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Baxi 800 System

Includes an Adey Micro2 Magnetic System filter, providing industry leading system protection.

  • Features
  • Dimensions

  • 10 year parts and labour warranty*

  • Built in the UK using top quality brass components

  • Comes with an Adey Micro2 magnetic system filter to protect the heating system and boiler

  • Fits inside a standard kitchen cupboard

  • Compatible with market-leading Megaflo Eco cylinder

  • Certified to work with 20% hydrogen

*Terms and Conditions apply.


  • Boiler width = 390mm

  • Boiler height = 700mm

  • Boiler depth = 285mm

  • Side clearance = 5mm

  • Upper clearance = 178mm

  • Lower clearance = 200mm

  • Front clearance = 5mm in operation, 450mm for servicing


Installer Information

Technical Features

  • 18kW and 24kW
  • Compact cupboard fit
  • Only 27.7kg lift weight
  • 10 year parts and labour warranty
  • Compatible with Megaflo cylinders
  • IFOS systems weather compensation compatible
  • Includes Adey Micro2 Magnetic System filter
  • Brass hydraulics block
  • Built in stand off frame
  • OpenTherm interface
  • Pre-formed copper tails
  • Extensive flue options up to 20 metres
  • Simple hanging bracket
  • Certified to work with 20% hydrogen



  • Boiler width = 390mm

  • Boiler height = 700mm

  • Boiler depth = 285mm

  • Side clearance = 5mm

  • Upper clearance = 178mm

  • Lower clearance = 200mm

  • Front clearance = 5mm in operation, 450mm for servicing

Technical Data Table

Baxi 818 System Baxi 824 System
Sales Code Boiler Only 7728645 7728289
Controls and accessories
User adjustable DHW temperature Range - 30'C to 60'C N/A N/A
User adjustable CH temperature Range - 25'C to 80'C Yes Yes
Temp/status/fault diagnosis display LCD Display LCD Display
uSense Wired (optional accessory) 7649277 N/A N/A
Integral 24 hr Electro-mechanical timer (optional accessory) N/A N/A
Wired 24 hr Electro-mechanical timer (optional accessory) 720971401 N/A N/A
7 day RF Digital Programmable Room Thermostat (optional accessory) 720030501 N/A N/A
Single Channel WiredProgrammable room Thermostat (optional accessory) 7212438 N/A N/A
Single Channel Wired Timer (optional accessory) 7212444 N/A N/A
Wired Room Thermostat (optional accessory) 720971601 Optional Optional
Multifit Twin Channel Wired Programmer (optional accessory) 7212443 Optional Optional
Multifit IFOS weather compensation (optional accessory) 7724181 Optional Optional
Multifit IFOS Extension (optional accessory) 7724260 Optional Optional
Multifit IFOS System (optional accessory) 7729979 Optional Optional
Ridge Tile IFOS (optional accessory) 7729943 Optional Optional
Baxi Easy-fill Permenant Filling Link 7665482 N/A N/A
Natural gas Yes Yes
Propane LPG N/A N/A
Inlet supply pressure (natural gas) mbar (nominal) 20 20
Maximum Gas Rate (G20) Qmax m3/hr 1.96 2.61
N0x mg/kWh 30 28
N0x Class 6 6
Heat input CH kW (max) Gross (QnHs) 20.6 27.4
kW (min) Gross (QnHs) 5.2 5.2
Heat Output CH (non-condensing) kW (Max) (Pn) 18 24
kW (Min) (Pn) 4.5 4.5
Heat Output CH (condensing) kW (Max) (Pnc) 19.4 25.8
kW (Min) (Pnc) 4.9 4.9
Heat Input Domestic Hot Water (DHW) kW max gross (QnwHs) N/A N/A
Heat Output Domestic Hot Water (DHW) kW max N/A N/A
ErP Product Information
Seasonal Space Heating Energy Efficiency 93% 93%
Sound Power Levels, indoors lWA dB 48 48
Space Heating Efficiency Class A A
Water Heating Declared Load Profile N/A N/A
Water Heating Efficiency class N/A N/A
Electrical Supply Volts / Hz 230 / 50 230 / 50
Permanent Live Required Yes Yes
Electrical Cable Supplied (0.75mm heat resistant flex) No No
Power consumption when firing Watts 70 100
External fuse rating Amps 3 3
Internal fuse rating Amps F2A H250V F2A H250V
Boiler IP rating (electrical protection) without integral timer fixed Approval category IPX5D IPX5D
Circulating pump exercise feature Yes Yes
Pump Overun Yes Yes
Integral 'boiler only' Frost Thermostat Yes Yes
Hanging Bracket Yes Yes
Isolating valves with pre-formed copper tails Yes Yes
Gas supply Connection (mm) 22 22
Central Heating Connections (mm) 22 22
Domestic Hot Water Connections (mm) N/A N/A
Condense Discharge Pipe Connections (mm) 21.5 21.5
Safety DischargePipe Connections (mm) 15 15
Pre-Plumb Jig (optional accessory) 7682545 Optional Optional
Rear Pipework Kit (optional accessory) 7682790 Optional Optional
Remote Secondary PRV kit (optional accessory) 5121379 Optional Optional
Maximum DHW flow rate (Delta T @ 35'C rise) l/min N/A N/A
Minimum DHW flow rate required l/min N/A N/A
Minimum Operating DHW pressure required bar 0.5 0.5
Maximum DHW System Pressure bar N/A N/A
Safety Discharge Pressure bar 3 3
Compartment Ventilation Required No No
Integral Expansion Vessel Size (litres) 7 7
Maximum Capacity of CH System Litres 100 100
Integral Automatic Bypass N/A N/A
CH System Inhibitor Required Yes Yes
Concentric flue systems
Concentric Flue Diameters (mm) 60/100 and

60/100 and

Standard telescopic horizontal flue (60/100) (mm) 315 - 500 315 - 500
Standard horizontal flue kit (60/100) (mm) 685 685
Max equiv length horizontal / vertical (60/100) m 10 10
Max equiv length horizontal / vertical (80/125) m 20 20
Equivalent length per 135' bend m 0.5 0.5
Equivalent length per 93' bend m 1 1
Installer Lift Weight (boiler) (kg) 27.7 27.7
Gross packaged boiler weight (kg) 33 33


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