(sorry if this gets posted twice - newsfeed playing up)

Timothy Murphy wrote:

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?

Depends on the circumstances. When you need to replace it for other
reasons then yes certainly, go for the best efficiency you can get all
other things being equal. Whether it is worthwhile scrapping a working
system requires some careful analysis. There is no point taking the
simplistic view of just comparing the raw cost of the boiler to the gas
savings, you need to look at the fuller picture.

Firstly how much are you spending on gas for your current boiler? The
model you list probably has an efficiency around about the 75% mark. So
going to a modern 90% model could reduce your gas bills by up to 15%.

What would it cost to have it changed - even a straight swap would
probably require some additional work for plumbing the condensate drain
etc. You may also need to spend some on upgrading controls to modern
build regs standards. Chances are even with a basic boiler you are
looking at £1500 unless you are up to doing the work yourself.

Modern high tech boilers are less likely to be happy going 14 years
without a service, so you need to factor in extra maintenance costs as
well.

To balance the costs you can also look at other factors: the modern
boiler will modulate over a decent range which combined with better
controls (TRVs on most of the rads etc) may give better temperature
regulation and comfort in your house. It may also take up less space and
be quieter / less ugly etc.

Environmentally the picture is less clear, since no manufactured product
is "environmentally friendly". These environmental costs of making your
new boiler and disposing of your old one are obviously hard to quantify
- but they are certainly not zero.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/