Have a Worcester Bosch 28i boiler fitted in the loft 18 months ago.

It has started running with or without thermostat on.

Keeping the house at about 18 degrees.

I thought at 1st it was running because it was so cold outside that the frost stat was kicking in , but it is not that cold now and yet it still keeps starting up for a while.

Any ideas?

[Edited on 2/1/09 by Surrey Dave]

your frost stat will set to around 5 degrees. It wil be still way below 5 degrees, turn the stat down as low as it will go eg -10 and see if it cuts boiler out.

none adjusatble frost stat on the i juniors check temp in loft if not is it rf or hard wired stat. if its rf check the batteries in receiver.

Thanks , what temp is the internal frostat set to.

Is it worth wiring an external one?

Or do I just let it do its thing to protect itself .


I could open the loft hatch and let some warm air up.

Its my new ventilated upvc soffitts blowing a chill through the loft maybe.

opening the loft hatch will only be a short term solution, it would cause condensation in the loft in the longer run. Maybe build a small insulated enclosure round the boiler, to keep it warmer than the rest of the loft.

Not another project!!

Yep as above given the temperature lately its your vented loft causing the frost stat to kick in. Easiest remedy is to put a large kitchen cupboard around the boiler to cut the draft down( check boiler litt for required clearances around it) and make sure all your pipes are well lagged!

Good luck