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Worcester Bosch Greenstar 30i Combi Boiler - Review


Worcester-Bosch is a UK-based boiler manufacturer with over five decades of experience. Worcester-Bosch's current product portfolio covers boilers, solar water heating, air heat pumps, and water heat pumps. Worcester-Bosch has transformed from a small engineering company in the 60s to a household name with their high-quality and highly efficient boilers being installed in homes nationwide.

Today we will be taking a closer look at the Worcester Bosch Greenstar 30i combi boiler.

Will the Worcester Bosch Greenstar 30i be suitable for my home?

The 30i is a slight upgrade over its top-selling 25kW combi boiler, the Worcester Bosch Greenstar 25i. Unlike the 25i, the 30i is more powerful in terms of water flow rate and is able to supply 12.3 litres of hot water per minute. To be clear, the output for the heating is the same for these two boilers (24kW), what differs is the hot water output, i.e. the power with which the boiler heats up water for anything but the heating, e.g. showers, kitchen taps etc. The 30i offers a heating output of 24kW and a hot water output of 30kW, which is ideal for small to mid-sized homes with up to 3 bedrooms and 1 bathroom. As far as energy efficiency is concerned, both boilers have a high rating of 93%, which is an A-grade overall.


The Greenstar 30i has a standard control panel, which has all the usual boiler controls to switch off the boiler or lower its output. Due to the simplicity of the 30i's control panel, it's now easier for an engineer to be able to diagnose any of your boiler issues over the phone, which will significantly reduce call-out fees. The build of the boiler itself is also relatively simple, which makes replacing parts and finding spare parts considerably easier.

Worcester Bosch offer a wide range of controls from mechanical to smart options. In addition to its control panel, you have the option of using a Smart Thermostat to have all of the control of managing your heating and hot water from a smartphone app.

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The smartphone app allows you to schedule your heating, monitor energy use, and remotely switch your heating on and off while you’re away from home as long as you have an internet connection. If you don’t want all the singing and dancing features of a smart thermostat, the Greenstar Comfort, a simpler digital thermostat may be the best option for you.


As for its sizing, the Worcester Bosch 30i is quite average at 710x400x330mm, which may be a red flag if you’re looking to install a combi boiler in one of your kitchen cupboards. Worcester Bosch also offers a few compact boiler options if you prefer a smaller boiler, such as the Worcester Bosch Greenstar 25Si Compact.


Each Worcester Bosch boiler model from the Greenstar range comes with a standard 5-year warranty free of charge for your peace of mind. A lot like Vaillant’s Advanced Installer extended warranty offer, Worcester Bosch offers extended warranties if your boiler is installed by a Worcester Accredited Installer.

Energy Efficiency

The 30i is definitely a “green” boiler, with an ErP (Energy-related Products) rating of 93%, which is an A grade for efficiency. So, in addition to incredible performance, you will start saving money on your energy bills while playing your part in the reduction of carbon emissions.

The ErP directive tests each boiler and energy product to ensure that they pass certain performance criteria. If a boiler is tested and comes out with a poor efficiency rating, the directive will step in to recommend design improvements to reduce the amount of energy wasted.


The Worcester-Bosch Greenstar 30i is perfect for smaller to mid-sized homes, especially if you have one bathroom with a bath installed. The entire Greenstar i range is one of the highest rated boiler ranges on the market for efficiency, which will save you money in the long term. In addition to high efficiency, the Greenstar boiler range has won the Which? Best Buy award for 7 years in a row due to their high-quality build and performance.

 Worcester Bosch Greenstar 30i
ErP rating (energy efficiency)A (93%)
Size (HxWxD in mm)710x400x330
Heating output (kW)24
How water output (kW)30
Flow rate (litres/min)12.3
Standard warranty (years)5 (extended warranties available)
Other available sizes (kW)25

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Which? boiler review

The consumer group Which? review each boiler on the market to find the most (and least) reliable boilers according to a survey completed by thousands of boiler owners. In each review, Which? supply a brand score percentage and star ratings for each category. Take a look at the Worcester Bosch Greenstar 30i ratings below:

Which? Score 
Efficiency rating★★★★★
Brand reliability★★★★★
Brand customer score★★★★★
Ease of repair★★☆☆☆
Ease of service★★★☆☆
Availability of parts and spares★★★★★
Build quality★★★★★
Engineer recommendation★★★★★
Brand score86%

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If you'd like to learn more about the Worcester Bosch Greenstar 30i combination boiler, check out our quick video review below:

Video transcript

Hello and welcome to Hometree, home of the stress-free boiler installation. Today we are looking at the Worcester Bosch Greenstar 30i combi gas boiler, one of our best-selling combination boilers here at Hometree. If you didn't already know, Worcester Bosch is a UK-based manufacturer with 50 years of experience in manufacturing energy products and is a much-loved boiler brand, due to reliability. For eight years running, they have been a top trusted brand in the Which? annual boiler survey.

In our review, we're gonna run you through all of the elements of the Worcester Bosch Greenstar 30i combi boiler and why this might be the right boiler for you.

The Greenstar 30i is a slight upgrade from the popular 25-kilowatt version, the 25i. This powerful combi can supply up to eleven litres of hot water per minute. The hot water output of the 30i is at 30 kilowatts; which is great for homes with three bedrooms and one bathroom. This boiler comes in an average size which can fit in most kitchen or hall cupboards. This excludes any space needs for ventilation, pipework or cables. The Greenstar 30i comes with a standard control panel on the boiler which allows you to switch the boiler on and off or lower the output. It's worth noting that each Hometree boiler installation comes with a FREE smart thermostat, so you'll be able to control your heating from your smartphone. Most smartphones are compatible with this model.

For extra peace of mind, the simple build of the Greenstar 30i means it is easier to diagnose problems and replace parts on the boiler. With this Worcester Bosch model, there is a five-year standard warranty. But if you choose Hometree, we'll provide you with a 10-year warranty, for free, for your peace of mind. The 30i has an energy efficiency rating of 93%, which is also an A-grade. We all want to avoid wasting energy and spending extra money which is why this boiler is an excellent choice.

The Worcester Bosch brand has an outstanding 86% Which? score as well as a five-star customer score. It's not surprising really when you look at the exceptional efficiency, the brands reliability, availability of parts and spares and that is easy to maintain. The team at Hometree can discover which boiler type and size is suitable for you, just by asking some simple questions on our website or over the phone. Hometree will then provide you with an A-rated boiler and boiler installation at a great price and at a time that suits you. Unlike some traditional boiler installers, we won't send pushy salespeople to your home. Instead, we will do a video survey using a smartphone with one of our Gas Safe engineers.

At Hometree we know that a warm home is too important for a broken boiler to get in the way, so we provide stress-free boiler installations. To get the right boiler at a great price, fitted by a local gas safe engineer at a time that suits you visit