ok so heres another somewhat uncertain area. im fitting a heatslave combi next week, and the customer wants it in the utility room. The room is approx 8ft x 10ft with a upvc back door and a upvc window. it has a flat roof of some descript. The owner is going to half the room somehow to incorperate a downstairs w/c for an elderly occupant, so the room will have a radiator. so not completely unheated, but when heating is off probably one of the coldest rooms. does anyone think that frost protection is still required ????