Is it possible to have the Evohome controller call for heat in a multi zone setup?

[jonnyhibbert]

I have a Honeywell Evohome, connecting to several HR91 TRV's across the house. The hallways and a couple of rooms don't have TRV's, and the EvoHome controller acts as the temperature sensor for those rooms, labelled as 'Common Areas'.

I want the 'Common Area' zone to be able to call for heat when it gets below X temp, but I can't see the best way to configure this as it seems zones HAVE to be bound to a device to be setup.

Is it incorrect to double bind the boiler relay to this zone, as well as the primary boiler control? Otherwise, how do you configure it so that it works?

[lloyd]

Not an expert, but I suspect that you are going to have to have a HR91 (or 92) on at least one of those radiators. The controller can act as the sensor, but it is expecting to control a TRV. I'm not even sure the TRV needs to be on a radiator, just needs to exist. It is worth noting that the controller is quite poor as a sensor, as the it seems sensitive to periods when the batteries are charging, or it is being handled. You might be better with a standalone sensor

[gordonb3]

While the BDR can hold up to four binds, double binding sounds like a source for error as one (the `zone`) is supposed to control the other (boiler). I wouldn't even try it. I'm not really aware of the controller being unreliable as a sensor, but one of the options you could consider is to install a Round (T87RF) and have that take a second bind to the BDR boiler module. Of course that will mean it is a rogue zone that will not be controllable through Evohome.

[DBMandrake]

I have a Honeywell Evohome, connecting to several HR91 TRV's across the house. The hallways and a couple of rooms don't have TRV's, and the EvoHome controller acts as the temperature sensor for those rooms, labelled as 'Common Areas'.

I want the 'Common Area' zone to be able to call for heat when it gets below X temp, but I can't see the best way to configure this as it seems zones HAVE to be bound to a device to be setup.

Short answer is no, you can't do what you're trying to do. In a multi-zone Evohome installation every zone must have an actuator, you can't just have a zone with a temperature sensor and no actuator.

Is it incorrect to double bind the boiler relay to this zone, as well as the primary boiler control? Otherwise, how do you configure it so that it works?

Yes it's incorrect to double bind the relay as both the boiler relay and as a zone valve relay, even though it will let you do this.

It may appear to work at first but you will have problems, and will most likely see "comms errors" start to be logged periodically. Some people say they have this configuration working but when I have tried it I always had problems and it is definitely not supported by Honeywell.

If you had another spare BDR91 you could bind it as the actuator for a zone valve type zone, and just not connect that relay to anything (other than power) and this would "fool" the system and avoid the issues with double binding but I don't recommend this kind of setup.