Worcester Bosch 4000 25kW Combi Boiler with 15mm Scale Reducer

The Worcester Bosch 4000 25kW Combi Boiler with 15mm Scale Reducer is a premium heating package designed to provide reliable central heating and instant mains-pressure hot water for small to medium-sized homes. Supplied with a 15mm Scale Reducer, this complete solution helps minimise limescale build-up in hard water areas, protecting the boiler and maintaining long-term efficiency and performance. The Greenstar 4000 is one of Worcester Bosch's quietest and most advanced combi boilers, delivering outstanding comfort, energy efficiency, and everyday reliability.

Part of the award-winning Worcester Bosch Greenstar 4000 range, this boiler features QuickTap® hot water technology, a modern full-colour display, intelligent modulation, and compatibility with EasyControl smart heating controls. Its compact design makes it suitable for installation inside a standard kitchen cupboard while delivering exceptional heating performance.

Key Features

• 25kW Natural Gas Combination (Combi) Boiler
• Includes 15mm Scale Reducer
• Fuel Type: Natural Gas
• Instant mains-pressure hot water
• No separate hot water cylinder required
• ErP A Rated for heating and hot water
• Up to 94% efficiency
• Super quiet operation
• Quiet Mark certified
• QuickTap® hot water pre-heat function
• Stainless steel heat exchanger
• Full-colour LCD display
• Compact cupboard-fit design
• Compatible with Worcester Bosch EasyControl
• Intelligent boiler modulation
• 10-Year manufacturer's warranty (subject to installation and registration terms)

Ideal for Small to Medium Homes

The Worcester Bosch 4000 25kW Combi Boiler is ideal for apartments, flats, and small to medium-sized homes with one bathroom. It provides both central heating and domestic hot water directly from the mains, removing the need for a separate hot water cylinder while delivering dependable performance throughout the year.

The included 15mm Scale Reducer helps reduce limescale accumulation, making this package particularly suitable for homes in hard water areas.

Efficient Heating & Instant Hot Water

Delivering 25kW domestic hot water output and a 10.2 litres per minute flow rate (Δ35°C), the Greenstar 4000 provides consistent hot water for everyday household use while maintaining efficient central heating performance.

Its innovative QuickTap® technology pre-heats the plate heat exchanger, helping reduce waiting time for hot water while minimising water wastage. Combined with intelligent condensing technology, it delivers exceptional efficiency without compromising comfort.

Compact Design

Designed to fit neatly inside a standard kitchen cupboard, the Greenstar 4000 combines powerful performance with a space-saving footprint.

Dimensions

• Height: 724mm
• Width: 400mm
• Depth: 310mm

The supplied 15mm Scale Reducer provides additional protection against limescale, helping to maintain boiler efficiency and reduce long-term maintenance requirements.

Advanced Energy Efficiency

Rated ErP A and delivering up to 94% efficiency, the Greenstar 4000 helps reduce gas consumption and lower household energy bills.

Its advanced condensing technology and wide modulation range enable the boiler to operate efficiently even at lower heating demands, providing excellent seasonal performance.

Smart Heating Control Compatibility

The Greenstar 4000 is fully compatible with Worcester Bosch EasyControl, allowing homeowners to control their heating remotely, create personalised schedules, and optimise energy usage for greater comfort and efficiency.

Reliable Performance & Easy Maintenance

Engineered with Worcester Bosch's renowned build quality, the Greenstar 4000 features a stainless steel heat exchanger, installer-friendly internal layout, and a modern full-colour interface for easy monitoring and diagnostics.

Its Quiet Mark certification makes it one of the quietest boilers in its class, making it particularly suitable for kitchens and open-plan living spaces.

Warranty & Peace of Mind

The Worcester Bosch 4000 25kW Combi Boiler with 15mm Scale Reducer includes a 10-Year manufacturer's warranty (subject to installation by an accredited installer and product registration), providing long-term confidence and dependable after-sales support.

Why Choose the Worcester Bosch 4000 25kW Combi Boiler with 15mm Scale Reducer?

• Premium boiler and scale protection package
• Efficient 25kW combi boiler
• Natural Gas compatible
• 10.2 L/min domestic hot water flow rate
• Includes 15mm Scale Reducer
• Quiet Mark certified
• QuickTap® hot water technology
• EasyControl compatible
• Compact cupboard-fit design
• 10-Year manufacturer's warranty