I think ajrobb has hit the nail on the proverbial.UK heat calcs do not consider -6*c as the norm.Insulate as much as you can without affecting ventilation.
is their anyway in which i can gage an idea of how much difference/how much warmer the room will be if i change from what rads i have now to bigger ones?
it might be useful to know how the rooms are insulated, how draughty, is there an open fireplace or a conservatory open to the habitable rooms, what size and type of windows, are internal doors kept closed, are there holes in ceilings for downlighters etc, is it damp, are there bare floorboards.
sounds to me like there is a heat loss he has not allowed for.
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