Hi, I have bought a Honeywell CM900 to replace the manual thermostat I have in the hall. Seems a fairly simple job to fit, only two wires. I have one small query. I would ask the Honeywell help desk but it appears they don't deal with householders. I have a basic central heating boiler system The wiring diagram shows that I connect to terminals A and B but it also shows a link from A to C. As all the variations for different heating systems show this link, do I assume that the unit already incorporates this link or do I have to put a wire in to link A and C. Any help would be appreciated, Thanks, Lawrie
Honeywell CM900
Nov 13, 2011
2 Replies
The link from A to C exists internally to the stat when the heat demand is satisfied. You don't need to add a wire.
Thanks very much for your help, John. Much appreciated, Lawrie
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