Worcester Bosch Greenstar I System Boiler Prices- Compare, Expert Reviews Buyers Guide

Mornings in the UK can be torturous for you if you want to stay fresh at your work. Don’t worry, we’ve got your back. You don’t need to shiver every morning just to look fresh. A boiler is an efficient solution available in the market currently to avoid such problems. You don’t need to bother if you don’t have much idea about the boiler. A boiler can be used to heat the water before using it by increasing the temperature of the water or heating the room altogether. But while buying it, we must be aware of the consequences of this action on our pocket and environment. Certain things, which need to be kept in mind while choosing the right boiler are: a boiler should be feasible, efficient, and environment-friendly.


There are various types of boilers available in the market today, be it offline or online. So, the problem starts with the selection of the right boiler for you and your family. Lemme guide you through this.

Although a majority of the UK population prefers combi boilers to other boilers to get heat and hot water, system boilers can be a better option in many ways. The households where space is not the problem and the demand for hot water is very high daily, going for the system boilers can be proved to be the best decision ever. However, the variety of brands present in the market may confuse you to some extent, one of the most reliable brands, which has been proved to be the most efficient and pocket-friendly is “Worcester Bosch Greenstar I System Boilers”.

NameOur RatingAvailablePriceOnline Rating
Worcestershire Bosch Greenstar I System Boiler9/10Yes£861.78 to £1090.134.6 out of 5 Stars 20,566 Global Rating

Prices for different models of the WORCESTERSHIRE BOSCH GREENSTAR I SYSTEM Boiler:


  • Dimension- H- 710, W- 400, D- 330
  • Max Flow Rate-N/A
  • Output- 9kW
  • Efficiency- 93%
  • Typical Price- £861.78

This boiler made by Worcester Bosch is very beneficial for the small and medium houses where the small family resides. This Greenstar 9i boiler is wall-mounted. This proves to be beneficial in many ways. It has its advantages. This is one of the most efficient boilers with 9kW output and an efficiency rate of 93%.


  • Dimension- H- 710, W- 400, D- 330
  • Max Flow Rate-N/A
  • Output- 12kW
  • Efficiency- 93%
  • Typical Price- £884.92

These boilers are perfect for if you have a 1-2 bedrooms house or bungalow. It has a central heating output of 12kW. It is compatible with the solar panel. It can accommodate not more than 10 radiators. So, if you are looking for more than 10 radiators, you must go for the boilers with higher outputs.


  • Dimension- H- 710, W- 400, D- 330
  • Max Flow Rate-N/A
  • Output- 15kW
  • Efficiency- 93%
  • Typical Price- £938.02

15i System boilers are ideal for small household and due to its low output, it is economically-feasible. The output of this boiler is 15kW and can heat up to 10 radiators. It requires a cylinder since it is a system boiler.


  • Dimension- H- 710, W- 400, D- 330
  • Max Flow Rate-N/A
  • Output- 18kW
  • Efficiency- 93%
  • Typical Price- £1001.78

The Greenstar 18i system boiler is a wall-mounted highly efficient boiler. It is compatible with Greenskies solar panels which helps in cutting energy bills. Its efficiency is known to be 94%.


  • Dimension- H- 710, W- 400, D- 330
  • Max Flow Rate-N/A
  • Output- 21kW
  • Efficiency- 93%
  • Typical Price- £1014.90

the Greenstar 21i system boiler is a popular choice with customers especially if you are upgrading from the previous old boiler to the new boiler. The basic expected output is 21kW which is sufficient for a small house or flat.


  • Dimension- H- 710, W- 400, D- 330
  • Max Flow Rate-N/A
  • Output- 24kW
  • Efficiency- 93%
  • Typical Price- £1047.63

These boilers have a basic output of 24kW. These boilers have been designed to be ideal for a house with 3-4 average size rooms. These boilers are best if you are thinking of replacing the old boiler with an upgraded system.


  • Dimension- H- 690, W- 390, D- 280
  • Max Flow Rate-N/A
  • Output- 27kW
  • Efficiency- 93%
  • Typical Price- £1044.76

The compact dimension of the Bosch Greenstar 27i System boiler enables this boiler to be installed in a variety of places. This 27kW output of this boiler can cut the heating and hot water bills by 15-20%.


  • Dimension- H- 690, W- 390, D- 280
  • Max Flow Rate-N/A
  • Output- 30kW
  • Efficiency- 93%
  • Typical Price- £ 1090.13

This boiler with 30kW output seems to be ideal for houses with 3-5 bedrooms. It can heat up to 10-14 radiators. This seems to be the product of the highest price. The compactness helps you to install it anywhere even if the property is small or medium.


These boilers are different from combi and regular boilers in many ways. These boilers run on gas and require an additional cylinder to store water. Worcester Bosch Greenstar I System Boilers are available in eight outputs. The price range of these boilers varies from £861.78 and £1,090.13 including VAT and excluding installation charges. Eight different models with different outputs available in the market are below.


  • Ideal for small house and family.
  •  More than 93% efficiency rate.
  • Compatible with Greenskies Solar Panel.
  • Designed to cut energy consumption.
  • Environment- friendly
  • Perfect for the high demand for heat and hot water supply.
  • An additional cylinder to store hot water in storage.
  • Designed to reduce emissions and increase efficiency.
  • Doesn’t affect the operation of the radiators while heating the water.
  • Ideal for stone-built houses and high ceilings.
  • Reduce the emission of pollutants which makes it quite environment-friendly.
  • Doesn’t need a loft tank.


  • Requires more space.
  • Not ideal for large families.
  • Can’t operate more than 5-8 radiators.
  • Requires cylinder to store water.
  •  Not as green as combi boilers
  • Fits only in the fully-pumped system houses.
  • The efficiency is the same but the price is higher than the 9i model.
  • Doesn’t fit in a standard-sized kitchen cupboard.
  • Not easy to transfer from one house to another.


  • It requires an additional cylinder to store hot water, unlike a combi boiler.
  • It is a wall-mounted boiler.
  • It’s a high-efficiency boiler so it needs to be fitted with a fully pumped system.
  • It requires a large cupboard size space in the kitchen to fit perfectly.
  • It can operate on Greenskies Solar panel to reduce the emission and the energy bill.
  • It is a wall-mounted boiler.
  • Compatible with Greenskies solar panel.
  • Two taps can be used simultaneously to get hot water.
  • Performs perfectly when fitted with the fully-pumped system.

Product Specifications

  • Model- Worcester Bosch Greenstar 9i System Boiler
  • Type- System
  • Dimension- H- 710, W- 400, D- 330
  • Output- 9kW to 30kW
  • Efficiency- 93%
  • Typical Price- £ 861.78 to  £ 1090.13

Buying Guide

The variety of the system boilers currently available in the market, sometimes, confuses the buyers a lot. To avoid this confusion, you must have a clear understanding of your basic requirements. There are lots of factors that dictate the selection of the right boiler for you. Things which need to be kept in mind are the size of your house and the total number of rooms where you need hot water. The space available for the boiler in your kitchen can be one of the most important factors.

System boilers can be beneficial than other boilers in many ways but it requires a hot water cylinder for storage and flue which can be horizontal or vertical. While buying a system boiler, things that need to be compared with other boilers are output range, efficiency, environment-friendliness, price range, etc.

As, output, measured in kW, helps to determine the capabilities of the boiler and the number of radiators it is capable of heating. Efficiency gives us an overview of the boiler how much cost can it helps us to cut in the terms of the energy bill. A boiler must be environment-friendly which means the boiler which emits a meagre amount of pollutants. Warranty is one of the key factors which can help us to cut the extra cost if the product gets damaged or needs repair. Usually, a boiler has 2-5 years of the standard warranty, however, it can be extended up to 10 years.

Things to keep in mind when looking for the right WORCESTERSHIRE BOSCH GREENSTAR I SYSTEM Boiler for your home:

Efficiency of the boilers – this is one of the most determining factors we must consider before buying a boiler as the efficiency controls the expense of your annual energy fuel bills. This also affects the environment around us.

 Maximum Flow Rate – This determines how fast the water will be filled in the cylinder. The boiler with the low MFR will take more time to fill the cylinder and the boiler with high MFR will fill the cylinder fastly.

Number of Radiators – This number of radiators to be used in the house must be counted to decide the output of the boiler. It will help you to look for the boiler with proper output to fulfill the demand for hot water and the energy required to run the radiators.

Warranty – It gives you the satisfaction that your boiler is going to have a good life and even if it gets damaged due to some unavoidable reasons, you don’t need to worry about the repair and the maintenance of the boiler till the boiler is covered under warranty period.

Facts you didn’t know about WORCESTERSHIRE BOSCH GREENSTAR I SYSTEM Boilers:

  • The company was founded by Cecil Duckworth as Worcester Engineering in Worcester in 1962.
  • Boilers can provide various types of heating. It’s important to know whether you have steam or hot water heating so you can properly maintain your system.
  • One of the main differences is that hot water systems will always have two pipes coming from the radiator. A steam system may only have one.


What do the experts have to say?

Worcester Bosch is the first boiler brand to have been awarded the Which? Best Buy endorsement 10 times since 2009, enhancing its reputation for reliability and satisfaction following feedback from both homeowners and engineers once again. Scores based on engineer recommendations, ease of servicing, fixing a common fault, availability of parts and spares and build quality have seen Worcester Bosch perform highly. Reliability is the single most important consideration when buying a new boiler and Worcester Bosch has it in spades. We’ve been running boiler reliability surveys for 10 years and Worcester Bosch has impressed us every single year. Reliability and customer scores were worked out based on three main criteria – the number of faults boilers developed in customer’s homes, customer satisfaction and their likelihood to recommend the product. The manufacturer smashed it on all accounts, swooping up impressive scores. We’ve been running boiler reliability surveys for over 10 years and Worcester Bosch has impressed us every single year. The silver lining is that replacing an old non-condensing boiler with a modern condensing system can improve your boiler’s efficiency by more than 30%, saving you a substantial amount on your annual heating bill.

Matt Knight


Customer Reviews

  • Name of Reviewer: William Valentine
  • Date: 09/09/2020
  • Rate: 4.5 out of 5 Stars.

 Feedback: I decided to go for Worcester Bosch based on research I did prompt by your advert last Autumn (2019); including other’s feedback, effectiveness and efficiency of the combi boiler and primarily the 12-year guarantee having been let down by other manufacturers previously. It was more expensive but I thought the far better than average warranty was worth it. The installer’s crew (Premier Heating Solutions) worked really hard initially as there were complications during that. We’ve had a couple of issues that needed the installer to come back out subsequently, but all covered by the warranty so while it’s not been perfect from day 1 (which would be 5 stars), the service has been good since.

  • Name of Reviewer: Janet Salisbury
  • Date: 25/12/2020
  • Rate: 5 out of 5 Stars

Feedback: It was the start of the Christmas holidays last year when our old boiler broke down. We shivered for two weeks because SSE engineers were on leave. When our Worcester Bosch boiler finally arrived it was wonderful, instant warmth everywhere and piping hot water, so much better than our original boiler which didn’t really keep the house warm. Since then our home has been cosy and our bills have come down. Thank you

  • Name of Reviewer: MURIEL GODDARD
  • Date: 10/08/2020
  • Rate: 5 out of 5 Stars

Feedback: My previous boiler was about 10 years old, so to have a new, modern boiler was great. My boiler is in my garage so to alter anything I would have to go in there, which was a pain! Now, I have the luxury of the controls being in my house and once I got used to the ‘computer’ set up, it was a big improvement, and I love it. I gave it four stars as I have only had the boiler for a year so not sure yet how it will affect my gas bill. Perhaps in a year, I will give it five stars!

  • Name of Reviewer: Martin Cripps
  • Date: 19/11/2020
  • Rate: 3 out of 5 Stars

Feedback: The boiler was installed and has failed on numerous occasions. We are under the impression that the product is so new that even Worcester Bosch engineers do not know how it operates, to the extent that we have had 3 different engineers out on several occasions. The Worcester Bosch engineers seem to have no communication with their office as they turn up with no, or incorrect parts even though they should have been informed by the previous visits. Leaving us very disappointed with Worcester Bosch boilers and wishing we had stayed with a valiant boiler.

 Real-World Case:

Our Worcester Bosch boiler was installed by a highly reputable Worcester Bosch installer – all the technicians worked hard and their work was exemplary. The technology has improved beyond recognition allowing the customer to control the heating and hot water functions more efficiently and economically. The actual heating controls are very adaptable to the customer’s housing situation e.g Is heating required on all day? Is heating required just twice a day perhaps? Both these circumstances can be programmed to the customer’s needs. The boiler itself is very stylish and neat fitting into our kitchen in a corner by the door. Our previous boiler was a Worcester Bosch so this new one has been enhanced many times over.

Philip Gill



  1. Why do boilers have a minimum flow requirement?

Boilers with low water volumes require a minimum flow requirement to prevent localized boiling and subsequent heat exchanger damage in a low to zero water flow situation. Minimum flow requirement varies by boiler design.

Regardless if a boiler itself has a minimum flow requirement; every hydronic heating system needs to be designed to carry the energy being created away from the boiler to avoid high temperature shut down.

2.Can heat pumps heat swimming pools?

Yes, heat up from cold is slower than traditional fuels, but long term the system will run more efficiently.

3. What to do if no hot water is available?

There are a few scenarios that can lead to a lack of hot water. These include a faulty diverter valve (typical, if the heating works, but hot water doesn’t). But, it could also be due to lack of power, a stuck Y/S-plan valve, faulty PCB unit, or even a problem with the heating pump. If your boiler is out of warranty and needs a diverter valve replacement, it might be wise to invest that cash in a new unit with a long warranty. If that doesn’t sound like the issue, head over to our article specific to Worcester boiler faults causing no hot water.

4. What to do if it is losing pressure?

If your Worcester boiler problem relates to your unit losing pressure; you leak. Sure, it might not be visible, but it’s there somewhere. And, this is not necessary a leak on the boiler. Any leak throughout your central heating will cause a boiler to lose pressure. This could be a pin-hole in a radiator, a loose connection on a rad valve, or even a weak soldering joint on the copper pipe. When a Worcester boiler gets below a certain pressure, it will lockout. To fix this, you’ll need to re-pressurise it using the external filling loop. But, that’s only a temporary fix. To solve the problem with your Worcester, and clear any fault codes, the leak needs to be found and fixed


After going through all the RnD materials available on the internet, you’ll find that Worcester Bosch Greenstar I System Boiler is worth its cost. It has its own advantages and disadvantages. However, the advantages of these boilers overweigh the disadvantages. You can rely more on this boiler than any other boilers.

Add a Comment

Your email address will not be published. Required fields are marked *