Thanks darren for your reply- we’ve been in the property for just over a year now and up to now boiler has been ok, we have a vented cylinder with header tanks in attic and hot water for washing up is always in good supply just conscious of age of boiler and our future plans for property in that seeking to replace.
Another question I have is the plan is to relocate the existing boiler from the kitchen to the attic with the flue installed through the roof. This will make it easier when we come to extend the property as it won’t need to be moved and the removal of the old hot water cylinder and header tanks to make the bathroom bigger.
It had been recommended to us to go for the 40 kw as it has a flow rate of 16 litres per min, as when the bathroom is refurbed we want a rain shower with plenty of power and the hotter the better. The plumber for the bathroom had suggested a unvented system instead of acombi as he says the pressure on hot taps is superb. Could I still achieve a good pressure on the shower by having a 40 kw combi boiler?