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Thread: The (next) most common evohome Q's & A's - FAQ

  1. #1

    Default The (next) most common evohome Q's & A's - FAQ

    Dear All

    Here is a FAQ with the most common Q&A Honeywell gets asked by consumers and installers, after the initial introduction. I hope this helps

    Had to do as a drop box download (sorry file limit here on the forum) - its only 280k.

    https://dl.dropboxusercontent.com/u/...me_FAQ%27s.pdf
    getconnected.honeywell.com | I work for Honeywell. Any posts I make are purely to help if I can. Any personal views expressed are my own

  2. #2
    Automated Home Guru
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    hi Ramases

    thanks for those (and your other posts) - I'm still confused why honeywell decided that you don't need a local override from a hr92 reflected in the main controller. I understand that it might be part of a bigger zone, but why not let the override from the hr92 specified as the thermostat from the zone be reflected in the controller. The controller is aware of the local override because it can trigger a boiler demand so the information is in the controller.

    in the various reviews I've seen most people point to this as a bug - but it's obviously by design. It really reduces the effectiveness of local override (in my opinion) as you've no way of knowing which radiator have been adjusted or to what temperature.

    Of all the foibles in the evohome system I find that the most irritating.

    Any clue to the logic behind this decision ?

  3. #3
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    Of all the foibles in the evohome system I find that the most irritating.
    Ditto to that - especially with inquisitive kids around I've ended up disabling local control on all of the HR92's

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    Thx for the informations!
    If I could add one... how is it possible to update evotouch's firmware?

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    Thanks for the FAQ. A good read.

    Do you have a wiring diagram for the S Plan arrangement to take control of the boiler cycle rate, please?

    In particular, how is the BDR91 wired at the boiler?

    Thanks

    Robert

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    Quote Originally Posted by Hampshire View Post
    Thanks for the FAQ. A good read.

    Do you have a wiring diagram for the S Plan arrangement to take control of the boiler cycle rate, please?

    In particular, how is the BDR91 wired at the boiler?

    Thanks

    Robert
    Hi Robert,

    The cycle rate/min on time can only be used with an S plan...

    1. If you have HR92's on all radiators when using the evohome hot water kit or
    2. If you have evohome doing the heating only (existing programmer doing the hot water) with or without HR92's.

    In situation 1. you can completely electrically disconnect the heating zone valve (S Plan minus as I like to call it) from the wiring centre and leave the heating zone valve lever in the manually open position. The 'Boiler Relay' BDR91 is then wired into the wiring centre so that the switched live from terminal B on the BDR91 is wired into the same terminal as the orange wire from the hot water motorised zone valve. This will give you the switched live demand back to your boiler/pump and will allow you to set the evohome controller to use cycle rate and minimum on time. You also need to make sure you set-up the hot water guided configuration as 'hot water only valve' and obviously configure the system with a 'boiler relay'.

    In situation 2. it will work like this out of the box with the heating BDR91 wired as per page 46 of the evohome installation manual.

    Hope that helps.

    Richard

  7. #7
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    OK. Thanks for that explanation. (and for supplying my Evohome kit!)
    So it cannot go in series with the switched live from the heating motorised valve, or in place of roomstat connections on the boiler?
    The fog is beginning to clear.
    Does the opentherm boiler controller bring any benefits, if the boiler is compatible?
    Robert

  8. #8
    Site Sponsor The EVOHOME Shop's Avatar
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    No problem Robert (to both counts).

    The main problem is using a 'boiler relay' (which is required for boiler cycling). If you use it to switch a heating motorised zone valve when you have an evohome Hot Water Kit, it will turn on at the same time as the hot water demand (evohome will signal the 'boiler relay' for the heating and hot water demands). Nothing worse than heating and hot water! Best way to do is is as mentioned with S Plan minus (less things to go wrong too).

    Opentherm for evohome is not available through Honeywell UK at the moment - there is benefits to the OT system rather than 'on/off' demand but we are always a little behind here in the UK.

    Many thanks again,

    Richard

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    Quote Originally Posted by Rameses View Post
    Dear All

    Here is a FAQ with the most common Q&A Honeywell gets asked by consumers and installers, after the initial introduction. I hope this helps

    Had to do as a drop box download (sorry file limit here on the forum) - its only 280k.

    https://dl.dropboxusercontent.com/u/...me_FAQ%27s.pdf
    Sorry, can't access the FAQs... broken link?

    Thanks

    M

  10. #10
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    I started another thread about OT and Evohome... it's getting pretty confusing to me...

    OT SHOULD help saving energy, just because a condensing boiler has a better efficiency at lower water temperatures and modulating the flame could lead to longer burn times at lower temperatures. Way better than the "time modulation" that, in my opinion, puts a lot of stress on the boiler itself switching it repeatedly on and off. Having an OT compatible boiler, I bought a Evohome - because I saw that around Europe (expecially in the Netherlands) it's sold along with an R8810 OT boiler controller. Now it's the R8810 OT controller that's giving me troubles...

    Back to the Evohome "features"... A thing I don't like much is the lack of feedback about zone status, boiler status etc. on the controller and on the app. I'm playing around with APIs as well, ant it appears as the whole system is designed without any feedback from the controlled systems, that doesn't sound optimal (as I recall from Uni...) as a control method...

    Another OT remote controller unit that I was looking at before buying an EvoHome was capable of showing all boiler parameters (DHW and CH setpoints, flame status, external temperature sensor, ...). Others that look way simpler, have the ability to indicate - at least - if the boiler is firing or not (if it's ACTUALLY firing, not if it's just SUPPOSED TO because the thermostat set point is above room temperature). Some informations are on the controller for sure, some others may be very useful to better control the whole system and help saving energy (e.g. external temperature could help setting CH water temperature).

    Best control practices should be based on feedback loops. Having feedback information from the controlled systems should thus be useful at least...


    bye

    M

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