Best LPG Combi Boilers

Overview

From German manufacturer Viessmann, the Vitodens 100-W is a highly regarded gas combi boiler that can be converted for use with LPG, making it a popular choice for off-grid homes.

Known for its strong build quality, compact design, and competitive pricing, the Vitodens 100-W offers an excellent balance of performance, efficiency, and value, particularly for homeowners who want a premium brand without the premium price tag of higher-end models.

Is the Viessmann Vitodens 100-W right for my home?

The Vitodens 100-W is well suited to homes where space, efficiency, and quiet operation are key priorities.

Key benefits include:

• Compact footprint, ideal for kitchen cupboards
• ErP A-rated efficiency, helping to reduce running costs
• Quiet operation, with noise levels typically around 48–49 dB

These features make it a strong choice for flats and small to medium-sized homes, or properties where the boiler is installed close to living or sleeping areas.

Output options and suitability

The Vitodens 100-W range is available in several outputs, typically:

• 26kW
• 30kW
• 35kW

Smaller homes with 1–3 bedrooms and one bathroom are usually well matched to the 26kW or 30kW models, while homes with higher hot water demand may benefit from the 35kW version.

As with any boiler, final sizing should always be confirmed by a Gas Safe–registered engineer experienced with LPG installations.

Efficiency and technology

The Vitodens 100-W features Viessmann’s proven Inox-Radial stainless steel heat exchanger, which is designed for durability, corrosion resistance, and long service life.

Combined with modern condensing technology, this allows the boiler to deliver:

• High real-world efficiency
• Consistent performance
• Lower fuel consumption compared with older non-condensing boilers

When converted for LPG, the boiler continues to meet current efficiency and emissions standards.

Size and installation

With a depth of approximately 350mm, the Vitodens 100-W is one of the more compact LPG-compatible combi boilers available and fits comfortably inside most standard kitchen cupboards.

Its lightweight design and straightforward connections also make installation relatively simple for qualified installers.

Warranty and reliability

Viessmann has a strong reputation for reliability and build quality. When installed by a Viessmann-approved engineer, the Vitodens 100-W can be supplied with a warranty of up to 10 years, providing long-term peace of mind.

Verdict

The Viessmann Vitodens 100-W is an excellent all-round LPG combi boiler, particularly for homeowners who want:

• A compact, cupboard-friendly design
• Strong efficiency and quiet operation
• Trusted German engineering at a sensible price

While it lacks some of the advanced features found on Viessmann’s premium models, it remains one of the best value LPG combi boilers available, making it a go-to option for small to medium-sized homes.

Did you know?

Viessmann has consistently scored highly in independent surveys for build quality and reliability, and the Vitodens 100-W range has previously received Which? Best Buy recognition — reinforcing its strong reputation among homeowners and heating engineers.

Specification

Please select a model below to view its specifications.

• 26kW
• 30kW
• 35kW

Overview

From German manufacturer Vaillant, the ecoTEC Pro 28 LPG is the only dedicated LPG combi boiler in Vaillant’s ecoTEC Pro range and is designed specifically for small to medium-sized off-grid homes.

Positioned as a reliable and cost-effective option, the ecoTEC Pro 28 LPG delivers solid performance, quiet operation, and proven Vaillant build quality — without the higher price tag of more advanced premium models.

Is the Vaillant ecoTEC Pro 28 LPG right for my home?

The ecoTEC Pro 28 LPG is well suited to properties with moderate heating and hot water demand.

Key outputs include:

• Central heating output: approx. 24kW
• Hot water output: approx. 27kW

This makes it a good match for:

• Flats and apartments
• Small to medium-sized homes (typically up to 3 bedrooms)
• Properties with one main bathroom

It provides enough hot water for a bath or shower without the cost or size of higher-output LPG boilers.

Efficiency, noise and controls

The ecoTEC Pro 28 LPG is ErP A-rated, with efficiency figures of around 94%, helping to keep running costs down compared with older or non-condensing boilers.

Other key features include:

• Quiet operation, with noise levels typically up to 49 dB
• Front-mounted digital display showing temperatures, system pressure, and fault codes
• Compatibility with Vaillant heating controls and smart thermostats

While the controls are more basic than Vaillant’s premium ranges, they are straightforward and easy to use.

Size and installation

The ecoTEC Pro 28 LPG measures approximately 720 × 440 × 338 mm.

It is:

• Wall-mounted
• Compact enough for many kitchen installations
• Sometimes too tall for standard kitchen cupboards, depending on layout

Where cupboard space is limited, it can also be installed on a kitchen wall or in a utility or storage cupboard.

Warranty and reliability

Vaillant has a long-standing reputation for reliability and engineering quality. The ecoTEC Pro 28 LPG typically comes with a standard manufacturer warranty, which can often be extended when installed by a Vaillant Advance-approved engineer.

Parts availability and installer familiarity remain strong across the UK.

Verdict

The Vaillant ecoTEC Pro 28 LPG is an excellent value-focused LPG combi boiler for homeowners who want:

• Reliable performance
• Quiet operation
• Trusted brand support
• Sensible upfront cost

While it doesn’t offer the advanced controls or ultra-high efficiency of premium LPG boilers, it strikes a very good balance between performance, reliability, and affordability, making it a strong choice for small to medium-sized off-grid homes.

Specification

Please select a model below to view its specifications.

• ecoTEC Pro 28 LPG