Written by Stephen Day
Gas Safe Engineer
Updated: 15th August, 2025
One of the most popular compact combi boilers on the market, here we take an in depth look at the main talking points and key features of the Worcester Bosch Greenstar CDi compact.
As one of the world's leading names in heating innovation, Worcester Bosch, founded in 1962, is synonymous with customer satisfaction.
Blending high end technology with assured traditional engineering, has made the brand one of Europe's most trusted boiler manufacturers.
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At iHeat, we stock a wide range of Worcester boilers. However, today we're going to be talking about the popular Greenstar CDi compact model. One of the best compact boilers on the market.
The Worcester Bosch Greenstar CDi Compact has been created to follow the form of the extremely popular original Greenstar branch of the Worcester Bosch range.
Combining the latest in heating design and energy efficient application, the Greenstar hallmark represents a modern icon of the boiler industry.
The versatile Greenstar CDi compact comes in three available kW outputs and flow rates:
kW (kilowatt) Output Size | Flow Rate - l/min (litres per minute) |
28kW | 11.4 l/min |
32kW | 13.1 l/min |
36kW | 14.7 l/min |
Efficiency rating | 94% |
Energy efficiency class | A rated |
Mounting | Wall mounted |
Weight | 32.9kg |
Dimensions | 680mm (Height) x 390 (Width) x 280mm (Depth) |
Get an instant free quote and fixed price on the Greenstar CDi compact range today here at iHeat.
The Greenstar CDi compact has an A rated ErP score with a 93% efficiency rating. An energy efficient new boiler can significantly reduce an owner’s energy bills, with an A rated boiler considerably helping homeowners save money compared to an old boiler or antiquated system.
Cold weather complications account for a huge number of boiler unreliability or breakdown issues, this often results in service or repair fees.
The Greenstar CDi compact releases condensed flue gases via a CondenseSure siphon, in cyclical bursts to reduce blockages stemming from a frozen condensate pipe.
The smallest model in the CDi range, the sleek design of the compact means it can be easily wall mounted or fit into a standard kitchen cupboard.
The CDi compact is ideally suited to heat small properties but does have the power outage and flow rate in its 36kW capacity to sufficiently heat a medium sized home.
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Combi boilers are a popular choice for a number of reasons. Unlike conventional boilers, combi (combination) boilers link a home’s central heating system and water heating; no separate hot water tank is needed which is cleaner as it avoids potential rust or debris build up.
This allows a compact boiler which could fit into a standard kitchen cupboard or be wall mounted, to thoroughly heat a home without stealing lots of space.
Combi systems are also easier to service or for boiler replacement due to their popularity, meaning greater availability.
The CDi compact comes as standard, as do all Worcester Bosch boilers, with an aluminium heat exchanger.
Although initially efficient, aluminium is far more susceptible to corrosion compared to stainless steel heat exchangers. Heat exchangers can become faulty over time, but this is a relatively simple fix.
The Greenstar CDi compact is fully compatible with smart thermostats like the Worcester Bosch easy control system.
This means thanks to the brainy bunch who manufactured your new boiler, it can be easily controlled at the touch of a button for rapid regulation and optimisation.
The price of the Greenstar CDi compact varies on the output you require, the higher the kW output, the more the initial boiler unit cost.
iHeat offers prices ranging from £2190-£2690 on the CDi compact range, this includes free next day installation by a Gas Safe registered engineer.
Overall the CDi compact is a great choice for a new central heating and hot water system.
A lightweight unit, that is both space saving and highly efficient, making it a perfect fusion of design and application for small or medium sized properties.
Providing a substantial heat output for this size boiler, the CDi compact combi definitely provides a healthy cost value from a trusted UK brand.
Get an instant free quote and fixed price on the Greenstar CDi compact range today here at iHeat
Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.
Effectively, new boiler cost can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer.
Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.
Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).
Installation Type | Price (inc VAT) | |
Combi to combi swap | £1,845 | |
System to combi conversion | £2,499 | |
New boiler install | £2,899 | |
Back boiler to a combi | £3,299 | |
System to system | £1,945 |
Last updated: 15th August, 2025
Written by Stephen Day
Gas Safe Engineer
Stephen Day is a Gas Safe registered and FGAS certified engineer with over 20 years of hands-on experience in the heating, cooling, and renewable energy industry, specialising in boiler installations, air conditioning, and heat pump systems.
LinkedInArticles by Stephen Day are reviewed by iHeat’s technical team to ensure accuracy and reliability.
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