"Peter Smithson" wrote in message
...

My friends need a boiler to replace the conventional floor mounted one
which works the central heating and the hot water system. The HW is
gravity fed and the CH is pumped round a single pipe system of
radiators. It's a fair sized 3 bedroom detached house.

They'd like a wall mounted one but one quote says they can't have a
gravity fed HW system wall mounted. Any idea why he'd say that?

Small tubed heat exchangers require a pumped circuit at all time.

They also thought about getting a combi boiler as the idea of always
having hot water available sounded good but on the minus side they've
learnt that

1) combi boilers don't last very long - maybe 5 years or so.

No so.

2) In a hard water area, having mains water run through the heat
exchanger doesn't do them much good either.

Firstly some combi's have reduction controls. Secondly, on any system in a
hard water area always have a phosphor scale reducer on cold water mains
(the drinking taps can't be off it. Thirdly, most new combi's have plate
heat exchangers which resist scale.

3) Some people say you can't have a combi
with a single pipe system (for
some reason).

A combi is no different to any other boiler in this respect. Single pipe
system are best ripped out, or amended to 2 pipe.

Is that right? They're aware of the other things like only one hot tap
at a time and reduced flow but it's these points that sound worse as
they don't want to have to get a new boiler that often. The
conventional one in there has been there for decades.

There are high flowarte combi's around, so don't go on old wives tales.

Don't know if it matters they have a conservatory so the flue would have
to be angled so it goes out through the wall and up through the
conservatorey roof as it does at present.

Not a problem with modern flexible flues.




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