The Efficient Home Forum

Hello, Any advice or thoughts on improving the situation below please.
I have an S-plan plus configuration. i.e. three two port valves each with a wireless relay connected (BDR91).
The first is for Hot Water DHW , the second is for Radiators HTG and the third is for a single zone of Underfloor heating UFH.
There is a wiring diagram in the EvoHome installation for S-plan but not S-plan plus. When I queried this with Residio they said the EvoHome system does not work this way. When I then spoke with The EvoHome shop AND the Honeywell local area sales manager about how to add a single zone of UFH they both said I just needed an extra BDR91. This has been purchased and the system wired as per the S-Plan plus schematic from Worcester Bosch (attached)
If I manually override each BDR91 everything works as expected with each zone valve opening and sending hot water demand to boiler BUT I have had great problems trying to configure the EvoHome base controller and after much research I have configured the EvoHome base controller as follows:
The DHW BDR91 is linked to the CS92A sensor and configured as the hot water storage (normal configuration);
The HTG BDR91 is configured as the boiler relay (wiring not changed)
The UFH BDR91 is configured as the actuator for the Y87RF room thermostat in the UFH heating area.
This works in so far as ANY demand for heating with trigger the HTG BDR91, not the end of the world as all the radiators on this circuit have HR92 radiator valves so are controlled as zones.
It would be better if the HTG BDR91 was only “linked” to all the HR92 valves and only activated if any of these signalled, and the UFH BDR91 only linked to the Y87RF but I am told the EvoHome does not operate this way?

Hope this all makes sense., please offer any suggestions if the EvoHome base can be configured in a better way.

This system configuration is quite typical for evohome, but it is the physical (mechanical) layout and system setup that is the issue here verse an 'S Plan Plus'.

Correct way to do it is as follows...

evohome Controller & Wireless Relay Box BDR91 wired directly to boiler switched live - Setup via SYSTEM DEVICES > APPLIANCE CONTROL* > WIRELESS RELAY BOX (*19.33 firmware terminology)

Radiator Heating Circuit (No Motorised Zone Valve) - Must have HR91 or HR92 fitted to all radiators

UFH Motorised Zone Valve - BDR91 & T87RF - Setup via ADD ZONE as ZONE VALVE zone

Hot Water Zone Valve - BDR91 & CS92A - Setup via GUIDED CONFIGURATION > STORED HOT WATER CONFIGURATION > (*Bind CS92A*) HOT WATER ONLY VALVE

All orange and grey motorised zone valve wires made safe, as they are not needed.

Hope that helps?

The EVOHOME Shop wrote:This system configuration is quite typical for evohome, but it is the physical (mechanical) layout and system setup that is the issue here verse an 'S Plan Plus'.

Correct way to do it is as follows...

evohome Controller & Wireless Relay Box BDR91 wired directly to boiler switched live - Setup via SYSTEM DEVICES > APPLIANCE CONTROL* > WIRELESS RELAY BOX (*19.33 firmware terminology)

Radiator Heating Circuit (No Motorised Zone Valve) - Must have HR91 or HR92 fitted to all radiators

UFH Motorised Zone Valve - BDR91 & T87RF - Setup via ADD ZONE as ZONE VALVE zone

Hot Water Zone Valve - BDR91 & CS92A - Setup via GUIDED CONFIGURATION > STORED HOT WATER CONFIGURATION > (*Bind CS92A*) HOT WATER ONLY VALVE

All orange and grey motorised zone valve wires made safe, as they are not needed.

Hope that helps?

Thanks for this information.

As there is already a two port valve on the Radiator Heating circuit I will leave it linked to the boiler relay, so that any time the boiler fires up this valve will be open. No need to pay a plumber to remove it.

rslough wrote:Thanks for this information.

As there is already a two port valve on the Radiator Heating circuit I will leave it linked to the boiler relay, so that any time the boiler fires up this valve will be open. No need to pay a plumber to remove it.

Personally I wouldn't do this, as the boiler relay is linked to the other evohome products and you end up with a valve swinging about that is not necessary (and will fail). Just electrically disconnecting the valve and leaving in the manually open position is sufficient.