🕑 9 minutes read

Heating is really important in the UK. So, when you're thinking about buying a boiler, there are some things you need to think about first.

The Worcester Bosch 4000 boiler, which replaces the old Greenstar i, is currently one of the top boilers on the market, known for its reliability, warranty, price, and outputs.

The Worcester 4000 combi boiler is the newest version of the most commonly used boiler in the UK.

Are you considering upgrading your boiler to a Worcester Bosch Greenstar 4000 30kW? This top boiler manufacturer is highly praised by homeowners and consistently chosen as a Best Buy by Which?. They prioritise quality above all else in their company goals.

If you're a London homeowner, ensuring efficient heating and hot water is crucial, especially during the chilly months.

Let's find this serviceteam blog review to understand the key features and advantages of the Worcester Bosch 4000 30kW boiler to help you make an informed decision.


Worcester Bosch Greenstar 4000 30kW


Introducing the Worcester Bosch Combi Greenstar 4000, the latest upgrade in the Worcester Bosch Combi boilers collection. This boiler model has many improvements compared to the Greenstar i.

It offers increased hot water output and operates more quietly. With its sleek curved edge design, digital display, and user-friendly push control buttons, the 4000 30kW presents a modern look. Its removable side panels make servicing a breeze, and it comes with a reassuring 10-year guarantee when installed by an accredited professional.

The Worcester Bosch Greenstar 4000 achieves an impressive 94% energy efficiency rating, indicating that only 6% of the energy used for heating water is lost, resulting in reduced energy costs.

The Greenstar 4000 combi boiler also features modulation at 1:10, allowing for a 10% reduction in power output during periods of low demand. This not only enhances energy efficiency but also prolongs the boiler's lifespan.

A notable addition to the Greenstar 4000 is the 'Quick Tap' feature, which eliminates the wait for hot water. Simply turn on the tap briefly, and hot water will flow within seconds, making daily tasks more convenient and efficient.

How Many Radiators Can a Worcester 4000 30kW Run?


The Worcester 4000 30kW boiler can power up to 16 radiators, making it suitable for homes with many heating units.

Whether you have a large household or extensive heating needs, this boiler offers ample capacity to keep your entire home warm and comfortable during the colder months.

How Good Is The Worcester Bosch Greenstar 4000 Boiler?

The Worcester Bosch Greenstar 4000 boiler is renowned for its reliability, efficiency, and durability. Its advanced technology and superior build quality offer homeowners peace of mind and consistent performance throughout the year. Whether you're looking for a new boiler installation or a replacement for an old boiler, the Greenstar 4000 boiler is a reliable choice to meet your heating needs efficiently.

The Worcester Bosch 4000 30kW is widely regarded as the best output due to its versatility.

What Is The Difference Between Worcester 4000 25kW & 30kW?

The difference between the Worcester 4000 25kW and 30kW models lies in their heating capacity and suitability for different home sizes.

The 25kW model is ideal for smaller homes with up to 10 radiators, providing a flow rate of 10.5 litres per minute and a heat output of 25kW. On the other hand, the 30kW version is better suited for homes with two bathrooms, as it can meet higher hot water demands.

Should I Buy a 25kW or 30kW Worcester 4000 Boiler?

Deciding between a 25kW or 30kW boiler depends on your home's requirements. If you have around 10 radiators, a 25kW combi boiler should suffice. However, if you have about 15 radiators, it's better to go for a 30kW combi boiler.

Key Features of The Worcester Bosch Greenstar 4000 30kW Boiler

Energy Efficiency Energy-efficient-logo

The boiler has advanced energy-saving features such as wireless controls, a 'Quick Tap' function, and 1:10 modulation, ensuring efficient operation. These features also help homeowners save on bills while reducing their carbon footprint.

The Greenstar 4000 boasts impressive energy efficiency, helping homeowners save on energy bills.

Quiet Mark Accreditation

The Worcester Greenstar Greenstar 4000 is exceptionally quiet, boasting a noise level 10% lower than its predecessor, the Greenstar i range. The Noise Abatement Society recognises this for its quiet operation; it is one of the quietest boilers available.

Despite the subtle difference, the Quiet Mark accreditation is a testament to its impressive noise reduction capabilities, especially considering the low noise levels of the previous model. Additionally, its ability to fit snugly into kitchen cupboards ensures it remains discreet and unobtrusive.

Say goodbye to noisy boilers! The Greenstar 4000 operates quietly, ensuring a peaceful living environment.

User-Friendly Controls PCB-of-a-Worcester-Bosch-4000-30kW-boiler

The boiler features intuitive controls that allow homeowners to adjust settings and monitor performance easily.

Simple Switch & Wall Mounting Frame

Good news for owners of the old Greenstar i model, as Worcester has made transitioning to the new 4000 model effortless. By maintaining identical parts positioning, swapping out the old for the new is a breeze, ensuring seamless integration with existing setups.

While the 4000 can fit into cupboards, special consideration may be needed for kitchen boiler cupboards to accommodate its dimensions.

Reliable Performance

Built to last, the Greenstar 4000 delivers reliable heating and hot water whenever needed, ensuring comfort throughout the year.

A-kid-is-bathing-hot-water-in-a-tub Easy Access to Key Components

Designed with convenience in mind, the Worcester 4000 provides easy access to essential components, such as the PRV and heat exchanger, facilitating straightforward maintenance and repairs.

Front access to these components ensures hassle-free servicing, which is ideal for situations where time is of the essence or when the boiler is installed in tight spaces.

Intelligent Auto Filling System

Unlike traditional boilers requiring manual water pressure adjustment, the Greenstar 4000 features an intelligent auto-filling system. This system eliminates the need for manual adjustments, ensuring optimal water pressure levels without the risk of flooding or water shutoff.

Say goodbye to worries about low boiler pressure. The intelligent auto-filling system automatically takes care of it, providing peace of mind and hassle-free operation.

Bosch Easy Control SystemA-home-owner-is-controlling-the-boiler-temperature-using-his-smart-phone

One standout feature of the Greenstar 4000 is its compatibility with the Bosch EasyControl system. This smart system allows homeowners to manage their home's temperature using their mobile phones conveniently. Whether adjusting the central heating remotely or utilising voice commands via Alexa or Google Home, this system offers flexibility and energy efficiency.

Fuel Type

It runs on gas and is hydrogen-ready, capable of handling up to a 20% blend of hydrogen.

Compact Design

With its compact size, the Greenstar 4000 is ideal for homes with limited space, making installation hassle-free.

Flow Rate

The boiler offers a flow rate of 10.2 litres per minute, ensuring a steady hot water supply when needed.

Award-Winning Brand

Worcester Bosch has consistently won the Which? Best Buy Award for 10 consecutive years.

What Is The Cost Of a Worcester Bosch Greenstar 4000 30kW Combi Boiler?

The Worcester Bosch Greenstar 4000 30kW combi boiler is priced between £1,200 and £2,500. However, the boiler price can vary based on factors like installation difficulty and added features. Despite the price fluctuation, this boiler provides excellent value for its efficiency and durability. Investing in a high-quality boiler like the Greenstar 4000 can result in long-term savings on bills and maintenance costs.

Get an online boiler quote within 20 seconds!

  • Free Instant Quotes are Available
  • Vaillant Accredited Installer
  • Which? Trusted Trader
  • Up To 12 Years Manufacturer's Guarantee
Get a Quotation Now! logos

Technical Aspects of Worcester Bosch 4000 30kW boiler

The Worcester Bosch Greenstar 4000 is hailed as the company's most eco-friendly boiler yet, boasting impressive technical specifications.

It's designed to modulate at an impressive 1:10 ratio, meaning even a 30kW model can operate efficiently at just 3kW if necessary, minimising energy waste.

What sets the Worcester Bosch Combi Greenstar 4000 apart is its wireless compatibility with the Bosch EasyControl thermostat (available separately). This innovative feature allows you to remotely control the temperature of individual rooms via your smartphone, contributing to further energy savings.

What Is The Warranty Period of Worcester Bosch Greenstar 4000 30kW?

In terms of warranty, the Worcester Bosch Greenstar 4000 offers peace of mind with a standard 7-year guarantee. However, this can be extended to an impressive 10 years when the boiler is installed by an accredited installer.

Pros and Cons of the Worcester Bosch Greenstar 4000 Combi Boiler



  • Quick Tap' Feature
    Homeowners can enjoy instant hot water with the 'Quick Tap' feature, reducing water wastage. With an efficiency rating of A and output options ranging from 25kW to 30kW, the Worcester Bosch Greenstar 4000 ensures both energy efficiency and reliable performance for London homeowners.
  • Environmentally Friendly
    This boiler boasts an A-rated energy efficiency for both central heating and hot water. Additionally, 99.9% of its packaging is recyclable.
  • Smart Control
    The Worcester 4000 is compatible with the Bosch EasyControl smart thermostat, enabling users to monitor energy usage remotely and control heating room-by-room. Users can also utilise voice commands with Alexa or Google Home Assistant (Bosch EasyControl system sold separately).
  • 1:10 Modulation
    The boiler can modulate its output to as low as 10%, reducing fuel bills and minimising wear and tear.
  • Quiet Operation
    It awarded Quiet Mark accreditation for silent operation, ensuring no disturbance to household members.
  • Simple Switch
    Easy upgrade from the Greenstar i boiler to the Greenstar 4000 combi through Worcester Bosch's Simple Switch program.


While the Greenstar 4000 30kW offers numerous benefits, it may not be suitable for every home and energy requirement. Before making a decision, it's important to carefully weigh the advantages and drawbacks.

Some drawbacks of this boiler include:

  • Stock Shortages
    Boiler Central reports supply issues with the Greenstar 4000 due to microchip shortages, which could potentially limit availability.

Call Serviceteam Heating Engineers for Boiler Installation or Replacement


Serviceteam is an accredited Worcester Bosch installer in London. Look no further than Serviceteam Heating Engineers if you're considering upgrading to the Worcester Bosch Greenstar 4000 30kW boiler or need assistance with installation or replacement.

Our team of experienced professionals specialises in boiler installation and replacement services designed specifically for homeowners in London.

Call us to schedule a consultation or a heating engineer to ensure your home stays warm and comfortable all year round.

To learn more about the Worcester Bosch, check out our blog, Worcester Bosch 4000 boiler review, in the blog section.