Combi boiler for disabled bathing?

[tartansand]

I have recently installed a "disabled" bath which has a large water capacity requirement.
As it happens I also need to relace my old central / water heating system

I'm trying to get as much info as possible before I get any "salesmen" in for quotations and would appreciate some advice from experts like you who have no vested interest!

Right now the thermostatic mixer tap doesn't work properly.
Set to the hottest setting the hot water is just lukewarm and I've have had to fit oridnary taps meantime.

This I assume is because the header tank feeding the hot water cylinder is just above the bathroom ceiling and the mixer has to have to have a decent and equal pressure hot / cold to work properly (cold water feed is at a high mains pressure)

The bath also takes forever to partially fill
Choosing a new "regular" system would mean fitting a very large water tank to fill the bath.

The combi option appears to be the better solution in order to satisfy the large bath's appetite and provide the pressure needed for the mixer tap, but I've read much about the downsides of having a combi boiler (poor flow etc)

To counter this I'm considering fitting a Worcester Bosch Greenstar 40CDi which appears to give decent capacity / flow rate and also seems to be one of the recommended manufacturers

It's a 3 bed house with large living kitchen and a separate shower which (ideally) might be used at the same time

I'm also puzzled by the boiler's water heating pipe outlet size that's shown as 15mm (as are all the ones I've looked at) yet the pipes to the bath are 22mm, which I understand is normal to get a decent flow.

Any comments or advice gratefully received
Thanks
Mike

 

[ChrisR]

15mm is ok because its at mains presssure, not gravity.
Differences in pipe resistances between outlets still matter though.
You need a good mains supply, which you will have read, and if the bath tap is open full you may not be able to use the shower.

 

[bab]

As long as the mains water supply is good u should consider a mains fed cylinder or themal store & stick to a standard boiler. u would need to hav a 25mm incoming water supply as well to make it worth it. other alternative is to store lots of low pressure hot & cold & boost with a Stuart Turner pump. Both systems are a dearer option but thats how it is. You should be getting the work done @ 0 vat which is a good saving.