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Baxi 800 System Boiler

Small and reliable, the Baxi 800 System is built using high-quality brass components and combines fantastic performance with high efficiency.

Ideal for homes with high hot water demand, the Baxi 800 System is a compact system boiler that fits inside a standard kitchen cupboard and requires a separate cylinder to provide hot water as and when you need it. In addition to being certified to work with 20% hydrogen, this boiler is available in two heat outputs to suit your requirements and comes with a generous manufacturer-backed warranty. 

How Much Does this Boiler Cost?

Baxi’s 800 System boiler comes in 18kW and 24kW outputs and will cost you between £900 and £950, not including installation. Boiler installation costs can vary massively and depend on the installer and how much work is involved. Getting a fixed-price quote from local and national installers should help you find the best price and avoid any hidden costs. Also, you must make sure your chosen installer is Gas Safe registered. 

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

System boilers can save space because they don’t need tanks in the loft, but they do require a separate hot water storage cylinder, which most people keep hidden away in an airing cupboard. They cope well when using multiple showers or taps simultaneously because the storage cylinder maintains the pressure. That means the Baxi 800 System is a good option for homes with more than one bathroom and high demand for hot water. 

It’s always best to consult a Gas Safe registered engineer for advice on the correct boiler type and size for your home. 

Is it a High Efficiency Boiler?

The Baxi 800 System is a condensing A-rated boiler and one of the most efficient boilers you can get installed. This system boiler is endorsed by the Energy Saving Trust, meaning it meets the highest energy efficiency standards. 

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

Yes. The Baxi 800 System is small enough to fit inside a 290mm deep kitchen cupboard and has built-in pipes within its casing to save space and time. It has top quality brass components and an industry-leading Adey Magnaclean Micro2 magnetic system filter that protects the boiler and heating system. This compact system boiler comes with a hanging bracket and front access to all components to save time when servicing. It also has an OpenTherm interface and is compatible with the market-leading Megaflo Eco cylinder and IFOS systems weather compensation. 

How long is the Warranty on this Boiler?

Baxi’s 800 System comes with an impressive 10-year parts and labour warranty as standard.

Summary of Important Information

  • Expect to pay between £900 and £950
  • Heating output of 18kW or 24kW
  • Dimensions of 700mm (H) x 390mm (W) x 285mm (D)
  • Uses gas as its fuel source
  • A-rated for efficiency
  • 10-year warranty as standard

Pros and Cons

If you want a reasonably priced boiler that can handle high hot water demand with ease, the Baxi 800 System could be the perfect solution. Below, you can check out the pros and cons of this condensing gas system boiler from Baxi. 


  • Baxi has a Which? brand score of 76% – correct at the time of writing – January 2022
  • Considerably cheaper than some other boiler brands
  • Fits inside a kitchen cupboard
  • Suited to small, medium and large-sized homes 
  • Easy to install, use and service
  • Industry-leading Adey Magnaclean Micro2 magnetic system filter – protects the boiler and heating system
  • Front access to all components – saves time when servicing
  • Compatible with the market-leading Megaflo Eco Cylinder
  • Provides maximum energy efficiency – reduce fuel bills and carbon emissions
  • Energy Saving Trust endorsed product
  • Excellent rating on Trustpilot – correct at the time of writing – January 2022
  • 10-year parts and labour warranty


  • Requires separate cylinder 
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