be doing the rest of the install myself, so I'm wondering what's the best approach.

    With the controller wired up to the combi and paired with the central controller/screen, I guess I can test that the boiler is being controlled correctly just by using the controller as a thermostat and once that's verified as working I can replace the existing TRVs on each rad in turn, testing each as I go along?

    Does that seem sensible or am I missing something/should I leave it to a professional?
    Last edited by JohnOC; 26th September 2018 at 07:16 PM.

  2. #2
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    I suppose you would need to create/associate at least one HR92 to your controller.
    But you don't need to associate one that is fitted on a radiator, you could well do that off your radiator, and then force heating to 30C for example.

    This is, if you want to check and validate that the Evohome can request heat to your boiler, and the boilers understands, and acts accordingly
    Do you plan on connecting your boiler with a simple relay (BDR91) or with Opentherm (R8810A) ?

  3. #3
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    Quote Originally Posted by oxygen View Post
    I suppose you would need to create/associate at least one HR92 to your controller.
    But you don't need to associate one that is fitted on a radiator, you could well do that off your radiator, and then force heating to 30C for example.

    This is, if you want to check and validate that the Evohome can request heat to your boiler, and the boilers understands, and acts accordingly
    Do you plan on connecting your boiler with a simple relay (BDR91) or with Opentherm (R8810A) ?
    It'd to connecting to a simple relay so I guess a BDR91.

    I'm guessing the HR92s talk to the wireless stat/controller? Or do they talk to the BDR91?

  4. #4
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    From my understanding, everything talks to the controller.
    It is the controller that decides what are the relevant actions based from the data it receives.

    The simple relay is simple enough, you "just" need to get it connected to the boiler so it fires it up.

    Testing it is equally simple from the evohome, with a single zone, just request a high temperature, and it should fire up.
    This would allow you to test the Evohome<>BDR91 connection and the BDR91<>Boiler connection.

    Side note: You can also Manually Overide the BDR91 status, by pushing its button (short push). Even if I've never tested it, it should be possible. This would allow you to manually fire-up the boiler and therefore test the BDR91<>Boiler connection

  5. #5
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    Quote Originally Posted by oxygen View Post
    From my understanding, everything talks to the controller.
    It is the controller that decides what are the relevant actions based from the data it receives.

    The simple relay is simple enough, you "just" need to get it connected to the boiler so it fires it up.

    Testing it is equally simple from the evohome, with a single zone, just request a high temperature, and it should fire up.
    This would allow you to test the Evohome<>BDR91 connection and the BDR91<>Boiler connection.

    Side note: You can also Manually Overide the BDR91 status, by pushing its button (short push). Even if I've never tested it, it should be possible. This would allow you to manually fire-up the boiler and therefore test the BDR91<>Boiler connection
    Thanks for the useful info.

  6. #6
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    An evotouch controller can be used as a single zone controller without any HR92's, using it's built in temperature sensor to emulate a traditional single zone thermostat.

    However for two or more zones you must have HR92's or some other actuator (such as a BDR91 switched zone valve) for every zone. Once you have two or more zones you can't have one zone that has no actuator. *

    * Technically there are ways to work around this using binding tricks, but they're not recommended or supported by Honeywell, and having tried this myself, I don't recommend it either.
    Last edited by DBMandrake; 28th September 2018 at 03:12 PM.

  7. #7
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    Quote Originally Posted by DBMandrake View Post
    Once you have two or more zones you can't have one zone that has no actuator. *

    * Technically there are ways to work around this using binding tricks, but they're not recommended or supported by Honeywell, and having tried this myself, I don't recommend it either.
    If I understand correctly, each room that has a wireless stat (be it a wireless TRV or wall-mounted stat) is a zone - are you saying that all radiators/rooms in my house must have an actuator?

    I was planning on just installing HR92s in the bedrooms, lounge and kitchen, with the touch controller in the hall controlling the temperature for there. I was going to leave a few rads without wireless actuators/TRVs and just have standard TRVs on them, such as towel rads and the utility room rad.

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    No I'm saying that when you have more than two zones configured in the controller, they all must have actuators. EG you can't create a zone called Hallway on the controller for a radiator without an HR92 if there are other zones as well.

    That doesn't mean you can't have radiators with manual TRV's - I did the same thing myself for a while as I bought my HR92's gradually.

    It certainly wasn't optimal though because in moderate weather you often can't get enough call for heat from zones with HR92's to heat the rooms with the manual TRV's, as the Evohome isn't aware they need heat. (The same does apply to a conventional single thermostat system as well of course, so the ability for all zones with HR92's to call for heat is one of the advantages of a complete Evohome system over a traditional system...)

    The other issue I found is that if I needed any room to be on at night like a child's bedroom I would need to manually turn down the manual TRV zones before bed and turn them up again in the morning so they weren't heating all night, which was a bit of a pain. Not a problem if you have the system off completely at night.

    Now that I have HR92's on all zones I wouldn't want to go back to having any manual TRV's for these two reasons, but if it helps you build up a system over time as it did for me it's a workable entry path if the upfront cost for all radiators is too much.
    Last edited by DBMandrake; 28th September 2018 at 04:57 PM.

  9. #9
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    Ah okay, so if I want 6 zones, say, hallway, lounge, kitchen, bedroom1, bedroom2 and bedroom3, I can't have 5 HR92s for all except the hallway and use the touch controller for the hallway, I'll actually need 6 HR92s and the touch controller will be used to just control the 6 zones and will not behave as an actuator for the hallway? Have I got that right?
    Last edited by JohnOC; 28th September 2018 at 07:37 PM.

  10. #10
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    Quote Originally Posted by JohnOC View Post
    Ah okay, so if I want 6 zones, say, hallway, lounge, kitchen, bedroom1, bedroom2 and bedroom3, I can't have 5 HR92s for all except the hallway and use the touch controller for the hallway, I'll actually need 6 HR92s and the touch controller will be used to just control the 6 zones and will not behave as an actuator for the hallway? Have I got that right?
    The controller can be a remote temperature sensor for the zone but it still needs an HR92 or some other actuator to control the radiator itself in a multi zone configuration.

    But if you have no HR92's at all you can use the controller as a conventional single zone thermostat that just controls the boiler. (Although personally I don't see the point!)
    Last edited by DBMandrake; 28th September 2018 at 09:12 PM.

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