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Thread: (New) cool mode in Evohome

  1. #1
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    Default (New) cool mode in Evohome

    Are there any users here who have Evohome connected to a heatpump with the ability to cool as well?

    This year (before summer ) I want to use Evohome to switch on the cool mode of the Heatpump. So it was good news last year that heatpump control is added to Evohome. Especially the heat/cool function was welcome.
    Since the heatpump and heat/cool function is quite new, I have the feeling that the manuals by Honeywell are not describing everything (yet).

    My system setup is:
    * Honeywell Evohome, firmware 02.00.19.33
    * 2 HCE80 to control floorheating
    * Evohome for now configured with: heating with a BDR91 and cooling with a BDR91T
    * House with floorheating on all floors
    * Remeha Elga Ace Heatpump 6 kW, this is a hybrid one so the boiler is switched on if needed (which is hardly ever, mostly seen during defrosts)

    My questions are concerning cooling:
    1. The HCE-80 has the option to be switched into cooling mode; by configuration first, and then by a on/off contact to "tell" if heating or cooling is on. For this cooling mode the HCE-80 can (or must?) be configured with an additional thermostat to control the cooling temperature. At the moment it is unclear for me, if with the new Evohome firmware this additional thermostat for cooling is still needed?

    2. After adding the new BDR91T1004 as a device to control heating/cooling the Evohome menu gets the option to switch between heating and cooling. After switching to cooling the Evohome shows a cooling symbol for each room and a different set temperature for cooling. For now I am using the old BDR91 for heating-control and the new BDR91T(1004) for cooling-control. This seems to work nicely: in heating mode the BDR91 switches on and after switching to cooling mode the BDR91 (heating) switches off and the BDR91T (cooling) switches on. For now I have not yet configured the HCE80 for cooling, will do so somewhere the next weeks (haven't had the time yet). I was a bit surprised however that the BDR91 (heating) switched on after a few minutes as well. I was not expecting that both would give an on signal; I would expect either a heat request or a cool request, not both together? Is this normal behaviour, or might this be because (a) I have not configured the HCE80 for for cooling yet or (b) because I am using a BDR91 together with the BDR91T?

    3. Is Evohome with the latest firmware in cooling mode supposed to control all zones with the existing room thermostats? That would be most intuitive; a set room temperature at 20 degrees Celsius should lead to cooling if the temperature is (much) too high or heating if the temperature is too low. Or should I still assign cooling zones to the HCE80 with a seperate thermostat for the cooling temperature? (this question is a bit similar to my 1st)

    Thanks for thinking with me!
    Last edited by Fmb; 15th March 2021 at 02:27 PM.

  2. #2
    Automated Home Jr Member
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    Ok, just concluded one thing already. For heating/cooling the Evohome works with 2 signals;
    Signal 1. The Evohome heat requests by the 1st BDR91T means: if in heating mode “heat” is requested and if in cooling mode “cold” is requested. So the signal is used to request both heat and cold.
    Signal 2. The Evohome heat/cool contact (2nd BDR91T) simply tells if the Evohome thermostat is en heating mode or in cooling mode.

    My heatpump (Remeha Elga Ace) expects an on/off signal to heat and a separate on/off signal to cool (both cannot be on at the same time offcourse). So I need to put something in between (I can do that by Domotica) which will translate:
    Signal 1 on AND signal 2 off: heat request
    Signal 1 on AND signal 2 on: “cold” request

    And next I need to figure out how the Evohome controls the HCE80. I have not yet seen the HCE80 opening zones in cooling mode. That could mean even with the new Evohome firmware a seperate thermostat is needed voor de cooling zones of the HCE80.

    If I have some further testresults I’ll report back!

  3. #3
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    Maybe you will need to use Signal2 BDR91Ts to signal to the HCE80s to switch to cooling mode.

  4. #4
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    Quote Originally Posted by kevinsmart View Post
    Maybe you will need to use Signal2 BDR91Ts to signal to the HCE80s to switch to cooling mode.
    Yes, that is what I am going to try as well. At this moment the heatpump should do the same, it gives an on/off signal when it is cooling and this is wired to the HCE80’s. But in my setup I think it is better to use the signal directly from “Signal2 BDR91T”; should be faster and also stays on when the heatpump should decide it should stop cooling.

  5. #5
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    Ok, so yesterday I made the following changes in the setup:

    1. As said: my heatpump expects 2 different on/off signals; a signal with a heat demand and a signal with cool demand. Both off means no demand. Both on should not happen (there should not be both heat and cool demand).

    So I am now using a Fibaro Smart Implant to give those 2 signals. It translates the on/off signal from the 1st BDR91T (heat/cool demand) and the on/off signal from the 2nd BDR91T (mode: heat or cool) into 2 separate on/off signals which it gives to the heatpump. It seems to work, but I cannot really test the “cool mode” since it is too cold outside ;-)

    2. The 2nd BDR91T (heat/cool mode) is connected directly to both HCE80 to switch them to cool mode.

    So now I need to wait for higher outside temperatures to finish the setup. It is still not clear for me if the HCE80 needs a separate cooling zone(s) to be added with a seperate room thermostat or if the Evohome when switched to cooling mode can control everything directly in cooling mode.
    Last edited by Fmb; 11th April 2021 at 08:11 AM.

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