Quick Thermostat Question

[Ste Crook]

I want to replace this honeywell thermostat with this Salus one, and I cant work out which wires are meant to go into which, any help would be greatly appreciated

On the Honeywell one I think the Live goes to number 1 (on the right) and the neutral into number 2 (second from the left)

I am pretty much just baffled with the last one?

Cheers
Ste

 

[davesparks]

Based on the information provided you need to run another cable to the thermostat from another part of the central heating control circuit where the permanent live of the system is present. This is due to there being no permanent live at the existing thermostat.

Wires at the existing thermostat are as follows:
Red - Sw live from programmer
Yellow - Sw live to valve
Blue - Neutral

 

[Ste Crook]

Cheers Dave,
It should work as it is though shouldn't it? The previous one worked ok until the heating started turning on even though the thermostat was right down.

 

[Meggerman]

You could just link L to COM but display will only be on when programmer is calling. I would buy another room stat that you can use the wires you have.

 

[Ste Crook]

You could just link L to COM but display will only be on when programmer is calling. I would buy another room stat that you can use the wires you have.

When the programmer is calling? Sorry i'm not that well up on boilers, and the reason I bought a wireless thermostat is I don't want the thernostat in the same room as its already in as its significantly colder than any other room in the house

 

[davesparks]

Cheers Dave,
It should work as it is though shouldn't it? The previous one worked ok until the heating started turning on even though the thermostat was right down.

Does the old thermostat make a click sound when turned up and down?

Does turning the heating off at the programmer prevent this problem?

How was the faulty thermostat diagnosed?

Based on experience that mechanical thermostat is likely to be fine, my first port of call for this fault would be an issue with the valve.

 

[Meggerman]

When the programmer is calling? Sorry i'm not that well up on boilers, and the reason I bought a wireless thermostat is I don't want the thernostat in the same room as its already in as its significantly colder than any other room in the house

Sorry, I just saw the back of it and assumed it was a room stat not an RF one. In that case you need to replace it with a programmable room thermostat (will do both timings and temp) and convert your existing red wire to perm live at either wiring centre or programmer (you have not stated if S / Y Plan or combi).

 

[davesparks]

You could just link L to COM but display will only be on when programmer is calling. I would buy another room stat that you can use the wires you have.

No it won't, that's a wireless thermostat receiver he's got there, you can tell by the writing on the label and the fact its got dip-switches to set and address.

 

[Meggerman]

No it won't, that's a wireless thermostat receiver he's got there, you can tell by the writing on the label and the fact its got dip-switches to set and address.

Yeah , I realised after writing it, see my last

 

[Ste Crook]

Does the old thermostat make a click sound when turned up and down?

Yes, but usually always at the same place

Does turning the heating off at the programmer prevent this problem?
There is a timer with a Off / Twice / Once / 24Hr in another room, I tend to turn the heating off here as otherwise the thermostat has a constant red light on it (showing its active?)

How was the faulty thermostat diagnosed?
It wasnt really, I just wanted a new one, its in a hallway which has no heating so is always cold

Based on experience that mechanical thermostat is likely to be fine, my first port of call for this fault would be an issue with the valve.

 

[Ste Crook]

Also its a combi boiler

 

[davesparks]

Rules out a valve then!

 

[Meggerman]

Rules out a valve then!

He may have 2 heating zones..... but unlikely

 

[davesparks]

Ok then, bearing in mind the roomstat should be in a room without a TRV on the radiator.

Is the new roomstat programmable or just a roomstat?

If programmable you could get a suitably qualified person to connect it directly into the combi boiler and disconnect the existing controls. Do not do this yourself

If it is just a stat then it may be best mounted next to the timeswitch where all of the necessary connections should be available (or could be made available easily). The existing roomstat could then be replaced with a blank plate.

 

[davesparks]

He may have 2 heating zones..... but unlikely

Using a little bit of logic he has not said anything about the fault only affecting downstairs or upstairs heating or any mention of the heating of a specific area.
And the colour of the existing cables gives a good guide to the age of the installation, sometime before multi-zoned installations became popular.