Worcester Bosch 21Ri Heat Only Boiler Including Flue & 15mm Scale Reducer

The Worcester Bosch 21Ri Heat Only Boiler Including Flue & 15mm Scale Reducer is a compact and highly efficient heating package designed for homes with a traditional open-vent or conventional heating system. Supplied with a horizontal flue kit and a 15mm Scale Reducer, this complete package provides dependable central heating while helping protect the boiler against limescale build-up in hard water areas, ensuring long-term performance and reliability.

Part of the trusted Worcester Bosch Greenstar Ri range, the 21Ri is ideal for properties with an existing hot water cylinder and cold water storage tank. Its compact cupboard-fit design, quiet operation, and compatibility with modern heating controls make it an excellent choice for replacement installations and heating system upgrades.

Key Features

• 21kW Heat Only (Regular) Boiler
• Includes Horizontal Flue Kit
• Includes 15mm Scale Reducer
• Fuel Type: Natural Gas
• Designed for open-vent and conventional heating systems
• Requires a separate hot water cylinder and cold water storage tank
• ErP A Rated for heating
• Up to 92% seasonal efficiency
• Compact cupboard-fit design
• Multi-directional flue options
• EasyControl compatible
• Solar compatible
• Simple fascia-mounted temperature control
• Quiet operation
• Up to 10-Year manufacturer's warranty (subject to installation, registration, use of a Worcester Bosch system filter, and manufacturer's terms)

Ideal for Traditional Heating Systems

The Worcester Bosch 21Ri Heat Only Boiler is ideal for small to medium-sized homes that already have a traditional heating system with a separate hot water cylinder and cold water storage tank. Heat only boilers are particularly suited to replacing existing regular boilers while retaining the current system pipework and hot water storage.

The included 15mm Scale Reducer helps minimise limescale build-up, making this package especially suitable for homes in hard water areas.

Reliable Central Heating Performance

With a 21kW central heating output, the Greenstar 21Ri delivers efficient and consistent heating throughout the home. As a Heat Only (Regular) Boiler, it is designed exclusively for central heating and works alongside a separate hot water cylinder to provide stored domestic hot water.

Its advanced condensing technology helps maximise energy efficiency while reducing gas consumption and household heating costs.

Compact Design

Designed to fit neatly inside a standard kitchen cupboard, the Greenstar 21Ri offers exceptional installation flexibility without sacrificing performance.

Dimensions

• Height: 600mm
• Width: 390mm
• Depth: 270mm

The included horizontal flue and 15mm Scale Reducer provide a complete installation package while helping maintain long-term boiler efficiency.

Advanced Energy Efficiency

Rated ErP A with 92% seasonal heating efficiency, the Greenstar 21Ri uses advanced condensing technology to maximise heat output while reducing energy consumption.

Its compatibility with renewable technologies such as solar thermal systems also provides greater flexibility for future heating upgrades.

Smart Heating Control Compatibility

The Greenstar 21Ri is compatible with Worcester Bosch EasyControl and a range of Worcester heating controls, allowing homeowners to improve comfort, optimise energy usage, and manage heating more efficiently.

Reliable Performance & Easy Maintenance

Built with Worcester Bosch's renowned engineering quality, the Greenstar 21Ri features a durable, installer-friendly design with simple controls and easy servicing access.

Its compact dimensions and flexible flue positioning make installation straightforward in both new and replacement heating systems.

Warranty & Peace of Mind

The Worcester Bosch 21Ri Heat Only Boiler Including Flue & 15mm Scale Reducer includes up to a 10-Year manufacturer's warranty when installed with a Worcester Bosch system filter by an accredited installer and registered in accordance with the manufacturer's warranty terms.

Why Choose the Worcester Bosch 21Ri Heat Only Boiler Including Flue & 15mm Scale Reducer?

• Complete boiler, flue, and scale protection package
• Efficient 21kW heat only boiler
• Natural Gas compatible
• Designed for traditional heating systems
• Includes Horizontal Flue
• Includes 15mm Scale Reducer
• Compact cupboard-fit design
• EasyControl compatible
• Solar compatible
• Up to 10-Year manufacturer's warranty