By Boiler Quotes Editorial Team · Updated 20 July 2026
How Much Does It Cost to Replace a Combi Boiler?
A like-for-like combi replacement is the most common and the most affordable boiler job in the UK. The new boiler goes where the old one was, the existing gas, water and flue connections are reused where they meet current standards, and the work is usually finished in a day.
For that scenario, expect £1,800 to £2,600 supplied and fitted. The figure climbs as soon as the job stops being a straight swap.
| Scenario | Typical cost | Time on site |
|---|---|---|
| Same make and position, existing pipework fine | £1,800 - £2,300 | Around 1 day |
| Different make or size, minor pipework changes | £2,100 - £2,600 | 1 to 1.5 days |
| Moved to a different wall or room | £2,400 - £3,400 | 1.5 to 2 days |
| Replacement plus radiator or pipework upgrades | £2,800 - £4,000 | 2 to 3 days |
Why Combi Replacements Are Cheaper Than Conversions
If you already have a combi, the hard work was done the first time. There is no hot water cylinder to remove, no cold water tank in the loft to drain and take out, and the pipework already runs to the right places. The engineer is swapping one appliance for another rather than redesigning how your heating and hot water work.
That is why a household moving from a regular boiler to a combi typically pays £1,000 or more above a household simply replacing a combi that is already there.
What Should Be Included in the Price
A complete combi replacement quote should cover more than the appliance and a day's labour. Look for:
- The boiler and standard flue kit, with any extension needed for your wall.
- A system flush appropriate to the age and condition of your radiators.
- A magnetic system filter, which many manufacturers require for the full warranty.
- Controls meeting current regulations, which for a new gas combi in England means time and temperature control plus one additional efficiency measure such as smart controls or weather compensation.
- Removal and disposal of the old appliance.
- Commissioning, the Benchmark checklist completed, Building Control notification and warranty registration.
If a quote looks unusually cheap, it is normally one of these items that has been left out rather than the labour being genuinely keener.
Does the Brand Change the Price Much?
Yes, but perhaps less than you would expect once the whole job is priced. The appliance is typically between a third and a half of the total, so a £300 difference in the boiler price becomes a smaller proportion of the fitted figure. What that £300 often buys is a longer warranty and better hot water flow, both of which matter more over ten years than the initial saving.
The more useful comparison is not brand against brand but the same specification quoted by different installers. Ask each installer to quote for a comparable output and warranty, and the differences in their labour and materials become obvious.
Should You Replace or Repair?
A single repair on a boiler under about eight years old, with parts still available and a decent service history, is usually worth doing. Repeated repairs on an older appliance rarely are. As a rough test, if the repair costs more than a third of the price of a replacement and the boiler is over ten years old, replacement generally makes better financial sense.
Efficiency is part of that calculation too. An older combi running at 80 percent efficiency wastes noticeably more gas than a current model at 92 percent or above, and that gap shows up on every bill for the rest of the boiler's life.
How to Get the Best Price
- Get at least three quotes for the same specification so you are comparing like with like.
- Book outside peak season if you can. Installers are busiest the moment the weather turns cold.
- Be flexible on brand where the warranty and output are equivalent, as installers often get better trade pricing on particular makes.
- Ask what the price would be without extras you may not need, and what it would be with a longer warranty, so you can see the trade-off.
- Check the warranty conditions before choosing on price alone, since an annual service requirement is a real ongoing cost.
Want to know what replacing your combi will cost? Compare free, no-obligation quotes from up to 3 Gas Safe registered installers using the form below.
