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Baxi 400 Combi

Extremely quiet, compact and lightweight, the Baxi 400 Combi can be installed virtually anywhere in your home.

  • Features
  • Dimensions
  • 5 year parts and labour warranty*
  • Fits inside a standard kitchen cupboard
  • Highly efficient - could save money on fuel bills
  • Certified to work with 20% hydrogen'

*Terms and Conditions apply.


  • Boiler width = 395mm
  • Boiler height = 700mm
  • Boiler depth = 279mm
  • Side clearance = 5mm
  • Upper clearance = 178mm
  • Lower clearance = 200mm
  • Front clearance = 6mm in operation, 450mm for servicing

Installer Information

Technical Features

  • 24 and 28kW
  • Optional stand-off frame
  • Simple hanging bracket
  • Choice of flue lengths
  • Compatible with uSense smart control
  • Combine this product with a uSense to be Boiler Plus compliant - Find out more


BAxi 200 Combi
  • Boiler width = 395mm
  • Boiler height = 700mm
  • Boiler depth = 279mm
  • Side clearance = 5mm
  • Upper clearance = 178mm
  • Lower clearance = 200mm
  • Front clearance = 6mm in operation, 450mm for servicing

Technical Data Table

Baxi 400 Combi 424 Combi 428 Combi
Sales Code

Boiler only




Concealed User Controls No No
Operating mode selector switch with reset Yes Yes
User adjustable DHW temperature Range - 35° to 60° (±5ºC) Yes Yes
User adjustable CH temperature Range - 25° to 80° (±5ºC) Yes Yes
Temp/status/fault diagnosis display LCD display LCD display
Integral 24 hour mechanical timer combi Optional Optional
Plug-In 24 hour mechanical timer combi Optional Optional
Plug-In receiver 7 day RF thermostat-combi Optional Optional
 Single channel 7 day wired programmable thermostat-combi   Optional Optional 
Single channel wired timer Optional Optional
Room thermostat Optional Optional
Wired outdoor weather sensor Optional Optional
Baxi 200 and 400 stand off kit (7659335) Optional Optional
Multifit filling loop (2498221) Optional Optional
SAP 2009 Annual Efficiency (PCDB/SEDBUK) % 89 89
NOx class 5 5
ErP Product Information
NOx mg/kWh 38 40
Sound Power Level, Indoors LWA dB 48 50
Space Heating Efficiency Class A A
Water Heating Declared Load Profile XL XL
Water Heating Efficiency Class A A
Heat Input CH kW max gross (QnHs) 22.87 27.42
kW min gross (QnHs) 5.44 5.44
Heat Output CH (non condensing) kW (Pn) 20 20
kW (Pn) 4.8 4.8
Heat Output CH (condensing) kW max (PnC) 21.8 21.8
kW min (PnC) 5.2 5.2
Gas supply pipe size (mm) 22 22
Inlet supply pressure (natural gas) mbar (nominal) 20 20
Maximum gas rate (natural gas after 10 mins) m3/hr 2.61 3.06
Mechanical and hydraulic
Heat input domestic hot water (DHW) kW max gross (QnwHs) 27.4 32.1
Heat output domestic hot water kW max 24 28
Maximum DHW flow rate (Delta T @ 35ºC max) l/min 9.8 11.5
Minimum DHW flow rate required l/min 2 2
Minimum operating DHW pressure required bar 0.15 0.15
Maximum DHW system pressure bar 8 8
Safety discharge pressure bar 3 3
Compartment ventilation required No No
Flow / return pipe size (mm) 22 22
Integral expansion vessel Size (litres) 7 7
CH system inhibitor required Yes Yes
Condensate discharge pipe size (mm) 21.5 21.5
Electrical supply Volts/Hz 230V/50Hz 230V/50Hz
Permanent live required Yes Yes
Electrical power cable required core 3 x 0.75 3 x 0.75
Power consumption when firing Watts 84 94
External fuse rating Amps 3 3
Internal fuse rating - Connection board Amps 0.5 0.5
Internal fuse rating - Man PCB board Amps 1.6 1.6
Boiler IP rating (electrical protection) without integral timer fitted Approval category IPX5D IPX5D
Circulating pump exercise feature Yes Yes
Pump overrun Yes Yes
Integral 'boiler only' frost thermostat Yes Yes
Concentric flue system
Standard telescopic concentric flue Length in mm 315-500 315-500
Horizontal concentric (60/100 mm) Max equivalent length (m) 10 10
Reduction per 135° bend (m) 0.5 0.5
Reduction per 93° bend (m) 1 1
Horizontal concentric (80/125mm) Max equivalent length 20 20
Installer lift weight (boiler) Max (kg) 26 26
Gross packaged boiler weight (kg) 30 30

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

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