Like you I have always been sceptical about combi boilers but have been pleasantly surprised by the performance of the one we inherited when we moved into our present 2 bedroomed bungalow, which has 200mm loft insulation, cavity wall insulation and we recently upgraded some old UPVC windows and installed a light weight insulated roof on a conservatory which is an extension of the second bedroom. Our boiler is a Worcester Bosch 28i junior and heating wise has coped very well even up here in the Pennines. DHW can be a slight problem, the boiler supplies two basins, kitchen and bathroom and also a bath. Running the two basin taps is fine a momentary drop in temp if one is turned on after another. The only issue is the bath which can take an age requiring careful regulation but then again we only shower. Both our washing machine and dish washer are cold fill only. We are soon going to upgrade the bathroom and will replace the current electric shower with an electronic one which will take it's hot feed from the DHW supply and I am confident it will cope. What I am pleased about is that our heating bills have halved compared to our previous 3 bed semi with a condensing system boiler. Admittedly we have two less rooms to heat and a much smaller corridor and the last house did not have cavity wall insulation, but I feel the a good proportion of the savings is due to the efficiency of the boiler. For the likes of bungalows a combi seems to make sense and if ours packed up tomorrow I would gladly replace it with another. One other benefit is we have gained a useful airing cupboard by not having a cylinder despite having the boiler mounted there.

Richard