I have a worcester greenstar 30si, and the only way i can get the house to an acceptable temperature (above 20C) is to have the central heating temp control all the way round to between 6 and max. I know this depends on the size of house and number of rads etc, ( a smallish 3 bed semi), however my bro-in-law has a larger house and the same boiler and only needs his setting to about mid way to heat the house. Any ideas?