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Last updated: 10th May, 2024


Worcester Bosch Greenstar Ri Heat-Only Boiler Review

Worcester Bosch Greenstar Ri Heat-Only Boiler Review

Key takeaways

  • The Worcester Bosch Greenstar Ri is a compact and practical heat-only boiler.
  • Models possess high energy efficiency ratings, promising potential savings.
  • The range offers varied capacities to suit diverse domestic requirements.

Heat-only boilers, also known as 'regular' or 'conventional' boilers, form a vital component of many UK home heating systems.

As homeowners evaluate their heating systems, the Worcester Bosch Greenstar Ri series stands out for those requiring a heat-only regular boiler. Known for its compact size, the Greenstar Ri series offers a variety of models that fit snugly within a standard kitchen cupboard, making them an ideal choice for homes with space constraints. 

This series represents Worcester Bosch's commitment to combining practical design with unobtrusive installation, catering to different home heating needs without imposing on living space.

The Worcester Bosch Greenstar Ri boilers are commended for their efficiency and performance. These boilers are characterised by their ErP ratings, with models like the 24Ri achieving an A grade for efficiency, which can translate to savings on energy bills for consumers. 

Suitable for a wide range of domestic properties, the Greenstar Ri boilers come with different capacities and technical specifications, offering versatility for users looking to replace an old boiler with minimal disruption.

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Heat-Only Regular Boilers Explained

Heat-only boilers, also known as 'regular' or 'conventional' boilers, form a vital component of many UK home heating systems. These units are typically employed in scenarios where a property has a traditional radiator network connected to a separate hot water cylinder.

InstallationThe installation of a heat-only boiler necessitates a cold water storage tank, usually situated in a loft space to feed water into the cylinder. This setup allows for the storage and heating of a large volume of water, suitably meeting the demands of a busy household.

FunctionalityRegular boilers provide central heating directly, whereas domestic hot water is heated and stored in the separate cylinder. The availability of stored hot water allows for instantaneous access without waiting for a heating cycle.

Advantages of Regular Boilers:

  • Ideal for homes with multiple bathrooms

  • Capable of delivering water to several taps simultaneously

  • Compatible with older, traditional heating systems


  • Requires significant space for a cylinder and a tank

  • Water pressure may be lower than with system or combi boilers

  • Not as energy-efficient as combi boilers, due to heat loss from the hot water cylinder

SuitabilityRegular boilers are particularly suitable for homes where several people often need to use hot water at the same time. They are also a pragmatic choice for properties with old radiators that might not cope with the high pressure delivered by system or combi boilers.

Overview of the Worcester Bosch Greenstar Ri Range

The Worcester Bosch Greenstar Ri is a line of compact, wall-mounted regular boilers favoured for its space-saving design and suitability for small to medium-sized homes within the UK.

Key Features of Greenstar Ri Boilers

  • Size: Designed to fit into a standard kitchen cupboard, offering a practical solution for homes with limited space.

  • Energy Efficiency: Known for high efficiency, contributing to lower household energy bills and reduced carbon footprint.

  • Control: Allows precise control over central heating, ensuring comfort and convenience.

Greenstar Ri 27kW & 30kW

  • Output: These variants deliver higher heating capacities suitable for larger homes with greater demands for hot water and heating.

  • Installation: Despite their robust output, they maintain a compact size for cupboard installation.

Greenstar Ri 12kW to 24kW

  • Range: This range includes boilers with outputs from 12kW up to 24kW, ideal for various smaller property sizes.

  • Flexibility: Compatible with a multitude of Worcester Bosch high-efficiency Greenstore cylinders.

Comparing with Worcester Bosch Combi and System Boilers

  • Type: Unlike combi and system boilers, the Greenstar Ri is a 'heat only' or 'regular' boiler, best suited for homes with a traditional heating and hot water system.

  • Compatibility: Greenstar Ri boilers work well with old central heating systems, which makes them preferable for boiler replacement in existing homes.

Design and Installation Considerations

When selecting the Worcester Bosch Greenstar Ri boiler, there are essential factors to consider regarding its design and suitability for installation. These factors include the unit’s size with respect to fitting into limited spaces and the specifics of the required pipework.

Compact Size and Kitchen Cupboard Fit

The Greenstar Ri series bolsters its appeal by delivering compact dimensions that are conducive to kitchen cupboard installations. Being designed to fit neatly inside standard kitchen cupboard sizes, the boiler offers an unobtrusive solution for homes where space is at a premium. For instance, the smallest models in the range have been engineered with dimensions that ensure a snug fit into kitchen cabinetry without compromising on accessibility for maintenance.

Pipework and Installation Requirements

The installation of a Greenstar Ri boiler necessitates attention to pipework. It is essential that all associated pipework adheres to the necessary gas supply regulations and is capable of supporting the boiler's efficient functioning. Prospective installers should note that the boiler comes with clear installation guidelines

A certified local installer is usually well-versed in these requirements and can ensure that the pre-existing system is compatible or can be suitably adapted. The arrangement of the pipework, often a complex aspect of boiler installation, needs to consider the ease of future servicing and maintenance.

Thorough planning during installation plays a pivotal role in the boiler's performance. It's recommended to engage with authorised service providers who can guarantee that the boiler is installed correctly, thereby ensuring that it operates at its optimal efficiency while adhering to safety standards.

Performance and Efficiency

When assessing the Worcester Bosch Greenstar Ri boiler, two key aspects stand out: its reliable heating output and notable efficiency ratings which are central to its performance.

Heating Output and Efficiency

The Worcester Bosch Greenstar Ri range displays exemplary efficiency with its heating output. The boiler's ability to deliver heating efficiently is evidenced by its high-efficiency figures. For instance, the popular 24kW model not only offers sufficient heat for an average-sized home but does so with a marked level of energy efficiency, attaining up to 92% seasonal space heating efficiency.

ErP and Energy Efficiency Ratings

All models within the Greenstar Ri line carry 'A' ErP ratings, conveying their alignment with the Energy related Products Directive. This signifies a commitment to energy-saving and environmentally conscious heating solutions, adhering to vigorous European regulations designed to decrease emissions and promote energy efficiency.

Seasonal Space Heating Efficiency

With seasonal space heating efficiency reaching beyond 90% across the range, these heat-only boilers are recognised by the Energy Saving Trust for their ability to reduce energy consumption and lower heating bills. The advanced technology within the Greenstar Ri boilers ensures that they utilise fuel to the utmost degree, translating directly into savings for the household and reduced carbon footprint.

Capacity and Suitability

Choosing the right type of boiler is pivotal for ensuring efficient performance tailored to a homeowner's demands. Factors such as the boiler type, capacity, and the home's heating system design are paramount.

Regular vs Combi: Assessing Your Home's Needs

The Worcester Bosch Greenstar Ri is a regular (heat-only) boiler, suitable for homes that already have a traditional heating and hot water system in place with separate hot water cylinder and cold water tank. Regular boilers, such as the Ri series, excel in providing heat to multiple taps simultaneously without a drop in pressure, making them ideal for larger households with higher hot water demands.

On the other hand, combi boilers combine central heating and hot water in one device without the need for a separate hot water cylinder. These are typically more suited to smaller homes with less space for additional tanks, and where hot water needs can be met without requiring simultaneous supply from multiple outlets.

Hot Water Performance

The Greenstar Ri boiler range provides an efficient solution when paired with a high-performance hot water cylinder. The series includes models with various kW output options, catering to different sizes of homes. A larger kW output with a compatible hot water cylinder can comfortably accommodate homes with multiple bathrooms, maintaining a steady supply of hot water.

  • Worcester Greenstar Ri (27kW): Suitable for medium to large homes with one or two bathrooms.

  • Worcester Greenstar Ri (30kW): Can provide for larger properties with multiple bathrooms, offering a more robust hot water performance.

When assessing hot water performance, it is important to match the boiler's capacity with the hot water cylinder's volume, ensuring a balanced system capable of meeting peak hot water demands.

Technical Specifications and Options

In this section, we'll explore the Worcester Bosch Greenstar Ri heat-only boilers, focusing on their technical specifications and the compatibility with other home heating systems, such as solar thermal installations.

Understanding the Tech Specs

The Worcester Bosch Greenstar Ri series comes in different central heating outputs to cater to a variety of home sizes. Notably, the 27kW and 30kW models are engineered for medium to large-sized homes. These boilers stand out due to their compact design, allowing installation within a standard kitchen cupboard. They manifest high efficiency and are categorised in SEDBUK band A, indicative of top energy performance ratings.

Key Specifications for Greenstar 27Ri:

  • Central Heating Output: 27kW

  • Energy Efficiency: A-rated

  • Design: Compact, wall-mounted

Key Specifications for Greenstar 30Ri:

  • Central Heating Output: 30kW

  • Energy Efficiency: A-rated

  • Design: Compact, wall-mounted

The boilers' compatibility with high-efficiency Greenstore cylinders ensures they work seamlessly in a complete system solution.

Compatibility with Solar Heating and Other Systems

The Greenstar Ri boilers are designed with future-proofing in mind. They integrate smoothly with sustainable solutions, such as solar thermal systems, which can provide domestic hot water. This synergy allows homeowners to not only reduce their carbon footprint but also enjoy potential savings on energy bills.

  • Suitable for use with Worcester’s Greenskies solar panels

  • Can be combined with Greenstore hot water storage cylinders

These boilers form part of a versatile heating system that adapts to both current and evolving household needs, providing a long-term heating solution for those looking to invest in eco-friendly technology. They are also compatible with a range of programmable controls for improved efficiency and user comfort.

New Boiler Costs

Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.

Effectively, new boiler cost can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer. 

Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.

Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).

Installation Type

Price (inc VAT)

Combi to combi swap


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System to combi conversion


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New boiler install


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Back boiler to a combi


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System to system


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Frequently Asked Questions

What is a Worcester RI boiler?

The Worcester RI boiler is a heat-only or regular boiler range produced by Worcester Bosch, designed for residential use. It's wall-mounted, compact, and suitable for small to medium-sized homes or as a replacement in existing heating systems.

How efficient is the Worcester RI boiler?

The Worcester RI boiler is known for its high efficiency. Its energy efficiency falls within SEDBUK Band A, indicating it is among the top-rated boilers in terms of energy usage and can offer low running costs.

What is the rating of the Worcester Greenstar Ri?

The Greenstar Ri series possesses an excellent energy rating, situated in SEDBUK band A. These boilers are therefore very efficient and can lead to cost savings on domestic energy bills.

How do I reset my Greenstar Ri boiler?

Resetting a Greenstar Ri boiler can be accomplished by pressing the dedicated reset button on the front of the boiler. This safely resets the system and attempts to restart the boiler in the event of a lockout or fault.

Why is my Worcester Greenstar boiler not firing up?

A Worcester Greenstar boiler may not fire up because of several issues like low water pressure, a disruption in gas supply, a fault in the ignition system, or a lockout condition caused by a component failure.

What happens when you press the reset button on a Worcester boiler?

Pressing the reset button on a Worcester boiler initiates a reset procedure that clears any temporary faults and attempts to restart the boiler. If the system does not have any serious issues, this action usually resumes normal operation.

How long does a Worcester boiler take to reset?

The reset process for a Worcester boiler is typically immediate. Once the reset button is pressed, the system should attempt to restart within a few seconds, unless there is an underlying issue preventing it from doing so.

Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.