The Baxi 436 Combi 2.1 is the highest-output model in Baxi's revamped 400 Combi 2.1 range, delivering a 36kW domestic hot water output for medium to larger UK homes with higher hot water demand — multiple bathrooms, larger families, or higher-flow showers. Despite the increased output, it remains lightweight and compact enough to fit inside a 290mm deep cupboard.
Inside, a stainless steel heat exchanger and brass hydraulics are paired with an ErP A energy efficiency rating for both space heating and hot water. The boiler runs on natural gas or LPG without needing a separate conversion kit, and is solar compatible for pre-heated system water.
Everyday reliability features include a pre-heated condensate trap to guard against freezing in cold weather, a combined pressure relief valve with separate drain for safer, faster drain-downs during servicing, and an external analogue pressure gauge that lets homeowners top up system pressure themselves, cutting down on avoidable call-outs.
15.0 l/min
DHW Flow Rate (ΔT 35°C)
30kg
Installer Lift Weight
7L
Integral Expansion Vessel
5 Yr
Parts & Labour Warranty
Good to Know
This is the 36kW model (436) — the highest output in the Baxi 400 Combi 2.1 range. The same platform is also available as the 24kW (424 Combi 2.1) and 30kW (430 Combi 2.1) for smaller properties with lower hot water demand — check property size and radiator count before ordering.
High Output for Bigger Homes
A 36kW DHW output and 15.0 l/min flow rate at ΔT 35°C make this the top-spec choice in the range for larger households or higher hot water demand.
Dual Fuel Ready
Works on natural gas or LPG without a conversion kit, so the same unit code covers both fuel types on site.
Compact Despite the Output
At 395 x 700 x 285mm it still fits 290mm deep cupboards, keeping installation flexibility even at the highest output in the range.
Robust Build
A stainless steel heat exchanger and brass hydraulics are used throughout for long-term corrosion resistance and reliability.
Winter-Ready Condensate
A pre-heated condensate trap reduces the risk of the condensate pipe freezing during cold snaps, helping avoid winter lockouts.
Smart Control Ready
Compatible with the Baxi uSense 2 Smart Room Thermostat and the Baxi Easy-Flue system for quicker, safer one-person flue installation.
Please Note
Boiler installation, commissioning and any gas or LPG conversion work must be carried out by a Gas Safe registered engineer in accordance with current Building Regulations and Benchmark requirements.
Identification
Manufacturer Part Number (MPN)
7872837
Product Range
Baxi 400 Combi 2.1
Boiler Type
Gas Combi Boiler
Gas & Efficiency
Fuel Type
Natural Gas or LPG (no conversion kit required)
Inlet Supply Pressure, Natural Gas (nominal)
20 mbar
Maximum Gas Rate, G20 (Qmax)
3.9 m³/hr
Heat Input CH, Max Gross (QnHs)
25.7 kW
Heat Input CH, Min Gross (QnHs)
7.2 kW
Heat Output CH Non-Condensing, Max (Pn)
25 kW
Heat Output CH Non-Condensing, Min (Pn)
7.2 kW
Heat Output CH Condensing, Max (Pnc)
27.1 kW
Heat Output CH Condensing, Min (Pnc)
7.6 kW
Heat Input DHW, Max Gross (QnwHs)
36.9 kW
Heat Output DHW, Max
36 kW
Water Heating Efficiency Class
A
Space Heating Efficiency Class
A
Hydraulic
Maximum DHW Flow Rate (ΔT 35°C rise)
15.0 l/min
Minimum DHW Flow Rate Required
2 l/min
Minimum Operating DHW Pressure Required
0.5 bar
Integral Expansion Vessel Size
7 litres
Maximum CH System Capacity
100 litres
Integral Automatic Bypass
Yes
Electrical
Permanent Live Required
Yes
External Fuse Rating (connection board)
F0.5A L250VP
Integral Boiler-Only Frost Thermostat
Yes
Dimensions, Weight & Noise
Front Clearance (operation / servicing)
5mm / 450mm
Installer Lift Weight
30kg
Flue & Compatibility
Maximum Horizontal Flue, 100mm
10m
Maximum Horizontal Flue, 125mm
20m
Maximum Vertical Flue, 100mm
10m
Maximum Vertical Flue, 125mm
20m
Smart Thermostat Compatibility
Baxi uSense 2 Smart Room Thermostat
Flue System Compatibility
Baxi Easy-Flue (internal fit, short & long)
Warranty
5 years parts and labour
What is the output of the Baxi 436 Combi 2.1?
The Baxi 436 Combi 2.1 (MPN 7872837) has a 36kW domestic hot water output — the highest in the 400 Combi 2.1 range — with a condensing central heating output of up to 27.1kW. It suits medium to larger UK homes with higher hot water demand.
Is the 436 a good fit for a home with multiple bathrooms?
Yes. With a 15.0 l/min DHW flow rate at ΔT 35°C, the 436 is the highest-flow model in the range, making it better suited to properties with multiple bathrooms or higher simultaneous hot water demand than the 424 or 430 models.
Can this boiler run on LPG?
Yes. The Baxi 436 Combi 2.1 is designed to work on natural gas or LPG without requiring a separate conversion kit, though installation and any fuel-related setup must still be carried out by a Gas Safe registered engineer.
Will it fit in a standard kitchen cupboard?
The boiler measures 395mm (W) x 700mm (H) x 285mm (D) and is designed to fit within a 290mm deep cupboard, despite being the highest-output model in the range.
What smart thermostat is this boiler compatible with?
The Baxi 436 Combi 2.1 is compatible with the Baxi uSense 2 Smart Room Thermostat, which allows heating schedules to be controlled remotely via a smartphone app.
What warranty does the Baxi 436 Combi 2.1 come with?
It carries a 5-year parts and labour warranty as standard, subject to annual servicing and registration in line with Baxi's terms and conditions.
