The Vaillant ecoTEC Plus 424 LPG is a wall-hung, room-sealed condensing open vent (heat-only) boiler rated at 24kW, purpose-built for LPG installations such as off-grid properties and static caravans, and supplied here complete with the Vaillant Standard Horizontal Flue Kit (0010039324). Designed for traditional open-vented heating systems with a feed-and-expansion cistern, it pairs a high-specification aluminium heat exchanger with electronic self-setting gas and air modulation for precise, low-emission combustion. At just 602 x 375 x 316mm, it is one of the most compact open vent boilers Vaillant produces, making it a practical drop-in replacement for older LPG gravity or pumped systems.
8.0 – 25.7kW
Modulation Range
2 yrs
Guarantee (Standard)
Gas Safe Registration & LPG Installation Requirements
This is an LPG-specific boiler and must only be installed, commissioned and serviced by a Gas Safe registered engineer holding the relevant LPG qualification (e.g. CCLP1). It must not be connected to a natural gas supply. The horizontal flue terminal must be positioned in accordance with the clearances in the manufacturer's flue installation instructions, and a Benchmark commissioning checklist must be completed and left with the end user.
Open Vent System — Check Compatibility Before Ordering
This is an open vent (heat-only) boiler, not a combi or sealed system boiler. It is designed to work with an existing open-vented heating system incorporating a feed-and-expansion cistern in the loft, and a separate hot water cylinder. It does not supply domestic hot water directly and does not include a pump, cylinder, or expansion vessel. Confirm your system type before ordering.
Why This Bundle
Purpose-Built for LPG
Factory-configured for liquefied petroleum gas rather than field-converted, this model is the correct specification for off-gas-grid properties, rural conversions, and static caravan installations running on LPG.
Aluminium Heat Exchanger
A high-specification aluminium heat exchanger is designed for a longer service life, easier maintenance access, and reduced running costs across the boiler's working life.
Electronic Self-Setting Combustion
The electronic gas and air modulation system automatically fine-tunes the air-to-gas ratio as the burner modulates, improving combustion efficiency and cutting emissions without manual recommissioning.
Wide 1:5 Modulation
Nominal output modulates from as low as 8.0kW up to 25.7kW, letting the boiler match output closely to demand rather than cycling on and off at full power.
Compact Footprint
At 602 x 375 x 316mm, the ecoTEC Plus 424 is small enough for kitchen cupboard installation, easing replacement of older, bulkier open vent boilers in tight spaces.
Push-Fit 60/100 Horizontal Flue Included
The bundled 0010039324 flue kit uses tool-free push-fit joints and is compatible with the wider Vaillant 60/100 extension, elbow and plume management accessory range.
Technical Specification
| General |
| Boiler article number |
0020231355 |
| Flue kit article number |
0010039324 (60/100mm, 990mm length) |
| Boiler type |
Wall-hung, room-sealed, fan-assisted condensing open vent (heat-only) |
| Gas type |
LPG (propane, G31) — factory set, not field-convertible from natural gas |
| Dimensions (H x W x D) |
602 x 375 x 316 mm |
| Guarantee |
2 years standard; upgradeable to 5 years via Vaillant Advance, 10 years with Boiler Protection Kit |
| Heating Performance |
| Nominal heat output range (50/30°C, condensing) |
8.0 – 25.7 kW |
| Nominal heat output range (80/60°C, non-condensing) |
7.6 – 24.3 kW |
| Maximum flow temperature |
80°C |
| Flow temperature range |
10 – 80°C (75°C factory setting) |
| Approximate condensate volume (50/30°C) |
3.06 litres/hr |
| Performance & Emissions |
| ErP efficiency (Heating) |
94% / A rated |
| NOx emissions (EN 15502-2-1) |
35 mg/kWh |
| Sound power (ErP) |
49 dBa |
| Boiler lift weight (dry) |
23.8 kg |
| Flue & Clearances |
| Maximum horizontal flue length (60/100) |
0.7 m (LPG-specific limit) |
| Minimum clearance, sides |
5 mm |
| Minimum clearance, top (60/100 flue) |
150 mm |
| Minimum clearance, below |
150 mm |
| Minimum clearance, front |
600 mm |
Frequently Asked Questions
Is this the same boiler as the natural gas ecoTEC Plus 424?
No. This is a dedicated LPG variant (article 0020231355), factory set for propane (G31) operation. It carries a different article number to the natural gas ecoTEC Plus 424 (0010021223) and must not be run on natural gas without a manufacturer-approved conversion.
Does this boiler supply hot water?
No. This is an open vent heat-only boiler for central heating. Domestic hot water is provided by a separate hot water cylinder connected to the same open-vented system, not by the boiler itself.
Why is the maximum horizontal flue length so much shorter than the natural gas version?
Vaillant's technical data sheet specifies a maximum horizontal 60/100 flue length of 0.7m for the LPG variant of the ecoTEC Plus 424, considerably shorter than the 10m permitted on the equivalent natural gas model. Plan the flue route accordingly before ordering extensions.
What system components do I need in addition to this bundle?
As an open vent boiler, you will also need a feed-and-expansion cistern, open vent and cold feed pipework, a separate pump if not integral, and a hot water cylinder — none of which are included in this listing.
Can I install this boiler myself?
No. UK law requires that all gas boiler installation, commissioning and servicing work is carried out by a Gas Safe registered engineer holding the appropriate LPG qualification.
Is the horizontal flue kit long enough for my installation?
The bundled 0010039324 kit provides a 990mm physical length, but the maximum permitted total flue run on this LPG model is only 0.7m including elbows — check your wall thickness and termination position carefully before ordering additional extensions.
