Worcester Bosch Greenstar 28CDi Compact

What is the Greenstar 28CDi Compact?

The Greenstar 28CDi Compact is a wall-mounted gas combi boiler and the entry-level model in the Greenstar CDi Compact range. It was specifically designed to fit inside a standard kitchen cupboard, making it one of the smallest boilers Worcester Bosch had ever produced at the time of its launch.

Despite its compact dimensions, the 28CDi Compact delivered strong heating and hot water performance thanks to Worcester Bosch’s innovative WB7 heat exchanger. It provided instant hot water on demand from the mains without the need for a cylinder or storage tank, making it a practical choice for homes where space was at a premium.

The 28CDi Compact was part of the Greenstar CDi Compact range, which offered the performance of the larger CDi Classic in a cupboard-sized footprint.

> Explore the full Worcester Bosch Greenstar range

Greenstar 28CDi Compact: Key Specifications

Boiler type: Combi boiler

Central heating output: 24kW

Hot water output: 28kW

Efficiency rating: A rated / 90.5%

Fuel type: Natural gas or LPG

Dimensions: 690mm x 390mm x 280mm

Flow rate: 11.4 litres per minute

Frost protection: Yes

Smart control compatible: Yes, including Bosch EasyControl

Suitable for: 1 to 3 bed homes, up to 15 radiators, 1 bathroom

Who is this boiler suitable for?

The 28CDi Compact was designed for smaller homes where space was limited but performance still mattered. It is best suited to properties with:

• 1 to 3 bedrooms
• 1 bathroom
• Up to 15 radiators
• No existing hot water cylinder
• Limited installation space, such as a kitchen cupboard

The key advantage of the 28CDi Compact over the larger CDi Classic range was its cupboard-sized dimensions, making it suitable for properties where a standard wall-mounted boiler simply would not fit. If you already have a 28CDi Compact 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 28CDi Compact

Although the 28CDi Compact 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 and surrounding areas.

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 28CDi Compact 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 28CDi Compact

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 28CDi Compact has been replaced by the Worcester Bosch Greenstar 4000, which offers meaningful improvements across efficiency, warranty and controls while maintaining a compact footprint.

The Greenstar 4000 25kW is the natural modern equivalent for homes currently running a 28CDi Compact. It delivers better efficiency, a longer warranty and full compatibility with the Bosch EasyControl smart thermostat.

Greenstar 28CDi Compact vs Greenstar 4000 25kW

Efficiency: 90.5% vs up to 94%

Warranty: 2 to 5 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 CDi Compact models, across Buckinghamshire, Berkshire and surrounding areas.

• 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 28CDi Compact

Is the Worcester Bosch Greenstar 28CDi Compact still available to buy?

No. The 28CDi Compact is no longer manufactured. The modern equivalent is the Worcester Bosch Greenstar 4000 25kW combi boiler, which offers improved efficiency and a longer warranty while maintaining a compact design.

Can the Greenstar 28CDi Compact still be serviced?

Yes. Parts remain widely available and our Gas Safe engineers service and repair all CDi Compact models across Buckinghamshire and Berkshire. Annual servicing is recommended to maintain efficiency and safety.

What replaced the Greenstar 28CDi Compact?

The Greenstar 28CDi Compact was replaced by the Worcester Bosch Greenstar 4000. The 4000 offers up to 94% efficiency, smart control compatibility and up to a 10-year warranty when installed by a Platinum Accredited Installer.

How efficient is the Greenstar 28CDi Compact?

The 28CDi Compact achieves 90.5% seasonal efficiency with an ErP A rating. Modern replacements such as the Greenstar 4000 achieve up to 94%, which can make a noticeable difference to running costs over time.

Will the Greenstar 28CDi Compact fit in a kitchen cupboard?

Yes. The 28CDi Compact was specifically designed to fit inside a standard kitchen cupboard at 690mm x 390mm x 280mm. This was its key advantage over the larger CDi Classic range and made it ideal for homes with limited installation space.

How long should a Greenstar 28CDi Compact last?

With regular annual servicing, a well-maintained 28CDi Compact 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.