Hi,
A plumber charge 1400 for fitting a condensing baxi boiler to an existing heating system in a 4 bedroom 1970s detached house. After initially working for one day it stopped. He then charged another 800 pounds to replace the boiler with a different larger baxi combi 105 HE model (he said that he was not charging for labour for this he was just charging for the boiler). He also replaced the hot water storage tank with a small radiator and redirected some of the water flow by taking out some old pipes and soldering a new set. It now works fine.
He said that initially he was trying to get the job done using a method that may save money and that these new condensing boilers have some kind of digital logic inside them that means that they will stop working altogether if something isn't quite right and that they are trickier to fit than other boilers you could fit before April this year.