Sunvic TLM2253 room thermostat faulty?

[Ant1]

I have a Sunvic TLM2253 room thermostat (http://www.sunvic.co.uk/tlmrt.html) which does not seem to work. Basically if I turn it down to the minimum the heating is still on, and it does not make any difference turning it up to the max. The temperature is always the same.

How can I test the thermostat to check if it is faulty or not?

Thanks,
Ant

 

[breezer]

with a multi meter.

how may wires have yoiu at the stat?

in theory if you remove the stat, and seperate all wires the heating should not work. if it does wiring is wrong.

if it doesnt its the sat (unlikely) or you wired it wrong

 

[giblets]

If you have motorised valves could be the the heating one is stuck open. Does the thermostat click when you turn it up & down?

 

[Ant1]

If I remove all the wires from the stat, the heating does not work which is a good start.

I have 4 wires connected to the stat:
1. Earth = yellow/green cable
2. Permanent Live = red cable
3. Switched Live = yellow cable
4. Neutral = blue cable

Here is a picture:

TLM2253 Pic

• Ant1
• 6 Apr 2008
• 1

and compared it to the one from the wiki (//www.diynot.com/wiki/electrics:how_to_replace_a_room_stat).

Note that I did not install this stat, this was done by the previous owner around 15 years ago, it seems properly wired to me.

I do not hear any click when turning the stat from max to the min (and vice versa). But I noticed that if I remove the front cover and wheel and turn the stat to the min manually (as it can go a bit further), then I can hear a click and the heating stops.

By the way the voltages are:
- 242 Volts between Permanent Live <-> Neutral
- 242 Volts between Switched Live <-> Neutral

The voltage between the Switched Live and Neutral is always at 242 Volts, no matter if the stat is set to 10 or 25 degrees. However it goes to 0 Volt when stat is turned to minimum (ie without front cover and wheel).

My question is now:
Should the voltage between the Switched Live and Neutral decrease together with the stat temperature?
ie 10 degrees on the stat should be equal to 180 Volts or something like that?

 

[giblets]

Sounds like the stat has died.

Suggest a new one be got and fitted.

BTW the stat is an on/off type - no reduced voltage as temperture rises/falls.

 

[Ant1]

I agree with you giblets, the stat does not cut off the heating when set to 10 degress with a room temperature of 18 degrees, even after waiting for half an hour. Therefore it looks dead to me.

I will replace the stat and will update this thread.

Thx everyone for your help.

 

[Ant1]

Ooops, forgot to update this thread. Replacing the stat fixed the problem.