21 Oct 2019
Reaction score
United Kingdom
Can anyone help please? I need some advice please on replacing my wired room thermostat. I’ve had a Worcester 27cdi boiler fitted in my loft recently and an old style dial wired room thermostat on the floor below. The problem is that the lowest temperature setting on the dial is 10 degrees. I’d like to be able to turn off the central heating with a zero setting on the room thermostat or as low as possible without having to go into the loft.

I’m keen to have a wired room thermostat and not wireless or radio frequency. Is there a wired room thermostat with a zero rating or one with lower than 10 degrees and / or is it possible to get a wired room thermostat that includes a programmer (not wireless) that I could use? There’s already a programmer in the loft by the boiler (just hard to access) so it’s not essential but would be convenient. I just don’t like heating coming on in the winter when the boilers on and I’m out or sleeping and I don’t keep regular working hours each day so need flexibility.

Please let me know if any model you suggest is two wired or 3 wired as it may affect the mains cable already fitted and I need to get something compatible with that and the new boiler.

Thank you
Sponsored Links
Which current thermostat do you have installed? Some of them have 10 on them, but go lower than that.
What kind of installer puts a programmer in ther loft!?

Have you considered a smart thermostat, something like a Honeywell T6 for example? It would really suit your irregular hours, as you can set it up to automatically turn the heating off as you leave the house, and turn it back on when you're on your way home.
Sponsored Links
Thank you everyone for the advice.

The room thermostat has a lowest setting of 10 degrees it doesn’t have a lower area on the dial.

I only want traditional wired not Smart type thermostat thank you.

Thank you especially for the suggestion of the Dayton combined thermostat / programmer, would this override the programmer by the boiler or would that one (one next to boiler) need to be disconnected and removed first? I’m trying to keep things straightforward for the electrician who is doing the replacement as he doesn’t usually do boiler electrics though he did run the mains cable to the existing thermostat. (I haven’t been able to get a CH engineer to do a small job like this as they are inundated with installations and boiler replacements and there’s lots of new build in my area).

The original CH boiler installer said that the programmer had to be fitted near the boiler and couldn’t be fitted on a different floor. I was given to understand that Worcester boilers have particular programmers with particular requirements. The boiler was put in the loft as it’s a condensing one and the fumes need to be kept away from people as they tend to hang about an at a lower level. In a small terrace this can be aggravating for garden users including neighbours.

I’ve seen discussion on forums about a wired version of the Honeywell CM907. Would that be suitable?

Many thanks...
No need to remove the existing programmer just set it to constantly on and the programmable room stat will then control everything
Hi Again,

Just wanted to check if anyone knows if the Honeywell T4 wired programmable room thermostat would be non wireless and non radio frequency (and does it need batteries?) and compatible with the Worcester 27cdi combi condensing boiler and whether it would be a two wire or 3 wire connection or would that depend on what mains cable is already fitted to the existing room thermostat?

And if anyone knows how this Honeywell would compare with the Dayton thermostat suggested above?

Thank you
The T$ wired is non radio frequency and is hard wired, it does however require batteries as do nearly all and yes it is compatible with your boiler
use quality batteries like Duracell and you usually get a few years out of them before changing them, I havent actually installed the T4 but have seen a few and they look decent enough

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links