On Tue, 12 Oct 2004 11:00:57 GMT, "John Orrett"
wrote:
Thanks for that. Don't know why the guy in the shop insisted we need a
combi. They are not plumbing merchants, so there would be no extra finacial
gain for them.
OK. Basically what he is saying is that the taps are of a design
that is intended to run on mains pressure (hot and cold) rather than
from a roof tank arrangement. The path for the water through the
tap is smaller in those intended for mains use.
This is quite a typical scenario for taps orginating from countries in
continental Europe - often Italy, Spain, Denmark.
He was only aware of, or has been told that a combi boiler is needed
to achieve a reasonable flow rate through this type of tap.
In fact, there are at least two other mains pressure HW solutions,
including having a pressurised cylinder or a heatbank.
Alternatively, you could use a shower pump with a roof tank based
system to increase the pressure and flow for both the bath and shower.
The real issue is whether your system can supply enough hot water at a
sufficient rate to fill the new bath in a reasonable time (will the
new bath be bigger than your existing one?). This is also not
dependent on whether the boiler is combi.
At present we need both the immersion and the boiler to give us a decent
bathful of hot water.
OK. Is that because the boiler on its own heats the water too
slowly or not to a high enough temperature or some other reason?
If your new bath is a similar size to the old one, and you can
happily fill it at the moment, you don't need a new boiler.
My wife wants one of these 'shower baths', the ones with a bulge at one end.
I don't know capacities or volumes of our standard bath compared to a shower
bath, but it looks to me like it would need a lot more hot water or end up
with half a bath!
Ah... that's new information.
Does your wife's love of baths mean that she is like to want a good
flow rate on the shower, e.g. for washing hair etc.?
If so, and you are thinking about a combi, then look very carefully at
performance. An 11lpm model would produce enough water in the
winter to run a small shower head with fine jets but not particularly
good flow. If she would like good flow, then you need something
producing a good 15lpm. Is this bath/shower likely to be the only
use of HW simultaneously in the house, or do you have a second
bathroom or other substantial use of water? If so, and simultaneous
use is needed, then a larger combi would be needed and may be
marginal.
One of the stored solutions (cylinder or heatbank) would be a better
choice then.
As far as baths are concerned, capacities do vary. You can roughly
estimate volume from the dimensions of the bath and assuming a flat,
square bottom - this would slightly over-estimate the need. Some of
the shower baths have narrower sections where your legs go than a
standard bath, so it really depends. If you can get a scale diagram
of the bath, you can estimate the area on graph paper.
Then the crucial question is how deep does she like the water to be? I
am pretty sure I know the answer to that question. Don't forget to
factor Archimedes into the equation, but of course be diplomatic with
your wife about that :-)
If you work on the premise that a simple combi, without any form of
storage will produce its specified rate of bath temperature hot water
in the winter, then that will give you the worst case time for filling
the bath.
..andy
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