just before i go to get quotes for a new boiler i wanted to work out what size they should be quoting for as i prefer if the quotes are all for the same boiler and size. I have used the heat loss calculation and my 4 bed detached house that measures 6x12m is coming up at needing 9.5kw and this includes 2kw for the immersion. Does this seem possibly correct or is it way under. Its got 200mm loft insulation, double glazing, cavity wall insulation, south coast. would i be right in thinking if i get them to quote for a 12kw it will modulate down when it needs too, or even a 15kw maby. thanks