/ Home & Energy

Boiler trouble? Our cameras reveal the truth about repairs

Boiler broken down? About to call an engineer to get it fixed? When they put away the toolbox, how do you know your boiler’s been correctly repaired or you’ve been charged the right amount? We went undercover.

Everyone’s winter nightmare is that their boiler breaks. Our boiler went last year – cue electric heaters, lots of blankets and, yes, occasional trips to the pub to keep warm.

Fixing boilers can be expensive and it’s also crucial that it happens fast – so the cards aren’t exactly stacked in your favour. If the guy (or girl) fixing my boiler tells me it’s the valve, or the printed circuit board, or the controls, how am I going to know if they’re right or wrong?

Which? goes undercover

With this in mind we decided to go undercover here at Which?. We invited ten engineers to service a gas boiler to which we had introduced a minor fault and watched their job with hidden cameras. This was a fault that should be fixed during the service at no extra cost (we basically disconnected a lead which stopped the boiler from lighting – a five minute job). So, how did they get on?

Two engineers suggested that we needed expensive repairs when we didn’t. One independent engineer said he wasn’t sure what the fault was – he thought it was either the board or the gas valve, with repairs predicted to cost around £500.

Another said it would be at least £200 for the part but suggested we might be better off getting a whole new boiler. We also found that two others missed key checks when trying to service the boiler. So not only are some of these engineers suggesting expensive, unnecessary repairs, others aren’t carrying out basic checks.

Do you need boiler breakdown cover?

We’ve passed our findings to the Gas Safe Register and it said it will investigate any potential safety issues.

But we didn’t stop there – we also looked at whether it would be a good idea to get boiler breakdown cover. We found that cost-wise most people wouldn’t save money taking this out. This is because the average spent on servicing is £75 and you probably won’t need repairs.

However, we also know that most people who have boiler breakdown cover do so for peace of mind, so we surveyed Which? members to find out who’s best. You can read this in more depth in our boiler contracts review. Let’s just say than one boiler servicing company got a much higher customer score than the others in our survey.

So, if you have boiler cover, do you think it’s worth it? And if you’ve ever had your boiler serviced or repaired, did the engineer do a good job and charge you a fair price?


In 1982 I moved into a house with a fairly new gas boiler and the seller passed the the installation/servicing instructions that were marked as not intended to be passed on to the customer.

I have serviced my boiler regularly and the only repairs needed have been two thermocouples. I’m not sure whether this is illegal but I live alone and the only person I’m likely to kill is myself.

On the basis that I had to get Corgi-registered gas fitters back to fix two leaks below the floor in my parents’ house and they ignored instructions about the diameter of pipe required for a boiler I have felt unwilling to have my boiler serviced.

When I pension off my boiler for a complex, modern boiler (more efficient but probably less reliable) I will leave that to the experts.

I appreciate that there are good gas engineers and I have found a garage that I trust to do larger jobs on my car after bad experience in the hands of the main dealers.

Some of the stories I have read in Which? magazine over the years have made me worried about bringing in professionals into my home, plus doing repairs and servicing yourself saves a lot of money.

I’m not suggesting that anyone services their own gas boiler!

Recommendations (either personal or from Which? members) can comment on value for money, whether an engineer turns up on time and whether they fixed problems at the first visit, but the average person is not going to know whether a gas engineer, electrician or motor engineer does all the inspections and tests needed for the job, particularly with regard to safety.

This is, as we can see, a can of worms.
I’d like to add to it: British Gas engineers do NOT have to be Gas Safe Registered – they are deemed to be competent and train dot Gas Safe Standard by virtue of working for British Gas.
Which would be fine and dandy were it not for the fact that British Gas engineers refuse to even look at boilers more than 15 years old and simply tell youth buy a new one.
This cannot be safe (or morally acceptable) since it leaves many people not having heir appliance serviced in order to avoid the hard sell but continuing to use it, not knowing if it’s safe or not, because they don’t want or can’t afford a replacement.
But getting right back onto the topic: I have my 31 (almost 32) year old boiler serviced by a Gas Safe registered plumber once per year and it’s in fine fettle. When it used to be on the British Gas three star service plan all the man did was stick a probe down the flue once a year, read the score on his little machine and walk off. My plumber strips the boiler, cleans the burner, checked ever seal, tests the flue and cleans out the burner chamber, not to mention physically inspecting the heat exchanger for wear. The cost? Last time I was on the BG plan it was £149 per year, my plumber charged me £20 this year. I know which is the better deal!

Geminii says:
19 August 2011

I had a British Gas Engineer to service my one year old boiler and he tried to make out it was leaking and I needed a new one. Since then I have had an independent Company regularly service each year, but even they try every visitv to get me to change to a new type condensing boiler – which will probably last only 7 years, whilst my 18 year boiler was recently repaired by me getting the relevant spare part from a refurbishment place and getting my regular service man to fit it. I had to send back the old part for it to be refurbished for further sale and I was happy to do this. Total cost £150 for engineener +£65 for part. Quote for new boiler £7500.

The new condensing boilers are flawed in their design. The condensate is piped away in a too small diameter pipe, invariably outside the building, where it freezes up in winter and the boiler stops working. Condensing boilers are fine in large blocks of flats in Germany where they are appropriately installed to service large numbers of households. They do not scale down effectively.

AstridV says:
16 November 2012

Hello Dave D,

Sound like you have a damn good honest plumber…
Can you share the Plumber’s details please…

Plumber info: see which? local

gas brains says:
15 November 2014

great,how it should be,fair play,so why do b,g, exist?

From the introduction: Fixing boilers can be expensive and it’s also crucial that it happens fast – so the cards aren’t exactly stacked in your favour. If the guy (or girl) fixing my boiler tells me it’s the valve, or the printed circuit board, or the controls, how am I going to know if they’re right or wrong?

Until the 60s or 70s, many people used to service and repair their own cars and domestic appliances. Though it’s not wise to tinker with gas appliances, there is nothing very difficult about diagnosing and fixing some problems with pumps, valves and leaks on central heating systems. Precautions need to be taken when working with electricity, but there is useful information in books, leaflets and websites.

gas brains says:
15 November 2014

what, and put the new wave engineer to shame,please have some pity on those trying to fleece you.

Adam says:
19 August 2011

Where is the full article? I can’t find it anywhere. I’d like to know what the ‘minor fault’ was and how the companies failed!

Hello Adam, the full article is in our September issue of Which? Magazine on page 62. If you’re not a Which? member you can read more about it on this Which.co.uk news story: http://www.which.co.uk/news/2011/08/how-british-gas-fared-in-which-boiler-service-test-260758/

Adam says:
19 August 2011

I’m a member – where do I find the September issue. I must say I do find the website extremely frustrating to navigate! Surely if I’m logged in there should be a link on the article!

Hello Adam, you can find a PDF of the magazine article here: http://www.which.co.uk/documents/pdf/p62-64_boilerservicing-263578.pdf

Or if you’re subscribed to the mag it should be on your door-step soon. Thanks, Patrick

Adam says:
19 August 2011

That’s a review on boiler reliability …. where’s the article on the servicing?

Sorry Adam, I pasted in the wrong link – I have replaced it with the correct one now 🙂

Adam says:
19 August 2011

Thanks, it works!

Any chance of making this available online so members (who pay for access) can actually find it? It so frustrating to read the teasers but never find the real content

Renegade Master says:
19 August 2011

I think you get good and bad in everything.
When I moved house – the boiler packed in. I got a local guy in who looked at it saying the whole system was needing to be replaced. I said I’d think it over. The system packed in over the weekend (the next day coincidentally) and the chap refused to come out to repair it saying I was looking at his quote for an overhall of my entire system. I called British Gas, enrolled on their service plan. They came out very quickly and simply changed a circuit board saying the system was otherwise fine. That was over 4 years ago.
My boiler has been no trouble at all. In fact it burns so efficiently and cleanly they have had to repeat the tests ! At the last service they warned me my boiler parts are going to become hard to come by and I should consider getting a new one over the next 2-3 years. My personal experience of British Gas Boiler Service has been very good.

M Gourlay says:
19 August 2011

We are gratefull in having kept up our Boiler service and repair cover with Ideal Boilers (Homeserve).
Our boiler is now 11years old. We had boiler and heating system installed when we moved to this house. Our first boiler lasted 1 year, fault in heat exchanger and funny noise. Next boiler stopped working suddenly and required a lot of expense covered by policy. We do not trust the boiler enough to stop the cover which includes a yearly service. When this boiler gets too old we shall definately not choose the same make.

gas brains says:
15 November 2014

that’s right,think of your boiler as a bloke called fagin,

johnnyl says:
19 August 2011

Can anyone explain why I pay an additional charge for my gas listed as Gas Trasportation Charge?

gas brains says:
15 November 2014


Eddie R. says:
19 August 2011

Recently I had hot water running tepid and as my boiler was under service contract with Scottish Power, called them out. After four visits by different engineers and three weeks of coming and goings with many expensive ‘parts’ being fitted, the problem persisted.
I complained to the top brass, so they sent out their top man who diagnosed the problem in five minutes. My boiler was actually working perfectly and the fault was my bathroom shower mixer valve was faulty, by letting cold water pass through the mixer valve into my hot water system and cooling the water temperature.
This took THREE WEEKS to diagnose and the FOURTH engineer gave the correct diagnosis. It doesn’t instil confidence in service contracts if that is the level of competence.

gas brains says:
15 November 2014

perhaps the other three were going to morrisons,jesus.

K Fitchew says:
21 August 2011

I had my oil boiler serviced. The company had serviced it previously. After a few days it was clear that the hot water temperature had dropped and was now onlt hand hot. I asked them to check. A senior person came and after lookinng over the installation recommended repairs estimated at hundreds of pounds. Apparently the boiler was ok but the heat was not being transferred to the tank. He implied the piping was badly furred or blocked. He did n’t explain why it had worked perfectly before the service. Logic tells me that if the water is not hot enough, the tank thermostat would turn on the boiler to make it hotter. But the boiler is rarely on for longer than a few minutes. The central heating works as well as before. Any clues. I have an emmersion heater, so I can top up if necessary. The figures he was quoting would buy an awful lot of electricity!

PaulG says:
21 August 2011

We have owned a Rayburn Nouvelle gas boiler /cooker for around 20 years. For much of this time it worked really well, providing heating for the house and excellent cooking facilities. Then one day the cooker pilot light went out. The thermocouple was replaced but to no avail. Every time the cooker pilot light is lit it is okay for a while but when the boiler fires up, the cooker pilot light goes out.

We have now had two Rayburn approved heating engineers to examine it and one other. One told us to renew the gas supply from the meter in 22mm (it was 15mm) to increase the flow, which we did but this made no difference. All three heating engineers gave up and did not return, still charging us what added up to be a considerable sum.

What are we supposed to do, employ yet another Rayburn approved engineer and splash out more wasted money? When we enquired, Rayburn wouldn’t send one of their own engineers but merely emailed their list of approved engineers. Basically they were no use whatsoever.

Any ideas anyone?

I think PaulG is right and the problem is probably not inside the Rayburn, which is why the gas engineers could not find a fault. Observing the pilot lights should give a clue about what is happening. Operation of the cooker and boiler should not affect the size of the pilot light flames.

Sorry. I mean Eddie R rather than PaulG

Eddie R. says:
21 August 2011

To Paul G.
You need to have the gas pressure checked at the cooker and have the boiler come on at the same time to see if the cooker pressure drops. In my case, the gas pressure was too low to feed both boiler and cooker simultaneously .
It could simply be dirt or water in the pipes as water was removed from my gas supply at pavement level and they then fitted 22mm to replace 15mm pipe.
Any competent engineer should be able to check the pressures and shame on the engineers who walked away.
When my boiler was checked at a routine service, it was then immediately shut down for H&S reason when the engineer found low pressure and the gas emergency service stepped in and removed the water and replaced the pipe size, so don’t delay where gas pressure is suspect.

Dave D says:
15 July 2012

This is very interesting and reminds me of when I had to have a new cooker back in the days of British Gas – as in The Gas Board. My old cooker developed a very minor gas leak around the oven thermostat (“Regulo”) but British Gas refused to repair it and instead disconnected the cooker and fixed a condemned notice on it. Being a week before Christmas I felt I had no option but to buy a new cooker. I bought this from a British Gas showroom (well, in those days, if you bought a gas appliance you naturally went to the Gas showroom didn’t you!) and they came and fitted it on Dec 23rd. Right form day one the cooker did not work properly and in particular the oven used to go out completely every time the boiler came on.

Now, at that time my boiler was less than 10 years old and on the British Gas three star service plan as it had been from new. It had also been fitted by the Gas Board.

I had the Gas Board back dozens of times over the next 18 months and every engineer tried to tell me that it was a different problem. Most engineers tried to tell me that the boiler was faulty, but as soon as I pulled out my Three Star service plan paperwork and showed it to them they hastily changed their minds and said it was something else.

By the time I scrapped it at age 18 months the cooker must have been like the proverbial Irish Man’s pick axe, but many times over: “It’s the same one I’ve had all my life but it’s had lots of new heads and lots of new handles”. There can’t have been a single part in that cooker that was in it when it was fitted. And still it never ever worked properly.

I tried an electric cooker for a while but I really prefer gas so about 8 years after the original gas cooker had been condemned I bought a new gas one (which I still have now) from, of all places, a Great Universal Catalogue. I had it fitted by my trusty plumber, who I had only just discovered at that time, and as soon as he arrived he said “You’ll need a new pipe from the meter for that to work”. He hadn’t even opened his tool box at this stage. I asked why he said that and he pointed to the old lead gas pipe, which ran from the meter to the cooker point, where, about 6 inches below the cooker connection, the copper pipe, installed by British Gas when they fitted the boiler, was joined into it and said “Those old lead pipes might look fat on the outside, but the hole down the middle of that is less than 10mm. It’s a wonder it’s supplying your boiler with enough gas to work, but it won’t supply a cooker as well.”

I told him about the 18 moths fiasco with the cooker and he said something in broad Anglo-Saxon to the effect that it was typical Gas Board shoddy work which they knew they could get away with because unlike anyone else they never have to have their work tested. I did ask how come the ancient cooker which had been there long before the boiler had worked OK and he said most of the very old cookers were far less sensitive to changes in pressure than new ones so it was either that or sheer good luck.

So, plumber fitted nice new copper pipe from meter to cooker, reconnected boiler and hey presto! I’ve had a trouble-free cooker and boiler for over two decades now, with never a hitch.

And the moral? I will never, ever, use British Gas for anything ever again. They can’t be trusted.

gas brains says:
15 November 2014

oh,i disagree,my mate fagin and dodger work for them, seen my wallet?my world don’t look so good.

SaraJayne says:
22 August 2011

We had to move house because of incompetent boiler repairmen. We rent, and the heat exchange rusted through, causing the overflow pipe to spit out water constantly. Thankfully this didn’t cause the boiler to stop working, but it did cause excessive damage to the outside wall, particularly the downstairs neighbor’s, who had to have his wall replaced once it was done — they took so long doing the proper repair. The conman (not really repairman) replaced everything he thought he could get away with charging the landlord, spanning months of visits, instead of simply replacing the £250 heat exchange. He didn’t do it right, I think he needed to flush the rust out of the system or something, so a year later it had rusted through again, and needed replacing again. Once again, he stretched it out, bilking the landlord for thousands and annoying us and our neighbor beyond words. Once again, our neighbor had to replace his back wall, it’d gone on so long. Once again, he didn’t do it right, and it did the same thing again, a year after that. Yep, three times in three years. This time, he talked the landlord into replacing the boiler altogether. The landlord finally told the letting agency to send someone else (they wouldn’t pay any attention to our demand to not send that conman back), who was more polite but either incompetent or another conman. Once the new boiler was in, which again took several months (four, I think it was this time), the landlord announced to us that he’d be selling the flat, so he wouldn’t have to deal with this again. My husband had been a tenant for five years, and the only thing either of us ever wanted them to do was make the boiler work properly; now the place has sat vacant, up for sale, for over six months. All because the boiler repairmen turned out to be conmen, along with the letting agency.

Happily for us, we’ve found a much nicer place, still in the location we really love, with private landlords and no letting agency to get in the way and screw us out of our place to live, and with the option to buy when we’re ready. So really it’s worked out for the best, at least for us, and in the end I’m happy about it. Just a shame we had to go through a year’s worth of heartache to get a stinking boiler fixed. There really should be better oversight of these repairers, to make sure they’re not just out conning one consumer after another.

gas brains says:
15 November 2014

don’t,dont,call them incompetent,they will get big heads.

Christine Bell says:
22 August 2011

Which are better,gas or electric boilers? If we went over to an electric boiler would we have to change our radiators? Also do electric boilers need annual servicing?

According to our recent boiler survey, electricity is the fuel of choice of 17% of Which? Connect members for their heating and 27% for their hot water. It is most common to need an electric powered boiler in rural areas where oil or gas access may not be available, but also some new housing projects or flats are being fitted with electric boilers by choice.

Several brands in the UK offer a range of types and makes of electric boilers, with a range of heat outputs from 4kW up to 14.4kW. This range of heat outputs is quite small – a big electric fan heater can usually produce 3 kW, so these boilers are probably best suited to small, well-insulated flats and homes with a low heat demand.

Manufacturers claim that an electric boiler can replace any other small to medium size boiler in the home, and are known to be light, small and compact, often completely silent and boasting the main benefit of a low running cost due to the price of electricity in comparison to oil or gas.
Another benefit is that with no flue to lose heat through, electric flow boilers are highly efficient – 99.8% efficiency is claimed by several manufacturers for their boilers.

They can be used with conventional ‘wet’ heating systems using radiators and also with hot water cylinders to provide the hot water. You’d need to talk to the installer about whether your current radiators could still be used.

Yes, they do need to be serviced regularly.

These manufacturers offer electric boilers:
Heatrae Sadia – The ElectroMax Electric Combi Boiler; a compact boiler, designed to fit easily into a standard domestic airing cupboard. The Heatrae Sadia Amptec Electric Heating Boiler; a boiler with several available sizes depending on need, more suited for mobile homes or family houses.

Electric Heating Company – Fusion Electric System Boiler; these run in a range from 6kW to 14.4kW, requiring no flue, suitable for underfloor heating and suitable for central heating only, or central heating with hot water using a hot water cylinder. Fusion Electric E10 Combination Boilers; larger units, running from a 9kW/150 litre electric combination unit right up to a 14.4kW/170 litre electric combination unit for the more demanding household.

Thermaflow Electric Combi Boilers – Thermaflow 9kW Electric Combi Boilers; with 210, 250 and 330 litres, these are large and heavy in stainless steel. The components of the boiler come with a 2 year guarantee, with the main stainless steel cylinder protected by a 25 year guarantee.
Thermaflow Electric Combi Boilers – Thermaflow 12kW Electric Combi Boilers; also with 210, 250 and 330 litres, these are similar in size to the 9kW boilers by Thermaflow, and are also protected by a 2 year component part guarantee and a 25 year guarantee on the stainless steel cylinder of the boiler.

Dimplex Electric Boilers – Dimplex Ascari Modulating Electric Heating Boiler; a low maintenance boiler requiring no annual check, compatible with both standard radiators and underfloor heating, with 4-12kW maximum power. Small and stylish, this is ideal for the kitchen and will fit well beside most kitchen cabinets.
Trianco Electric Boilers – Trianco Aztec Classic Electric Boilers: a wall mounted practical central heating system that is well-suited to nearly all applications. The Aztec electric boiler range is available in five outputs, which range from 2kW to 12kW, as well as the option to link the boilers in combination to create even larger outputs. Trianco Aztec Gold Electric Boilers; a small electric boiler, designed for heating smaller areas, such as caravans, conservatories and loft-extensions.

bruce p says:
22 August 2011

I used a local ‘expert’ just to clean and service my domestic boiler. What a mistake, never worked properly after and he couldn’t be contacted despite many messages and calls with his wife.
So left with choice of new boiler or another harrowing experience.
Fortunately, new man was good. he replaced most internals at a cost of about £1000.
Better that than all new pipes and radiator valves according to regulations for a new boiler.
Next time it’ll be an electric boiler.

gas brains says:
15 November 2014

he wasn’t called jesse and robbed trains?

Christine D says:
22 August 2011

We have used same engineer for 20 years. Services 1976 Glo worm and does minor repairs if needed, pump, pilot light or leaks etc.
Neighbour talked into replacing their boiler and are now on their THIRD replacement.
Our gas bills are low, once the house is warm heating goes off and stays off.
Don’t be conned into buying a new Fuel EFFICENT system.

Dave D says:
15 July 2012

Couldn’t agree more: 1979 Glow Worm 52B Super and NO cavity wall insulation or double glazing in my semi. Neighbours in other half of semi pair have 2010 Combi fitted by British Gas, breaks down without fail every winter, three floods form leaking pipes on it, and in spring of 2011 (the long cold spell with lots of snow) their bill from Jan to Mar was more than £750 and mine for the same period was just under £300.

Energy Saving Trust calmly informed me when I asked about this “all combi boilers use more gas than traditional ones”

No brainer eh?

gas brains says:
15 November 2014

this is not allowed,you need to be robbed by new boiler,told a pack of lies about how marvellous it is,and have an engineer around youre house to fleece you on a weekly basis attempting to repair it,stop gloating.

Continuous problems with my boiler has been an ongoing problem in my house since 1999 when I had a Potterton Suprima boiler installed and so far there has been nothing ‘supreme’ about it!

Just a week after it was installed, it failed and kept on switching itself off. After three visits, the private heating company which installed the boiler managed to diagnose that there was a tiny fault on the circuit board, which they fixed straight away at no extra cost.

It worked fairly well for a couple of years and I made sure that I had it serviced annually and then after about four years things started to fail and since 2003, I have had the thermostat, fan, pump and circuit board + every valve under the sun changed and my annual servicing bill has been increasing from around £350 to approx £500 for all the parts and labour needed. The circuit board (£300 inc. labour) that I had replaced in July this year lasted just three weeks, but after a thorough inspection today, the engineer came to the conclusion that the whole system needed a proper chemical flush, which at least they did not charge for and I’m keeping my fingers crossed that I will have hot water when I get back home this evening.

gas brains says:
15 November 2014

since1999 eh,dont worry the world ends in 2012,hopefully,only way the boiler problems will be solved.