On 13/11/2016 16:32, David wrote:
Brief background; visiting a friend with very old central heating -
reminds me of what was in our last house when we moved in in 1984.

An old Glow-worm 85 100 floor standing lump of iron. Kettles like a really
kettly kettle. Radiators of various vintages, some with suspiciously cool
bottoms.

It hasn't been serviced recently (then again, these are so simple that
there isn't much to service compared to modern boilers). This also
suggests it might do with a flush and some inhibitor.

I suspect a power flush might improve the effectiveness of the radiators.

This is a large long and thin 4 bedroom bungalow with a lot of glass,
patio doors, plastic roof conservatory as part of the dining room. So
probably not that thermally efficient.

I am assuming that a new central heating system will cost more than
£4,500; possibly quite a bit more given the length of the pipe runs.

Just wondering how long it normally takes to recoup the cost of a new
highly efficient system through fuel savings.

For example, a £4,500 system would need to save £450 a year to pay back
over 10 years.

I expect the costs to be higher and the savings per year to be perhaps a
little less.

When you get past 60 long term investment looks less attractive,
especially with a pay back tome of 15-20 years.

Piece of string question but just pondering.

It all hinges on the amount being spent per year on gas and what the
boiler replacement will cost. You may be able to get a 20% saving on
fuel, but will have to work out what that is worth. You may find you get
a much bigger return for the money adding insulation instead (depending
on the current levels). Just modernising the system controls, flushing
the system, and doing a bit of rad balancing may yield a noticeable
improvement for very little cost.

In my case the boiler cost me £1200 to install, and the gas saving alone
paid for it in about three years. But, that was made far more cost
effective by DIYing the work, and having ridiculously high gas bills to
start with.


--
Cheers,

John.

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