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Thread: Hacking Evohome... API Vs direct communication with devices

  1. #11
    Moderator Kevin's Avatar
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    Jan 2004
    West Yorkshire


    It sounds like you would really prefer to build your own system.

    There are many RF based TRV’s with varying levels of documented control protocols, e.g. ZigBee, Z-Wave, 6LoWPAN* or plain RF 433/868 MHz - even some using infra red. Then there are all the wired versions. As a project it would be much easier to select suitable TRVs and then build your controller around that rather than ‘hacking’ or replacing the controller on an existing system like evoHome.

    A lot lot of home automation applications and controllers (some free) offer direct support for TRV’s and therefore can be used as a scriptable heating controller. That would be the easiest path although dealing with individual room heating characteristics , efficiency, overshoots, optimisation and aspects like that will be challenging.

    There’s an awful lot of behind the scenes smarts and experience that Honeywell implement in evoHome via the controller that you would lose via your approach so you may as well just start with a new controller design using your choice of TRVs. HR92s are probably not the best option for such a project.


    * The 6LoWPAN ones even claim to never need batteries based on thermal energy harvesting. 30 ! I don’t know if there’s any ‘open’ protocol direct to TRV or if their ‘open’ API will offer any local hub control or just cloud.
    Last edited by Kevin; 28th January 2018 at 03:29 AM.

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