On Thu, 22 Dec 2005 19:10:43 +0000, danw
wrote:
Thanks for all the info.
Andy Hall wrote:
- If you are thinking about any form of direct mains fed hot water,
then measuring the cold water rate at the cold tap in the kitchen is
very important. If the supply is less than about 20 litres/min, you
will be quite disappointed by the results in comparison with the
existing storage system in terms of time to fill the bath. With two
small kids, this will matter increasingly.
Dumb question, but is measuring the water rate as simple as timing the
time it takes to fill a known volume, then extraploting?
Basically yes. Simply time how long it takes to fill a reasonable
volume (e.g. marked bucket) and calculate from there.
One thing to realise is that it is not so much the pressure that
matters but rather the flow rate, because that ultimately affects
basic cold delivery rate.
For example, in an older property, and even some newer ones, the
service pipe from the street may not be particularly large. This is
because the assumption was that you would be filling a tank. Within
the house, it's conventional to have 15mm for cold water mains from
the rising point to the roof tank. Obviously you can do something
about the latter because you would run a 22mm pipe to the combi and
the same to the bath from there. However, depending on distance, a
new service pipe can run to several Łk.
None of this is necessarily a problem, but it's a basic check that
people miss, assuming that because the supply now comes directly from
the main it must be faster and better. Yes, the pressure may be
higher on the back of your hand for low flow rates, but the flow rate
may be poor. The water suppliers are only legally required to
deliver 9 lpm which is pathetic.
Consider also that if you are likely to migrate to a shower, whether
you like the feeling of pressure or also good flow rate. It's
reasonably easy with a small shower head to produce a sensation of
pressure rather like needles on the skin (even using an electric
shower). However, you might or might not like that. Personally, I
like both flow and a degree of pressure rather than a dribble, but I
don't want to feel I'm pressure washing.
Nevertheless, with the caveats, this might be a good choice. Have you
thought about siting it in the airing cupboard instead of the
cylinder? Is recovering the cylinder space important?
Yes, at present, the boiler and the hot water tank are in our smallest
bedroom. We don't really want to place them in another bedroom and we
don't have anywhere else we can put it. Unless we go for the loft but we
have no brick wall in our loft, so that would increase expense we believe.
Another option is a heat bank. In your situation, a loft
installation of one could be a possibility and it can be heated with a
system boiler. With this, you can have mains pressure HW but
without a large box in the kitchen.
Have a look at
www.heatweb.com
--
..andy