The short version
- Repair if the boiler is reasonably young, the part is common and it has been reliable so far.
- Consider replacing if it is well past 10 years old, the part is discontinued or this is one of several call-outs.
- If the boiler is still under warranty, call the manufacturer before anyone else.
- Ask for the repair price first, and compare it against a fixed quote for replacement.
The short answer
Repair it if the fault is a common, available part on a boiler that has otherwise been reliable. Replace it if the boiler is old, the part is discontinued or expensive, or it keeps breaking down. Most decisions come down to 5 things: age, parts, repair history, efficiency and warranty.
We give you the repair price first and let you decide. If we think the money would be better spent on a replacement, we say so and explain why. You don’t have to decide on the spot.
The 5 questions to ask
| Question | Points to repair | Points to replace |
|---|---|---|
| How old is it? | Reasonably young, and serviced | Well past 10 years old |
| Can the part be found? | Common part, readily available | Discontinued or hard to source |
| How often has it failed? | First fault in years | Several call-outs recently, or the same fault again |
| How efficient is it? | A modern condensing boiler | An older non-condensing boiler or back boiler |
| Is it under warranty? | Yes: call the manufacturer first | Warranty long gone, nothing to protect |
If most of your answers sit in the middle column, a repair is usually sensible. If most sit on the right, it’s worth getting a replacement price before paying for another repair.
Age and repair history
Age matters less than how the boiler has behaved. A boiler that has been serviced every year and rarely gone wrong can be worth repairing well into later life. One that has needed a pump, then a fan, then a diverter valve in the space of a couple of winters is telling you something.
Keep a note of call-outs, the dates and what was replaced. Service records help too, because they show whether the boiler has been looked after. If the engineer finds a fault in a major part such as the heat exchanger on an older boiler, that is often the point where replacement makes more sense, because other parts of the same age are likely to follow.
Get a fixed replacement price to compareTwo minutes, no obligation, a Gas Safe engineer replies.
Start my quoteParts availability
For current and recent models, most parts are easy to get. For older models, manufacturers gradually stop making them. Once a key part is discontinued, the boiler may not be repairable at all, or only with a used or reconditioned part that comes with little assurance.
If your boiler is old and an engineer warns that parts are getting scarce, that is a strong reason to plan a replacement on your own timescale rather than wait for a breakdown.
Ask, too, how long a part will take to arrive. A common part can often be fitted on the first or second visit. A part that has to be tracked down can leave you without heating or hot water for longer, which matters more in January than in June.
Efficiency and warranty
Older non-condensing boilers, including back boilers, lose more heat up the flue than a modern condensing boiler. A new boiler won’t pay for itself overnight, and we won’t promise you a saving, but efficiency is a fair factor when the old one is already costing you in repairs. A new boiler also comes with controls that meet the Boiler Plus rules, which help you heat the home only when you need it.
Warranty works the other way. If your boiler is still covered, call the manufacturer first: most warranties need their own engineers to carry out repairs, and a third-party repair can affect the cover. A new boiler comes with its own manufacturer’s warranty. Its length depends on the manufacturer, the model and how it’s registered, and most need registering soon after fitting and an annual service to stay valid.
When safety decides for you
Sometimes the choice isn’t yours to weigh up. If an engineer finds the boiler is unsafe and it can’t be put right with available parts, it will be turned off and labelled, and it mustn’t be used until it is repaired or replaced.
That is rare, and it is why an annual service matters. A service checks that the boiler is burning and venting safely, and it often picks up worn parts before they fail. If you’ve skipped a few years, a service is a sensible first step before deciding anything.
Questions to ask the engineer
When an engineer diagnoses the fault, a few questions help you weigh the repair against a replacement. A good engineer will be happy to answer them plainly.
- What exactly has failed, and why do you think it failed?
- Is the part in stock, and is it still being made for this model?
- Is anything else on the boiler showing wear that is likely to fail soon?
- Is the boiler safe to keep using while I decide?
- If this were your boiler, would you repair it?
Write the answers down alongside the repair price. If you then ask for a replacement quote, you’ll be comparing like with like rather than making the decision in a cold house at short notice.
Making the call
Get both numbers if you can: the price of the repair, and a fixed, written price for a replacement. Then think about how long you plan to stay in the home, whether the boiler suits how you live now, and how you’d feel about another breakdown this winter. If anyone at home is elderly, very young or unwell, reliability may matter more to you than the cost of the repair.
If you lean towards replacing, the quote form takes about 2 minutes, and photos of the boiler and flue help us price it without a visit. If you’d rather keep it going, an annual service is the simplest way to catch problems early.