Hi,
Just recently purchased our Nest thermostat, haven't tried wiring it in yet but have been looking at the manual and just trying to get it right before I start.
Currently using the Honeywell CM921 thermostat and relay box with a Baxi Duo Tec combi boiler.
According to the Nest manual I need connect a Live and a Neutral which I get and can identify easily in the CM921. But also it says I need to connect a "call for heat" (2) and a "common" (3). The but I don't understand is there are two wires in the CM921 that are connected to a terminal block labelled A and B.
My question is, is A in the CM921 "call for heat" or is it the wire connected to B. Presumably if A or the B wire is call for heat the other would be common?
Any help would be appreciated.
Thanks
Just recently purchased our Nest thermostat, haven't tried wiring it in yet but have been looking at the manual and just trying to get it right before I start.
Currently using the Honeywell CM921 thermostat and relay box with a Baxi Duo Tec combi boiler.
According to the Nest manual I need connect a Live and a Neutral which I get and can identify easily in the CM921. But also it says I need to connect a "call for heat" (2) and a "common" (3). The but I don't understand is there are two wires in the CM921 that are connected to a terminal block labelled A and B.
My question is, is A in the CM921 "call for heat" or is it the wire connected to B. Presumably if A or the B wire is call for heat the other would be common?
Any help would be appreciated.
Thanks