Hello,
Firstly, welcome and thank you for many good tips already from other threads.
Unfortunately I was not able to find answers to all my concerns and that's why I'm starting separate thread. I would appreciate some help in planning my Evohome installation in my countryside house. For quite some time I'm planning to upgrade the current heating system with Evohome for remote control, however I have quite unusual set-up and I'm not sure how to handle it.
Current system is as follows:
I have a boiler room with 800l heat buffer. The buffer can be heated from several different sources (heat pump, electric, wood) and I don't want to control with Evohome this stage. Hot water from heat buffer is distributed over the house in 3 separate water circuits controlled by 3 separate circulation pumps (let's call them A,B,C). Each of the pumps is controlled by on/off thermostatic switche in 3 different areas of the house (currently with classic electromechanical thermostats):
  • Circuit "A" provides heat to underfloor heating in big living room (no zones or separately controlled loops)
  • Circuit "B" provides heat to radiators on the first floor. Here I have in fact only one master bedroom which requires separate temp control. All other radiators may stay with current mechanical thermostatic valves as they are in non-living parts of the house.
  • Circuit "C" provides heat to radiators on the second floor. Here I have two bedrooms and a bathroom. Thermostat controlling the pump is somewhere on the wall in the corridor.

Here is what I was thinking about:
  • to place 3 BDR91's instead of each of 3 thermostats in all areas of the house to control on/off for all 3 circuit pumps.
  • The Evohome control panel would be in the living room and would also serve as a temperature sensor for this zone and switch on/off it's BDR91 for circuit "A"
  • For circuit "B" (master bedroom) either:
    (a) HR92 connected to BDR91 demanding the heat from circuit pump "B" or
    (b) DT92/T87 placed in the bedroom paired with the BDR91 for circuit pump "B", but with old mechanical TRV's. In such set-up the TRV would be usually set to "high" and the room temp would be controlled by switching on/off the pump.
  • For circuit "C" (upstairs bedrooms)
    (a) HR92 in each room. All of upstairs HR92 paired with BDR91 demanding the heat from circuit pump "C". I guess this requires setting BDR91 "C" as a boiler control, right?
    (b) alternatively, DT92/T87 placed in one of the bedrooms paired with the BDR91 for circuit pump "C" and simply controlling all the upstairs as one zone.

After quite some research and discussions: here are my concerns/questions:
  • it looks like it's not possible to have HR92's TRV in two different heating circuits, controlling two different BDR91's - circuit B and C. Is this correct? That's why I have the alternative solution (b) for circuit "B" eliminating the HR92.
  • is it possible: to have 2-3 separate zones in circuit "C" each equipped with HR92; all HR92's demanding the heat from BDR91 "C", but at the same time keeping the circuit A and B independent? e.g. if there is a demand in circuit A and/or B, but no demand in circuit C the BDR91 A and/or B would be in "on" mode and BDR91 would stay in "off" mode? I'm under the impression this is possible if BDR91 A and B are in the "electrical heating" mode (no boiler demand) but not sure if this can be combined with the BDR91 C controlling the HR92's ?

I would be grateful for clear indication what and how can be done in such set-up and of course all other feedback on this design is highly appreciated!
Thank you!