WORCESTER BOSCH GREENSTAR 24i JUNIOR

What is the Greenstar 24i Junior?

The Greenstar 24i Junior is a wall-mounted gas combi boiler and one of the original models in Worcester Bosch’s Greenstar Junior range. For many years it was the go-to choice for smaller homes and apartments across the UK, known for its reliability, compact size and low maintenance requirements.

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. Despite being a smaller boiler, it was highly regarded for its consistent performance and the trust homeowners placed in the Worcester Bosch brand.

The 24i Junior was discontinued in 2015 and replaced by the Greenstar 25i, which offered improved flow rates and better efficiency. It has since been superseded by the Worcester Bosch Greenstar 4000.

> Explore the full Worcester Bosch Greenstar range

Greenstar 24i Junior: Key Specifications

✔ Boiler type: Combi boiler

✔ Central heating output: 24kW

✔ Hot water output: 24kW

✔ Efficiency rating: A rated / 89.1%

✔ Fuel type: Natural gas or LPG

✔ Dimensions: 710mm x 400mm x 300mm

✔ Flow rate: 9.8 litres per minute

✔ Frost protection: Yes

✔ Smart control compatible: Yes, including Bosch EasyControl

✔ Suitable for: 1 to 2 bed homes, up to 10 radiators, 1 bathroom

Who is this boiler suitable for?

The 24i Junior was designed for smaller homes and apartments with modest heating and hot water demand. It is best suited to properties with:

• 1 to 2 bedrooms
• 1 bathroom
• Up to 10 radiators
• No existing hot water cylinder
• Standard mains water pressure

The 24i Junior was ideal for running a shower in a small property but was not well suited to homes that needed to fill a bath quickly or run multiple outlets at the same time. For those needs, the 28i Junior offered a higher flow rate within the same range. If you already have a 24i Junior 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 24i Junior

Although the 24i Junior 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 24i Junior 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 24i Junior

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 24i Junior was replaced first by the Greenstar 25i and has since been succeeded by the Worcester Bosch Greenstar 4000, which offers significantly better efficiency, a longer warranty and modern controls.

The Greenstar 4000 25kW is the natural modern equivalent for homes currently running a 24i Junior. It delivers better efficiency, a longer warranty and full compatibility with the Bosch EasyControl smart thermostat.

Greenstar 24i Junior vs Greenstar 4000 25kW

Efficiency: 89.1% vs up to 94%

Warranty: 2 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 Junior 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 24i Junior

Is the Worcester Bosch Greenstar 24i Junior still available to buy?

No. The 24i Junior was discontinued in 2015 and replaced first by the Greenstar 25i and then by the Worcester Bosch Greenstar 4000. The Greenstar 4000 25kW is the current modern equivalent.

Can the Greenstar 24i Junior still be serviced?

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

What replaced the Greenstar 24i Junior?

The 24i Junior was replaced in 2015 by the Greenstar 25i, which offered improved flow rates and better efficiency. The 25i has since been replaced by the Worcester Bosch Greenstar 4000.

How efficient is the Greenstar 24i Junior?

The 24i Junior achieves 89.1% seasonal efficiency with an ErP A rating. Modern replacements such as the Greenstar 4000 achieve up to 94%, which represents a meaningful improvement in running costs over time.

What size home is the Greenstar 24i Junior suitable for?

The 24i Junior is suited to smaller homes with 1 to 2 bedrooms, 1 bathroom and up to 10 radiators. For properties needing higher hot water output, the 28i Junior offered a higher flow rate within the same range.

How long should a Greenstar 24i Junior last?

With regular annual servicing, a well-maintained 24i Junior can last between 12 and 15 years. Given that this model was discontinued in 2015, many units are now approaching or beyond that age. If this applies to your boiler, it may be worth considering a boiler replacement to avoid repeated repair costs.