How long should a boiler last....?
This is a question I'm asked regularly. It's usually asked by people who are
surprised to have been advised they 'need' a new boiler, even though their
current boiler is less than a decade old.
It's a difficult one to answer. There are millions of perfectly good boilers
installed and working nicely out there, and from a technical standoint most are
likely to be good for 30 years or more. Yes they will have the occasional
breakdown but the only technical reason compelling you to replace such a boiler
would be a breakdown needing parts which are no longer available.
However, there are a number of other reasons for deciding to replace a boiler
BEFORE the day arrives when a part needs replacing and it cannot be obtained:
1) Jump before you are pushed.
You know for sure that certain components in your boiler are no longer
available. The boiler is running reliably but it can make sense to replace
BEFORE it breaks down and you find you need an unobtainable part and therefore
have to have a replacement fitted in a hurry. A planned replacement.
2) Persistent breakdowns.
Some boilers models are plain unreliable, and therefore expensive to
maintain. Imagine your boiler has suffered a breakdown every six months for the
past three years. A different problem every time. Each time you fix it you think
that will be the last of it, but the breakdowns keep on coming. Eventually you
lose patience and decide to replace it rather than 'waste' more money on
3) A high-cost repair is needed.
A repair costing say, £700 will get a 20 year old boiler working again, but
you may consider it makes commercial sense to fit a new boiler rather than spend
that much on repairing a boiler approaching the end of its life.
4) Flue problems
A boiler needs a flue. The flue carried the potentially dangerous products of
combustion safely to outside. If the flue is found to be unsafe then this can be
very expensive, or impossible, to repair. Flue components corrode and often
cease to be available long before spare parts for the boiler itself. Further,
builders often conceal flues inside the structure of the house or flat and
exposing a flue for maintenance leaves a hefty bill for making good of
boxing-in, decoration etc. May be better to not even try, but to fit a new
boiler and flue instead.
5) Fuel efficiency and environmental pollution.
These two issues are different, but inextricably entwined. Older boilers were
designed in the days of cheap and plentiful natural gas. Global warming caused
(arguably) by 'greenhouse gases' was not an issue. Carbon dioxide is produced in
larger quantities by older boilers purely because they are less fuel-efficient
and burn more gas for a given amount of useful heat in the house than new
boilers. A modern condensing boiler will extract in useful heat energy around
90% of the energy available in the gas it burns. A 30 year old boiler will be
closer to 60%. If you want to Save The Planet AND reduce the amount of gas you
pay for by around one third, then your 60% efficient boiler has reached the end
of its life!
6) Boiler noise
Elderly boilers that work perfectly well often make irritatingly loud 'kettling'
noises. Kettling is usually caused by products of corrosion of the insides of
the radiators etc accumulating inside the boiler heat exchanger. A black sludge.
This can sometimes be removed by powerflushing but the results are not that
reliable and silence cannot be guaranteed. May be better to replace the