Vaillant Ecotech 840 Combi Boiler with Horizontal Flue & 15mm Scale Reducer

The Vaillant ecoTEC Plus 840 Combi Boiler is a premium 40kW combination boiler designed to provide powerful central heating and exceptional mains-pressure hot water for larger homes with high demand. As a combi boiler, it delivers both heating and instant hot water without requiring a separate hot water cylinder or cold water storage tank, helping to save valuable space while maintaining outstanding performance.

Featuring Vaillant's latest condensing technology, intuitive semi-touch controls, and intelligent combustion management, the ecoTEC Plus 840 is engineered for maximum efficiency, simplified installation, and long-term reliability. It is fully compatible with Vaillant smart controls and renewable heating technologies, making it a future-ready heating solution.

Key Features

• 40kW Combination (Combi) Gas Boiler
• Fuel Type: Natural Gas
• Instant mains-pressure hot water
• No hot water cylinder required
• ErP A Rated for heating and hot water
• High-efficiency condensing technology
• Intuitive semi-touch user interface
• IoniDETECT intelligent combustion technology
• Up to 1:10 modulation ratio
• Domestic hot water flow rate: 19.0 L/min (Δ30°C)
• Domestic hot water flow rate: 16.3 L/min (Δ35°C)
• Hydrogen Blend Ready (up to 20%)
• Smart home ready with myVAILLANT connect
• Compatible with Vaillant heating controls, flues, and renewable technologies
• Stainless steel heat exchanger
• Standard 5-year manufacturer's warranty
• Extendable to 10 years when installed by a Vaillant Advance Installer (subject to terms and conditions).

Ideal for Larger Homes

The ecoTEC Plus 840 is designed for larger homes with one or more bathrooms and high domestic hot water demand. Its powerful output ensures reliable heating while supplying multiple hot water outlets with excellent pressure and consistency.

As a combi boiler, it removes the need for a separate hot water cylinder, making it an ideal space-saving solution for modern homes.

Powerful Heating & Exceptional Hot Water Performance

Delivering 40kW of heating output and an impressive 19.0 litres per minute domestic hot water flow rate (Δ30°C), the ecoTEC Plus 840 is built for homes where comfort and performance are a priority.

Vaillant's IoniDETECT technology continuously monitors combustion conditions and automatically adjusts burner performance for optimum efficiency. Combined with a 1:10 modulation ratio, it reduces fuel consumption while maintaining consistent heating and hot water performance.

Compact Design & Easy Installation

Despite its high output, the ecoTEC Plus 840 maintains a compact, installer-friendly design.

Dimensions

• Height: 720mm
• Width: 440mm
• Depth: 386mm

The familiar installation footprint and redesigned internal layout provide easy access to major components, helping reduce installation and servicing time.

Advanced Energy Efficiency

The ecoTEC Plus 840 combines advanced condensing technology with intelligent combustion monitoring to maximise seasonal efficiency while helping reduce household energy costs.

The boiler is also Hydrogen Blend Ready, allowing operation with gas supplies containing up to 20% hydrogen, helping prepare your heating system for the future.

Smart Heating Control Compatibility

Compatible with myVAILLANT connect and Vaillant's latest smart heating controls, the ecoTEC Plus 840 enables homeowners to monitor and adjust heating remotely via smartphone.

Its intelligent modulation and weather compensation capabilities help maximise comfort while improving energy efficiency throughout the year.

Reliable Performance & Easy Maintenance

Built with a durable stainless steel heat exchanger and Vaillant's intelligent linBUS communication technology, the ecoTEC Plus 840 is engineered for dependable long-term performance.

The intuitive commissioning wizard and improved service accessibility make installation, maintenance, and servicing faster and more convenient for heating engineers.

Warranty & Peace of Mind

The Vaillant ecoTEC Plus 840 comes with a 5-year manufacturer's warranty as standard. When installed and registered by a Vaillant Advance Installer, the warranty can be extended to 10 years, providing additional long-term protection and confidence.

Why Choose the Vaillant ecoTEC Plus 840?

• Powerful 40kW combi boiler
• Instant mains-pressure hot water
• Up to 19.0 L/min hot water flow rate
• IoniDETECT intelligent combustion technology
• Up to 1:10 modulation ratio
• Hydrogen Blend Ready (20%)
• Smart home compatible
• Stainless steel heat exchanger
• Compact, installer-friendly design
• Up to 10-year warranty available