"Andy Hall" wrote in message
...
On Sun, 24 Aug 2003 23:46:25 +0100, Daniel Loshak
wrote:
Help please....
I've got about 2 bar coming into my Victorian house in London. My new
multi-head shower needs at least 3 bar (not sure of the flow rate).
The more important point is what is the flow rate? You can have
perfectly good pressure (although this isn't brilliant), but a lousy
flow rate.
COuld you maybe measure the flow at a tap (normally the kitchen cold
tap). THis can easily be done by taking a vessel of known size
(e.g. a 10 litre bucket) and timing how long it takes to fill. You
can then do the sums to work out that flow rate in litres per minute.
It's pointless getting into discussions about different types of
system unless the flow is good enough to provide what you need.
To run two normal showers you need to have at least 10 l/min each,
preferably 15. Your multihead one probably needs 15 - 20 for
results that make it worthwhile - so realistically 30 l/min for the
property is the minimum.
A Conventional system will take up too much room and require
reinforcement
in the loft area
If it turns out that you have an inadequate water flow, you will have
the choice of upgrading the supply from the road or of using a
conventional system with a roof tank and a pump.
If the flow is adequate, then this implies some sort of instant heat
solution.
For this, you could use a combi boiler, except that at the flow rate
you need, even a large one is going to fall short in cold weather and
you would be running the showers at lower than normal flow.
Two boilers could be used, but you need to watch out for the total
heat input requirement. A domestic gas meter (IIRC) is able to
deliver a supply for up to 62kW of heat equivalent and large combi
boilers are in the 28-30kW range, meaning nothing left for other
requirements. In this scenario, if you could split the requirement
appropriately, you might be able to go for one large and one small or
something.
A heat bank or thermal store are other approaches. These use a
cylinder of water heated by the boiler to 76-80 degrees. This is
then used to heat the water indirectly. You do have to find some
space for the cylinder, but a large roof tank is not needed - just a
small CH one. Some of these appliances have the header tank integral
with the cylinder.
These are able to deliver a lot more heat than a combi does (could be
as much as 200kW) so are less likely to run into difficulties when the
water is really cold. You can also arrange that the boiler comes on
and starts replenishing the stored heat as soon as it starts to be
used. However, the store cylinder does need to be adequately sized
to deliver the output heat for as long as is required. If you are
drawing stored energy at a 100 kW rate to heat the water and
replenishing from the boiler at only 30kW, the stored heat runs out
eventually and the system becomes, in effect, like a combi.
What options do I have? I have ordered a 4 bar pump but have been led to
believe that this is only suitable for a convential system as opposed to
a
combi or Megaflow system.
I would hold off on the pump until you have the rest figured out.
The house has 3 bathrooms, only one requires high pressure and high flow
rate, but I do need the ability to have at least 2 hot showers at the
same
time.
Not really a tall order I would think? What are my options?
You wouldn't think so, but this is asking a lot unless you have a good
flow of water, so that's the place to start.
Many thanks in advance...
P.S A water softner needs to be placed somewhere...
That also needs to be a high flow model. Most are these days, but it
will have something of a reducing effect on flow. Generally they are
quite small so finding a home should not be too big an issue.
It may be prudent to check the cold mains and then get a softener
supplier in to do a demo. Measure the rate that you get then and see
if it is enough.
8/10 Andy. I have taught you nearly well. You know it is always that last
bit that is elusive.
You flailed on the softener. He can use a phosphor descaling canister which
is only £45 from B&Q. And you failed on the combi. Many high flowrate
combi's can deliver the flowrate, and you don't know the flowrate yet. Keep
trying though. I will step in when you don't get it right.
Keep up the good work.
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