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Baxi is one of the most familiar boiler brands in the UK. With BoxHeat, a Baxi combi costs from £2,290 fully fitted. The main decision isn't the brand but the range: the 400, 600 or 800.
This guide explains how the three ranges differ, whether you need a combi, system or regular boiler, which size to choose, and what each option costs fitted. To browse every model, see our Baxi boilers page.
Is Baxi a good boiler brand?
The short answer: yes. Baxi has its roots in Lancashire, where Richard Baxendale started the business in 1866, and it still makes boilers at its production site in Preston. It's now part of the European BDR Thermea group.
- Clear ranges: the 400, 600 and 800 make it easy to choose between budget, mid-range and premium.
- Lots of sizes: combi, system and regular boilers, with combis up to 36kW.
- Up to 10 years' warranty on the 800 range.
The Baxi range at a glance: 400 vs 600 vs 800
All three ranges are A-rated condensing gas boilers. The higher the number, the more premium the boiler and the longer the warranty.
- Baxi 400: the budget option for a straightforward swap, available as a combi or regular boiler, with a 5-year warranty. View the Baxi 400
- Baxi 600: the mid-range choice, with combi, system and regular versions and a 7-year warranty. View the Baxi 600
- Baxi 800: the premium range, with a 10-year warranty. The combi has a stainless steel heat exchanger and fits a kitchen cupboard just 290mm deep. View the Baxi 800
Baxi's 10-year warranty on the 800 depends on a magnetic system filter being fitted and registered with the boiler. Every installation we do includes a magnetic filter.
Combi, system or regular: which Baxi do you need?
The type of boiler matters more than the range, and it's mostly decided by what you already have at home.
- Combi: no hot water cylinder or loft tank. Best when hot water is mostly used in one place at a time. Baxi 400, 600 and 800, from £2,290.
- System: a hot water cylinder but no loft tank. Best when several showers or taps are often used together. Baxi 600 and 800, from £2,550.
- Regular: a cylinder plus a cold water tank in the loft. Common in older homes. Baxi 400, 600 and 800, from £2,230.
Not sure which you have? Our guide to boiler types shows you how to tell.
What size Baxi combi do you need?
Tip: bigger isn't better. An oversized boiler costs more and can switch on and off more often, which wastes gas. Our guide to what size boiler you need explains more, and we confirm the right size when we quote.
Baxi boiler prices, fully fitted
These are our fixed prices for a like-for-like replacement, correct in October 2026. Your exact price depends on your home and is confirmed in your online quote, with no surprise extras on the day.
| Model | Type | Output | Fitted price |
|---|---|---|---|
| Baxi 400 | Combi | 24kW / 30kW | £2,290 / £2,335 |
| Baxi 600 | Combi | 24kW / 30kW / 36kW | £2,500 / £2,695 / £2,780 |
| Baxi 800 | Combi | 24kW / 30kW / 36kW | £2,600 / £2,780 / £2,870 |
| Baxi 600 | System | 15kW / 18kW / 24kW | £2,550 / £2,630 / £2,720 |
| Baxi 800 | System | 18kW / 24kW | £2,780 / £2,900 |
| Baxi 400 | Regular | 15kW / 18kW / 24kW | £2,230 / £2,280 / £2,340 |
| Baxi 600 | Regular | 16kW / 25kW / 30kW | £2,550 / £2,680 / £2,750 |
| Baxi 800 | Regular | 30kW | £2,820 |
Prices include the boiler, a magnetic system filter, removal of your old boiler, a system flush, controls set-up and installation by a Gas Safe registered engineer. If your home needs extra work, such as moving the boiler or converting to a combi, it's included in your fixed quote. You can also spread the cost with boiler finance.
Baxi boiler questions
Find the right Baxi boiler for your home
Get my fixed priceReviewed by our technical team. All BoxHeat articles are written by experienced heating professionals and reviewed by our team of Gas Safe registered engineers to ensure accuracy, safety, and compliance with current UK building regulations and manufacturer guidelines.
