Baxi 400 Heat

The Baxi 400 Heat is the perfect replacement for your old heat only boiler. It's compact design means that the Baxi 400 Heat can be fitted in homes with minimal space, and at only 19.5kgs it's the lightest boiler available in the UK*.

The Baxi 400 Heat does not require a pump overrun or permanent live, meaning that installation is easy and discreet, and for added peace of mind, it comes with a 5 year warranty as standard.

*As of June 2014.


Baxi 400 Heat
Get a quote

Find an approved installer near you for a no obligation installation quote

  • Available in outputs of 12kW, 15kW, 18kW, 24kW and 30kW to suit most property sizes
  • Comes with a 5 year parts and labour warranty** as standard
  • Only 19.5kg installer lift weight
  • Cupboard fit
  • Easy fit wall mounting bracket
  • No pump overrun or permanent live required
  • Wide choice of flue lengths, bends and accessories

    **Terms and conditions apply.

  • A: Boiler width = 370mm

    B: Boiler height = 625mm

    C: Boiler depth = 270mm

    D: Side clearance = 5mm

    E: Upper clearance = 190mm

    F: Lower clearance = 120mm

    G: Front clearance = 5mm in operation, 800mm for servicing

    Baxi 400 Heat 12 15 18 24 30
    Sales code Boiler only 7668931 7668933 7668934 7668935 7668936
    Operating mode selector switch with reset Yes/no Yes Yes Yes Yes Yes
    User adjustable CH temperature Range - e.g. 30ºC to 80ºC (+/- 5ºC) Yes Yes Yes Yes Yes
    LED status/fault diagnosis display Yes/no Yes Yes Yes Yes Yes
    SAP 2009 Annual Efficiency (PCDB/SEDBUK)  % 89.2 89.2 89.2 89.1 89.1 
    NOx class 1-5 5 5 5 5 5
    ErP Product Information
    NOx  mg/kWh    18 20  21  23  24 
    Sound Power Level, Indoors  LWA dB  32  33  34  35  37 
    Space Heating Efficiency Class  
    Heat Input CH kW max gross (QnHs)  14.88  18.32  21.75  28.62  34.35 
    kW min gross (QnHs) 8.59  8.59  8.59  8.59  8.59 
    Heat Output CH (non condensing)  kW max (Pn) 13 16 19 25 30
    kW min (Pn) 7.5 7.5 7.5 7.5 7.5
    Gas supply pipe size (mm) 22 22 22 22 22
    Inlet supply pressure (natural gas) mbar 20 20 20 20 20
    Maximum gas rate m3/hr 1.42 1.75 2.07 2.73 3.27
    Mechanical and hydraulic
    Compartment ventilation required No No No No No
    Flow / return pipe size (mm) 22 22 22 22 22
    Condensate discharge pipe (mm) 21.50 21.50 21.50 21.50 21.50
    Electrical supply Volts / Hz 230V/ 50Hz 230V/ 50Hz 230V/ 50Hz 230V/ 50Hz 230V/ 50Hz
    Permanent live required Yes/no No No No No No
    Switched live Yes/no Yes Yes Yes Yes Yes
    Electrical power cable fitted as standard 1m of 3 core Yes Yes Yes Yes Yes
    Power consumption Watts 17 20 23


    External fuse rating Amps 3 3 3 3 3
    Internal fuse rating 1.6T 1.6T 1.6T 1.6T 1.6T
    Boiler IP rating (electrical protection) Approval category IPX4D IPX4D IPX4D IPX4D IPX4D
    Pump overrun Yes/no No No No No No
    Concentric flue system
    Standard telescopic concentric flue Length in mm 315-500 315-500 315-500 315-500 315-500
    Standard in-case rear telescopic concentric flue Length in mm 220-345 220-345 220-345 220-345 220-345
    Horizontal concentric (60/100mm) Max equivalent length (m) 6 6 6 6 6
    Reduction per 135º bend (m) 0.5 0.5 0.5 0.5 0.5
    Reduction per 93º bend (m) 1 1 1 1 1
    Horizontal concentric (80/125 mm) Max equivalent length (m) 12 12 12 12 12
    Reduction per 93º bend (m) 1 1 1 1 1
    Installer lift weight Max (kg) 19.5 19.5 19.5 19.5 19.5
    Gross packaged boiler weight (kg) 21.5 21.5 21.5 21.5 21.5


    Additional heating and hot water accessories can improve the overall efficiency and performance of your heating system. This could reduce your fuel consumption and your energy bills.

    For more information on any of the below accessories please speak to your installer as they will be able to advise you on the controls that are right for you.

    • Baxi Twin Channel Wired Programmer
    • Baxi Room Thermostat

    For more information on the Baxi 400 accessories, click here

  • Baxi 400 Heat Installation & Servicing manual (PDF 5.11MB, 09/03/2017)
  • Baxi 400 Heat Consumer Guide (PDF 0.65MB, 09/03/2017)
  • Baxi 200 & 400 Heat Range Guide (PDF 3.09MB, 09/03/2017)
  • We don't sell our products directly to consumers which is why our prices aren't on our website.

    Find out more
    Find an installer

    Find an installer

    We have Gas Safe Registered installers all over the UK who will be able to give you a quote for the installation of your new boiler. Simply enter a few details into our Find an Installer tool and we'll contact them on your behalf. The installer will get in touch to arrange a site survey and give you a competitive, no obligation quote.

    Find an installer

    For more information about heat only boilers, please use the links below:

    FAQs about heat only boilers

    How do heat only boilers work? 

    Benefits of heat only boilers

    Register your warranty

    We offer free product training at our training centres across the UK for installers who want to get hands-on with Baxi boilers.


    From construction and installation to functions and features, our expert trainers will give you a complete understanding of working with Baxi boilers.

    Sign up for our free training
    Find a boiler
    About the boiler types
    Find an installer

    How to buy information