Choosing the right Worcester Bosch Combi boiler for your home

Company type: Manufacturer

HQ: Worcester, England

Founded: 1962

CEO: Carl Arntzen

Combi boilers are incredibly popular, thanks to their compact size and easy installation, and account for over half of all new domestic boilers installed in Britain every year.

Whether you are replacing your current boiler or looking to install one into your new home, Worcester Bosch Combi boilers are designed to suit different house sizes and installation requirements.

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What is a combi boiler?

A combi boiler combines a water heater and a central heating boiler into one highly-efficient compact appliance (thus the name). A combi boiler uses the mains water pressure to supply both hot water and heating upon demand. This eliminates the need for bulky cylinders, making a combination boiler a popular choice for homes with limited space.

Although most Worcester Bosch combi boilers are wall-mounted and are often small enough to fit inside a kitchen cabinet, some are designed to stand on the floor and can be placed outside.

Are Worcester Bosch combi boilers energy efficient?

Worcester Bosch combi boilers are very efficient units, all within the 'A' efficiency category, which means they have an energy efficiency of 92% or higher. In financial terms, a rating of 92% means that for every £1 you spend on energy to heat your home, 8p of that is lost to the heating process.

Traditional boilers generally have lower efficiency rates than combi boilers, meaning increased energy costs. Combi boilers allow you to save money as they heat water in small quantities, compared to traditional boilers that require you to heat up an entire cylinder full of water just to wash your hands!

What homes are combi boilers best suited for?

Although Worcester Bosch Combi Boiler range is wide enough to ensure comfort for homes of all shapes and sizes, combi boilers are generally best suited for properties with little loft space and moderate hot water demands. Continue reading to find the right sized Worcester Bosch Combi boiler for your property.

What size combi boiler do I need for my home?

Below is a rough guide to how powerful your boiler should be to efficiently heat different sized properties. Use these values to estimate the recommended energy output of your Worcester Bosch combi boiler.

Property Type No. of Bathrooms No. of Radiators Recommended energy output Recommended hot water flow rate
Small house or flat 1 Up to 10 24-27 kW 9-12 litres/minute
Medium house 1 or 2 Up to 15 28-34 kW 12-16 litres/minute
Large house 2+ Up to 25 35-45 kW 16+ litres/minute

Choosing a combi boiler with the right energy output will ensure comfort in your home and will help you avoid unnecessary energy costs. Higher energy outputs also provide better hot water flow rates, which makes combi boilers with higher kW more suitable for houses with more than one bathroom.

Overview of the Worcester Bosch combi boiler range

Take a look at all of the Worcester Bosch combi boilers you can currently buy and their specifications.

Property size Model Output kW Hot water flow rate (l/m) Fuel type Installation Max. Guarantee ERP rating Water efficiency rating Dimensions (mm) Sound power (dB)
Small/Medium 2000 25 or 30 9-10.8 Gas Wall-hung 6 years A A 724 x 400 x 300 43
Small/Medium CDi Compact 24 10-12.9 Gas Wall-hung 10 years A A 690 x 380 x 280 52
Small/Medium 4000 25 or 30 10-12.9 Gas Wall-hung 10 years A A 724 x 400 x 310 45
All Heatslave II 12-32 15-22 Oil Floor 5 years A B 950 x 770 x 640 56
Medium/Large 8000 30-50 10.7-18 Gas Wall-hung 12 years A A 780 x 440 x 365 48
Medium/Large CDi Highflow 29.2-30.6 20-25 Gas Floor 10 years A B 850 x 600 x 600 52

Worcester Bosch combi boilers for small and medium sized homes

Greenstar 2000 Combi

The Greenstar 2000 is one of the smallest and lightest boilers out of the entire Worcester Bosch Combi Boiler range and it is designed to comfortably fit between kitchen cupboards. With hot water flows of up to 12 litres per minute, it provide enough water for apartments and houses with one bathroom. It’s also recognized as the quietest Worcester Bosch combi boiler, making it even more appealing for small properties where it’s not always easy to install boilers away from the bedroom.

Key features:

  • Part of the most recent range of Worcester Bosch combi boilers, introduced in 2021.
  • The lowest-priced Worcester Bosch combi boiler, with prices starting from £900
  • The quietest Worcester Bosch combi boiler wwith a sound energy level of just 42 dB. For reference, normal conversation between two people is around 65 dB.
  • The Greenstar 2000 comes with a multitude of installer benefits, including removable side panels for easy internal access.
  • The ‘Quick tap’ feature helps you save water. To activate it, open the tap and immediately close it. While it remains closed, the boiler will fire up and heat up the water within 30 seconds. Then open the tap and enjoy the instantly available hot water!
  • Comes with a generous standard guarantee of six years, when installed by any installer.

Perfect for: Those looking for an entry-level, super-quiet boiler with some great features.

Interested in purchasing? Prices - from £900.

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Greenstar CDi Compact

If you live in a flat or a small house and are looking for a budget-friendly combi boiler from an industry-leading brand, then the Greenstar CDi Compact is an excellent option. As suggested in the name, the CDi compact is the smaller version of CDi Highflow and is the smallest Worcester Bosch combi boiler currently available. The Greenstar CDi Compact combi boiler is suitable for small to medium-sized homes with one bathroom. This boiler is designed to fit within a standard kitchen cupboard and has an easy-to-use control that allows you to fine-tune your comfort.

Key features:

  • This is the lightest and smallest Worcester Bosch combi boiler.
  • Worcester Bosch quality at a reasonable price: prices start at just £950.
  • Simple boiler control knobs with clear temperature display.
  • Frost protection is included, which reduces frost risk when the boiler is installed in a garage or a loft.
  • Comes with a standard guarantee of 7 years; a maximum guarantee of 10 years is available when installed with Greenstar system filters.

Perfect for: Those looking for a powerful, yet compact boiler that can fit into very small spaces.

Greenstar 4000 Combi

Designed to replace the best-selling Greenstar i range, the Greenstar 4000 would be a great fit for most households in the UK. Being a mid-range Worcester Bosch combi boiler, it offers everything the i range did, along with a solid 10-year guarantee. It also has some new major features, such as wireless connectivity and a user-friendly digital interface. It is a great choice for houses and flats with up to 2 bathrooms. To find out more, check out our Greenstar 4000 range review here.

Key features:

  • Part of the newest Worcester Bosch Combi boiler range, introduced in 2021.
  • Front access to all key components of the boiler, meaning it’s fully serviceable without the need to dismount it from the wall.
  • Comes with a generous guarantee of up to 10 years, when installed with the Greenstar system filters.
  • Sleek design and clear informative display.
  • Compatible with Worcester Bosch Smart Controls and third-party products like Hive. These smart thermostats allow you to control your heating remotely using a smartphone.
  • Prices start at £1200 for the 30kW output, making it a powerful, yet relatively affordable boiler.

Perfect for: Those looking for a solid mid-range boiler to replace the legendary Greenstar i.

Interested in purchasing? Price - from £1200.

Get a quote

Greenstar Heatslave II

This Worcester Bosch combi boiler is suitable for small, medium and large sized homes with up to two bathrooms. The Greenstar Heatslave II is the only Worcester Bosch combi boiler that operates using oil and is available for both indoor and outdoor installation. The outdoor installation allows to save up space and the model comes in a durable casing that protects the boiler and ensures it’s resistant to poor weather conditions.

Key features:

  • Oil fired
  • Comes in a range of power outputs (12-32 kW) to meet the needs of smaller homes as well as two bathroom properties
  • For external installation, comes in a green powder coated cabinet that blends in with your garden.
  • In-built frost protection.
  • This model is compatible with EasyControl, which allows you to control your boiler via phone or tablet.
  • Prices start at £2300 and go up to £3000 for larger kW outputs.
  • Up to 7 years guarantee.

Perfect for: Those looking for an oil-fired boiler to install in the garden.

Worcester Bosch combi boilers for larger properties

Greenstar 8000 Combi

Greenstar 8000 Combi is a beautifully designed high-efficiency boiler, available in multiple power outputs of up to 50kW. This means it has enough power to supply more radiators with heat, but also means it can handle far greater hot water demands than its medium-sized sibling, the 4000. This makes it suitable for larger homes with multiple bathrooms. It also comes with the longest guarantee of 12 years, which makes it worth the investment.

Key features:

  • Part of the newest Worcester Bosch Combi boiler range, introduced in 2021.
  • Wireless connectivity with Worcester Bosch smart thermostat, EasyControl, as well as third-party devices like Hive.
  • Comes in a sleek modern design, available in black or white, with an optional glossy finish.
  • Easy-to-use full colour boiler display.
  • Quieter operation than most similar-sized boilers on the market.
  • Guarantee of up to 12 years, when installed by a Worcester Bosch Installer with Greenstar System Filters.
  • Prices start at £1400 for the lowest energy output (35kW) and go up to £2000 for higher energy outputs. /li>

Perfect for: Those looking for a top-of-the-range boiler, with stylish design and all of the latest features.

Interested in purchasing? Price - from £1400.

Get a quote

Greenstar CDi Highflow

The Worcester Bosch Greenstar CDi Highflow is a well-established floor standing combi boiler that is renowned for its industry-leading hot water flow rates. With impressive 20 and 25 litres/minute hot water rates, the Highflow will be a great fit for houses with two or more bathrooms, providing enough pressure to run multiple showers at the same time.

Key features:

  • Fits underneath a standard kitchen worktop.
  • Comes in higher energy output options to supply larger houses, with prices starting at £2000.
  • Ensures high hot water flow rates, providing high pressure at all taps and showers.
  • Frost protection is included, reducing frost risk when the boiler is installed in a garage or a cellar.
  • Comes with a guarantee of up to 10 years.
  • Simple boiler control knobs with clear temperature display.

Perfect for: Those looking for a combi that can handle super high hot water demands.

Interested in purchasing? Price - from £2000.

Get a quote

Still need help with your Worcester Bosch boiler?

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0333 772 6247