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Baxi 400 Combi LPG

The Baxi 400 Combi LPG is a competitively priced condensing gas boiler for small and medium-sized homes that are off the mains gas grid.

Part of Baxi’s 400 series, this LPG boiler uses liquefied petroleum gas to provide efficient heating and hot water. It comes in an output of 28kW and delivers an excellent hot water flow rate of 11.5 litres per minute, making it ideal for small to medium-sized properties that are not linked to the mains gas grid. If you like the idea of transforming the boiler into a smart appliance, you can do so by purchasing the optional uSense smart room thermostat.

How Much Does this Boiler Cost?

This LPG boiler has a typical price tag of £730 including VAT, but you may be able to pick it up for less if you shop around and compare prices from a range of trusted suppliers and installers. You need to remember that you’ll also need to pay installation fees, so be sure to get quotes on the fitting work as well. We recommend you get at least a few fixed price quotes on the boiler and installation to increase your chances of finding a competitive deal.

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

The Baxi 400 Combi LPG is a combination boiler that doesn’t need any tanks in the loft or a separate hot water cylinder in the airing cupboard. It’s also an LPG boiler, making it a sensible option if your property is not on the gas grid because it uses liquefied petroleum gas instead of natural gas as its fuel source. It can heat water instantly and directly from the mains as and when you need, but it won’t be the best choice if you have more than one bathroom or use a lot of hot water at the same time.

To find out if the Baxi 400 Combi LPG is perfect for your household, you must consult a qualified heating engineer. If you choose the wrong type or size of boiler, it won’t able to operate efficiently nor will it be capable of meeting your heating and hot water demands.

Is it a High Efficiency Boiler?

It doesn’t have the highest rating we’ve ever seen but the Baxi 400 Combi LPG is an A-rated boiler nonetheless. Its actual rating is 89%. This boiler can also be used with a range of optional controls that improve efficiency levels. It’s even compatible with the smart uSense thermostat that allows you to monitor your energy use and control everything from a smartphone or tablet to help lower your energy bills.

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

Baxi’s 400 Combi LPG comes with the usual standard controls, such as a reset button, mode selector and switches that allow you to adjust heating and hot water temperatures. The user controls can be found on the front of the boiler, as can an LCD display that lets you see the boiler status, temperatures and any faults that may arise. Optional timers and room thermostats can be purchased to increase comfort and performance levels. This boiler also comes with an integral frost thermostat, a range of flue lengths and a special hanging bracket.

How long is the Warranty on this Boiler?

The Baxi 400 Combi LPG is covered by a 5-year parts and labour warranty as standard, as long as the boiler is serviced annually.

Baxi 400 Combi Price and Size

ModelTypeDimensionsMaximum Flow RateOutputEfficiency RatingTypical Price
400 Combi LPG 28CombiH – 700 mm
W – 395 mm
D – 279 mm
11.5 l/min28 kWA 90% and above£730

Summary of Important Information

  • Average price of £730
  • Heating output of 28kW
  • Hot water flow rate of 11.5 litres per minute
  • Dimensions of 700mm (H) x 395mm (W) x 279mm (D)
  • Uses LPG (liquefied petroleum gas) as its fuel source
  • A-rated for efficiency
  • Smart compatible
  • 5-year warranty as standard

Pros and Cons

We believe the Baxi 400 Combi LPG is an affordable energy efficient option for off-gas grid homes that are on a tight budget. Below, you can find a list of the pros and cons to help you reach an informed decision about this boiler.


  • Fits in a 290mm deep kitchen cupboard
  • Suited to flats and small to medium-sized houses
  • No need for separate cylinder or loft tanks
  • Easy to use and service
  • NOx Class 5 boiler – kinder to the environment
  • Provides maximum energy efficiency – reduce fuel bills and carbon emissions
  • Compatible with uSense smart room thermostat – can monitor your energy use and control your heating using a smartphone or tablet, wherever you happen to be
  • 5-year parts and labour warranty


  • Baxi boilers have and overall Which? score of 54%
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