The Baxi 430 Heat Only is a 30kW regular (open vent) gas boiler designed for central heating in conjunction with a separate hot water cylinder and feed & expansion tank. Its lightweight, compact casing fits discreetly into a standard airing cupboard, and with no pump overrun required, it is a straightforward like-for-like replacement for ageing open vent systems. Backed by a 5-year parts and labour warranty, it delivers reliable heat-only performance for traditional heating layouts.
5 Years
Parts & Labour Warranty
Installation must be by a Gas Safe registered engineer
This appliance must be installed, commissioned and serviced only by a Gas Safe registered engineer, in accordance with Building Regulations and the manufacturer's Installation and Service Manual. A Benchmark Commissioning Checklist must be completed on installation.
Requires a separate hot water cylinder and F&E tank
As a heat-only (regular/open vent) boiler, this unit provides central heating only. A compatible hot water storage cylinder and feed & expansion tank must be specified and installed alongside it — hot water is not supplied directly by the boiler.
No pump overrun, no permanent live required
Because the Baxi 430 Heat Only has no pump overrun function and does not require a permanent live electrical supply, it can directly replace many existing heat-only boilers without rewiring the system controls, simplifying like-for-like swaps.
Key Features
Compact, Lightweight Casing
At just 625mm high and 370mm wide, the boiler is sized to fit discreetly into a standard airing cupboard, keeping the installation footprint small in traditional heating layouts.
No Pump Overrun Required
The absence of a pump overrun function means this boiler can directly replace many existing heat-only boilers without additional wiring changes to the system controls.
Front and Side Serviceable
Key components are accessible from both the front and side of the casing, reducing the clearance an engineer needs during routine servicing and maintenance.
Rear Flueing Option
In addition to the central top flue, a rear flue option is available, giving installers flexibility when routing the flue run through tight or awkward cupboard spaces.
Integral Boiler-Only Frost Thermostat
A built-in frost thermostat protects the boiler itself from freezing in cold weather, supporting flexible siting even in less insulated plant spaces.
93% Seasonal Efficiency
The boiler achieves a 93% seasonal space heating efficiency, contributing to its A-rated ErP classification and helping to keep running costs down in traditional heat-only systems.
Technical Specification
| Performance |
| Max Heat Output (Non-Condensing, 70°C Mean Water Temp) |
30 kW |
| Min Heat Output |
7.5 kW |
| Max Heat Input (Gross) |
34.35 kW |
| Min Heat Input (Gross) |
8.59 kW |
| Seasonal Space Heating Efficiency |
93% |
| Water Heating Efficiency Class |
A |
| Max Gas Rate (Natural Gas, G20, after 10 mins) |
3.27 m³/hr |
| Hydraulic |
| Heating System Max Pressure |
2.5 bar |
| Heating System Min Pressure |
0.5 bar |
| Heating Temperature Range |
25°C to 80°C |
| Integral Expansion Vessel |
7 litres |
| Boiler Type |
Regular / Open Vent (Heat Only) |
| Gas & Electrical |
| Fuel Type |
Natural Gas |
| Electrical Supply |
230V~ 50Hz (earthed supply required) |
| Max Power Consumption |
44 W |
| Pump Overrun |
Not required |
| Integral Boiler-Only Frost Thermostat |
Yes |
| Dimensions & Weight |
| Height |
625 mm |
| Width |
370 mm |
| Depth |
270 mm |
| Gross Weight (inc. Packaging) |
19.5 kg |
| Warranty |
| Parts & Labour |
5 Years (subject to manufacturer's T&Cs) |
Frequently Asked Questions
Does the Baxi 430 Heat Only provide hot water on its own?
No. As a heat-only (regular) boiler, it heats the central heating circuit only. Hot water is supplied via a separate cylinder connected to the system, with its own feed & expansion tank.
Can this replace my existing heat-only boiler without rewiring?
In most cases, yes. Because it has no pump overrun and does not require a permanent live, it is designed to directly replace many existing heat-only boilers without extensive changes to the control wiring — though a Gas Safe engineer should always confirm compatibility with your specific system.
Will it fit in my airing cupboard?
At 625mm (H) x 370mm (W) x 270mm (D), the Baxi 430 Heat Only is compact enough to fit into most standard airing cupboards.
Does it need a permanent electrical live supply?
No. Unlike combi and system boilers in the Baxi 400 range, the Heat Only model does not require a permanent live connection, simplifying electrical installation.
What warranty does the Baxi 430 Heat Only carry?
It comes with a 5-year parts and labour warranty, subject to registration and an annual service carried out by a Gas Safe registered engineer.
