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Honeywell CM907 Thermostat problem. Please help.


 
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hankdesign

from United Kingdom

Joined: 08 Dec 2010
Posts: 2
Location: Wiltshire,
United Kingdom

PostPosted: Wed Dec 08, 2010 8:06 am Reply with quote

Hello all.

I have an issue with the Honeywell CM907 thermostat. I have it set on Automatic and the heating in the house is supposed to turn off at 10pm and not come back on until 6am. However it seems to be going on and off throughout the night and now im worried that I am going to accumulate and huge bill.

Is there some sort of setting to stop this from happening or could it be a fault? Any help will be greatly appreciated. We are in a brand new house and its only 4 months old.

Thanks.
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MJN

from United Kingdom

Joined: 30 Apr 2008
Posts: 538
Location: Wiltshire,
United Kingdom
Thanked: 63 times

PostPosted: Wed Dec 08, 2010 10:36 am Reply with quote

hankdesign wrote:
I have it set on Automatic and the heating in the house is supposed to turn off at 10pm and not come back on until 6am. However it seems to be going on and off throughout the night

There might be a misunderstanding here of how these programmable thermostats work.

They do not have 'on' and 'off' times as such, but rather temperature set points. Thus, between 9am and 10pm the temperature set point might be 21C, however between 10pm and 9am your stat might be set at 15C. During 'normal' weather conditions this might be for all intents and purposes be 'off' however during this particularly cold period the house (or the room the stat is in) could be dropping below 15C hence the boiler is being called for heat.

Check to see what the temperature set point is for the overnight periods, and lower it if you don't want the boiler firing.

Mathew
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hankdesign (8 Dec 2010)
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hankdesign

from United Kingdom

Joined: 08 Dec 2010
Posts: 2
Location: Wiltshire,
United Kingdom

PostPosted: Wed Dec 08, 2010 10:43 am Reply with quote

MJN wrote:
hankdesign wrote:
I have it set on Automatic and the heating in the house is supposed to turn off at 10pm and not come back on until 6am. However it seems to be going on and off throughout the night

There might be a misunderstanding here of how these programmable thermostats work.

They do not have 'on' and 'off' times as such, but rather temperature set points. Thus, between 9am and 10pm the temperature set point might be 21C, however between 10pm and 9am your stat might be set at 15C. During 'normal' weather conditions this might be for all intents and purposes be 'off' however during this particularly cold period the house (or the room the stat is in) could be dropping below 15C hence the boiler is being called for heat.

Check to see what the temperature set point is for the overnight periods, and lower it if you don't want the boiler firing.

Mathew


Wow that explains a lot. Now you have mentioned it I think you are right. We werent shown anything about the thermostat when we bought the house.
So if I set the temp at around 10c throughout the night it will hopefully not come on. I will test tonight and report back.

Thanks.
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MJN

from United Kingdom

Joined: 30 Apr 2008
Posts: 538
Location: Wiltshire,
United Kingdom
Thanked: 63 times

PostPosted: Wed Dec 08, 2010 11:02 am Reply with quote

No worries. It is a somewhat alien concept to those used to traditional on/off controls and you might be forgiven for wishing things were nice and simple. However, if you take your time to understand it you will soon appreciate the potential benefits of having different temperatures at different times of the day.

If you haven't already got a copy of the user guide you can download it here. I recommend giving it a good read - two or three times if necessary - as its operation does become fairly straightforward once you've got a little used to it. Check out the holiday/party functions too - very handy things to have but I dare say a great many are unaware of their existance.

Mathew
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