Copyright 2019, Michael Bryant
Site last updated 27th January 2019
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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 standpoint 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 repairs.
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 boiler.
On the other hand your boiler may be 25 years old and has not missed a beat in all the years you’ve had it… until now. So as it has been such a reliable workhorse for so long, and you’ve heard all the horror stories about modern condensing boilers being so unreliable, you just want it fixed. Often this is perfectly feasible. Parts for surprisingly elderly boilers are often freely available. Feel free to contact for my opinion on yours, here.
Page first published approx 2007
Last updated 16th August 2018