The Worcester Bosch Greenstar 8000 sits at the top of the Worcester residential range and competes directly with Viessmann's Vitodens. We've installed dozens of them — here's our honest assessment.
Efficiency
The Greenstar 8000 achieves up to 95.3% ErP seasonal space heating efficiency. That puts it among the most efficient gas boilers available in the UK. In practice, this translates to lower gas bills versus a standard A-rated boiler.
Build quality
The 8000 features a stainless steel heat exchanger, which Worcester Bosch claims outperforms aluminium alternatives on longevity. Build quality feels premium — the casing is solid and the internal components are well-engineered.
Warranty
Up to 12 years when installed by a Worcester Bosch Accredited Installer. This is the longest warranty of any mainstream brand and is a significant selling point. We are Worcester Bosch Accredited, so all our Greenstar 8000 installations carry the full 12-year cover.
Controls and connectivity
The 8000 is OpenTherm compatible and works natively with the Worcester Bosch Wave smart thermostat. The app interface is clean and responsive. OpenTherm modulation means the boiler runs at partial load more efficiently rather than cycling on and off.
Noise
One of the quieter boilers we install — typically 47–49 dB at 1 metre. Suitable for kitchen and hallway installations without being intrusive.
Verdict
The Greenstar 8000 is genuinely excellent. The 12-year warranty alone justifies the premium over mid-range alternatives. Highly recommended for homeowners who want the best available gas boiler.