Thermostat - faulty ?

[jamma-plusser]

I think that my boiler's thermostat might be faulty - the oil-fired boiler is in a cupboard off the utility room and the thermostat is in the hall.

Noticed about a week ago that the radiators were only warm when the thermostat was turned up to about 20. Turned it up to 25 and all was well.

Today the same thing happened again, but turning it up to 27 has got the radiators hot again.

Now it's definitely not my imagination, ie it IS getting colder in the house when it should be warm, ie it's not just me imagining it's colder!

So is the thermostat at fault?

It's an old 'Lifestyle' thermostat with a square surround and a round dial.

Could I perhaps repair/service it myself? Or is it a job for a plumber?

Or could I replace it? Or is that too a job for a plumber?

Thanks

[F]

Are you *sure* it's colder? Have you checked with a thermometer? Cold radiators don't mean the house is cold, they're just not being heated at the time you check them.

With colder weather, 'cold' spots' in the house suddenly seem more noticeable. With decent insulation it's possible to have cool or cold radiators with the house still warm.

Alternatively, is the radiator in the hall oversized compared with the others in the house? If it is then the thermostat will be satisfied and turn the heating off before other rooms are warm. If that's the case, close the lockshield a little to reduce the flow on that radiator.

[Harry Bloomfield]

jamma-plusser explained on 05/01/2010 :

It sounds like an old mechanical 'clicky' thermostat. Does the stat click as you crank it up and down?

If it is clicking OK, then probably it is OK. Do you perhaps have a two port valve, which directs the heat to radiators or water heating? They frequently stick and or fail.

[jamma-plusser]

Thanks for the replies.

F - yes, it's definitely colder in the house, but a good idea re lowering the temp of the radiator in the hall.

Harry - yes, it clicks, but only if I turn it way down or way up. I'm sure it used to click at more 'intervals' ........

[Harry Bloomfield]

There should be a small gap between the clicks, maybe a degree or so, but certainly not a need to swing the dial end to end to get it to click. There should be just one click on the way up and one on the way down. Turn it down slowly until it clicks, then as soon as it does turn it back until it clicks again - the difference between the two points should be quite small.

[jamma-plusser]

It seems to vary, sometimes it's quite large, but at the moment it will click on about 16 then on about 19 and vice versa.

Is that too large a gap?