IMM wrote in message ...

I assume you haven't bought any equipment yet.

That's correct.

In your situation which I
assume you have 1 bath and two showers, and I would go:

1. Combi boiler (to do the two showers only)
2. A "combination" cylinder with quick recovery coil. (cold tank and hot
cylinder all in one space saving unit). This operates at low pressure
http://www.rcmgroup.co.uk/specialized.htm RCM will make a large cold tank
section for you. They will ake the hot and cold section sizes to order.

The CH side of the combi acts as a normal system boiler heating the
cylinder
and CH. The cylinder does the bath and therest of the house to give good
fillups. The water side of the combi only does high pressure showers.
Something like an Alpha CB50, W-B Greenstar high flow condensing combi
would
do. The W-B Greenstar 40kW model can deliver 16 litres/min and you need
to
add cold to the showers, so a decent shower had if two on at the same
time.
This approach is cost effective and no power shower pump used.


Sorry, I'm misunderstanding something here. I thought that the total flow
rate was limited by the available flow rate at the incoming service pipe. Or
is hot water stored in the combi boiler and pumped to the shower on demand?
Apologies for my ignorance.


Will you really have the bath filling and a shower on at the same time?
A
relative has had a single shower power shower pump serving two showers for
10 years. Not once has two showers been on at the same time.


I would like to budget for a bath and shower that are on simultaneously. I
have a large family.