"Andy Hall" wrote in message
...
On Wed, 8 Oct 2003 16:48:03 +0100, "Suz" wrote:




Yes, and my comment is "no point in having 2 bathrooms if you don't
intend
to use them both at the same time"

Exaactly.


Consider that in effect in cold weather the specified flow rate of the
combi will be all that you will get at shower temperature. If the
mains supply is (say) 8 degrees and the shower 40, then at the
standard 35 degree uplift temperature by the boiler you will not be
mixing much cold in with this and the combi flow rate becomes the
total rate.

Check out the flows that you want for the showers (personally I
wouldn't accept less than 15 litres/min each) plus the bath and you
may be in trouble with a combi - even a large one.

We had considered putting an electric shower in for the girls and hogging
a
brilliant one for ourselves, but we reckoned they would just hijack ours
when they grow up.

Electric showers are very disappointing. 5 litres/min if you are
lucky. They won't thank you for that when they are washing their
hair I can promise you.

As to hijacking, I can confirm that they will hijack both and will
leave both in a condition other than that in which they would hope to
find it.

They are great at hanging up the clothes that you just washed as well
- until they run out of floor space.

A permanent supply of bin liners is essential while they go through
the teenage metamorphosis.



You may find that you need to have some form of heat storage, whether
it be a pressurised cylinder or a heatbank. There is nothing to
stop you heating one of these from a combi using its CH side and
motorised valves (effectively like a non-combi), then using the hot
water production from the combi to run some of the hot water services
and the stored water the rest.....

We have been looking at the Megoflo brochure.

A couple of questions came out of this:
Is it not a waste of energy to have hot water stored and therefore lose
heat/energy before it gets used?

Not really. If you have good insulation the heat loss becomes tens
of watts - i.e. less than a light bulb.


If you are having a shower and hot water gets drawn off somewhere else,
do
you get frozen in the shower?

Not if the plumbing is designed properly. If you have either a
stored hot water system where the water is used directly, having been
heated to 60 degrees, or a heatbank where it is hotter, but the stored
water is used indirectly through a heat exchanger then you are rather
better isolated from the effects of temperature change in the cold
water affecting the hot water production rate.

If you mix 60 degree hot water with some cold to produce 40 degree
water for a shower, even if the cold water temperature varies over the
year the effect is not as great as if you are using a combi and *all*
of its production is used for the shower. Then you would be
vulnerable. This is one reason why IMM is suggesting that two combis
might be an option. The peak needs might not be met by one.

Having some form of storage would improve the overall system
performance considerably - whether it's a pressurised cylinder or a
heat bank.

Or two combi's. Liberating space is one aim here. Combi's neatly fix to
walls. Unless a heat bank is designed to be square and sit at the bottom of
a cupboard taking up little space. Long thin cylinders take up space.



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