You do NOT have to get a combi - you have to get a condensing boiler and all boilers sold today - Combi or not Combi are condensing boilers - waste heat is used to partially warm the water.
A combi is good for a small house and delivers mains pressure water to the hot taps. A combi is easier to install in a new house because it requires no loft tanks and pipes. Not necessarily so if it's a replacement boiler.
A combi is more complex than a regular boiler and will therefore be less relaible. A combi does not need a hot water storage tank and therefore you lose the the protection of an immersion heater for hot water. A combi can have problems filling a bath quickly - 20 minutes is not unheard of.
I would never consider a combi. Others think they're OK.
In many trade forums engineers speak well of Worcester Bosch boilers. Any new boiler may well require a new gas pipe to be run to it - the regulations now require 22mm rather than 15mm gas pipe - this may add to the cost.
Expect to pay at least £3000 for a new boiler - unless you go with British Gas when it will probably be double.
Reading on here many people seem to have problems with Wireless-operated room-thermostats. Quite why anybody would want one of these things is a mystery to me. Overly complex, unreliable and with no particular advantage to the user.
Consider TRVs on your radiators when the work is done - add £200 or so.
Good luck...
Peccavi
February 2010
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