Age of the house, wall type, floor area, what you heat with now, and whether there is anywhere to put a cylinder. That is enough to tell you whether a survey is worth £280 of your money.
What happens after
—A ten-minute call, usually the same week
—An honest yes, not yet, or no — about a fifth are not yet
—If yes: a £280 heat loss survey, refunded against the install
—You keep the calculation whether or not you use us
Unit 4, St Philips, Bristol BS2 0117 000 0000 · hello@kelvinheat.example Covering Bristol, Bath and North Somerset