Worcester Bosch Greenstar 4000 Review [Updated for 2022] Boiler Central (2023)

Worcester Bosch Greenstar 4000 Review [Updated for 2022] Boiler Central (1)

The Worcester Bosch Greenstar boiler range is one of the latest boilers from one of the top manufacturers in the UK. Replacing the legendary Greenstar i range, the Worcester 4000 combi boiler has picked up where this has left and then added some more features on top, as you would expect.

If you were to ask a boiler engineer which is one of the most installed boilers, we think you’d be on to a pretty safe bet to put your money on the Worcester Bosch 4000 boiler.

Worcester Bosch Greenstar 4000 Review [Updated for 2022] Boiler Central (2)

Use this online tool to get a price on a Worcester 4000 boiler – Click here

With glowing reviews from homeowners and a consistent place in the Which? Best Buy choices, this leading boiler manufacturer places quality at the top of their company aims.

Click Here for a Worcester 4000 combi boiler quoteIncluding our exclusive 12 years warranty for the price of 10!

Watch our latest review of the Worcester 4000 now

How good is the Worcester Bosch Greenstar 4000 boiler?

Worcester Bosch Greenstar 4000 Review [Updated for 2022] Boiler Central (4)

This new model is available as both a combi and a system boiler range, and it was launched in May 2021. Need to know, right now, what this replacement offers above the Greenstar i?

Well, there’s a new technology, a sleek design, and a compact size. In fact, this new kid on the block has everything it needs to become Worcester Bosch’s latest top seller. It has fast become one of the top selling gas boilers in the UK

The new Worcester 4000 is the old Greenstar i replacement

So, it came as a bit of a surprise when they decided to mothball their best-selling boiler, the Greenstar i. To take that bold decision, we knew that Worcester Bosch must have something special up their sleeve, and they did, in the form of the Worcester 4000. Hailing new technology to increase energy efficiency, keep bills down and give your more control over your heating, the 4000 is arguably the best-selling combi boiler right now and sits comfortably in the mid-range price bracket.

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Q What kind of fuel does your boiler use?

Worcester 4000 boiler: Key features

The new 4000 had to be better than the old one, so with features galore, you can be sure that this mid-range combi boiler will be perfect for most small to medium-sized homes in the UK. Not only that, if you are looking for a replacement for an old Greenstar combi, then don’t let the looks put you off, the internal fittings and fixtures are all in the same place, it just has a new body kit.

Worcester Bosch Greenstar 4000 Review [Updated for 2022] Boiler Central (5)
  • A mid-range model
  • Hydrogen ready boiler (20% blend)
  • Quieter operation compared to the Greenstar i
  • Compatible with Worcester Bosch controls and products such as Nest, tado and Hive
  • An excellent choice for small to medium-sized homes
  • Easy access for servicing with its removable side panels
  • Maximum of a 10-year guarantee
  • ErP rating 94%: A-rated
  • Dimensions: 710 x 400 x 310

Worcester Bosch 4000 combi boiler review

For smaller homes with one bathroom, getting the best combi boiler with an instant hot water supply is a great choice. The Greenstar 4000 combi boiler is available in two different power outputs. This ensures that it is suitable for more homes in the UK. The Greenstar 4000 is ideal for kitchen cupboards, but we always suggest measuring up first!

(Video) Worcester 4000 boiler - LATEST Worcester Bosch Greenstar 4000 Combi Boiler Review ##special offer##

Worcester Greenstar 4000 25kW combi boiler

The Worcester 4000 25kw great choice for smaller homes with up to 10 radiators. The 25kW combi boiler provides a flow rate of 10.5l/min and heat output of 25kW. If you have a home with 2 bathrooms then you should definitely go for the higher output 30kw version. In the right home, these combi boilers can save you hundreds of pounds every year on your utility bills.

Get the Worcester 4000 25kW version with full installation now

As you may have already guessed the Worcester 4000 25kW version is selling like hot cakes already and although it is less popular than the 30kW version, it may be a good idea to get your new boiler installed during the warmer months while demand is low and prices are low too. You can get a fixed price quote online now for the 25kw 4000 at Boiler Central now.

Worcester Greenstar 4000 30kW combi boiler

The Worcester 4000 30kw combi boiler is ideal for small to medium-sized homes with up to 16 radiators. That extra 5kW of power increases the flow rate up to 12.3l/min. These combi boilers can cope with homes with 2 bathrooms too, so if you have higher hot water demand then we suggest that you go for the 30kw version over the 25kw.

Get the Worcester 4000 30kW version with installation now

The Worcester 4000 30kw is one of the best-selling boilers right now and you can get this 30kw combi boiler installed in your home with Boiler Central right now. As the Greenstar 4000 30kw version is so popular at the moment ensure you get yours fitted before the winter rush and enjoy our low summer prices.

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Q What kind of fuel does your boiler use?

Worcester Bosch 4000 system boiler review

The Worcester Bosch 4000 system boiler is ideal for larger homes with more than one bathroom or when you may find that a combi just isn’t able to provide the hot water you need. That’s when a system boiler comes in with its hot water storage cylinder. It can produce lots hot of water, very quickly to many outlets.

There are five different power outputs available for the Worcester 4000 system boiler as below:

  • Worcester 4000 System 12kW
  • Worcester 4000 System 15kW
  • Worcester 4000 System 18kW
  • Worcester 4000 System 21kW
  • Worcester 4000 System 24kW

Worcester Greenstar 4000 efficiency

Boiler efficiency is high up on the list for both boiler manufacturers such as Worcester Bosch and every homeowner. When we have an efficient boiler, it burns less fuel, which, in turn, means that fewer carbon emissions are released into the atmosphere.

Worcester Bosch Greenstar 4000 Review [Updated for 2022] Boiler Central (6)

This, in turn, is great news for the environment as carbon is believed to be a key reason behind climate change.

There’s another significant advantage too, in that your hard earnt cash isn’t going to going to be going up in flames in boiler inefficiency.

What does the efficiency level mean?

Both the combi and system models achieve an impressive 94% level of efficiency.

Efficiency levels are calculated by assessing how much of the fuel, so the gas, LPG or oil, is turned into usable energy and then how much is wasted during the heating process.

At 94% efficiency, that means that just 6% of the energy used to heat the water is lost during the heating process. And you’ll see that 6% as the gases being emitted via the flue pipe. If we think about this in financial terms, for every £1 you spend on energy to heat your home, 6p of that is lost to the heating process.

All new boilers now need to be at least 90% efficient, but in the past, it wasn’t unusual for boilers to have efficiency levels of between 60 to 70%. If you currently have an old boiler, 40% of your energy costs could be wasted! Now is the time to get a new boiler quote.

What is the Worcester Bosch 4000 ErP rating?

All of the boilers in the 4000 range, both system and combi, achieve an ErP rating of ‘A’.

(Video) Top 5 Best Combi Boilers - Which is the best combi boiler to buy right now in 2022?

Worcester Bosch Greenstar 4000 Review [Updated for 2022] Boiler Central (7)

ErP stands for the Energy Related Products Directive. Launched by the EU, its main aim I to phase out all inefficient household appliances. The ErP makes it easier to know which products are more efficient, resulting in reduced carbon emissions and the opportunity to save on energy bills.

So, that means that boilers must be labelled with their certified efficiency level, and that goes from G, which is the lowest level of efficiency right up to A+++ for the highest efficiency.

The directive also introduced Ecodesign, a set of new regulations that manufacturers have to follow. This meant that those heating systems that didn’t meet the required standards had to be phased out by the boiler manufacturers.

Worcester 4000 boiler- Key features reviewed in detail

Simple switch

Do you want all the great features of a new boiler but none of the hassles of installation? Well, Worcester Bosch has done everything they can to make it as pain-free as possible with what they’ve called Simple Switch. That means that you’re looking at seamless swapping out for the following boilers:

  • Greenstar i Junior combi (2005 – 2013)
  • Greenstar i Junior combi (2013 – 2015)
  • Greenstar Si combi (2005 – 2013)
  • Greenstar i ErP (2015 – 2021)
  • Greenstar i System (2005 – 2015)
  • Greenstar i System ErP (2015 – 2021)

Quick tap

When you turn on your hot water tap, what do you do while you wait for the heated water to appear? Wait impatiently? Run your hand back and forth through the water, waiting for that flow to go from cold to lukewarm and then finally to hot? And all the time that cool water is running into the waste pipe.

Quick Tap allows you to turn your hot water tap on and then immediately turn it off. That tells the boiler that you need hot water. Wait for just twenty seconds, turn the tap back on, and you’ll have hot water flowing straight away.

No more wasted time stood at the sink waiting for the hot water to arrive and much less wasted water.

Enhanced levels of efficiency

The Greenstar 4000 is the most environmentally friendly boiler available from Worcester Bosch. This is a boiler that can modulate at 1:10. That means that the power output can be reduced to 10% of its maximum output.

So, a 30kW boiler can drop down to 3kW when there are low demand levels on the heating system. Not only does it make the 4000 incredibly efficient, but it also means lower fuel bills and less wear and tear on the boiler.

Greater control

Taking control of our heating needs to be made easy, and that’s precisely what Worcester Bosch has done. With Bosch EasyControl, the Greenstar 4000 can be controlled wirelessly no matter where you are. It also allows you to track your energy usage. Drop the temperature even by just a single degree and then see the impact on your energy bill.

Then there are thermostatic radiator valves. Installed onto each radiator, they allow you to set the temperature for each individual room. Prefer your bedroom cooler and your living room warmer? Now you can have that with Bosch EasyControl; all set up from the app on your mobile phone.

If you have Alexa or Google Home Assistant, then you can also control the heating with voice commands.

99.9% recyclable product packaging

Yep, you read that correctly. The Worcester Bosch Greenstar 4000 comes in 99.9% recyclable packaging. This is a company that has already made a strong commitment to reducing the impact that they have on the environment. They’ve already achieved carbon neutral status, but it looks like that’s not good enough for them!

Full-colour text display

The LCD display panel combined with push-button controls make the 4000 much easier to programme and find information about the boiler status. This may seem like a relatively minor detail, but if your boiler isn’t working as it should, the last thing you want to deal with is confusing information.

Worcester Bosch Greenstar 4000 Review [Updated for 2022] Boiler Central (8)

Intelligent filling system

This is a feature that’s been carried through from the Greenstar i range. The intelligent filling system is a software programme that ensures that the boiler pressure is always at its most efficient level.

So, that means that if the pressure is lower than it should be, the internal filling valve will open, and it automatically fills the heating system to the correct level and then switches back off again.

(Video) Best Worcester Boilers - Is it the Worcester 2000, Worcester 4000 or Worcester 8000? Find out now!

If the pressure becomes too low, so maybe through a leak in the heating system, then it will alert you to the problem

The intelligent filling is only available on the Greenstar 4000 combi boiler and not on the system version. This is an optional extra also, so if you need to repressurise your Worcester bosch combi boiler and you don’t have this, you will need a filling key.

Quiet Operation

The Greenstar i was already quiet when it was operating, so it is pretty impressive for the 4000 to make even less noise. The combi version, for example, operates at 45dB. With a normal conversation being around 65dB and a vacuum cleaner being 75dB, the 4000 is not going to be annoyingly noisy.

Check out the here as they do have more options in terms or price and outputs.

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Q What kind of fuel does your boiler use?

Is your boiler futureproof? The Greenstar 4000 is!

The UK is known for having a world-leading gas network, and because of that, we’ve all become very reliant upon it. In fact, 85% of homes and businesses use natural gas for their heating needs, including their hot water supply and for cooking.

The problem is that if we’re to tackle the climate emergency, then we need to dramatically reduce our household carbon emissions. But, to do that we need to stop using natural gas.

Worcester Bosch Greenstar 4000 Review [Updated for 2022] Boiler Central (9)

The Energy Savings Trust estimate that household carbon emissions just from our heating, need to drop from close to 3 tonnes a year right down to 138kg, and that needs to happen by 2050.

If a blend of gas and hydrogen is pumped through the gas grid, that could save nearly 6 million tons of carbon dioxide emissions every year. That’s the equivalent of 2.5 million cars being taken off the road.

Like all of the Worcester Bosch range of boilers, the Greenstar 4000 can already run on a 20% hydrogen blend. With a government commitment in place to make this happen by 2025, you’ll be able to relax knowing that there’s no need to make any alterations to your heating system.

How long is the Worcester 4000 warranty?

The warranty with the Worcester 4000 new boiler is there to give you peace of mind in your new purchase. Should anything go wrong, then you know that you can simply call the manufacturers helpline, and an engineer will be dispatched as soon as possible.

However, there are some significant differences between the warranties offered by different boiler companies. And of course, there’s also the need to take a close look at the small print in the terms and conditions!

For the Greenstar 4000, Worcester Bosch offers a generous guarantee of up to ten years. So, that’s:

  • Standard guarantee – 7 years
  • Guarantee when a Greenstar System Filter is fitted – 8 years
  • Guarantee when a Greenstar System Filter is fitted, and payment made of £150 – You can get 10 years
  • 12-years if you order this boiler from Boiler Central*

Like any top boiler brand, you must ensure that you get your boiler serviced every year to ensure that the warranty is kept valid. A boiler service is worth it not only for the warranty, but it will also keep your 4000 as energy efficient as possible over its lifespan.

Is there many Worcester 4000 boiler problems?

Due to the Worcester 4000 range only coming out in 2021, there have not been any major problems except supply issues. Worcester have had significant supply issues with the 4000 model and also the Worcester 2000 combi boiler range due to microchip shortages which is a knock-on effect from COVID-19.

(Video) Worcester Bosch Greenstar 4000

Over the last few months of 2021, Worcester has pretty much run out of all 4000 models and have stopped production until they can get hold of these microchips. This is the same for the 2000 model too.

So yes, there is huge problems with this new Greenstar range boiler, but only due to supply issues. We have not had any problems with the actual boilers installed in customers’ homes, so that’s a big plus.

Worcester 4000 vs Worcester 8000

We get asked quite a lot if there is much point in upgrading from the 4000 to the 8000 Greenstar range, so hopefully, this will help settle your mind.

Just to give you some overview, the Worcester 2000 is the entry-level range, the 4000 is the mid-range and 8000 boilers are the top end of the Greenstar lineup.

They are all excellent boilers that will last for years to come and each need a full article on why they are a good or bad choice for your property. You can view the Worcester 2000 boiler review here and the Worcester 8000 Style review here and the Worcester 8000 life review here.

However to summarise, if we had to choose between the 4000 or 8000, the 4000 would be chosen if price and boiler size was an issue, as the 8000 is more expensive and is much larger in size.

If you want to consider other manufacturers then check out our head to head in the Worcester 4000 vs Viessmann Vitodens 050 comparison review.

Worcester Greenstar 4000 manual

If you are looking for the Worcester 4000 manual, you can view this here

Guarantee terms and conditions

As with all cover, whether that’s a guarantee or a warranty, it’s essential to understand the terms and conditions. For the Greenstar 4000, you need to ensure:

  1. The boiler must be installed and commissioned by a competent and officially certified installer such as a Gas Safe registered engineer
  2. The boiler must be registered within 30 days of the boiler installation
  3. The boiler is installed into a domestic home
  4. A gas safe engineer must service the boiler on an annual basis – see boiler service costs here and find out how you can get a service plan with our boiler cover

Worcester Bosch Greenstar 4000 – Should you buy one?

We must admit that we were more than a little surprised when Worcester Bosch decided to replace their top-selling boiler replacement range. But now that we’ve seen the specification for the 4000, it all makes much more sense.

This is a boiler that’s been carefully designed to give you all the functionality you need while still being incredibly user friendly to use and providing high levels of efficiency. We’re in no doubt that the 4000 will become the next top-selling boiler in the Worcester Bosch range.

So, is the 4000 the right model for you? We think it’s got a huge amount of appeal for small to medium-sized homes. However, getting a personalised quote is a great way of being provided with a choice of boilers that are going to meet your heating and hot water needs.

You can then ensure you get the best new boiler cost from Boiler Central, which are 5-star rated on Trustpilot with 1,000s of reviews.

Simply provide a few household details and we’ll do the rest for you, get a price online with our free quotation tool below:


How many radiators can a Worcester 4000 run? ›

The Worcester 4000 30kw combi boiler is ideal for small to medium-sized homes with up to 16 radiators. That extra 5kW of power increases the flow rate up to 12.3l/min.

What is the difference between Greenstar 4000 and 8000? ›

The 4000 also offers a 'Quick Tap' water saving function to help you reduce water waste. The key difference between the Greenstar Style 8000 is the availability of power outputs. The 8000 is more powerful and designed for larger homes that require greater heating and hot water.

What is the difference between Worcester Bosch 2000 and 4000? ›

The Worcester Bosch 4000 is slightly smaller in height compared to the Worcester Bosch 2000, however, both have been designed to fit neatly inside a standard kitchen cupboard.
What's the difference between the 2000 and 4000 series?
ModelGreenstar 4000 Combi
Condensing in domestic hot water (combi)Yes
7 more rows

What temperature should my Worcester boiler be set at for central heating? ›

Ultimately, the best settings for your boiler depend on your central heating and hot water needs. Having a thermostat at a temperature ranging between 18 degrees to 23 degrees and hot water ranging between 55 degrees to 60 degrees gives you a ballpark estimate.

How long do Worcester Greenstar boilers last? ›

"Our boilers are designed to last for between 12 and 15 years and the failure of durable components after just two years is normally down to outside influences.

Which Worcester combi boiler is best? ›

The Worcester Bosch Greenstar 4000 is one of the most efficient combi boilers on the market, with an efficiency of 94% and an ErP A-rating.


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