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Thread: Can anyone help advise how to move from a cm927 to Evohome please?

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    Default Can anyone help advise how to move from a cm927 to Evohome please?

    Hi,

    I have decided to move from a honeywell cm927 thermostat to Evohome to enable me to gain more control over individual radiators and rooms. I have an Ecotec plus 831 combi boiler which was installed 4 years ago along with new radiators and pipe work. Can anyone advise what kit I will need to do this and do I need to use a new BDR91? If not can I buy the Evohome thermostsat without the BDR? Many many thanks in advance..

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    Quote Originally Posted by FUNKYDADDIO View Post
    Hi,

    I have decided to move from a honeywell cm927 thermostat to Evohome to enable me to gain more control over individual radiators and rooms. I have an Ecotec plus 831 combi boiler which was installed 4 years ago along with new radiators and pipe work. Can anyone advise what kit I will need to do this and do I need to use a new BDR91? If not can I buy the Evohome thermostsat without the BDR? Many many thanks in advance..
    The ordering options for the controller are shown on the controller data sheet: https://products.ecc.emea.honeywell....-uk07r0814.pdf. If you plan to buy the separate wall mounted charger then the pack without a table top charger may work out, as the BDR91 you already have with the CM927 can be paired with it. You'll notice that if you want a table top charger stand it also comes with a BDR91.

    Just the controller at 185 (eg http://www.discountedheating.co.uk/h...ontroller.html) doesn't look to be much cheaper than the Base Pack (with charger stand and BRD91) at 205 (eg https://theevohomeshop.co.uk/honeywe...p921r3100.html) though. You can probably sell the extra BDR91 for to someone who want so set up separate boiler and zone control, or maybe put it to good use yourself to get finer control of things.

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    You'll presumably want radiator valve heads (HR92 devices) as well. Do you understand the wiring and water valve installation that you have? It'll probably need no modification, but mat be worth reviewing.

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    Quote Originally Posted by Little Tinker View Post
    The ordering options for the controller are shown on the controller data sheet: https://products.ecc.emea.honeywell....-uk07r0814.pdf.
    That link is pointing to the older 2nd generation evohome controller. For evohome WiFi (current generation) see www.honeywelluk.com/Documents/All/pdf/Honeywell_Evohome_Brochure_ERP_6.pdf

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    Do you understand the wiring and water valve installation that you have? It'll probably need no modification, but mat be worth reviewing.
    No need to worry about wiring. Combi boiler already has BDR91 connected to it. Just bind new evohome controller to the existing BDR91 and add HR92s to radiators for zoning.

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    As others have said, the very first thing is to figure out what you already have. If you've got a CM927 room thermostat at the moment, you'll already have a BDR91 already. I think you've figured that one out yourself as you're asking whether you need a "new" BDR91.

    do I need to use a new BDR91
    You're pretty much in the same boat as I was when I started (see this thread).

    You need to look at your existing BDR91 and try and figure out what this is connected to and how. It might be as simple as taking the battery out of your existing CM927, clearing the binding on the existing BDR91, and bind it to the new evoHome controller.

    In terms of kit you'll need

    - a wireless controller pack (e.g. here) which basically replaces the existing CM927

    - Electronic TRVs (e.g. pack of 4)

    Have a look at the thread I linked above, the scenario is very similar to yours. You'll find that the installation instructions have their limitations, but there are some amazing people on this forum who I cannot praise enough. I couldn't have figured out some (probably fairly basic) questions without them.

    Good luck

    Martin
    Last edited by mart1711; 28th November 2016 at 09:07 AM. Reason: edited - overlooked the fact it's a combi boiler

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    Although your existing BDR91 will work, these things contain (non-updatable) firmware, so for the sake of a few I think it would be wise to go for a newer one, which will have the latest revision.

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    Quote Originally Posted by paulockenden View Post
    Although your existing BDR91 will work, these things contain (non-updatable) firmware, so for the sake of a few I think it would be wise to go for a newer one, which will have the latest revision.
    Good point. If you go for the wireless pack linked above that contains a BDR91 too (which in my case I've kept for spares). You could do the reverse (keep your existing one for spares), if your new one packs up...

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    Quote Originally Posted by paulockenden View Post
    Although your existing BDR91 will work, these things contain (non-updatable) firmware, so for the sake of a few I think it would be wise to go for a newer one, which will have the latest revision.
    Do we have any evidence that there have ever been different firmware versions for the BDR91 though ? And even if there were revisions, that older versions might have issues with the Evohome ?

    I haven't heard a thing in this regard - the only issues I've heard of are older firmware on HR80's. I wouldn't be surprised to find that BDR91's have had the same firmware since day one. Is it even possible to query the firmware version ? Maybe by examining messages captured by an HGI80 ? (I think devices do report their firmware versions over Ramses II during binding)

    In short I wouldn't worry about using the older BDR91, it should be fine.

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    Quote Originally Posted by DBMandrake View Post
    Do we have any evidence that there have ever been different firmware versions for the BDR91 though ?
    Well, one of the first things Honeywell support asks you when there's a potential BDR problems is the code on the unit so they can identify how old it is.

    And I'm also inferring from comments posted here by the Honeywell guys. But of course, like most things Evohome, there's no way of knowing for sure....

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