Boiler efficiency arithmetic

Lack of familiarity mainly, but a suspicion that if the things are so clever the service engineers

I'm afraid I do confine myself to topping up various fluids on cars nowadays, and the odd bit of tinkering with an OBD-II lead.

I've scratched my head on non-condensing boilers. It's more a matter of good quality ones versus bad: condensing doesn't necessarily detract from reliability.

Anecdotal evidence? Hmmm :-|

There are two near me, one in new build, one retro fit.Seem to work OK. The problem you experienced was down to the cowboys, not the technology.

I was going to say if they need a flue analyser to check the workings (and maybe custom software to make adjustments?) then I'll not bother.

Its often a "catch all" for new technology boiler vs old cast iron lump. Most of the complexity of a modern boiler was added long before condensing made it into the mix.

There was an interesting talk at Ecobuild a couple of years ago by someone from the EST involved with monitoring a number of early (pre MCS qualification scheme) GS (and, IIRC, AS) installations. Some of them had been installed *really* badly. I think in at least one case the heating was effectively being provided by peak-rate electricity! They were aiming to improve practice to get COPs more in line with those achieved in (I think it was) Switzerland, where they get 4 or even 5.