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BDR91 evohome settings for heat pump

Posted: Sat Nov 06, 2021 10:13 pm
by brian84cw
Hi all,

I have a heat pump with underfloor heating on the ground floor and radiators on the first floor.

The system is currently controlled by a Heatmiser system. The ground floor is split into 4 underfloor zones controlled by an individual temperature stat for each zone. the radiators upstairs are controlled via a single temperature stat connected to a dedicated radiator zone on the Heatmiser unit.

I am going to replace the upstairs zone with the evohome system. I have only recently become aware of the two different relays (BDR91A and BDR91T). I have the BDR91A 2021 model. I understand that the BDR91T is designed for heat pumps but I am struggling to understand the difference between the two. I plan to use the relay to supply a signal to the Heatmiser unit which will signal the heat pump. Am I ok to use the BDR91A relay? I have read on some sites that the BDR91A 2021 model is compatible with Heat Pumps, is this accurate? Do I need to adjust the settings on the evohome to support this function?

Appreciate any help on this :)

Re: BDR91 evohome settings for heat pump

Posted: Mon Nov 08, 2021 10:09 am
by Richard
BDR91T has different firmware on it to make it compatible with heat pumps. BDR91A is unfortunately not compatible afaik.