Worcester Bosch Greenstar Heatslave II External 18/25 Oil Combi Boiler (2022+)

Product Description

The Worcester Bosch Greenstar Heatslave II External 18/25 Oil Combi Boiler is a powerful and space-saving heating solution designed for outdoor installation. Ideal for homes with limited indoor space, this external unit delivers both central heating and instant hot water from a single appliance.

Built for durability and performance, it operates efficiently even in harsh weather conditions, making it a reliable choice for year-round use. The one-piece stainless steel primary baffle allows for quicker servicing and maintenance, while the quiet operation ensures minimal disruption.

With high hot water output and compatibility with optional programmers and system filters, this boiler offers flexibility, convenience, and long-term reliability.

Why Customers Should Buy This Product

• External installation frees up indoor space
• All-in-one combi system for heating and hot water
• High hot water flow rate (22 l/min) for strong performance
• 25kW output suitable for medium to larger homes
• Designed for outdoor durability in all weather conditions
• Quiet operation for minimal noise impact
• Easy servicing design with stainless steel primary baffle
• Compatible with optional programmers and controls
• Upgradeable warranty up to 5 years with system filter
• Trusted reliability from Worcester Bosch

Key Specifications

• Brand: Worcester Bosch
• Range: Greenstar Heatslave II
• Product Type: Oil Combi Boiler (External)
• Output: 25kW
• Fuel Type: Oil
• ERP Rating: B
• Mounting Type: Floor Standing (External)

Dimensions:

• Height: 950 mm
• Width: 640 mm
• Depth: 770 mm

Performance:

• Heat Output: 25 kW
• BTU Output: 85,000 BTU
• Hot Water Flow Rate (ΔT 35°C): 22 litres/min
• CH Condensing Max Output: 25 kW

Features:

• External weatherproof design
• Stainless steel primary baffle
• LCD display
• Quiet operation
• Solar compatible
• Optional programmer compatibility

Flue:

• Max Vertical Flue Length: 5 m

Warranty:

• Standard: 2 Years
• Extended: Up to 5 Years (with Greenstar system filter)

Installation & Compatibility

• Suitable for properties requiring external boiler installation
• Ideal for off-grid homes using oil fuel
• Compatible with Worcester Bosch controls and accessories

What’s in the Box

• 1 x External Oil Combi Boiler Unit
• Installation Instructions

Important Information

• Oil-fired boiler – requires oil storage tank
• External installation only
• Flue and additional accessories may be required depending on setup