In message , at 12:50:25 on
Fri, 27 Nov 2015, e27002 aurora remarked:

My limited experience with combi boilers is that they are far from
reliable.

I have experience with precisely one, and it has been as reliable as
one might expect a system boiler to be.

How many have you experienced, and how old? The technology doesn't
differ that much from a system boiler. It's just that if it fails
there is no hot water backup.

I've had a few, and the main problem is they don't deliver hot water
fast enough to fill a bath in a sensible length of time. Let alone
filling up a bath at the same time someone else is having a shower.

Nothing to do with low pressure British plumbing then?

The reverse, actually. Try filling the bath faster and the water goes
lukewarm. It's not a problem getting the water through, it's the
capacity to heat it up "on demand" in the first place.
--
Roland Perry