Honeywell CM927 thermostat says room temp is 40 degrees!!!

26 Feb 2011
Reaction score
United Kingdom
Hi, Had new boiler and this thermostat installed last year. Worked perfectly but today the screen on the thermostat was blank, so I replaced the batteries and it came back on but its saying the room temp is 40 degrees (its cold and raining). I've tried taking batteries out again but comes back on saying the same. I couldnt find a way to reset it apart from taking batteries out. Any ideas? At the moment I can't put the heating on as the max temp the heating will go up to is 35 degrees!!!
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Try the following
ii) Reset the built-in program to the factory default
Press the time button once. The display will show ‘RESET PROGRAM’.
Press the or buttons to select the preferred setting (0=user program,
1=factory program) and the display will flash, indicating a change has been
made. To confirm this change press the green button :p

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