/ Home & Energy

Boiler blips and breakdowns – are you ready for winter?

Radiator with scarf, hat and gloves

It’s one of the most important items in your house and yet few of us understand it. As the temperature plummets, it’s time to think about what tlc your boiler might need.

I’ve seen pictures of warehouses stock piling packages for the winter in the papers this week. Sadly, it’s not the elves filling up the shelves ready for Santa’s rounds but rather companies getting in supplies for boiler servicing and repairs over the winter months.

The dreaded scenario is the boiler packs up on a chilly December morning. There is the inconvenience of not having a hot shower, the difficulty of finding a decent boiler engineer and then, in the worst case scenario, the shock of having to shell out thousands of pounds to get a boiler installed. It’s certainly a headache that most of us could do without.

A costly boiler repair

Now one of the most consistent complaints that we get from members at this time of year is about boiler servicing contracts. Not many seem to be content with the cost or breadth of their cover and yet a third of Which? members still have boiler servicing contracts. So are they worth it?

Well it’s easy to see the upsides of having a boiler servicing contract in place. Earlier this year, our researcher Victoria Pearson wrote about how grateful she was to have a boiler servicing contract in place after her boiler gave up the ghost.

But it seems Victoria may be one of the lucky ones. Last year we did an investigation in to boiler servicing contracts with alarming results. Four out of 10 boiler engineers failed to do their job properly in our undercover test, with two recommending hundreds of pounds of unnecessary work.

Boiler contract unlikely to save you money

Our conclusion was that you’re unlikely to save money if you take out a boiler servicing contract because the average spent on a service is £75 and you’re unlikely to need repairs.

So how do you look after your boiler? If you’ve home emergency cover you might find your particular policy covers your boiler too (although beware as our money investigation discovered a number of home emergency exceptions).

Perhaps you prefer putting aside a little money each month so you’ve got some money for home emergencies throughout the year. But how many of us could could confess to being that organised?

How do you care for your boiler?

I cross my fingers and hope for the best (35%, 95 Votes)

I have a boiler servicing contract and think it’s worth it for the peace of mind (34%, 91 Votes)

I put a little bit of money aside each month to cover home emergencies (16%, 42 Votes)

I have a boiler servicing contract but doubt it is providing value for money (15%, 41 Votes)

Total Voters: 271

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NukeThemAll says:
15 November 2012

It’s all very well for ‘experts’ to declare that the best choice for boiler repair and service is a local gas fitter. But…..you can predict that when your boiler breaks down, your friendly fitter will be on his/her month-long winter sun holiday. Even a ‘small firm’ is subject to the vagaries of gas fitter availability.

Fine if you can wait for the repair, but that’s unrealistic for most of us. Hence we are dealt into the arms of the likes of British Gas, who at least have promises of response times especially for customers deemed to be vulnerable. I could write a much longer post regarding my experiences of local firms v BG, for both my boiler and that belonging to my very elderly father-in-law…..but not today.

I have serviced my own gas boiler for 30 years, making use of the manufacturer’s instructions. In that time it has cost me approximately £7 in parts. If modern boilers were reliable and trouble-free I might have replaced mine years ago, but I know of so many people who have had problems that I would rather stick with with what I have got, even if it is less efficient than a modern condensing boiler.

A common problem with gas boilers is ‘circuit board’ faults. I know enough about electronics to say that properly designed circuits built using appropriate components are incredibly reliable and the increased cost is not great. It is shameful that manufacturers of boilers and many other domestic items make third rate products.

NukeThemAll says:
15 November 2012

wavechange, I couldn’t agree more – well said! Our condensing boiler has been amazingly unreliable, with multiple failures of the heat exchanger and control electronics. Green? – don’t make me laugh! Our previous boiler may have been slightly more fuel-hungry and ‘not green’, but factoring in the manufacturing impact of the new parts and their fitting, any fuel economy advantage has been more than negated. Fortunately for us it’s been repaired under a service contract – otherwise I would now be **very** much poorer. Now, hmmm, let me think, who’s gained £££ by making a shoddy unreliable boiler that needs shiny expensive new parts for every birthday and Xmas and Father’s Day and……(you get the picture)

Anyone out there tried a Sale of Goods action on a boiler manufacturer whose product substantially fails after 14 months?

Sorry to hear that. In order to pursue a claim under the Sale of Goods Act you would probably need to get an expert’s report that indicated that the fault was present at the time of manufacture. I have never seen this service offered despite the fact that every one of us has bought goods that have failed prematurely.

In the case of many faults, the fault probably did not exist at the time of manufacture but arose because of poor design or inadequate components. Your boiler circuit board probably has one or more transistors or other components that are running so hot that they eventually fail. In my younger days I used to upgrade components on circuit boards to help avoid premature failure.

I don’t think it’s within the remit of Which? but some organisation should be doing a failure mode analysis on consumer goods to identify design weaknesses. They could usefully start with Sony TVs, since websites are littered with stories of problems related to overheating of the display.

Steamdrivenandy says:
16 November 2012

When we first moved to our current house 3 years ago I took out a BG contract which cost £200 a year. After a year I spent £1,000 upgrading the heating system and controls, using a medium size local firm who have several employees living in our village, including the MD who drinks in the local pub. BG wanted something like 50% more for the same work.
Since then the local firm have done an annual service at £45 per time and replaced a failing boiler part for £144. They’ve also quoted £1,600 to replace the boiler as it is 20 years old and noisy. BG wanted nearer £2,500 for the same job.
So if I’d stayed with BG for all the work and the contract I’d have paid out about £4,600, whereas using a local firm the costs would be £3,000 for the same work/service. That £1,600 (53%) is better off in my bank account than BGs.

How do we care for our boiler

We still have a late 1980’s Baxi boiler and I’m sticking with it for as long as possible. We have a great “old school” local engineer who we get to give it a service costing about £80 every two years.

And by service he really doesn’t have a huge lot to do because they are so much simpler than the modern boilers – no electronic boards, no fans, no flimsey heat exchangers to disintigrate. He sticks £5 worth of new thermocouple in each service. In the 12 years we have been in the house it has broke down once needing the major component of a new gas valve assembly which cost about £100. About 3 years ago the heat exchanger started to leak water at its joint of its two halves. It got taken to a local engineering firm where they gave the faces a resurface for £20 on the milling machine, £5 for a new gasket and good as new again.

We are surrounded by neighbours who have all had new condensing boilers fittedand guess whos boiler was the only one not to break down at the first signof cold weather.

We had a service contract with British Gas many years ago. After we discovered the number of things that weren’t covered (which we only found out in a boiler breakdown situation, of course) we were put off and didn’t re-new it. Later, after moving, we decided to try again, but were told there were so many things wrong with our boiler they wouldn’t cover it and we needed a new one.

We didn’t take them up on their offer but got a plumber in who repaired the boiler. I seem to remember the repair costs less than the year’s contract would have cost, though I might be wrong about that. I do know it kept the boiler going for a couple more years by which time we could afford to replace it.

Gerard Phelan says:
16 November 2012

Its not just the Boiler that you need to think about, there is also the FLUE. I have enjoyed 20 years of fault free operation from my boiler. so British Gas were getting rich on the money I paid them for the service contract. However this July they condemned the open flue and declined to fix it pointing me to an exclusion clause added to the service contract a year or two ago.
When I contacted a local company (via Which? Local) they advised that the Gas regulations now prevented them from fixing the flue. All they could do was replace it completely at a cost of £1200, a cost that made no sense for a 20 year old boiler.

So now I have a Which? Best Buy Worcester Bosch Greenstar 24Ri condensing boiler installed by a top rated Which? Local installer: Fuller Heating.

As far as servicing goes, the local installer will carry out the mandatory annual safety check for £84, a big saving on the £260 British Gas was charging me for their plan. Given it comes with a Worcester Bosch 7 year parts and labour guarantee, than at current prices I should be £1232 better off on service costs by the start of year 8, when I would have to start paying the cost of maintenance and spare parts.

I am very happy with the new boiler, but I was also happy with the old one and cannot see any gain to my safety resulting from the regulation change that impacted open flues.

NukeThemAll says:
16 November 2012

We need to be very clear what we’re comparing here: a boiler service is indeed much cheaper than a BG service contract – which not only covers the service cost, but is an insurance policy with a promised response time: for some people that will be a vital issue.

Fortunately BG didn’t refuse cover or load my premium when my unreliable boiler went to boiler heaven several times. I’m now definitely of the opinion that if high-tech condensing boilers were manufactured properly they would be absolutely fine. But they’re not so they aren’t.

Of course the con trick is taken further with the energy rating for your property when you come to sell it: would-be buyers see the nice efficient condensing boiler, little realising that…….!

Bob Marcus says:
17 November 2012

About two years ago we needed to replace our old oil boiler because spare parts, when required, were no longer available (and HMG were offering some financial assistance). The boiler was installed in 1970 and although expensive on fuel had been economical on service costs and by 2010 we felt it didn’t owe us anything,
We are very happy with the new boiler (so far) but will be very surprised if it lasts anywhere near as long.

I’ll stick to my 1979 Glow Worm 52BSuper, which is service every August by my local independent plumber for £20 and which has never ever broken down. A huge plus for me is that my gas bills are way lower than neighbours with a 2 yr old SEDBUK A condensing boiler which seems to break down about every 3 months on average.


As I installed my boiler and central heating myself over 45 years ago – and check it regularly (bi-annually) – I will repair it myself. So far the only problem was a birds nest in the flue 45 years ago that I had been “too busy” to put the cap on the flue after the installation. Since that glitch it seems reliable.

Maud Fitz says:
20 December 2012


I think using combi-boilers are more efficient and helps your save some money this winter. A good combi-boiler that runs on geothermal energy will be highly economical.


The Last Jones says:
8 January 2013

Hi all

I’m interested to hear your thoughts on a current issue I have. I’ve just moved into a 3 bed detached property with what I understand to be a ‘combination vented cylinder system’ running off a 21 year old Baxi One boiler. The boiler is in good order and has been serviced annually(according to the previous owners) since day 1. Central heating works great, no issues with temperature or timings however, there is an issue with the hot water in that any tap/shower will run hot for a minute or 2 and then drops off lukewarm to cold. I have had 3 engineers out who suggest that the tank is the issue and needs to be replaced.

My questions are…

1) At a cost of approx £800, the engineers can replace the water tank for a new direct system 210 litre tank but that leaves me with a 21 year old boiler that I am unsure how long it will last. If the boiler goes too, it will costs a further £1000(ish) to replace like for like. Total £1800…..
2) The engineer can fit a brand new combi boiler at a cost of £1700.

Which is the better option?

I should mention that at the moment it is just the 2 of us in the house so our usage is low and we would rarely need to draw 2 sources of hot water. We also do not intend to move for at least 5-10yrs.

Many thanks

Steamdrivenandy says:
8 January 2013

May I suggest you read Jeff Howells column from last Sundays Telegraph when he discussed heating systems. Specifically he said that he could not understand why anyone would install a combi boiler unless they had insufficient roofspace for a water tank. Plumbers/heating engineers like combis because they’re less work and easier to fit, but they were really only originally designed for flats with no roof space.
From your description it sounds like you have a system that uses a direct supply of hot water to run round the radiators and through the hot water tank. Indirect systems, where the water that runs through the boiler is pumped around the radiator circuit and through a coil in hot water cylinder which it warms to provide a store of warm water for baths/kitchen etc. The hot water cylinder is topped up with cold from the tank in the loft and you’d need to run an awful lot of baths etc to run out.
The problem with a combi boiler is that it has no hot water cylinder, and warms the water direct on demand, and maybe stores a small amount inside itself. This can lead to delays in hot water reaching the tap and being unable to keep up with high hot water demand. Combi systems also only work under pressure and are sealed, not vented. They have a habit of losing pressure which stops them working ’til the system is manually topped up, which can be inconvenient – and cold. Direct systems can also suffer very much in hard water areas where the pipes fur up very badly, very quickly. Indirect systems keep circulating the same water and therefore don’t suffer the same issues.
If I were you I’d ask for quotes to turn your current system into a pumped indirect vented one, which may cost a bit more, but won’t have as many potential issues.
We had our whole system (apart from boiler) upgraded 2 years ago, along with the latest wifi thermostic controls and it’s been brilliant. The boiler is 19 years old and bubbles and clonks merrily but I’m assured it is safe and could last another 5 years or more.
A replacement condensing boiler which will now be just a case of mounting and connecting has been quoted at £1,600, although this is quite a powerful one as we’re heating 150sq m of 1970’s house..

I have a 1979 boiler (i.e. now in it’s 34th year) and my parents have the same model but theirs is 2 years older. Neither have ever broken down in their entire lives and both are serviced annually by the local plumber rather than BG or the like. The plumber tells us every year that boilers the age ours are will run and run and run forever as there are virtually no parts to go wrong and they were built like tanks (as in military vehicle rather than water storage tank). Last August when he serviced mine he said that he thought the boiler would probably still be working when he retires in 10 years time …… so he clearly expects at least 45 years out of these.

My strong advice would therefore be that you DON’T replace the boiler until it stops working. Of course, none of us can guarantee that your boiler will go on for years, but if I was you I’d keep it going on the basis that you might just as likely get 10 more years before you have to spend money as you are to have to spend in 6 months, so earn a little interest on your cash until you need it!

I don’t understand the hot water issue – it sounds to me as though you have a cylinder, in which case you don’t have a combi boiler, and at the age your boiler is a combi would have been almost unheard of in the UK when it was fitted. It sounds to me a little more like a problem I had many many years ago when the coil inside my cylinder “sagged” with age, causing problems with trapped air, which meant that the coil became very inefficient and only heated a tiny volume of water right at teh top of the cylinder. The plumber I had at that time carried out a messy “medium term fix”, which I have to say gave the cylinder about another 4 years of life, but in hindsight I’d have had a new cylinder there and then given how much hassle and mess the repair made and the cost of it too. Particularly if your current cylinder is not factory lagged, I’d perhaps suggest that you look into that but the quote of £800 seems very high: my current cylinder, which is a TWIN coil, factory lagged, 275 GALLON cylinder connected to the solar panels and the boiler only cost £500 to buy and fit 4 years ago. I know prices are always going up but £800 for a direct cylinder, of only 210 LITRES capacity (which is very tiny) seems extortionate to me. Are you sure it’s litres and not gallons?

Hope this helps

Steamdrivenandy says:
8 January 2013

I I think the ‘combination’ bit in TLJs explanation probably refers to the fact that it heats both hot water and central heating and not that it’s what’s commonly called a ‘combi’ these days, which as you say probably weren’t around 20 years ago. The ‘vented’ bit also means it’s not what’s known as a modern combi as these are non-vented and run under pressure. ‘Vented’ also means there should be a cold water storage tank and ‘jockey’ tank up in the loft as well.

The thing that got me confused is the mention of replacing the water tank with a direct system tank and no mention of a pump anywhere. If he means he’s replacing the cylinder that’s fine, but surely you’d want a decent size indirect cylinder otherwise you’re using the hot water straight from the boiler into the cylinder as DHW and around the heating system as well, which can lead to big furring up issues as I said before. Maybe the terminology has got a bit mixed up.

Personally I’d go for a quote from BG, plus a quote from a local firm that comes recommended by neighbours etc and isn’t a one man band.

One man bands can be diamonds but can also be rip-off merchants who know very little. BG generally charge the earth but are normally technically competent. In my experience local firms that are big enough to have expertise but still provide value for money, are the way to go.

@Steamdrivenandy: I have to be honest and say that I have had, and know others who have had, exactly the opposite experience with BG, and have been left in an awful mess and with a huge bill.

Bu then again, I do know of one person whose had the same problem with an independent plumbing firm.

The strong advice here has to be “plus a quote from a local firm that comes recommended by neighbours etc” – in other words, get several quotes form different companies before you commit to anything at all.

It does also come to mind, now that you’ve mentioned the lack of mention of a pump, that this could just be a gravity fed hot water system, in which case it’s probably gathered air and isn’t working at all well. This can be cured very simply by bleeding the heating circuit, though if a bleed valve hasn’t been built in you do need a plumber to do this. If this is the case, having the system converted to a fully pumped one will make a massive difference and won’t cost very much at all.

Daniel Tissinngton says:
8 March 2013

How come my comment is not include in this column?

Regards Daniel Tissington

There are several Conversations about boilers and I remember seeing your name in one of them.

The best way to ensure your combi boiler condensate pipe doesn’t freeze up in very cold weather is to not run externally. instead, ask the heating engineer installing your boiler to ‘Tee’ the condensate into the nearest waste pipe. e.g. if you boiler is in your kitchen, then tee it into the sink waste pipe. Alternatively, if your boiler is in your airing cupboard then the bath or wash hand basin wastes would be ideal.

If you do have to have your condensate pipe running externally, you must never run it horizontally, (even if it’s fully insulated) as this will allow the ice to build up in layers in prolonged sub zero weather until the pipe is completely blocked.
If the condensate pipe length is kept to the bear minimum, fixed at a fairly steep angle to allow the condensation to run away quickly, and insulated with a decent quality weather proof pipe lagging with tie wraps to ensure it doesn’t come off in high winds, then you should have no further problems.

Unless the building regs have been changed in the last couple of years (since I last checked) it is a contravention of the building regs to connect the condensate outlet to any other pipe, internally or externally, other than direct to a Soil Stack below the height of any other connection.

On “You and Yours” 4 winters ago, when the entire country seemed to be moaning about frozen condensate pipes, the Climate Change minister of the day (I forget who he was off hand) was tackled over this very problem and his suggestion was that the building regs should be changed. Representatives of the Boiler manufacturing industry disagreed with him with some technical reason which I forget, and did not really think seemed valid, for keeping things as they were at the time – specifically the condensate drain must go out of the property as close to the boiler as possible and then into an open gully or soil stack.

If the regs have changed then Peter’s suggestion is a good one; if the regs have not changed you may set yourself up for trouble if you do this.

An alternative is to buy a small sealed sump with a syphon and connect the condensate pipe to that (such things are readily available from boiler suppliers and plumbers merchants). These work like a Urinal cistern and fill with water slowly (from the condensate pipe) then, when full, automatically syphon the whole lot out in one go. Because the water is discharged in a larger quantity, but then there is no more water discharged for a while, the pipe is less liable to freezing as there is not a constant trickle running down it. (I understand that most recent boilers of any quality have these siphonic sumps built into them now).

Fair comment Dave, you my very well be correct. However, I still think running the condensate pipe internally is by far, the lesser of the two evils. I’m certainly not encouraging people to contravene any building regs but unless your new boiler is being installed in a new build property, or in an extension that will need to be checked by building control, then who’s to know?

The stuff that comes out of a combi boiler’s condensate pipe is actually quite acidic and also toxic, so running it into an open gully is a real no no. There are good reasons for this; An animal such as a dog, cat, or even a hedgehog could try to drink from it, or Heaven forbid, a small child gets the acid on their hands and then rubs their eyes.
All externally run condensate pipes must finish below ground level, whether they go into a back inlet gully or a soak-away.

It seems incredible that boiler manufacturers did not think about the possibility of condensate freezing in drain pipes. As a child in the 1950s I was told to make sure that taps were not left dripping in cold weather because that could freeze waste pipes. Goods should be fit for their purpose.

I heard a Boiler Manufacturer’s Representative on a Radio Programme several years ago explaining that Combi and Condensing boilers were not designed for the UK climate and that we were trying to make them do something for which they are not suited by using them here. Apparently, this man was saying, they are designed for use in much colder countries than ours, where the return heating water going back into the boiler is much colder than it is in our climate. This, I believe, makes the condensing mode work properly and leads to not only better efficiency but also a near-constant **flow** (as opposed to trickle or drip) of condensate. Moving liquid, of course, is not so liable to freeze as standing liquid or very slow dribbles, so despite the countries being colder than here, freezing condensate is, it was said, not generally an issue. I would suspect that the countries concerned are probably more insulation-conscious than we tend to be and so the discharge pipes are probably lagged to a greater standard as a matter of course.

My plumber maintains that the problem is that the condensate drain outlets form most boilers is “overflow” pipe – i.e. 20 – 23mm diameter – thus tempting installers – especially those eager to cut costs – to use narrow-bore (overflow) pipe to the drain. This, of course, is far easier to block with frozen water (ice) than a larger bore pipe. The plumber tells me that many of the latest, and higher quality boilers now have 1.5″ waste pipe outlets and are thus connected to larger pipes. I believe (from the plumber) that even if the boiler has a ‘overflow’ type pipe on it, by connecting this directly to a sink-waste type pipe (1.5″) **at the boiler** and then running the wider pipe to the drain, most freezing / blockage problems can be eliminated.

Meanwhile I keep using my now 35 year old Glow worm which has still never gone wrong and still keeps me and my house cosy for less cost (in gas) than my neighbours now-4-year-old SEDBUK A rated condensing boiler which has gone wrong more than 11 times according to the neighbours. (Mind you they do seem to have the central heating on 24 hours a day for about 300 days per year, so it’s perhaps hardly surprising!)

Thanks Dave. I don’t have much sympathy with the manufacturer’s excuses because they should check that products are suitable for use in the UK before selling them to UK-based distributors.

My Glow-worm Space-saver 50 BF boiler has continued to work reliably. It was in the house when I moved in, in Feb. 82.