EVOHOME, Cenral Heating and Hot Water Control

[Devon Red]

Hi,
Just completed a new EVOHOME installation, controlling both the Central Heating and the stored Hot Water systems.
The system uses a mid port valve (Honeywell Y Plan).

When the demand is for Heating, the appropriate BDR91 is energised (green).
When there is call for Hot Water only, both the BDR91s are energised.

Is this correct?
I was expecting only the Hot Water BDR91 to be energised.
I have followed both the installation guides and YouTube videos, with the same result.

Any help gratefully received.

[DBMandrake]

Hi,
Just completed a new EVOHOME installation, controlling both the Central Heating and the stored Hot Water systems.
The system uses a mid port valve (Honeywell Y Plan).

When the demand is for Heating, the appropriate BDR91 is energised (green).
When there is call for Hot Water only, both the BDR91s are energised.

Is this correct?
I was expecting only the Hot Water BDR91 to be energised.
I have followed both the installation guides and YouTube videos, with the same result.

Any help gratefully received.

It sounds like you have bound the "heating" relay as a "boiler control" relay instead of or in addition to binding it as a heating relay.

A hot water relay turns on only for hot water demand, a heating relay turns on only for heating demand, but a boiler relay turns on for both heating and hot water demand.

In a two relay Y/S-Plan configuration (where the boiler is fired by the orange wire(s) on the zone valve(s)) you should not bind a boiler control relay. To fix this:

Clear the bindings on both BDR91's by holding the button on each unit for at least 15 seconds until you get a rapid flash. This clears the bindings at the relay end.

Go into the installer menu on the controller (long press on settings) and go to system devices. Change boiler control to none, then go into stored hot water, change it to none, then back out of the menus. Then go back into stored hot water and follow the binding process to bind the hot water sensor, hot water relay and heating relay as directed. Leave boiler control as none.

That should fix your problem.

[Devon Red]

Thanks for your prompt and accurate reply.
System working as expected.

Very best regards