wrote in message
oups.com...
We've just had a WB 40 CDi combi installed into a house that was
previously a standard boiler/tank/cylinder affair. The short story is
that we can't run a bath and shower off it at the same time (I don't
mean that the pressure drops off a bit on the shower - it actually
stops). Various plumbers and even the WB site itself would indicate
that you can't expect to do everything at once on a combi, but I did
expect more when just two outlets were opened.

Any ideas why this might be and/or what can we do?

Not *that* surprised. Combi's are really designed to run showers. Unless
it's a massive combi, a typical bath flow would take water at the maximum
rate the combi could heat it, leaving no flow left over for the [higher
resistance] shower. The usually reasonable assumption is that baths are
infrequent these days and as long as the combi can run one, the fact that
you can't take a shower at the same time is irrelevant as it won't often be
a problem. Stored water systems have no maximum flow but run out, combis are
flow limited but never run out. For perfect results you need a massive
installation of either! FWIW if you take a lot of deep baths, a combi isn't
for you. If several inhabitants in turn tend to take long showers (ie
teenagers) then a stored water system isn't for you! There are, of course
fancier hybrid systems available which you can look in the archives for.


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)