It’s official the new Greenstar 4000 Combi boiler has launched! Created from the original DNA of the Greenstar i, Worcester Bosch have built a totally transformed model but still with the tried and tested features of the Greenstar i.

What does the 4000 range include?

The Greenstar 4000 has the option of either a 25kW or 30kW combi and between a 12-24kW system.

It is also available in natural gas with LPG due to follow shortly. The system is compatible with a range of Worcester Bosch controls and boasts a simple and quick installation process.



  • Ease of inn SimpleSwitch to previous Worcester i Junior and Si models with pre-piping jig offering rear piping as standard.
  • Flexibility of siting provided by long flue lengths (up to 12m with 60/100mm flues), 500ml integrated condensate siphon to reduce the risk of freezing and the boiler’s ability provide full hot water flow rates in low water pressure areas.
  • Complete peace of mind for the end user with a 10-year heat exchanger and a 7-year product guarantee available as standard. Wide modulation range designed to optimise efficiency when heating demand is low.
  • High-end design, quiet operation (up to 45dB(A)) with an intuitive, long text, colour boiler display offering optional intelligent filling solutions.


Why Install a Greenstar 4000 Combi?

  • Reduce gas consumption
  • Lower energy bills
  • Water saving function to reduce water waste
  • Easy to use colour display
  • Wireless connectivity with Bosch EasyControl
  • Instantaneous hot water, always available
  • Suitable for small to medium sized homes
  • An extremely quiet combi boiler
  • Operates very well in low water pressure areas
  • 100% planet friendly packaging



The Greenstar 4000 combi is Worcester Bosch’s mid-range boiler, achieving a 4/5-star rating for price.

However, it’s important to note that the price (while not the cheapest available) does cover the excellent quality and aftercare provided.

For reliability it comes up trumps with a 5/5-star review, this is mostly down the reputation of Worcester Bosch and the fact that they have been rated as offering the best combi boilers of 2021.

They are also rated highly by Which? And have carried the Best Buy Award for over 10 years now.

Performance it also comes in at 5/5 with a heat output of up to 30kW and a flow rate of 12.3 l/min – this is better than the previous model.
There is the lower output option too, suitable for smaller properties.

It is also noted that the size is more slimline that the Greenstar i, making it ideal for fitting into smaller spaces, including kitchen cupboards.


To get yours installed, contact Green Flame today.


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