Help! I'm trying to replace the mechanical clock on a Baxi combi boiler (80e). It's got a round mechanical clock with 2 black, 1 brown and 1 blue wires. I tried connecting the blue and brown to the Honeywell cm907, but this blew the boiler fuse... Should I have used the black wires instead? (The CM907 has batteries).
Which wires for cm907 to replace mechanical clock on Baxi?
- Thread starter Jamesbaly
- Start date
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i take it you dont have an existing room stat so leave the clock on constant.
Go into the terminal strip and there will be a yellow link wire remove link and take your 2 wires for room stat from there basically in and out both are live no neutral req
Go into the terminal strip and there will be a yellow link wire remove link and take your 2 wires for room stat from there basically in and out both are live no neutral req
I'm planning on disconnecting the timer completely, as the Honeywell is a stat and 7 day timer.
Am I correct in saying the blue and brown wires are used to power the clock, and the 2 black wires are the switching ones? I'm going to isolate the blue+brown and use the 2 black to the A and B connections on the CM907.
See image from the baxi install manual.
Am I correct in saying the blue and brown wires are used to power the clock, and the 2 black wires are the switching ones? I'm going to isolate the blue+brown and use the 2 black to the A and B connections on the CM907.
See image from the baxi install manual.
Just fitted one of these to replace a room thermostat and blew the boiler fuse. The trick is that you only connect the live (brown wire) to connection A the neutral wire is supplied by the batteries in the unit itself. Tape off all other wires. Now all working fine!
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I'm planning on disconnecting the timer completely, as the Honeywell is a stat and 7 day timer.
Am I correct in saying the blue and brown wires are used to power the clock, and the 2 black wires are the switching ones? I'm going to isolate the blue+brown and use the 2 black to the A and B connections on the CM907.
See image from the baxi install manual.
Much easier to do what Gas112 has told you.
Buccaneer...don't "tape" off loose ends!! And there is no neutral in these stats. It is volt free switch.
The new stat/timer is installed and working great. Manual clock/timer is left always on and the stat is wired directly to the board (on far left side).
FYI, the blue and brown wires power the clock, and the two black wires are the switch. Don't wire blue and brown to the CM907!
FYI, the blue and brown wires power the clock, and the two black wires are the switch. Don't wire blue and brown to the CM907!
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