The smarter way to replace your boiler

  • Get FREE Quotes today
  • Compare quotes & save money
  • Over 5,000 engineers across the UK
Tell us about your job
Get Free Quotes

Baxi 400 Heat

The Baxi 400 Heat is a budget condensing gas boiler that is compact, lightweight and suitable for homes of all sizes.

Available in outputs from 12kW to 30kW, the Baxi 400 Heat is a powerful little boiler that can meet most heating and hot water demands. It is designed to be incredibly quiet and can be installed virtually anywhere in your small, medium or large property. Furthermore, this heat only boiler with good green credentials is extremely lightweight and easy to install, service and maintain.

How Much Does this Boiler Cost?

It really depends on which kW output you require. The boiler comes in five outputs of 12kW, 15kW, 18kW, 24kW and 30kW, with prices ranging from around £690 to £840 including VAT. Baxi 400 Heat prices also vary between suppliers and installers, as does the cost of installation, so be sure to shop around and compare quotes before agreeing to any work. Also, don’t be afraid to ask boiler companies and engineers if they’d be willing to beat a like-for-like quote in order to save some cash.

How will I know if this Boiler is Suitable for My Home?

The Baxi 400 Heat is a heat only boiler (also known as a regular, traditional or conventional boiler) and will require a cold water tank in the loft. Not only that but this boiler needs a separate cylinder that stores your hot water, which is usually installed in an airing cupboard. Heat only boilers are great for properties with more than one bathroom because they can send a lot of hot water to multiple taps that are running at the same time.

Because this model comes in a range of kW outputs, we suggest you ask a Gas Safe registered engineer to help you work out which size is right for your home. Whilst assessing your property and needs, a qualified heating professional will be able to recommend the correct boiler type for your home as well.

Is it a High Efficiency Boiler?

This boiler has an efficiency rating of 89.2%, meaning it doesn’t have the highest rating of all modern condensing boilers out there. It’s still highly efficient, though. The Baxi 400 Heat is also Energy Saving Trust endorsed, so that should leave you feeling confident that this boiler will help to reduce your fuel bills and lower your carbon footprint. Although efficient without one, the boiler can be used with an optional Meglflo Eco Cylinder for the best possible energy efficiency.

Does this Boiler have a Good Range of Controls and Features?

The controls are good and can be found on the front of the boiler. It has a reset button that is linked to an operating mode selector, as well as a switch that enables you to adjust the central heating temperature and an LED display which shows the boiler status and fault diagnosis. Baxi’s 400 Heat also comes with a wall-mounting bracket and various flue lengths so that the boiler can be installed almost anywhere in the home. As the boiler doesn’t require a pump overrun or extra wires and has front and side access to all of the components, it’s easy to install, service and maintain.

How long is the Warranty on this Boiler?

If you purchase the A-rated Baxi 400 Heat, you’ll be given a 5-year parts and labour warranty as standard.

Baxi 400 Heat By Size and Price


ModelTypeDimensionsMaximum Flow RateOutputEfficiency RatingTypical Price
400 Heat 12Heat OnlyH – 625 mm
W – 370 mm
D – 270 mm
N/A12 kWA 90% and above£690
400 heat 15Heat OnlyH – 625 mm
W – 370 mm
D – 270 mm
N/A15 kWA 90% and above£710
400 Heat 18Heat OnlyH – 625 mm
W – 370 mm
D – 270 mm
N/A18 kWA 90% and above£750
400 Heat 24Heat OnlyH – 625 mm
W – 370 mm
D – 270 mm
N/A24 kWA 90% and above£800
400 Heat 30Heat OnlyH – 625 mm
W – 370 mm
D – 270 mm
N/A30 kWA 90% and above£840

Summary of Important Information

  • Priced between £690 to £840
  • Heating output of 12kW, 15kW, 18kW, 24kW or 30kW
  • Dimensions of 625mm (H) x 370mm (W) x 270mm (D)
  • Uses gas as its fuel source
  • A-rated for efficiency
  • Megaflo Eco Cylinder compatible
  • 5-year warranty as standard

Pros and Cons

As the Baxi 400 Heat is very light and easy to fit in a cupboard or on a wall, it is well-liked by heating engineers across the UK. The boiler does have drawbacks too, all of which can be discovered in our list of pros and cons below.


  • Fits in a kitchen cupboard
  • Suited to small, medium and large-sized houses
  • Easy to use and service
  • Comes with a choice of flue lengths – can be installed virtually anywhere
  • NOx Class 5 boiler – kinder to the environment
  • Provides maximum energy efficiency – reduce fuel bills and carbon emissions
  • Compatible with Megaflo Eco Cylinders – increases energy efficiency and improves comfort levels and hot water performance
  • 5-year warranty


  • Baxi boilers have and overall Which? score of 54%
  • Requires separate cylinder and loft tanks
  • User controls are basic
Get Baxi Boiler Quotes

Get quotes to supply a new Baxi boiler now