On Thu, 17 Jun 2004 21:20:48 +0100, Colin eclipse 2 wrote:

I know - done to death.. A customer has asked me this question. I have come
up with the following list. Any other thoughts - sensible ones.. no need to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold) available if mains supply
fails
Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard
Cons
Cylinder needs replacement (in this case to comply with building regs)
Storing hot water not as energy efficient
More complex controls
More costly than combi to install


Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space
Cons
slower bath filling
No warm airing cupboard


The FAQ does contain an extensive and fair spectrum of opinions and views
on this matter. Doubtless such a spectrum will also become apparent in
this thread!

I agree with your list.
I estimate the 'half-life' of the heat in a Grade 3, Part L compliant
cylinder to be around 24 hours. [1]
The major issues in my experience.
a) Customer preference (they may well already be very pro or anti combis)
and it is just not worth reducating them if they have already made up
their mind.
b) Customer preference after being informed about the significant issues.
Backup yes/no. Cylinder space needed. Yes/No. Fast bath filling Yes/No.


[1]The water cools to "off then chill" (say 30C) if we go away for 48 hours with the
HW off. It is, however, really important to pay attention to details like
lagging the draw-off and vent pipes for a metre or so from the cylinder.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html