On Fri, 30 Sep 2005 13:45:47 +0100, Timothy Murphy
wrote:

| I just had my central heating boiler serviced
| by the gas company here,
| for the first time in 14 years.
|
| The service engineer said the boiler (Potterton "Profile Prima")
| as in good nick, which surprised me.
| But he mentioned that there are now "condensing boilers"
| which save a bit of heat, as they extract heat from the fumes
| which are expelled outside the house in older models.
|
| Is it worth going over to such a model?

It is well worth doing the sums to see how much you would save.
On our *very* well insulated extended semi, we spent only GBP 370 in 2004
on heating plus Domestic Hot Water, of which about GBP 150.

So if efficiency of a 25 year old boiler was about 70%, a high efficiency
one 80% (sedbuk) and a condensing boiler 90% (sedbuk) we could only save
GBP 37 per year going to a High Efficiency one and GBP 75 for a condensing
one. These give payback times of 5 to 20 years depending on how much one
allows for installation costs. In pure economic terms I would expect a
payback of more than 10 years, and preferably over 20 years, the expected
life of a boiler.

In our case, the change would not be cost effective. However, because the
boiler was clapped out and as part of a remodeling of the kitchen it will
go ahead, probably a condensing one, because it would be greener.

I would strongly suggest that you do some cost and savings estimates with
your own figures, allowing a reasonable inflation factor for gas costs,
before replacing a boiler which is in "good nick".

--
Dave Fawthrop dave hyphenologist co uk
The London suicide bombers killed innocent commuters.
Animal rights terrorists and activists kill innocent patients.