Worry about heating cost with boiler in garage

stars_bright

A few months ago we had a new boiler installed under the Warmfront grant. Our previous boiler was in the kitchen but because the new boiler had to have access direct to outside the new boiler couldn't go where the old boiler had been. They were very keen to fit the new boiler in the garage despite my concerns about the fact that the frost stat would kick in during cold weather - they said that the fact that the boiler was more efficient than the old one would outweigh any extra costs due to that. However I have noticed that during this cold weather the boiler is running nearly all the time, even when its timed to be off. This is due to the fact that when the boiler is timed to be off it automatically kicks on if the boiler temp goes below 5 degrees. Obviously the garage is below 5 degrees at the moment so boiler is nearly always on depsite the timer being off. We do not have thermostatic valves on each radiator so the whole house is at abouty 19 degrees day and night. I am rfeally concerned about what our gas bill is going to be next time! We can't switch the boiler off completely because it would feeeze and cause untold damage. Does anyone else have this problem?

Cardew

The frost stat doesn't usually need to be at 5C it is normally recommended to be 3C to 5C; I have mine at 3C.

david29dpo

Why on earth would a boiler have to have outside access? Plus i thought TRVs where a legal requirement now.

stars_bright

The boiler has to have direct outside access to vent (they said). When the frost stat kicks in should it really send the heat all round the house (I would have thought it would just heat up the boiler itself) ? If so it is still going to been the whole house is being heated whether it is set a 3 or 5 degrees while the weather is -17 ! They didn't mention TVRs at all but they were only replacing the boiler, not the radiators so maybe thats why? Last night it was so warm (19 degrees) all night I couldn't sleep! )That and worrying about the gas bill). Hubby is worse than useless but I have told him it won;t be any use complaining when we have a massive bill we need to sort this now.

david29dpo

OK. You need to dump the frost stat and fit a pipe stat to the return pipe to the boiler. This is because no heat gets to your present stat to turn it off.

Splott_Boy

We are getting something similar with a boiler in the garage. The old boiler was in there too and yes I know there are issues if you try and have a long flue from the boiler to the outside. Straight through the adjoining wall seems to be preferred.

At present this is happening occasionally, but its hard to say if we are out all day. When we have been in it seems to operate long enough to heat the nearest radiators to the boiler then it cuts out.

We have been wondering how we might reduce the frost stat temp as the boiler itself is probably in the coldest location. We have a Baxi boiler and Honeywell controls and I cannot find anything that directs how to reduce the temp (this may be deliberate of course.....).

Splott_Boy

Is the frost stat measuring the air temp or the temp of the water in the system ?

david29dpo

If the frost stat is on the wall in the garage, its measuring the temp around it. Useless as the boiler wont heat the garage. See post 5

Splott_Boy

Thanks David. If there is a risk though that pipework within the garage itself may freeze, then that may have been the justification for placing it there (and for it kicking in when it does). Even if the original poster has only a short run of pipe in the garage could the installer say that the frost protection needs to protect that short run - unless you can be totally confident of your insulation for the pipework.

Either way I can see that your suggestion in post 5 applies - thanks for this. Anyone any ideas why an installer would fit the wall mounted frost stat rather than pipe stat. Cost ? Convenience ? Lack of thought ?

david29dpo

lack of thought!