"David C. Partridge" wrote in message
...
I'm looking to replace an ageing (1986 vintage) e.l.m. leblanc
GLM 5.32 combination boiler (conventional flue).

Both CH and DHW are 37.2kW (128000 btu/hr) net. DHW is fully
modulating, CH modulates to low as it reaches running temperature.

Amazingly for such an old boiler efficiency is quoted at 86%!

Flow rate is fine for a shower. Our large bath takes a long time to fill.
If a second tap is turned on it's a bit of a disaster (especially for the
person
under the shower).

I'm considering two options:

a) replacing it with a new combi with a HIGHER DHW output

b) going for system boiler with a heat store or sealed system hot water
tank.
However the DHW store or tank can ONLY go in the loft so pipe runs and
control wiring could get a bit tricky. I'm also concerned about the
economics
of keeping this hot 24/7 (we can't predict DHW use well enough to cope
with
the "on twice" syndrome).

I'm currently leaning (strongly) to the first option, but I do realise
that
the second
would give better DHW flow.

I've looked at some of the modern combis, but can't find any that can
match
this
leblanc which does 16ltr/min for a 35K rise (though a few models from
Vaillant
seem to get close). I don't have the space to install two smaller ones,
and would
worry a lot about finding an engineer with the skills to do this right
anyway (I could
research it and DIM, but don't have the time or the Corgi certification).

Leblanc have withdrawn from UK and no longer make any high
output boilers anyway.

So what are the recommendations.

Thanks
Dave

Slightly off beam here, but would fitting restrictors to the hot-water taps
help out?
I have no experience on this but read about it somewhere, possibly on the
diyfaq.
ISTR that it was suggested that people turned on the hot water tap more than
they
needed, and restrictors minimised the impact of a second hw tap being turned
on
on the shower. Is your shower a thermostatic type btw? Just wondering if you
have
the old-fashioned type where you balance the hot and cold water manually and
are then vulnerable to taps or toilets being used.

Finally, what about the newer combis with a built in hot water
reservoir? ISTR
that you can get them with 11 litres or so stored away - would this feature
eliminate
the second hot tap problem ( as long as the second tap didn't use up all
those 11
litres )?

Just some disconnected thoughts to toy with,

Andy.