Baxi 800 Combi 2

Manufactured in the UK, the Baxi 800 Combi 2 has a 10-year parts and labour warranty*.

Due to the compact fit, the boiler can be installed neatly in a convenient safe place in your home. It’s compatible with the Baxi uSense smart control, when paired with our My Baxi App you can operate it wherever you are, using your phone or tablet.

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*Terms and conditions apply

Baxi 800 Combi 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 Assure 800 Combi 2 Line Diagram_ALT
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Product literature

Technical specifications

  • 24kW, 30kW and 36kW Combi (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 separate 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 specification 
Baxi 824 Combi 2 Baxi 830 Combi 2 Baxi 836 Combi 2
Sales Code Boiler Only 7814304 7814305 7814306
Natural gas or LPG Yes Yes Yes
Inlet supply pressure (natural gas) mbar (nominal) 20 20 20
Maximum Gas Rate (G20) Qmax m3/hr 2.61 3.26 3.9
Heat input CH kW (max) Gross (QnHs) 20.6 25.7 25.7
kW (min) Gross (QnHs) 4.9 6.0 7.2
Heat Output CH (non-condensing) kW (Max) (Pn) 20 25 25
kW (Min) (Pn) 4.8 5.8 7.2
Heat Output CH (condensing) kW (Max) (Pnc) 21.8 27.1 27.1
kW (Min) (Pnc) 5.2 6.3 7.6
Heat Input Domestic Hot Water (DHW) kW max gross (QnwHs) 27.4 30.9 36.9
Heat Output Domestic Hot Water (DHW) kW max 24 30 36
Water Heating Efficiency class A A A
Permanent Live Required Yes Yes Yes
External fuse rating Amps 3 3 3
Pump Overrun Yes Yes Yes
Integral 'boiler only' Frost Thermostat Yes Yes Yes
Maximum DHW flow rate (Delta T @ 35'C rise) l/min 10.2 12.2 15.0
Minimum DHW flow rate required l/min 2 2 2
Minimum Operating DHW pressure required bar 0.5 0.5 0.5
Integral Expansion Vessel Size (litres) 7 7 7
Maximum Capacity of CH System Litres 100 100 100
Integral Automatic Bypass Yes Yes Yes
Installer Lift Weight (boiler) (kg) 29.2 29.2 30.5

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More information


  • How to reset a Baxi boiler 
  • What temperature should a boiler be set at?
  • How do I top up the water pressure?
  • How old is my boiler?
  • How do I bleed a radiator?

If you are troubleshooting a Baxi boiler with a dedicated reset button:

  • In certain circumstances, your boiler may lock out. This is identified by the Red Lockout light constantly illuminated or flashing.
  • To reset the boiler, simply press the reset button until the red light goes away.
  • If your timer is calling for heat, the burner light will come on to indicate the boiler has fired up and is heating your system.
  • If lockout occurs frequently a fault is indicated and you should contact your installer or service engineer.
Read full FAQ

We all want to stay cosy in the winter. Some cosier than others. There’s no magic number for the ideal temperature. If you’re looking for a good balance of warmth and efficiency, you want to set your boiler to at least 65°C. Setting it a few degrees higher won’t hurt. But it’s important not to set it any lower than that. This is so bacteria in the water doesn’t grow, and cause nasty things like Legionella.

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It is quite simple to top up the water pressure in your boiler. You should be able to do it yourself without having to call a heating engineer. We have made some videos below to help you.

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You can find out how old your boiler is by visiting the official industry database.

Fill in details of your boiler and the dates when manufacture of that model began and ended will be displayed.

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Here, we explain the best way to bleed your radiators.

  1. While your heating is on, carefully feel the tops of each of your radiators to check if they are warm. Those which are cold at the top need bleeding
  2. Switch off your central heating, and let the radiators cool down before bleeding radiators.
  3. Look at the valve on the top of the radiator – some need a screwdriver to undo them, but for most you will need a radiator key. These are very inexpensive and widely available at DIY stores.

Read full FAQ