New boiler cost in the UK

What affects the cost of a new boiler?

Boiler replacement isn’t just the appliance. A quote typically covers the survey, removal of the old unit, installation, commissioning, safety checks, and any required controls or pipework adjustments. The biggest factors that influence total cost include:

• Boiler type (combi, system or conventional)
• Output size and hot water demand (number of bathrooms, simultaneous showers, etc.)
• Installation complexity (like-for-like swap vs conversion)
• Flue and condensate routing (distance, access, drilling, external runs, pumps if needed)
• Boiler location (straight swap vs moving the boiler)
• Upgrades to meet current standards (controls, system cleaning, safety components)
• Access and building work (cupboard modifications, boxing-in, making good)
• Parking, permits and disposal (varies by local area)

Boiler types explained (and how they influence cost)

Combi boilers

A combination boiler provides heating and hot water directly from the boiler. Because it usually doesn’t need a separate hot water cylinder, installation can be simpler in many homes. That said, combi suitability depends on your hot water demand and water pressure.

System boilers

A system boiler works with a hot water cylinder. This can be a good fit where multiple taps/showers may run at the same time, but you’ll need space for a cylinder. Costs can be higher where cylinder or pipework changes are required.

Conventional (regular) boilers

Also known as regular boilers, these typically work with a cylinder and a cold water tank. Replacing like-for-like can be straightforward, but conversions to a different boiler type can add complexity.

Like-for-like replacement vs conversion

One of the biggest price drivers is whether you’re doing a like-for-like replacement or changing the system layout:

• Like-for-like swap: replacing the same type of boiler in the same location is often the simplest route.
• Conversion: changing from regular to combi (or vice versa), adding/removing cylinders or tanks, or altering the pipework can increase labour and materials.
• Relocation: moving a boiler (e.g., kitchen to loft) can involve new flue routes, condensate changes, and additional pipework.

What should a boiler quote include?

When comparing quotes, you want clarity on exactly what you’re paying for. Ask for a written breakdown covering:

• Boiler supply (make/model may be specified by the installer)
• Labour and installation work (including removal of old boiler)
• Flue components and any extensions if required
• Controls (thermostat, programmer, TRVs where applicable)
• System cleaning approach (e.g., flush/clean and inhibitor dosing)
• Condensate routing and any necessary pumps
• Making good (what is and isn’t included: plastering, tiling, painting)
• Waste disposal (old boiler and packaging)
• Commissioning and certificates (e.g., safety and compliance paperwork)
• Warranty details and who you contact if there’s an issue

Common extras that can change the final cost

Some homes need additional work beyond a straightforward swap. These items may appear as extras, or be included depending on your installer’s scope:

How to reduce new boiler cost without cutting corners

• Get 2–3 like-for-like quotes with the same scope so you can compare fairly.
• Be clear on your hot water needs (bathrooms, showers, peak usage) to avoid overspec or underspec.
• Choose a sensible boiler location where possible to reduce flue/condensate complexity.
• Ask what “making good” includes so you’re not surprised by finishing costs later.
• Consider timing: availability can affect labour scheduling, especially in peak winter periods.

Questions to ask an installer before you book

1. Is this a like-for-like swap or will you be changing the system layout?
2. What’s included in the quoted price and what would be extra?
3. Will you inspect the flue route and condensate run before confirming the quote?
4. What controls are included, and will existing thermostats be reused?
5. How will you clean/protect the system (and is inhibitor included)?
6. What paperwork will I receive after installation?
7. What is the warranty length and who administers it?
8. How long will the job take, and will my heating/hot water be off?

New boiler cost FAQs