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Michael, Customer Service
Category: Appliance
Satisfied Customers: 9568
Experience:  I have been an appliance repair tech for over 30 years and will help you solve your problems.
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I used my CM 921 thermostat to switch on the central heating

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I used my CM 921 thermostat to switch on the central heating for an hour the other evening. The following morning I realised that the radiators were still warm. Checked the thermostat- yes, I had switched it off and it was on the minimum temperature setting of 5o. What could be the reason? Is it the thermostat that is faulty?
Secondly, when I was checking the thermostat, I realised that I am unable to set the date correctly, as, when I move on to the 'month' setting, the only choice I get is '0' or '1'. Any thoughts?
Thank you
Hi yes this sounds like a thermostat problem.
You may simply need new batteries. We cant be sure yet.
Below is a link to the user manual in case you need it.
If you will rate my service to you thus far as ok or better, before closing this page, I will be able stick with you until this fixed.
Please note it won't cost you anything more to rate, and it WILL ensure your question won't time out or end unexpectedly, then you can always contact me the very same way at no additional cost;-)
Thank you and have a wonderful day!
Tech Michael
Michael and other Appliance Specialists are ready to help you
Customer: replied 3 years ago.

There was no indication that the batteries needed changing, but I have now changed them. Let me know more. Thanks

Thanks for that info Anthony.
The Thermostat may have failed but try something for me first before we can be sure. Remove the batteries, make sure they are new and fully charged.
Then install them in the reverse direction and let it sit for 2 full minutes. Then remove them and re install correctly.
This will reset the T-Stat.
If that doesn't work then its a failed T-Stat.
I can help you get locate a new replacement if you need that as well ;-)
Customer: replied 3 years ago.

Thanks; I am trying this now

Sounds good, you should also reset the electronics at the boiler. By turning off power to it for 20 full minutes ;-)
Thank you
Tech Michael
Customer: replied 3 years ago.

I am trying this now. I switched the heating on for 10 minutes after I changed the batteries; doesn't seem that they are cooling down again, but I have now switched the power off.

The problem with setting the date did not change when I put new batteries in

Hi This really sounds like simply a failed T-Stat.
It will need to be replaced if the unit wont respond to even the time etc.
Tech Michael
Customer: replied 3 years ago.

Michael- I keep rating your service and then getting another email from you asking me to do so. I will do it once more. Last evening, having done everything you suggested, I put the heating on for a short while, and after I had switched it off, the radiators cooled down. Fine. I hope it carries on like that- if it doesn't, I will see about replacing the thermostat.

thanks for your help.

Hi Anthony you don't need to re rate no matter what it says, sometimes the site is a bit screwy lol.
Keep me posed if it causes issues again;-)
And have a great weekend glad I could help!
Tech Michael