4000 which

Created from the DNA of the UK’s best-selling Greenstar i

We’ve kept everything we know you and your customers love and then raised the bar with the ease of installation, commissioning and servicing.

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

Meet our Key Account team

Our specification team have the expertise and knowledge to help you with your needs. Find your local specification manager and get in touch for any enquiries. 

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Installation Benefits


simple switch


Seamless swapping out of i Junior, Si combi and i System boilers (2005-2015).

Fixing points, pipe centres and distance from flue to valves match predecessor models for minimum time, effort and re-work.

flue lengths

Max. flue lengths up to 12m (60/100)

One of the key enhancements of the Greenstar 4000, over the Greenstar i, is the flexibility offered with substantially longer flue lengths both horizontally and vertically.

condensate siphon

Condensate siphon

The large capacity 500ml condensate siphon increases the volume of condensate discharge - significantly reducing the risk of freezing.

Intelligent Filling System

Intelligent Filling System

Bringing the very latest innovative technology to more customers.

The Greenstar Intelligent Filling System constantly monitors the system pressure within the Greenstar 4000, and if ever this drops, it will automatically re-fill the system to the optimum level.

No customer interaction required.

Landlord Function

Available with Comfort+ RF key and Comfort+ I control.  3 service reminder be set for the occupier to be alerted.  If the reminders are ignored for 30 days, three actions can be selected.

- No reduction in comfort (factory default)

- Reduced CH and DHW comfort – 35°C for both

- Boiler off – frost protection is still active

Commissioning and control display benefits



Benchmark Commissioning Checklist

Complete the Benchmark Commissioning Checklist easily thanks to our clearly laid out Benchmark menu structure.

boiler status overview

Boiler status overview and clear menus

Set the boiler to achieve maximum comfort and efficiency for your customer.

current fault

Full text descriptions

Allows you and your customer to know the exact status of the boiler.

Servicing Benefits



Improved PRV and Hydraulics

The PRV is situated at the front and the secondary heat exchanger can be taken out of the boiler with the removal of just one screw.

heat exchanger

Primary Heat Exchanger

Our C6 heat exchanger has evolved from the Greenstar i. Access to burner and heat exchanger baffles by removing just one screw and one bolt.

Our heat exchanger continues to have a 10 year guarantee as standard.  Terms and conditions apply.

service reminders

Service Reminders

Service reminders can be set by the number of months (default is 12 months) or the number of burner operating hours. Specific dates can be selected when a Comfort+ or Comfort+ I RF is installed.

4000 Controls

Our Greenstar 4000 is compatible with a range of wired and wireless control options to suit your exact requirements, as well as third party controls.

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We provide a host of accessory to help ensure your heating system is fully optimised and in accordance with the latest safety and industry guidelines.

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Greenstar 4000 Specifiers guide

Greenstar 4000 Specifiers Guide