Frost Stat

Biggles

In the scenario posted, where the system was left 'On' even though all the TRVs were turned low, the pump and, to a lesser extent, the boiler would surely keep running throughout the night to circulate water through the system (even though it would only enter the radiators if called for by the TRVs)?

Cardew

Biggles wrote: »

In the scenario posted, where the system was left 'On' even though all the TRVs were turned low, the pump and, to a lesser extent, the boiler would surely keep running throughout the night to circulate water through the system (even though it would only enter the radiators if called for by the TRVs)?

As the OP has no room thermostat, that is correct!

The pump would run and as soon as the circulating water cooled, the boiler would fire up to re-heat that water.

pattycake

My programmer is a fairly basis clock which I have set to come on twice a day. It is off during the night but the frost stat is bringing the system on. I have no way of over-riding this even if that was a good idea.

The pump is running the whole time the boiler is on. The pump is situated in the airing cupboard next to my bedroom so if I wake up I can hear it humming.

Yes, the frost stat is just over the boiler. My house is on the side of hill and my garage has quite a high ceiling. The boiler is on the wall and the stat is really high up above it. I had the boiler and stat replaced about 7 years ago. The house is detached and I have 14 radiators of varying sizes.

I like the idea of noting how much gas has been used overnight. The gas meter is also high up in the garage and I have to stand on steps to read it. I expect it was installed by a man! However, I will do that tonight after the system has shut down via the programmer.

Cardew

You may well have a faulty frost stat, or it set too high?

It will be a simple and cheap job to replace - get an identical replacement and just connect the same wires

mikey72

pattycake wrote: »

My programmer is a fairly basis clock which I have set to come on twice a day. It is off during the night but the frost stat is bringing the system on. I have no way of over-riding this even if that was a good idea.

The pump is running the whole time the boiler is on. The pump is situated in the airing cupboard next to my bedroom so if I wake up I can hear it humming.

Yes, the frost stat is just over the boiler. My house is on the side of hill and my garage has quite a high ceiling. The boiler is on the wall and the stat is really high up above it. I had the boiler and stat replaced about 7 years ago. The house is detached and I have 14 radiators of varying sizes.

I like the idea of noting how much gas has been used overnight. The gas meter is also high up in the garage and I have to stand on steps to read it. I expect it was installed by a man! However, I will do that tonight after the system has shut down via the programmer.

Maybe, but if it's wasting heat it was set by a woman.

Seriously though, the frost stat should have a removeable cover, usually held by a screw. Behind it is (usually) a dial like a room stat, and it should be set to around 3 C.
I wouldn't advise replacing the stat itself unless you are happy to do so, it has 240v on it.
The stat only protects the area it's in, so it the wind is bad at the other end of the garage, it could be below freezing there, but still above 3 by the stat. For this reason among others all the pipes should all be well lagged. The stat can be inaccurate as well, so it's worth checking with a max min therometer what the garage falls to over winter.
Don't be tempted to override it, or discoonect it, as the boiler and pipes could then freeze.