A new boiler is one of the most significant home improvement purchases you will make. The price varies widely depending on the type of boiler, the size of your home, and the complexity of the installation.
The typical all-in installed cost for a gas combi boiler in 2026 is between £1,800 and £4,500. The average UK homeowner pays around £2,800 for a like-for-like replacement in a three-bedroom semi-detached house (Energy Saving Trust, 2026).
A new boiler in 2026 typically costs between £1,800 and £4,500 fully installed, depending on the type and size of your home
This price range covers the most common replacement scenario: swapping an old gas combi boiler for a new A-rated condensing combi boiler. The installed price includes the boiler unit, all necessary pipework, flue components, labour, and any minor adjustments to existing connections.
The cost varies because of three main factors. First, the boiler’s kW output must match your home’s heat demand. A small flat might need a 24kW boiler, while a large detached house could require a 40kW unit. Second, installation complexity matters. Moving the boiler to a new location, upgrading the gas supply pipe, or fitting a new flue adds labour and materials. Third, brand choice affects the price. Premium brands such as Worcester Bosch, Vaillant, and Viessmann typically cost 10–20% more than budget brands like Ideal or Baxi (MCS register installer survey data, 2026).
A system boiler costs £2,200–£4,800 installed, while a regular boiler costs £2,500–£5,500 installed
A system boiler works with a separate hot water cylinder but does not need a cold water tank in the loft. This makes it a good choice for homes with multiple bathrooms where several people may use hot water at once. The installed cost for a system boiler ranges from £2,200 to £4,800.
A regular boiler, also called a conventional or heat-only boiler, requires both a hot water cylinder and a cold water tank. It is the most expensive type because it involves more components and pipework. The installed cost for a regular boiler ranges from £2,500 to £5,500 (Energy Saving Trust boiler cost guide, 2026). Both system and regular boilers are typically more expensive than combis due to the additional equipment and longer installation time.
Quick numbers average boiler prices and installation costs in 2026
| Boiler type | Typical kW range | Unit price (excl. installation) | Installed price (incl. labour and parts) | Typical installation time |
|---|---|---|---|---|
| Combi (gas) | 24–40 kW | £800–£1,500 | £1,800–£4,500 | 1–2 days |
| System (gas) | 12–18 kW | £1,000–£1,800 | £2,200–£4,800 | 1–2 days |
| Regular (gas) | 18–24 kW | £1,200–£2,000 | £2,500–£5,500 | 2–3 days |
These prices are for gas boilers only. Oil and LPG boilers are separate categories with different costs (Energy Saving Trust, 2026).
The cost of a new boiler is driven by kW output, boiler type, and installation complexity
The kW output of the boiler is the primary factor determining the price. A 24kW combi for a small flat costs less than a 40kW combi for a large house. Your installer will calculate the correct size based on the number of radiators and the heat loss of your home.
Installation complexity adds significant cost. Moving the boiler location, upgrading the gas pipe, or fitting a new flue can add £300–£800 to the total. Replacing a system boiler with a combi boiler is a common upgrade that requires additional work to remove the cylinder and tank, which adds £300–£800 (MCS register installer survey data, 2026).
Brand premium is another factor. Worcester Bosch, Vaillant, and Viessmann typically cost 10–20% more than budget brands like Ideal or Baxi. The higher price often comes with longer warranties and better customer service records.
A new boiler can save you £200–£400 a year on your heating bill compared to an old G-rated model
An A-rated condensing boiler is 90% or more efficient, meaning it converts at least 90% of the gas it uses into useful heat. An old G-rated non-condensing boiler is typically only 60–70% efficient. The difference in efficiency translates directly into lower energy bills.
Energy Saving Trust data shows that upgrading from a G-rated boiler to an A-rated model can save a typical household between £200 and £400 per year (Energy Saving Trust boiler savings calculator, 2026). The actual savings depend on your current boiler’s efficiency, the size of your home, and how much you use your heating.
You may be eligible for a grant or loan to help with the cost, but the Boiler Upgrade Scheme only covers heat pumps, not boilers
The Boiler Upgrade Scheme (BUS) does not cover gas, oil, or LPG boilers. It provides grants for heat pumps and biomass boilers only. This scheme is built to support the transition away from fossil fuel heating.
For low-income households, the ECO4 scheme may cover a boiler replacement if your current boiler is broken or inefficient. This scheme is available to homeowners and private tenants receiving certain benefits. Home Energy Scotland also offers grants and loans for heating improvements (GOV.UK Boiler Upgrade Scheme, 2026; GOV.UK ECO4, 2026).
There is no universal UK government grant for a standard gas boiler replacement in 2026.
To get a new boiler installed, you must use an MCS-certified installer for any heat pump, but for gas boilers you need a Gas Safe registered engineer
For gas boiler installations, the legal requirement is a Gas Safe registered engineer. You can check an engineer’s ID card or verify their registration on the Gas Safe Register website. For heat pumps, the installer must be certified under the Microgeneration Certification Scheme (MCS). TrustMark is a general quality assurance scheme that covers both types of work.
FENSA is for windows and doors, not boilers. NICEIC and NAPIT are for electrical work. Always ask for proof of the correct certification before work begins. Get at least three quotes from different installers to compare prices and services (Gas Safe Register, 2026; MCS register, 2026). how to choose a heating engineer
The direct answer to “new boiler cost UK 2026” is £1,800–£4,500 fully installed for a gas combi, with the average homeowner paying around £2,800
This is the most common scenario: a like-for-like replacement of a gas combi boiler in a three-bedroom semi-detached house. The average cost of £2,800 reflects a mid-range boiler from a reputable brand installed by a Gas Safe registered engineer.
Prices vary by region. London and the South East tend to be higher, while the North and Scotland are often lower. Individual installer pricing also varies, which is why getting multiple quotes is essential (Which? boiler cost survey, 2026). best boiler brands for reliability
Frequently Asked Questions
A new boiler in 2026 costs between £1,800 and £5,500 fully installed. The average like-for-like gas combi replacement is £2,800, according to the Energy Saving Trust.
The cheapest type is a gas combi boiler, costing £1,800–£4,500 installed. System boilers start at £2,200 and regular boilers at £2,500, per MCS installer data.
Yes, boiler size affects cost. A 24kW unit for a flat costs less than a 40kW model for a large detached house, typically adding £200–£600 to the price.
Premium brands like Worcester Bosch and Vaillant cost 10–20% more than budget brands such as Ideal or Baxi. This is based on MCS register installer survey data.
The installed price includes the boiler unit, pipework, flue, labour, and minor adjustments to existing connections. Extra costs apply for moving the boiler or upgrading gas supply.
