Question about Honeywell Programmable Thermostat Heater

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Installing CM900 Honeywell into Junior 24 Bosch Combi

The honeywell manual wants me to connect 2 wires from points A and B in the honeywell to points labelled T1 and T2 in the boiler. The boiler manual doesn't use these letters but tells me I have a switched live, a live and a neutral (plus the neutral and live of the mains supply). Any ideas which the honeywell wants where?

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What kind of boiler are using is this boiler a on the demand electric or gas? You need low voltage wires. If you get me make and model # of off boiler i can try and find wiring diagram . Tell me a little more about you heat system to. Like baseboard heat or in floor how many zones

Posted on Jan 16, 2009

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  • Scott Magill Jan 16, 2009

    It looks like you need a 230volt thermostat so make sure the cm900 is a 230volt thermostat if it is connect supply to Ls , neutral to Ns and Lr is power when thermostat contact is closed. I will try and find wiring diagram for the cm900 it will take a little while. Do you have any information on the thermostat.

  • Scott Magill Jan 16, 2009

    have you got it to work. I haven't found anything on the cm900 t-stat

  • Scott Magill Jan 17, 2009

    Looks like you have to connect thermostat labled a to LS and B to LR.Sorry it took so long to find the cm900 thermostat you probaly have it installed by now. This will only work this way if you only have 1 thermostat in the hole house.


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