Greenstar 4000 - The best, reborn.

The best, reborn - introducing the new Worcester Bosch 4000 gas boiler

The Worcester Bosch Greenstar i has earned itself an unrivalled reputation as the UK’s best-selling gas combi boiler. Now, the team at Worcester Bosch have taken the DNA of this firm favourite and made it even better. Meet the all-new Worcester Bosch 4000.

Even more to love about your boiler

Built on all the tried, tested and much-loved features of the Greenstar i, the Greenstar 4000 gas boiler is instantly familiar and yet totally transformed.

Worcester Bosch have raised the bar with the speed and ease of installation, commissioning and servicing, alongside improvements in efficiency and control. And if that wasn’t enough, they’ve even kept the price the same as its predecessor.

Available in both natural gas and LPG

The 4000 range is available in both natural gas and LPG for:

  • Combi - 25kW and 30kW with hot water flow rates up to 12.3 l/min
  • System - 12 - 24kW

The 4000 will also carry the same guarantee lengths as its predecessor the Greenstar i. The Greenstar i System 27 and 30kW variants with the WB7 compact heat exchanger will continue to be available.

10 reasons to choose the Worcester Bosch 4000

1. SimpleSwitch and Wall mounting frame

The 4000 is truly the easiest option when replacing the i Junior, Si combi and i System models (2005-2015). SimpleSwitch refers to sharing the same positions for the top and bottom wall-frame screws, the pipework positioning, PRV, siphon and flue.

The wall-frame provides pre-piping option for all 7 combi pipe connections before the boiler is hung, along with the option to pipe vertically behind the boiler.

2. Front access to all key components including PRV

No component has been left unturned within the appliance. By merely loosening two screws, the front cover can be removed, meaning engineers will rarely need to remove the right side panel for further access. As a result, it is easier than ever to service and maintain.

The PRV (pressure relief valve) is at the front and the secondary plate heat exchanger can be removed with just one screw.

3. Intuitive full-text colour display

The new 4000 features the same control display as the design-led 8000 Style. This enables you to control the system more easily and comfortably, and helps engineers to complete commissioning and servicing faster, along with the ability to easily find any future faults.

4. Max. 12m flue lengths (60/100)

The 4000 has longer flue lengths compared the Greenstar i - up to 12m horizontal and vertical (60/100). For 80/125 the maximum flue length can go as far as 21m. This gives you more flexibility when it comes to locating your boiler.

5. Full flow rates from 1 bar mains pressure

The perfect choice for high-rise installations, such as flats or penthouses in addition to areas such as the South East and major cities with low mains pressure.

6. Large 500ml condensate siphon

The large capacity condensate siphon increases the volume of condensate discharge and significantly reduces the risk of freezing with the siphonic release increasing speed of flow, pre-warmed to internal boiler temperatures.

7. Quieter operation

10% quieter than the Greenstar i, the 4000 combi operates at 45dB(a) and our system variants are as low as 42dB(a).

8. 100% planet-friendly packaging

We’ve removed all polystyrene packaging and replaced it with a household recyclable honeycomb cardboard.

Plastic bags have also been removed and replaced with compostable bags. These bags can be placed in garden waste for composting or used as a food waste bin bag.

9. Intelligent auto filling

Our industry-first Greenstar Intelligent Filling System automatically monitors and adjusts system pressure, reducing the need for end-user intervention and associated system pressure call-outs.

10. Modulates down to 3kW CH - reducing gas consumption

Up to 1:10 modulation range reduces gas consumption, energy bills and wear and tear on components.

The 25 and 30kW combi can modulate down to 3kW and our 12kW system to just 1.9kW!

Find out more at

Ready to replace your boiler?

Interested in replacing your boiler with the brand new Worcester Bosch 4000? Get in touch with your trusted, local experts today. Call D. R. Plumbing & Heating now on 01978 291 923 / 01352 620 125. Don’t forget to ask us about affordable boiler finance.

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