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Thread: Heat pumps with evohome

  1. #11
    Automated Home Sr Member
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    Mar 2016
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    Quote Originally Posted by spiralp View Post
    I wasn't sure that I knew the answer to your question, because the heat pump installers never discussed this with me. However, I have had a closer look. The cable from the BDR91 goes into the back of the Panasonic heat pump controller and a separate wire comes out of the heat pump controller to the secondary pump. This implies I am using the "optional heat pump controller connection". However, on checking the Honeywell controller I can see the BDR91 is not set for hear pump controls, hence it looks more likely the evohome is only controlling the secondary pump. In order to answer your question fully I will need to get back to my heat pump installer, or perhaps I might just have a play and see what I can find.
    I wonder if the panasonic heat pump controller is doing all the hard work, and the evohome BDR just being an external "call for heat" . See if you can see from the panasonic controller manual what the input that the BDR 91 is wired to does - if its labelled "3rd party thermostat" or something like that?
    Ian

  2. #12
    Automated Home Lurker
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    Nov 2020
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    Quote Originally Posted by sandyman View Post
    I wonder if the panasonic heat pump controller is doing all the hard work, and the evohome BDR just being an external "call for heat" . See if you can see from the panasonic controller manual what the input that the BDR 91 is wired to does - if its labelled "3rd party thermostat" or something like that?
    Ian
    I think you are correct. From what I can see I have the earlier BDR91, which only allows for basic switching, rather than the later version which allows some heat pump control. I have looked through the documentation I have, but I do not have anything showing how the controller is wired. In fact, I think the documentation I have does not include everything that should have been provided. This is probably because my heat pump installation was completed just as we entered the first lockdown in March 2020, so the 'hand over' was done by phone. My relationship with the installer is good so I will go through all the documentation with them in March next year when the heat pump is next serviced.

  3. #13
    Automated Home Sr Member
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    Mar 2016
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    Quote Originally Posted by spiralp View Post
    I think you are correct. From what I can see I have the earlier BDR91, which only allows for basic switching, rather than the later version which allows some heat pump control. I have looked through the documentation I have, but I do not have anything showing how the controller is wired.
    if it was me, I'd download the manuals, take the cover off and follow the cables, buts its your system so your choice (btw I'm not suggesting that you change anything)

    I think given that you have a control system that is still treating the heat pump as an on/off boiler, you'll be getting a TPI input to the heatpump control - which may not be ideal for what the heatpump expects. Given that you have a good relationship with your installer, I'd be really interested to hear what they think . I don't know what the difference in behaviour is if you use the new BDR that has the "heatpump" binding options.

  4. #14
    Automated Home Jr Member
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    Oct 2015
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    I'll absolutely be an outlier here but I'm using Evohome with a combination of a gas boiler and air source heat pumps ( Daikin ) in several rooms. No direct link... just using BDR91s as dummy actuators plus room stats and using Domoticz for IP control of the heat pumps, tracking the EvoHome set point for the rooms in question.

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