Andy Hall wrote:
On Mon, 11 Oct 2004 19:21:37 GMT, "John Orrett"
wrote:

Hi all; my wife has advised me that we are getting a new bathroom
suite! she would like one that has the taps in the wall rather than
on the bath itself. The shop told her that we cannot do this at
present as we only have a Gloworm Ultimate 50 boiler and an
immersion heater, and not a combi.
Couple of questions that I would like some help with please.

1. Does a combi need any more ventilation space around it or
external venting than the present boiler (which is situated in the
kitchen behind a false cupboard door)?

It depends on the boiler and manufacturer. Most manufacturers have
this info. on their web site if you look in the installer section.
Don't forget about possible flue space.


2. Can I run the central heating via a combi?

Yes you can.

3. Cost wise, will a combi work out more cost effective than the
current boiler/immersion setup?

In running cost terms, yes, if you are using only electricity to heat
the water at the moment.


4. How much should I be paying for a decent combi, and any
recommendations on make and model etc?

Good ones are in the £800-1100 bracket.


My wife likes lots of baths, so the immersion is on quite a lot, and
obviously the central heating is now on a fair bit. To give an idea
on costs, our electric bill per month is £52 and the gas is £36. I
am in the process of swapping from British Gas for both to Powergen,
saving £200 per annum, but that's another story :-).
Any help appreciated,

Before you do anything else, check the water flow rate at the kitchen
cold tap using a stop watch and a bucket. If the rate is less than
about 15-20 litres/minute, using any kind of mains fed hot water may
be disappointing.

Smaller combi boilers are quite limited on hot water production rate.
It can be as little as 9 litres/min, with better ones achieving
15-18lpm. bear in mind that this is for a 35 degree rise in
temperature, so in the winter will represent the total rate at bath
water temperature.
Normally a tank/cylinder based system will fill a bath very quickly,
so as another test, using a bath tap adjusted to the rate of the
intended boiler, time how long it takes to fill the bath.
Smaller combis can take 15 minutes easily, so certainly ask your wife
whether that is acceptable.

Another option would be to keep the existing boiler and heat the
cylinder from it. This would be cheaper to run than the immersion and
much faster to re-heat. You may need to replace the cylinder, but it
would be cheaper than a new boiler.

.andy

Many thanks for the help Andy; much appreciated.
Regards
John