🔍 Key Features
Efficiency: Up to 94% ErP A-rated
Quiet Operation: Sub-45dB noise levels
Smart Controls: Compatible with Worcester EasyControl, Nest, Hive
Compact Design: Fits standard kitchen cupboards
Warranty: Up to 10 years with accredited installer
C6 Heat Exchanger: Aluminium-silicon design with decades of proven reliability
Performance & Build
The boiler uses the C6 aluminium-silicon heat exchanger, an evolution of the tried-and-tested WB3, refined over 20+ years. Excellent heat transfer and longevity make it a solid choice when paired with proper system maintenance. Its wide modulation ratio up to 1:10 reduces on/off cycling, enhances efficiency, and keeps temperatures consistent.
Hot water output (30kW version) reaches around 12.3 L/min at a 35°C rise.
💡 Controls & Smart Features
Clear LCD interface with intuitive push-buttons
Weather and load compensation for optimal efficiency
Works with third-party thermostats (Nest, Hive), though true load compensation and the highest efficiencies is achieved with Worcester’s native controls and sensors.
Worcester controls come with 24-month guarantees
🏡 Day-to-Day Use
Virtually silent operation
Smooth start-ups and stable heating
Easy servicing with removable panels
Compact enough for kitchen cupboards
🔧 Reliability & Maintenance
Proven C6 aluminium-silicon heat exchanger
Requires proper system maintenance: magnetic filter and inhibitor recommended
Annual servicing straightforward and cost-effective
Parts readily available
Up to 10-year warranty with accredited installation
🌍 Environmental Impact
Low NOx emissions (Class 6)
High efficiency reduces gas consumption and carbon footprint
Lower flow temperatures (50–60°C) improve condensing efficiency and future heat-pump readiness
💰 Costs & Installation
Boiler only: ~£1,200
Full installation: £2,000–£2,500 (including sundries and installation)
Warranty up to 10 years with accredited installer
🏆 Pros
Compact, cupboard-friendly design
Low noise operation
Excellent 1:10 modulation for efficiency and comfort
Proven C6 heat exchanger with decades of reliability
Compatible with smart controls
Up to 10-year warranty
Simple servicing and parts availability
❌ Cons
Aluminium heat exchanger requires clean, maintained water
Slightly higher cost than some rivals
No built-in Wi-Fi without EasyControl
Less suited to homes with very high hot-water demand (use heat-only boiler with hot water cylinder instead)
| Feature / Brand | Worcester Bosch Greenstar 4000 | Viessmann Vitodens 100-W | Vaillant ecoTEC Plus |
|---|---|---|---|
|
Heat Exchanger |
C6 Aluminium-silicon
|
Stainless steel
|
Stainless steel
|
|
Softened Water Use
|
Not recommended (requires bypass)
|
Yes
|
Limited approval
|
|
Modulation
|
Up to 1:10
|
Up to 1:10
|
Up to 1:6
|
|
Max Efficiency
|
94%
|
94%
|
94%
|
|
NOx |
Low (Class 6) |
Very low |
Low (Class 6) |
|
Smart Controls |
EasyControl, Nest, Hive |
ViCare |
sensoHOME |
|
Warranty |
Up to 10 years |
Up to 12 years |
Up to 10 years |
🏁 Final Verdict
The Worcester Bosch Greenstar 4000 Combi is a reliable, efficient, and quiet boiler for small to medium homes. Its modern controls, compact design, and long warranty make it a smart investment for Wokingham homeowners.
The Boilersmith offers expert installation in Wokingham, Woodley, Twyford, Winnersh, Earley, Lower Earley, Barkham, Finchampstead, Arborfield, Hurst, Spencers Wood, and Shinfield. As Worcester Accredited Installers and Gas Safe Registered Engineers, we ensure your boiler is installed to the highest standards with full warranty coverage.
For comparisons with Viessmann Vitodens or Vaillant ecoTEC, our team helps you find the best solution for efficiency, reliability, and comfort.