Worcester Bosch Greenstar 4000 Boiler Cost with Installation

This modern, highly efficient combi boiler from Worcester Bosch is a quiet, reliable option for small and medium-sized homes. Its compact and stylish design means it fits seamlessly into your home, allowing you to enjoy its great features without disruption. 

The Greenstar 4000 was voted as our best combi boiler and comes in two output sizes, 25kW and 30kW. It also features easy-to-use controls and is compatible with smart thermostats, giving you greater control over your energy use. 

Discover more about this boiler’s specifications below:

Worcester Bosch Greenstar 4000 Combi Product Table
	Available Outputs	25kW	30kW
	Type	Combi	Combi
	Fuel	Gas	Gas
	Condensing	Yes	Yes
	Efficiency Rating (%)	94	94
	ErP	A	A
	LPG Compatible	Yes	Yes
	Standard Guarantee	7 years*
	Max Output (kW)	25	30
	Flow Rate (l/min)	9	10.8
	Mounting	Wall mounted
	Dimensions (mm)	724 x 400 x 310
	Typical Price (inc VAT)	£1,200
	Typical Installation Cost (inc VAT)	£1,200
	Total Cost	£2,400

*Terms and conditions apply.

Worcester Bosch Greenstar 4000 overview

The Worcester Bosch Greenstar 4000 combi boiler is a stylish option, with lots of great features. It’s compact, quiet when running and can be used with advanced controls, but it’s also highly efficient at 94% (ErP A-rated). 

All of this means it’s easy to install, a dream to control and can even save you money on your energy bills. With two output options available, it’s suitable for multiple property sizes, as detailed below.

Worcester Bosch Greenstar 4000 Combi Range
Model output size	House size	Bathrooms	Radiators
25kW	Flats, small homes 1 to 3 bedrooms	1	Up to 10
30kW	Medium homes 3 to 4 bedrooms	1-2*	Up to 15

*One full bath and an en-suite.

The Greenstar 4000 combi boiler output range is fairly limited compared to its competitors (and other combi models within Worcester Bosch’s product line). With only two options, the power output of these models means this boiler is best suited to small and medium-sized homes with fewer than 2 bathrooms.

It’s not recommended for homes with multiple bathrooms, where simultaneous hot water use is required, as there isn’t enough power available.

For the smaller properties, however, this combi boiler offers quality and a wide range of features, all at a very competitive price.

Key benefits at a glance

• Energy efficiency of 94% (ErP rated A) for lower energy bills 
• Quiet Mark certified, for very low noise levels (42 – 45 dB)
• Compact size for easy, discrete installation
• More stylish appearance than some competitors
• QuickTap function prevents water waste and delivers hot water faster 
• Full-colour control display 
• Intelligent Filling System constantly monitors system pressure and refills automatically
• Compatible with smart thermostats, including Bosch EasyControl, Hive and Nest
• Up to a 10-year guarantee when fitted by accredited installers​
• Ready for a 20% hydrogen blend for futureproofing

Worcester Bosch Greenstar 4000 technical specifications

The Worcester Bosch Greenstar 4000 combi is a popular option for homeowners due to its high efficiency, smart features and guarantee options. 

While this boiler can save you money on fuel (compared to an old, inefficient model), it also comes at a lower price point than many competing brands, making it a smart choice. 

To learn more about how this boiler provides such great features, let’s look more closely at the technical details.

Output and efficiency ratings

The Greenstar 4000 combi comes in two output sizes, 25kW and 30kW. Each model provides instant heating and hot water while operating at the high efficiency level of 94%. This means that for every unit of fuel you burn, almost all of it is converted into usable heat.

In comparison, an older boiler (10 – 15 years old) might be operating around 60 – 70% efficiency, meaning you lose between 30 and 40% of your fuel as waste gases. 

In addition, these boiler models are A-rated on the ErP scale, which means the environmental impact is very low during use. 

Dimensions 

Both models in the Greenstar 4000 combi range come in very compact sizes, ideal for fitting into small spaces like a kitchen cupboard. They measure 724mm in height, 400mm in width and 310mm in depth. 

Compared to other brands on the market, the Greenstar 4000 combi is around midrange for its size. There are a few smaller models, such as the Ideal Logic Max Combi² and Baxi 800 Combi 2, which you might consider if you’re very low on space. 

Components included

When you choose a Worcester Bosch Greenstar 4000 combi boiler, there are some intelligent components built-in, or available with your purchase. For example, this combi is fully compatible with smart controls. 

You can control your heating wirelessly through an app, with Bosch EasyControl or other home assistants such as Amazon Alexa and Google Home. You can also use other thermostat options, such as Hive or Nest. 

The ability to use your heating more precisely, with timers or heating zones, can significantly reduce your energy use and lower your monthly bills.

This boiler model also includes a QuickTap function to rapidly deliver hot water and reduce your water waste. When you briefly turn your hot tap on and then back off, the Greenstar 4000 detects this action as a signal that you’ll soon need hot water. 

The boiler immediately begins preheating the water internally, so when you reopen the tap 15 – 20 seconds later, hot water flows instantly without the usual lag or water wastage.

Another great feature of the Greenstar 4000 combi is its automatic frost protection. Once the boiler detects drops in temperature to around 5 °C, it automatically warms itself to 12°C to prevent freezing. 

There is also a large 500ml condensate siphon to further reduce the risks of frost damage.

Prices and installation costs

The Worcester Bosch Greenstar 4000 combi boiler costs £1,200 for the unit on its own. Installation fees can add up to £1,200 to this total, bringing overall costs to around £2,400. 

These prices are based on our research and actual boiler prices submitted to WhatPrice by homeowners. However, total costs will largely depend on the complexity of your boiler replacement and the daily rates of your installer. 

To get an accurate price, based on your circumstances, it’s always best to request quotes from at least 3 Gas Safe registered installers. They will give you expert advice on the right boiler for your home, and you can compare quotes to get the best deal.

In addition, you can use the WhatPrice Boiler Cost Calculator to get a guide price for your installation. 

Warranty and support

Worcester Bosch offers a generous standard guarantee of 7 years on the Greenstar 4000 combi, which includes full parts, labour and call-out fees. 

The guarantee can also be extended, for example, if you install a Greenstar System Filter alongside your boiler you can extend the guarantee to 8 years.

To reach the maximum length of 10 years, you must include the filter and have the boiler installed by a Worcester Bosch Accredited Installer (or pay a £40 additional fee). 

To validate your guarantee, you must register your boiler within 30 days of installation via the Worcester Bosch website. This is something your installer can do on your behalf or guide you through on the day of installation. 

The guarantee does not cover normal wear and tear, faults caused by sludge, limescale or neglect or any errors due to non-approved accessories. 

Your guarantee will also be void if you don’t ensure annual servicing is carried out by a Gas Safe registered engineer. 

For any support or aftercare, Worcester Bosch provides UK-based services available 7 days a week, all year round. You can contact them via a helpline or online chat support through the Worcester Bosch website. 

Installation information

Choosing a new boiler can seem like a big task, so it helps to know what to expect from the installation process. If you opt for the Worcester Bosch Greenstar 4000 combi, installation costs can be up to £1,200. Keep in mind that every home is different, and the complexity of your current heating system may affect the final price.

What to expect on installation day

To help you understand what’s involved in a boiler installation, here’s a breakdown of the main steps:

1. Preparation and checks
   Your engineer will check the area where your new boiler will go, make sure everything’s ready, and plan how to remove your old system.
   
2. Removing the old boiler
   The old boiler will be safely disconnected from your gas, water, and power supply. If you’re switching to a combi (from a system or regular boiler), your water tanks or cylinder will also be removed.
   
3. Installing the new boiler
   If the new boiler is going in the same spot, the engineer will mount it and reconnect everything. If it’s moving elsewhere, they may need to reroute pipes or wiring first.
   
4. Configuration and controls
   Once fitted, your engineer will complete your wiring, set up your controls, and pressurise the system. They will also test your radiators and ensure everything runs smoothly and safely.
   
5. Switch on and hand over

Finally, your installer will switch on the system, carry out safety checks, and demonstrate how to use your new boiler. They’ll also handle the necessary paperwork and register your installation to activate your guarantee.

Sometimes, a bit of extra work is needed. For example, if you’re switching to a different boiler type or upgrading your pipework. Your installer will talk you through what’s required in advance, including any extra costs and how much longer the job might take.

Do you need a system flush or filter?

When installing a new boiler, your engineer might suggest adding a system flush or filter. These aren’t mandatory, but they’re both great ways to keep your heating system clean, efficient, and well-protected for years to come.

A system flush is normally done before the new boiler goes in. It uses a specialist cleaning solution to clear out any sludge or buildup in your existing pipework. This helps your heating system work more efficiently and prevents debris from damaging your new boiler’s components.

A filter, on the other hand, is fitted to your system to continuously capture dirt and rust particles before they can circulate through the boiler. It’s a simple addition that can make a big difference to long-term reliability.

While both options offer excellent protection for your heating system, they do involve extra costs. As a guide, a system flush typically costs between £350 and £800, and a filter between £65 and £300, depending on your setup.

Finding a Gas Safe registered engineer

In the UK, gas boiler work must only be carried out by a Gas Safe registered engineer. It’s a legal requirement designed to keep your home safe. By hiring a registered professional, you can be confident the installation meets strict safety rules and is completed to the correct standard.

Before deciding who to hire, it’s sensible to gather quotes from multiple Gas Safe registered installers. This gives you a clearer picture of pricing and helps you find someone with the right experience for your home. 

You can check an installer’s registration and ID number quickly and easily on the official Gas Safe Register website.

Reviews and ratings

As a brand, Worcester Bosch is a well-respected manufacturer with customer reviews scoring them highly. On sites like Trustpilot, they received 4.6 out of 5 stars and over 49,000 reviews. Worcester Bosch is also frequently given the Which? Best Buy award for their excellent products.

The Worcester Bosch Greenstar 4000 combi boiler is also very highly rated, with a strong reputation for reliability and performance. To find out more about the views of customers and installers, we’ve provided summaries from our research below.

Positive reviews

The Worcester Bosch Greenstar 4000 range earns consistently high praise from customers for its quiet performance, fast hot water delivery, and energy efficiency, with many stating they saw noticeable reductions in their heating bills.

Reviewers also appreciate its compact design, which makes installation straightforward and helps free up valuable storage space.

Users highlight the boiler’s ease of use, thanks to clear LCD controls and compatibility with smart technology, even for those less tech-savvy. 

Reliability is another recurring theme, with the boiler’s long guarantee (up to 10 years) and responsive after-sales support offering strong peace of mind. 

Negative reviews

While overall feedback for the Worcester Bosch Greenstar 4000 combi remains very positive, a small number of users have reported minor issues after installation, such as leaks or early faults. However, in most cases, these were resolved quickly with prompt engineer visits and efficient customer support. 

There are occasional mentions of build quality concerns, particularly around the use of an aluminium heat exchanger rather than the stainless steel units found in the brand’s premium models. 

Some customers also feel the price is higher than comparable boilers, but many believe the excellent warranty coverage and reliable service justify the cost. 

Overall, these criticisms represent a minority view, with the majority of reviewers on platforms like Trustpilot and Which? still describing the Greenstar 4000 as a dependable, well-supported choice.

How the Worcester Bosch Greenstar 4000 compares

Selecting the right boiler takes careful thought, so it helps to compare a few leading options. While the Worcester Bosch Greenstar 4000 combi remains a popular choice, it faces competition from three leading models: Vaillant ecoTec Plus Combi, Ideal Logic Max Combi²  and the Viessmann Vitodens 100-W Combi.

In the table below, we’ve listed the main pros and cons of these models, so you can get a clearer view of what they offer and how they compare. 

Worcester Bosch Greenstar 4000 Combi Comparison Table
Make and Model	Pros	Cons	Cost (excluding installation)
Worcester Bosch Greenstar 4000 Combi	7-year standard guarantee (extendable to 10 years) 94% efficiency  Quiet Mark certified Modern design Built-in Wifi (Bosch EasyControl) 4.6/5 on Trustpilot	Fewer output sizes (25kW, 30kW) Aluminium heat exchanger, less durable Some features are only available with premium controls	£1,200
Vaillant ecoTec Plus Combi	5-year standard guarantee (extendable to 10 years) 94% efficiency Wide range of outputs (26kW, 32kW, 36kW, 40kW) Quiet Mark certified 4.6/5 on Trustpilot	Higher upfront cost than some other brands  Standard guarantee is shorter than some other brands Larger in size than others (720mm x 440mm x 352mm)	£1,833
Ideal Logic Max Combi2	10-year standard parts and labour guarantee 94% energy efficiency (ErP A-rated) Compact size Includes system filter Built-in frost protection Competitive pricing Brand scores 4.8/5 on Trustpilot	Occasional issues with customer service Ideal engineers can be slow to respond  Not as quiet as other brands	£1,100
Viessmann Vitodens 100-W Combi	5-year standard guarantee (extendable to 12 years) 94% efficiency Stainless steel heat exchanger (longer lasting) Compact Modern design	Higher upfront costs than other brands  Fewer UK engineers means longer wait times Parts are harder to source in the UK and can be more expensive	£1,915

Keep in mind that this comparison focuses on key features, but there may be other details that matter more for your home. For personalised guidance on choosing the right boiler, we recommend speaking with a Gas Safe registered engineer.

Final thoughts – is the Worcester Bosch Greenstar 4000 combi right for you?

The Worcester Bosch Greenstar 4000 combi is a top choice for small to medium-sized homes, especially those with one bathroom and moderate hot water demand. It offers a 94% efficiency rating, Quiet Mark certification, and a compact design that fits neatly inside a kitchen cupboard. 

With smart thermostat compatibility, easy-to-use controls, and up to 10 years guarantee, it’s designed for comfort and peace of mind. 

This boiler won’t suit homes with multiple bathrooms, however, as there are only output options up to 30kW. This is not enough to supply hot water to many outlets at once, and therefore, is not ideal for homes with high hot water demand. 

The Greenstar 4000 combi has a comparable cost when you assess its competing brands. This model also has the quality, guarantee, and aftercare to back up the price. 

If you’re comparing options, the Viessmann Vitodens 100-W offers a stainless steel heat exchanger and great long-term value, the Vaillant ecoTEC Plus suits larger or high-demand homes, and the Ideal Logic Max provides a budget-friendly alternative. 

Overall, the Greenstar 4000 combi is one of the best choices for a single-bathroom home that prioritises efficiency, quiet performance, and dependable heating. To get expert advice on your new boiler, speak to a qualified engineer today.

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