Hi Lunat
Thanks for that, I suspected that would be the answer. The bit I don't get is the difficulty balancing - if the boiler is too small then that would explain the slow warm up but why would it make it difficult to balance?
We have a Vaillant Turbomax Pro 28e which is about 8 years old. Last year we had our house extended so that we now have 14 rads totalling approximately 28kw. The house is double glazed and well insulated but without cavity wall insulation.The recent cold spell has highlighted some problems...
