WORCESTER BOSCH GREENSTAR 25i

What is the Greenstar 25i?

The Greenstar 25i is a wall-mounted gas combi boiler and the entry-level model in Worcester Bosch’s Greenstar i range. Introduced in 2015 as a replacement for the 24i Junior, it became one of the UK’s best-selling boilers, praised for its compact size, reliable performance and straightforward controls.

As a combi boiler, it provides heating and instant hot water on demand directly from the mains without the need for a separate cylinder or storage tank. Its compact dimensions made it easy to install in kitchen cupboards, utility rooms and airing cupboards, making it a practical choice for smaller properties.

The Greenstar i range won the Which? Best Buy award multiple times. Discontinued in 2020 to 2021, the 25i has been replaced by the Worcester Bosch Greenstar 4000.

> Explore the full Worcester Bosch Greenstar range

Greenstar 25i: Key Specifications

✔ Boiler type: Combi boiler

✔ Central heating output: 24kW

✔ Hot water output: 25kW

✔ Efficiency rating: A rated / 93%

✔ Fuel type: Natural gas or LPG

✔ Dimensions: 700mm x 400mm x 330mm

✔ Flow rate: 10.2 litres per minute

✔ Frost protection: Yes

✔ Smart control compatible: Yes, including Bosch EasyControl

✔ Suitable for: 1 to 3 bed homes, up to 10 radiators, 1 bathroom

Who is this boiler suitable for?

The Greenstar 25i was designed for smaller homes and apartments with a single bathroom and modest hot water demand. It is best suited to properties with:

• 1 to 3 bedrooms
• 1 bathroom
• Up to 10 radiators
• No existing hot water cylinder
• Standard mains water pressure

The 25i is ideal for running a shower but will be slower to fill a bath than its sibling the 30i, due to its lower flow rate of 10.2 litres per minute. For homes with a bath and shower, the Greenstar 30i was the better choice within the same range. If you already have a Greenstar 25i installed and are unsure whether to service, repair or replace it, our engineers can assess your system and give you honest advice.

Servicing and repairing your Greenstar 25i

Although the Greenstar 25i is no longer manufactured, it can still be serviced and repaired. Parts remain widely available for this model and our Gas Safe engineers carry out full services and fault diagnosis across Buckinghamshire, Berkshire, West London and surrounding counties.

Regular servicing is important for any boiler, but particularly for older models. An annual service helps to:

• Maintain efficiency and keep running costs down
• Identify worn components before they cause a breakdown
• Keep your boiler operating safely
• Satisfy any remaining warranty or insurance requirements

> Book a boiler service

If your Greenstar 25i has developed a fault, our engineers carry a wide range of Worcester Bosch parts and aim to resolve most repairs in a single visit.

> Book a boiler repair

When to consider replacing your Greenstar 25i

If your boiler is over 12 to 15 years old or experiencing repeated breakdowns, replacement is often the more cost-effective long-term decision. The Greenstar 25i has been replaced by the Worcester Bosch Greenstar 4000, which was built on the same trusted foundations as the i range with improved efficiency, a longer warranty and updated controls.

The Greenstar 4000 25kW is the direct modern replacement for homes currently running a Greenstar 25i. It delivers better efficiency, a longer warranty and full compatibility with the Bosch EasyControl smart thermostat.

Greenstar 25i vs Greenstar 4000 25kW

Efficiency: 93% vs up to 94%

Warranty: 5 to 7 years vs up to 10 years

Controls: Basic display vs smart control ready

ErP rating: A rated vs A rated

Status: Discontinued vs current model

> Learn more about the Greenstar 4000

> View boiler costs

> Explore finance options

Why choose Heppelthwaite – Red Van Plumbers?

Fewer than 5% of UK installers achieve Worcester Bosch Platinum Accredited status. As Platinum Accredited Installers, we install, service and repair the full Greenstar range, including legacy i range models, across Buckinghamshire, Berkshire, West London and surrounding counties.

• Platinum Accredited Worcester Bosch Installers
• Family-run business established 1948
• Gas Safe registered engineers
• Free fixed quotations with no hidden costs
• Up to 10-year warranty available on new Greenstar 4000 installations

> Request a free quote or call 01628 533 550

FAQs – Worcester Bosch Greenstar 25i

Is the Worcester Bosch Greenstar 25i still available to buy?

No. The Greenstar 25i was discontinued in 2020 to 2021. The direct modern replacement is the Worcester Bosch Greenstar 4000 25kW combi boiler, which offers improved efficiency and a longer warranty.

Can the Greenstar 25i still be serviced?

Yes. Parts remain widely available and our Gas Safe engineers service and repair all Greenstar i range models across Buckinghamshire, Berkshire and West London. Annual servicing is recommended to maintain efficiency and safety.

What replaced the Greenstar 25i?

The Greenstar 25i was replaced by the Worcester Bosch Greenstar 4000. Built on the foundations of the i range, the 4000 offers up to 94% efficiency, smart control compatibility and up to a 10-year warranty when installed by a Platinum Accredited Installer.

What is the difference between the Greenstar 25i and the 30i?

Both models share the same central heating output of 24kW. The key difference is the hot water output and flow rate. The 25i delivers 10.2 litres per minute while the Greenstar 30i delivers 12.3 litres per minute. For homes with a bath and shower, the 30i was the more appropriate choice.

How efficient is the Greenstar 25i?

The Greenstar 25i achieves 93% seasonal efficiency with an ErP A rating. The Greenstar 4000 matches or slightly improves on this while offering a significantly longer warranty period.

How long should a Greenstar 25i last?

With regular annual servicing, a well-maintained Greenstar 25i can last between 12 and 15 years. If your boiler is approaching or has exceeded this age, it may be worth considering a boiler replacement to avoid repeated repair costs.