Baxi 800

At a glance

• Configurations: Combi, System
• Best suited to: Small to medium homes, especially tight cupboard installs
• Fuel: Mains natural gas (some variants are LPG-convertible, check the manufacturer’s data).

Specifications

Match the badge in front of you to a row before you use any of this. Every figure below was read from the Baxi literature listed under Sources at the foot of this page, checked 6 September 2026. Outputs, variants and part numbers change by year, so the appliance data plate is still the last word.

• The same model badge on a combi and on a system boiler carries a completely different GC number, so the badge alone is not enough to order parts against.
• Baxi publishes no digit-by-digit serial decode, so there is no honest way to read a build date off the number on site. Baxi states a 10 year parts and labour warranty on the 800 Combi 2 on condition that the Adey Micro 2 filter is installed and registered with the boiler, within 30 days.

Where the data plate is

Above the boiler controls on the 800 Combi 2, and on the top part of the boiler on the 800 System 2. The serial is the field marked s/n on that plate, with the boiler ID and serial also shown by the cable gland on the underside.

Worth knowing on site

• Compact, light casing with a bottom-centre connection layout.
• Combi and system variants; packs often bundle a filter, wireless thermostat and flue.

On the tools

As Baxi's flagship numbered range, the 800 is a common pick for tight cupboard installs thanks to its compact, light casing. Bundled packs (filter, wireless thermostat, flue) are often mentioned by engineers as a reason quoting and ordering for an 800 job is comparatively quick.

Variants and configuration

It is available in combi and system form, with a bottom-centre connection layout that differs from some rival brands, worth noting when planning pipework on a swap. Always confirm the exact configuration and output from the data plate before ordering a bundled pack.

Where it sits in the range

The 800 sits above the 600 in Baxi's current numbered line-up and represents the brand's newest, most feature-rich domestic combi and system range. It commonly replaces older Baxi boilers or rival mid-range appliances on straightforward like-for-like swaps.

Finding the manual and the data plate

For the exact outputs, gas rate, dimensions and commissioning figures, work from the appliance’s data plate and the manufacturer’s installation and servicing instructions. The GC (Gas Council) number and serial are on the data plate, usually behind the front panel or on the underside. Baxipublishes its manuals and support at Baxi support.