The Efficient Home Forum

I am building a system with an ATC928G3000 and 4 zones with a BDR91 for each zone valve. there is also a BDR91 boiler control
all are placed away from other devices and metalwork.

1 of the BDRs has the slow flashing red comms error light. remove any one of the other BDRs and the error goes, reintroduce it and the error returns. even with the error the BDR will pair and switch correctly so it works but its annoying having the flashing red light

Looks to me as if the ATC may not be able to poll this many devices.
is there a system limit to the number of devices the system can support?

Why do you need a BDR91 for each zone? The ATC controller is capable of 12 zones, and I only have 1 BDR91 controlling the boiler for the 12 zones with multiple HR91 TRV’s across some of those zones.

Just to confirm, there is no system limit to the amount of BDR91's you can have. 12 heating zones is the max limit for the evohome system, but each single zone 'could' have multiple BDR91's.