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Is it worth paying for boiler cover?

Our annual boilers survey has revealed a surprising nugget: those who pay for boiler cover could be better off forgoing their contract and paying for repairs on an ad-hoc basis. Do you pay for boiler cover?

Almost half of gas and oil boilers will develop at least one fault that needs a repair within the first six years of its life. Of course, getting yourself a Which? Best Buy boiler is a good idea, and drops this to fewer than two in five.

Despite the likelihood that your boiler will eventually develop some faults, we’ve found most people who own a boiler would be £50+ a year better off without boiler cover.

We compared the cheapest servicing contract (£183 per year), which includes an annual service, against the experiences of 5,322 Which? members who don’t have cover. Instead, these members paid for repairs on an ad-hoc basis as well as a yearly boiler check-up. The great majority (93%) are still better off without boiler cover to the tune of £50 or more.

My boiler servicing story

I’ve owned my combi gas boiler for just over three years now, having inherited it when I got the keys to my two-bed flat. I’ve never paid for boiler cover, but I have incurred some costly repairs. Here’s my story (violins).

About two years ago I woke up on a bank holiday weekend with water leaking from somewhere within the casing of the boiler. Being a bank holiday it was difficult to get hold of a plumber, but eventually I found one who was willing to interrupt his weekend to come out and take a look. He diagnosed the problem as a couple of corroded washers and came back the following day to replace them. The cost of the parts that needed replacing – £15. Total cost of call-out and repair on a bank holiday – £261. Ouch.

As a result of that rude introduction to boiler maintenance, I now pay £85 for a service each year to keep my boiler in good working order.

So in the three years I have owned my boiler, I calculate that it has cost me £431 to maintain it. This is the first time I’ve added it up and that seems like a lot for three years – I keep my fingers crossed that I won’t need any more costly repairs going forward!

My experience tallies pretty well with the results of our survey – even though I had a pretty costly repair to shell out for in one year, one of the unlucky few; I would have had to pay at least £549 over the last three years for even the cheapest boiler cover contract, so I am now more than £100 up.

I’ll continue to pay for an annual service and then any repairs as they come up as, despite my bad experience, I don’t see much value in a servicing contract at the moment. I might get scalded again with costly repairs, but for now it feels like an acceptable risk.

Your boiler servicing stories

So, how about you? I would love to hear about how much your boiler has cost you. Are you, like me, in the 93% who are better off without insurance? Or one of the unlucky 7% who have incurred very costly repairs?

Further, are we giving boiler cover too much of a hard time? It would be great to hear from those of you who have had great value from one of these contracts.


Annual gas safety checks are needed by landlords, housing associations, local authorities, hotels and B&Bs,colleges,boarding schools and hostels. In contrast, there is no requirement for householders to have their own appliances checked or serviced, though having this done annually is widely recommended. Likewise, there is no need to have household electrical installations or portable electric appliances checked. Why is it we are obsessed with some aspects of safety yet pay no attention to others?

Perhaps the high failure rate of modern gas boilers has a hidden benefit, because it means that they are likely to be inspected and serviced when repairs are carried out.

gas brains says:
15 November 2014

modern gas boilers are today the best,probably the biggest scam this country has ever seen,no one can repair thebloody things,a curse on a society,they go wrong on an unprecedented scale,and if you try to repair these things on a large scale I will say that there wil be a lot of gas engineers with mental health problems,in their later lives,and its not good for customers either listening to exscuses why the thing don’t work.fact.

Graham says:
25 September 2014

My central heating system was installed in 1977. The original boiler, which ran a constant pilot, lasted till 1988 when because it had a minor leak and I needed to accommodate the heating requirements of a large extension and a new location we replaced the boiler with a potterton netaheat 10/16, a boiler with +ve pressure inside and a spark ignition system. The system is open vented and contains an inhibitor.

The radiators are thus 37 year old with no signs of failure. The boiler (26 years old) has had two fan replacements and the spark igniter control board failed earlier this year as its only parts. the thermocouple hasn’t failed – yet! The boiler is not serviced. My system has never suffered from blocked radiators, although I confess to removing them when I decorate to flush out any debris in them. For the past 12 years the water used has been softened.

Other parts have failed- there have been several pumps, and a leak to the indirect cylinder necessitated a new one. That was also replaced when I had a solar thermal system put in some 7 years ago, but not because it had failed. The synchron motors in the motorised valves have been replaced too- the motors not the valves.

I reckon I’m quids in by having a solid reliable boiler with few of the more complicated features demanded by building regulations nowadays. These are attempting to save the planet in CO2 terms by making consumers buy and maintain ever more complicated and costly appliances which are inherently unreliable.

So would I be better off would boiler cover? Quite definitely no.

Would a boiler servicing contract have prevented any of the comparatively minor failures ever the years? quite definitely no.

Would I be any safer with a boiler servicing contract? No but other might be and they may also appreciate the peace of mind that such cover brings. I’ve always worked on the basis that I only insure to cover things that would cause me severe financial embarrassment if the happened or because its a legal requirement. So I insure my house, its contents, the car, my health and my life. Nothing else!

I fully accept though that others think differently


Graham – How do you soften the water? I’m interested because Beryl brought up the issue of water hardness.

In trawling through manufacturers’ instructions I have found some cautions, such as this one in a Worcester Bosch manual: “IMPORTANT: ARTIFICIALLY SOFTENED WATER MUST NOT BE USED TO FILL THE CENTRAL HEATING SYSTEM”

My own thoughts are that simple water softening where calcium and magnesium ions are exchanged for sodium ions would not be beneficial other than to avoid limescale deposits but use of purified water from which salts have been removed (as in water sold for use in irons) could be beneficial.

The nature of the heat exchanger (aluminium, stainless steel or old fashioned cast iron) could be a significant factor.

I agree that producing efficient but unreliable boilers is of questionable environmental benefit. Hopefully we can look forward to a compromise that combines decent reliability and efficiency, even if not the best in either category.


As far as I can see it is fine to use your normal tap water, with an inhibitor to minimise corrosion (giving the black sludge that accumulates in your radiators). The system is more or less closed and does not require regular additional water, so hard water should not be an issue. Is this the case?


With boilers containing aluminium heat exchangers, the pH is important. If the system water is alkaline, rapid corrosion will occur. A service engineer should check the pH routinely, using either a meter or simple test strips.

One of the big benefits of modern pressurised systems is that there should be little opportunity for oxygen to enter, except when the system is commissioned or drained for repairs or modification. I agree that tap water with inhibitor is OK but suspect that purified water (reverse osmosis is the primary treatment) will help prevent electrolytic corrosion that would occur when different metals and a conductive fluid such as tap water are present.

A heating system using a suitable grade of stainless steel for the boiler heat exchangers, radiators and plumbing and valves would avoid the fundamental flaw of using dissimilar metals, and might not be prohibitively expensive.

Graham says:
25 September 2014

All my water is softened – apart from the kitchen sink tap and that for the garden. I have a fitted water softener.

My system is fine. It has softened water, inhibitor and no magnetic filter. It utilises an old boiler with an iron based heat exchanger. Realistically there isn’t much to go wrong, and that turns out to actually be the case. If people really took the bother to understand how things work then they wouldn’t allow themselves to be fleeced by boiler servicing companies who charge a lot for doing practically nothing. Where is the evidence that those who have their boilers serviced suffer fewer or less expensive breakdowns? None of the failures I’ve experienced would have been prevented by a service.

Flue and casing safety is a different matter. CO can be fatal and often is.


In reply to those who question boiler servicing as useful or not.

As a gas engineer (plumber) I see many systems that have never been checked throughout their working lives and are 100% fine. Mostly standard efficiency models.

When it comes to newer A rated boilers, they produce a higher amount of acidic water from the spent flue gas. If this water happens to leak into the metal parts of the boiler then it will quickly eat its way through. If the main boiler casing becomes badly corroded then it’s pretty much new boiler time.
The A rated boilers are set up precisely to allow the correct ratio of air/gas mixture to burn properly and if this goes out of sync it loses efficiency and also becomes a health risk.

I would say that servicing is probably the wrong word to use for it as generally no parts are removed and cleaned etc like the older types used to need. We charge a standard call out for a “service” as its normally straight forward but still essential once a year I feel.

As for boiler reliability and parts. Absolutely shocking. Some manufacturers should be made to answer for producing such crap yet punishing the unlucky user by charging outrageous amounts for the spare parts to replace the garbage that they put in a boiler.

It’s embarrassing to have to tell somebody how much a part costs sometimes and I do feel bad when it joins a list of other repairs. Due to the amount of bad engineers out there there is a huge amount of distrust by the public towards engineers. The maintenance plans take this problem away as engineers can throw parts at the boiler till its fixed and it won’t cost the customer any more than the monthly fee.

Manufacturers don’t help engineers who are trying to fix their machines either as they want to use their own guys. Problem with boiler company repairs is that the price to even get them in the door is around £250 or higher. That could be for a 2 minute job.

Boiler companies should be made to answer. Training provided by them to assist engineers is only for sales.

rosemary says:
7 April 2016

Good for you! I agree entirely about what to insure and the reasons for doing so. I only pay to insure my house and my boat. Not contents, not my belongings, my health or even my life. Paying for insurance cover the years would have had a substantial financial impact on my life and my lifestyle choices so I am glad I decided to to this.
I do have “free” travel insurance with HSBC. This has proved ineffective to the nth degree, even when I missed my plane because the train I was on broke down I was not covered. Shame on them!

Graham says:
25 September 2014

Further to my previous post you might like to read from this link:


It appears that to comply with building regulations an inhibitor should be added, and boiler maker’s concerns over use of inhibitors relates to aluminium elements within the boiler which have now been resolved.


I am well aware what the building regulations say, and between satisfying a customer with a reliable heating system and complying with building regulations I would choose the former all the time.

This country imports almost all its heating technology (although it makes a few things) and we have no research and development based in the UK other than in, you have guessed it, inhibitors! Thats why we use inhibitors but other countries do not!

The result is that the people who are writing the regulations are not up to speed with the designs concepts behind various components… Importers of boilers, usually owned by the manufacturers just want to sell boilers, and don’t have the desire or inclinationation to (re) educate the people writing the building regulations. Their natural desire, is to sell to the lowest common denominator as defined by the regulations…

Building regulations don’t mention compensation controls either, but these offer benefits interns of reliability (longer running pipe times, lower temperatures, less thermal strain, less starts, less starts from cold). But if you use a cylinder sensor (as opposed to an on-off thermostat) with the boilers embedded controls controls you cannot comply with building regulations as they don’t recognise the benefits.


Alec – You have told us that you would not use inhibitors despite the fact that Viessman list ones that are compatible with their boilers, and now you tell us that you would prefer to ignore the building regs. I do hope you tell prospective customers about this before you start an installation. 🙂

You have mentioned that use of inhibitors is a UK peculiarity, so I am left wondering why the Fernox website can be viewed in a variety of languages.

Like Graham and Beryl, I’m going to stick with my old boiler.