Vaillant Ecotech 635 System Boiler with Horizontal Flue & 15mm Scale Reducer

The Vaillant ecoTEC Plus 635 System Boiler is a high-performance 35kW system gas boiler designed for larger homes with higher heating demands. Built for sealed central heating systems with a separate unvented hot water cylinder, it combines Vaillant's latest condensing technology with intelligent combustion management to deliver powerful, efficient, and reliable home heating.

Featuring an upgraded internal layout, intuitive semi-touch controls, and advanced smart technology, the ecoTEC Plus 635 is designed to simplify installation, commissioning, and servicing while providing long-term energy efficiency. Compatible with Vaillant controls, flue systems, and renewable heating solutions, it offers a future-ready heating solution for modern homes.

Key Features

• 35kW system gas boiler
• Fuel Type: Natural Gas
• High-efficiency condensing technology
• ErP A Rated heating efficiency
• Designed for sealed heating systems with an unvented hot water cylinder
• Intuitive semi-touch user interface
• IoniDETECT intelligent combustion technology
• Up to 1:10 modulation ratio
• Hydrogen Blend Ready (up to 20%)
• Smart home ready with myVAILLANT connect
• Compatible with Vaillant heating controls, flues, and renewable technologies
• Redesigned internal layout for easier installation and servicing
• 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 635 is designed for sealed heating systems with a separate unvented hot water cylinder, making it ideal for larger homes with multiple bathrooms and higher heating requirements.

Its integrated pump and expansion vessel simplify installation while delivering dependable and consistent heating performance throughout the property.

Powerful 35kW Heating Performance

Delivering 35kW of central heating output, the ecoTEC Plus 635 provides exceptional heating capacity for larger domestic properties.

Vaillant's advanced IoniDETECT technology continuously monitors combustion conditions and automatically adjusts burner performance for maximum efficiency. Combined with a 1:10 modulation ratio, the boiler precisely matches output to demand, helping reduce fuel consumption and improve comfort.

Compact Design & Easy Installation

Although it delivers a higher heating output, the ecoTEC Plus 635 remains compact enough for straightforward installation.

Dimensions

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

The redesigned internal layout offers quick access to all major components, helping installers reduce installation and servicing time while maintaining Vaillant's familiar installation footprint.

Advanced Energy Efficiency

The ecoTEC Plus 635 combines high-efficiency condensing technology with intelligent combustion monitoring to maximise seasonal performance while reducing gas usage and operating costs.

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

Smart Heating Control Compatibility

Compatible with myVAILLANT connect and Vaillant's latest smart heating controls, the ecoTEC Plus 635 enables homeowners to manage heating remotely, optimise energy usage, and improve everyday comfort.

It also integrates seamlessly with Vaillant renewable heating products and hybrid systems for greater long-term flexibility.

Reliable Performance & Easy Maintenance

The ecoTEC Plus 635 incorporates Vaillant's linBUS technology, providing intelligent monitoring of flow rates and pump performance to optimise system efficiency.

Combined with guided commissioning, intuitive controls, and improved internal accessibility, installation and maintenance are faster and more convenient than previous generations.

Warranty & Peace of Mind

The Vaillant ecoTEC Plus 635 includes 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, offering additional confidence and long-term protection.

Why Choose the Vaillant ecoTEC Plus 635?

• Powerful 35kW system gas boiler
• Ideal for larger homes with higher heating demands
• IoniDETECT intelligent combustion technology
• Up to 1:10 burner modulation
• Hydrogen Blend Ready (20%)
• Smart home compatible
• Compact installation footprint
• Easy installation and servicing
• Up to 10-year warranty available
• Compatible with Vaillant renewable heating solutions