Baxi 800 System 2

The Baxi 800 System 2 boiler has a 10-year parts and labour warranty* and can be installed with a hot water cylinder, such as the Baxi cylinder or Megaflo Eco

It is the perfect solution for homes that need lots of hot water or have more than one bathroom.

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*Terms and conditions apply

Baxi 800 System 2
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Features and benefits   |   Dimensions   |   Product literature   |   Technical specifications   |   Related products   |   FAQs

Features and benefits

*Terms and conditions apply
**The Adey Micro 2 Filter must be installed and registered at the same time as your boiler for your 10-year warranty to be valid


  • A: Boiler Width = 395mm
  • B: Boiler Height = 700mm
  • C: Boiler Depth = 285mm
  • D: Side Clearance = 2.5mm
  • E: Upper Clearance = 178mm
  • F: Lower Clearance = 150mm
  • G: Front Clearance= 5mm in operation (450mm for servicing)
Baxi 800 System 2 Line Diagram
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Product literature

Technical specifications

  • 18, 24 & 30kW System (Natural Gas and LPG)
  • Compact cupboard fit
  • Brass hydraulics block
  • Built in stand-off frame
  • Certified OpenTherm
  • Simple hanging bracket
  • Vertical sleeve recyclable packaging
  • Combined PrV with seperate drain
  • Colour-coded and removable wiring blocks
  • Pre-heated siphonic condensate trap
  • Easy-fill 2 permanent filling link
  • Includes Adey Micro2 Magnetic System filter


  • View full technical specifications 
Technical Table   Baxi 818 System 2 Baxi 824 System 2 Baxi 830 System 2
Sales Code   7814313 7814314 7814315
Natural gas or LPG   Yes Yes Yes
Inlet supply pressure (natural gas) mbar (nominal) 20 20 20
Maximum Gas Rate (G20) Omax m³ / hr 1.97 2.61 3.26
Heat Input CH kW (max) Gross (OnHs)  18.6 24.7 30.9
  kW (min) Gross (OnHs) 4.9 4.96.0
Heat Output CH (non-condensing) kW (Max) (Pn) 18 24 30
  kW (Min) (Pn) 4.8 4.8 5.8
Heat Output CH (condensing) kW (Max) (Pnc) 19.9 26.3 32.4
  kW (Min) (Pnc) 5.2 5.2 6.4
Heat Input domestic hot water (DHW) kW max gross (OnwHs)  N/A N/A N/A
Heat Output domestic hot water (DHW) kW max  N/AN/A N/A
Water heating efficiency class   A A
Permanent live required   Yes  Yes  Yes 
External fuse rating (on connection board) Amps F0.5A L250VP F0.5A L250VP F0.5A L250VP
Pump overrun   Yes Yes Yes
Integral 'boiler only' frost thermostat   Yes Yes Yes
Maximum DHW flow rate (Delta T @35'C rise)  l/min N/A N/A N/A
Minimum DHW flow rate required   l/min 
Minimum operating DHW pressure required bar 0.5  0.5  0.5 
Integral expansion vessel Size (litres) 
Maximum capacity of the CH system Litres  100  100  100 
Integral automatic bypass   Yes  Yes  Yes 
Installer Lift Weight (kg) 29 30 30 

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More information


  • Why should I have a filter and will having a magnetic water filter save me money? 
  • How to recharge the air gap on a Megaflo unvented cylinder
  • How to reset a Baxi boiler 
  • How do I bleed a radiator?

Many boiler breakdowns that occur are due to sludge in the heating system. This 'sludge' (which is also known as magnetite) is caused by fragments of rust and other debris in the pipes that accumulates over time and, if left, can cause cold patches on your radiators, make your boiler work harder to heat your home and can block or damage the components inside your boiler.

Read full FAQ


If you've noticed that water is dripping from the safety pipe outside or through the tundish on the outside of your cylinder, this is an indication that the air gap in your cylinder needs recharging. Watch our video to find out how you can easily fix this yourself, without calling a heating engineer.

Read full FAQ

Read how to reset your boiler, whether it has a dedicated reset button, an ON/OFF/SELECTOR switch or a thermostat control knob.

Read full FAQ

If you have cold spots at the top of your radiators, it means that there is trapped air that needs to be removed so your radiators will heat your room efficiently. Follow our simple steps for bleeding your radiators

Read full FAQ