New boilers UK.
Fitted costs and honest advice for 2026.
What a new boiler actually costs fitted, how combi, system and regular boilers differ, how long installation takes, when replacing beats repairing, and how to avoid overpaying for the same boiler someone else gets cheaper.
A like-for-like combi boiler swap typically costs £2,000 to £3,500 fully fitted, with budget installs from around £1,800 and premium brands or bigger jobs running past £4,000. Converting from a regular or system boiler to a combi typically costs £3,000 to £4,500. A straightforward swap is usually done in a day. Modern condensing boilers run at over 90% efficiency, so replacing a very old boiler usually cuts gas use noticeably. This guide gives you the honest picture rather than a sales pitch.
Combi, system or regular: which boiler do you need?
Nearly every UK home has one of three setups, and the cheapest, simplest replacement is almost always like-for-like. Here is how they differ.
Combi boiler
Heats water on demand straight from the mains, so there is no hot water cylinder or loft tanks. Compact, efficient, and the right choice for most small to medium homes with one bathroom. Hot water is effectively unlimited but only one strong outlet at a time, which is the main trade-off for larger households.
System and regular boilers
Both store hot water in a cylinder, so several showers and taps can run hot at once. A system boiler needs no loft tanks; a regular (heat-only) boiler uses them and usually suits older heating systems. The right choice for larger homes with two or more bathrooms, or anywhere mains water pressure is weak.
Thinking of switching type? Converting from a regular or system boiler to a combi typically costs £3,000 to £4,500, because the cylinder and tanks come out and pipework gets rerouted, and it usually takes 1.5 to 3 days rather than a day. It frees up an airing cupboard and can simplify the system, but if your current setup serves the household fine, the conversion premium usually is not worth paying.
How much does a new boiler cost fitted?
Fitted price depends on the boiler type, the brand and size of unit, whether you are swapping like-for-like or changing system type, and labour in your area. Here are realistic fully-installed ranges.
| Job | Fitted cost | Time | Notes |
|---|---|---|---|
| Combi swap (like-for-like) | £2,000 to £3,500 | 4 to 6 hours | Budget installs from around £1,800 |
| System or regular swap | Around £3,000 | 1 day | Cylinder usually stays |
| Conversion to combi | £3,000 to £4,500 | 1.5 to 3 days | Cylinder and tanks removed |
| Back boiler replacement | £3,500 to £4,500 | 2 to 3 days | Usually converted to a combi |
| Oil boiler | £3,300 to £4,000 | 1 to 2 days | For homes off mains gas |
Brand moves the price too. Vaillant is the usual mid-range pick, Worcester Bosch usually sits at the premium end, and Ideal and Baxi usually come in cheaper for a similar specification. The same boiler can be quoted hundreds of pounds apart by different installers, so always compare at least two quotes. If you want a price in minutes without a sales visit, you can get a fixed online boiler quote from Heatable by answering a few questions about your home.
Should you replace your boiler or keep repairing it?
Replace when the boiler is past 10 to 15 years old and repairs are becoming frequent or expensive, when a single repair quote approaches a third of a new boiler's cost, when parts are getting hard to source, or when a very old non-condensing boiler is running at 70% efficiency or worse against the 90%+ of a modern unit. On an old inefficient boiler, the gas savings from a new one usually take a meaningful bite out of the fitted cost over its first years.
If your boiler is under ten years old, reliable, and already a condensing model, replacing it rarely pays for itself. The efficiency gap between a 2018 boiler and a 2026 boiler is small. Spend the money on insulation, heating controls or a smart thermostat instead, and if your long-term plan is to leave gas entirely, it is worth reading up on heat pumps before committing to another 15 years of boiler.
Weighing up boiler vs heat pump? The £7,500 Boiler Upgrade Scheme grant applies to heat pumps, not gas boilers, which changes the maths for some homes. Our heat pump guide covers costs, the grant and when each one wins.
Get a fixed boiler quote online
Answer a few questions about your home with our partner Heatable and see fixed prices for a new boiler in minutes, with pay-monthly options usually available.
Get a fixed quoteSigns your boiler is on the way out
Worth acting on soon
- Repairs more than once a year, or a repair quote near a third of a new boiler's price
- Radiators heating slowly or unevenly despite bleeding and balancing
- Gas use creeping up year on year with no change in habits
- Regular pressure drops, leaks, or error codes that keep coming back
Get an engineer out the same day
- A yellow or orange pilot flame instead of crisp blue
- Soot marks or staining around the boiler casing
- Any smell of gas, or a carbon monoxide alarm sounding: these are emergencies, not replacement planning
Finance, warranties and installation day
Pay monthly options
Most national installers offer boiler finance that spreads the cost over several years, sometimes with no deposit, subject to credit checks. Compare the total repayable, not just the monthly figure.
Warranties up to 10+ years
Mainstream brands usually carry 5 to 12 year warranties when fitted by an accredited installer and serviced annually. A long warranty on a mid-range boiler usually beats a short one on a premium brand.
Installation day
A like-for-like swap takes 4 to 6 hours: old boiler off, new one on, system flushed, controls paired, and a Gas Safe engineer signs it off. Heating and hot water are usually back the same evening.
Gas Safe is non-negotiable
Anyone fitting a gas boiler must be Gas Safe registered. Check the register or ask for the engineer's ID card number. An unregistered install is illegal and voids the warranty.
Questions people ask about new boilers
A like-for-like combi swap typically costs £2,000 to £3,500 fully fitted, with budget installs from around £1,800 and premium brands past £4,000. A conversion from a regular or system boiler to a combi typically costs £3,000 to £4,500. Comparing at least two quotes usually saves hundreds on the identical boiler.
A like-for-like swap usually takes 4 to 6 hours, done in a day. Conversions to a combi usually take 1.5 to 3 days because the cylinder and tanks are removed and pipework rerouted. Back boiler replacements usually take 2 to 3 days.
Typically 10 to 15 years with an annual service. Past that, repairs usually get more frequent, parts harder to find, and efficiency falls well behind modern condensing models. Keep service records: they support warranty claims and help at resale.
A combi suits most homes with one bathroom: compact, no cylinder, hot water on demand. A system boiler with a cylinder suits homes with two or more bathrooms where several outlets run hot at once. Like-for-like replacement is usually cheapest; change type only if your current setup genuinely does not serve the household.
Usually only if it is old or inefficient. A pre-2005 non-condensing boiler can run below 70% efficiency against 90%+ for a modern unit, and replacing it usually cuts gas bills noticeably. A reliable condensing boiler under ten years old is rarely worth replacing early.
Usually yes. Most national installers offer pay-monthly plans over several years, sometimes zero-deposit, subject to credit checks. Interest rates vary a lot between providers, so compare the total amount repayable across quotes rather than the headline monthly price.
Related guides
Get a fixed boiler quote
Online quotes through our partner Heatable. Fixed prices in minutes, with pay-monthly options usually available.
Get my fixed quote