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Oct 1, 2021
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Aberdeen
Member Type
Heating Engineer (Has GSR)
I have a Vaillant eco plus 630, with hot water controlled by a Honeywell ST9100C and heating controlled by a Honeywell CM927installed around 8 years ago. The display is going on the CM927 (seems to be a common problem) so I am planning to get it replaced with the newer version Honeywell T4R and new relay box. Do I need to replace the ST9100C as well?
Is the T4R any good? Any alternatives that you would suggest (non internet based)?
 
I’ve fitted a few T3R‘s recently and haven’t had any issues with them failing as yet and the T range do get a lot of praise on forums. If your just replacing the thermostat, then no need to replace the ST9100C unless your getting one that controls the hot water as well. Honeywell are still a decent brand, but there are others, the choice is yours.
 
Thanks for the quick response.
I’ve fitted a few T3R‘s recently and haven’t had any issues with them failing as yet and the T range do get a lot of praise on forums. If your just replacing the thermostat, then no need to replace the ST9100C unless your getting one that controls the hot water as well. Honeywell are still a decent brand, but there are others, the choice is yours.
Thanks for the quick response. I like the functions on my old Honeywell thermostat so I think I'll go ahead with the T4R.
 

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