Inefficient boiler thermostat (thread no. 1) (WALL STAT) (Ed)

[neate]

My newly installed Worcester Greenstar Danesmore system utility boiler has a modern time controller for separate water and room heating (Honeywell ST9400).

The room heating side is linked to a wall mounted thermostat. That thermostat was previously linked to my old Grants boiler installed in 2005. I don't think the thermostat is working as it should. I would be grateful to know:
1. What products would be suitable as a replacement?
2. Is it job for an electrian or heating engineer?

Thanks in anticipation.

 

[Murdochcat]

Why don’t you think the room stat isn’t working ?

 

[cross thread]

What stat have you currently got ?

 

[CBW]

Need the above answered, especially post #3 if we’re to advise any kind of replacement. The job could be for either, as long as they understand heating wiring.

 

[neate]

Re Murdochat, I've put an ordinary thermometer next to it. And I always have to set the boiler thermostat 2 degrees more to get the boiler to come on.
Re cross thread, no name on it but I'll try and send a photo.
Re CBW, good point.

 

[CBW]

Re Murdochat, I've put an ordinary thermometer next to it. And I always have to set the boiler thermostat 2 degrees more to get the boiler to come on.
Re cross thread, no name on it but I'll try and send a photo.
Re CBW, good point.View attachment 327396

HoneywellHome - it might not have a neutral wire, so could be large temperature swings. If there’s a neutral available, then connecting it would be cheaper option. If there’s no neutral available, then a battery powered 2 wire thermostat would be better.

 

[Murdochcat]

If you have an old fashioned thermometer, place that near the room stat to see what is happening ….

 

[neate]

I've already done that.
Re CBW, installed 18 years ago perhaps that provides a clue. I could chat to our local electrician to see if has any experience.
Thanks everyone.

 

[CBW]

I've already done that.
Re CBW, installed 18 years ago perhaps that provides a clue. I could chat to our local electrician to see if has any experience.
Thanks everyone.

Are you sure? It doesn’t look 18 years old and I don’t think the name change came in until about 5/6 years ago. If you loosen the screw at the top (thin flathead) and drop the cover, take photo and post, refit the cover and we can tell you about the wiring.

 

[Murdochcat]

If you have an old fashioned thermometer, place that near the room stat to see what is happening ….

So it does work ?

 

[JohnD]

If the stat is 2 degrees out, does that matter?

Is it fixed to an external wall?

 

[CBW]

So it does work ?

Yes, @neate said “not as it should”, not “doesn’t work at all”.

 

[Murdochcat]

Yes, @neate said “not as it should”, not “doesn’t work at all”.

That’s what I thought but wanted to clarify.

The new one - can you pull off the knob and refit it one slot round to the left ?

 

[neate]

My new boiler was installed in Feb 2023. I saw the electrician doing something to the thermostat (on an interior wall by the way). I don't know if he fitted a new one. Must ask the boiler firm. In the meantime I send a photo of the inside of it.

 

[CBW]

Seems to have a neutral wire, so should work to within a degree or 2