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Worcester Bosch has become a household name for their continuous manufacturing of up-to-date boilers. Worcester was founded in 1962, later named Worcester Bosch in 1992 due to an acquisition by the Robert Bosch GmbH. Worcester Bosch has transformed over the last five decades from a small engineering company to the UK’s favourite boiler manufacturer.

We took a good look at Worcester Bosch's 25i combi boiler, just how good is the UK's most popular boiler?

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Will the Worcester Bosch Greenstar 25i be suitable for my home?

The Worcester Bosch Greenstar 25i combi boiler is currently their best-selling combi boiler and is suited to smaller flats and houses (1 to 3 bedrooms and 1 bathroom). With a high ErP (Energy Related Product) rating of 93% and a lightweight design, the 25i is the perfect successor to the 24i Junior. With a central heating output of 24kW, a domestic hot water output of 25kW and a flow rate of 10.2 litres/minute, the Greenstar 25i offers an efficient heating and hot water experience.


There are a wide variety of controls to choose from, which range from mechanical to smart options. The control panel on the boiler itself is what you’d normally expect to find once you’ve opened the flap on the Greenstar 25i. 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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This is a great option for you if you’re looking to have closer control of your energy use while setting heating schedules using the app on your mobile phone or other smart devices. However, if you’re looking to stick with digital thermostats, the Greenstar Comfort thermostat is a good choice.

Worcester Bosch has massively improved the simplicity with which engineers can access main components and parts within the boiler. An engineer can easily diagnose issues due to the control panel on the boiler, so that if a problem should arise, an engineer can perform diagnostics over the phone and easily fix it in person if needed, reducing call-out fees.

Get your quote for the Worcester 25i today!

At Hometree we know that a warm home is too important for a broken boiler to get in the way. If you urgently need a replacement boiler, we can help you today.

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Worcester Bosch offers a standard 5-year warranty free of charge for all their Greenstar boilers, however, if you have this boiler installed by Hometree, you can extend your warranty by a further 5 years.

Energy Efficiency

The Worcester Bosch Greenstar 25i lives up to its name as a “green” boiler. With an ErP (Energy-related Product) rating of 93% (which is an A-grade), you’re not just looking at a high-performance boiler but you'll also save money on those monthly energy bills while reducing your household's carbon footprint.

The ErP directive tests each product to see if it passes certain criteria based on their energy efficiency. For example, how the design of the boiler has been improved to lower carbon footprint and decrease the amount of wasted energy.

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In conclusion, the Worcester Bosch Greenstar 25i combi boiler is the perfect choice for a smaller home with one bathroom and up to 3 bedrooms. It packs a punch while being one of the highest efficiency rated boilers on the market.

The Greenstar gas boiler series has won the coveted Which? Best Buy award for 7 years running, which is a testament to the quality of the company’s products. It’s certainly an improvement over the 24i Junior and boasts a list of benefits from high efficiency to improved controls.

If you're looking for a more space-saving solution, check out our review of the Worcester Bosch Greenstar 25Si Compact.

 Worcester Bosch Greenstar 25i
ErP rating (energy efficiency)A (93%)
Size (HxWxD in mm)710x400x330
Heating output (kW)24
How water output (kW)25
Flow rate (litres/min)10.2
Standard warranty (years)5 (extended warranties available)
Other available sizes (kW)30

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 25i rating below:


If you'd like to learn more about the Worcester Bosch Greenstar 25i combination boiler, check out our quick video review below: