I live on my own in a 3 bedroom house and the staircase is in the living room. I have all of the bedrooms upstairs timed to come on a very low setting and I leave the doors open so that the heat from downstairs rises. I have never had a problem with mould or dampness and until the recent energy crisis, my bills have always been very low.
If the T is minus overnight it is cheaper even now to have the heating on very low overnight than to deal with burst pipes.
A quote for those blessed with a spouse:


