Home / Blog

Worcester Bosch Greenstar 42CDi Classic Combi Boiler – Review

Are you looking for a powerful combi boiler from a trusted UK brand? Well, you’ve come to the right place! Here’s a full review of the Worcester Bosch 42CDi Classic Combi to help you decide if it’s the right boiler for you.

First things first, let’s introduce you to Worcester Bosch. After all, it’s important to know a little bit about the brand you’re buying from.

Worcester Bosch is the UK’s leading domestic boiler manufacturer and has been around since the early 1960s. They’re a trusted brand, known for producing highly efficient boilers you can rely on. With several boiler ranges to choose from, you’ll have no problem finding one that meets the needs of your household. Shall we see if it’s the Worcester Bosch 42CDi? Let’s get started.

Will the Worcester 42CDi be suitable for my home?
The Worcester Bosch 42CDi is a classic combi boiler from the brand’s popular Greenstar range. It has a high central heating output of 30kW, making it powerful enough to heat between 15 and 20 radiators, in a large, spacious 4-bedroom home. The Worcester 42CDi also boasts a hot water output of 42kW and excellent hot water flow rate of 15 l/min. It is, therefore, a sensible choice for households with multiple bathrooms. If you need hot water fast, this boiler won’t let you down.

Before choosing a combi boiler, like the Worcester Bosch Greenstar 42CDi, it’s always a good idea to have your mains pressure checked by an expert. Combi boilers require a decent level of mains pressure in order to operate effectively.

If the Worcester Greenstar 42CDi sounds a little excessive for your household, you may want to consider a model with a slightly smaller output. The Worcester Bosch Greenstar 30i has a 24kW central heating output, 30kW hot water output and flow rate of 10.8 l/min. There’s also the Worcester Bosch Greenstar 36CDi, which has a central heating output of 24kW, hot water output of 36kW and flow rate of 12.9 l/min, along with the additional benefit of a compact design.

Do you want to compare it with a similar boiler from another leading brand? Take a look at the Vaillant ecoTec Pro 30 combi boiler. It offers the same 30kW central heating output as the Worcester 42CDi but a slightly lower flow rate of 12.3 l/min.

Worcester Bosch 42CDi Controls
The controls on the Worcester Bosch 42CDi are fairly straightforward. Under the flap, you’ll find a clear temperature display, along with buttons to increase and decrease the heating. There’s also the option to set certain modes, like ‘holiday mode,’ which will turn your heating off, and ‘eco mode,’ which will optimise your boiler to save energy.

Back in April 2018, new industry regulations, called Boiler Plus, came into play. Boiler Plus stipulates the level of energy efficiency boilers must operate, along with the need to have both time and temperature controls for easy programming.

Combi boilers, like the Worcester 42CDi, are also required to have one of the following features:

Smart control: Compatibility with a smart device (like a digital or smart thermostat) and controller for improved automation and efficiency

Load compensation: Functionality that allows water flowing from the boiler to alter temperature based on room temperature

Weather compensation: Functionality that allows water flowing from the boiler to change based on the temperature outside

Passive Flue Gas Heat Recovery Device: A device built into the combi boiler that re-purposes otherwise redundant flue gas and uses it to heat water

We personally believe the easiest way to make your combi boiler compliant with Boiler Plus is to link it with a smart device and controller. As well as achieving compliance, it’ll give you greater control over your heating system and the opportunity to reduce your bills through increased efficiency.

Worcester Bosch has two smart thermostats called the Bosch Easy Control and the Worcester Wave, which can be linked to an app on your smartphone. It gives you complete control over your heating and hot water, with options to pre-heat your home, turn off the heating in unused rooms and check your energy usage from any location.

However, you don’t have to choose a Bosch product. The Worcester Bosch 42CDi Classic Combi is compatible with the popular Nest and Hive smart thermostats too. Both have smartphone apps that allow you to monitor and programme your heating system on the go.

Would you rather get a smart device for free? Silly question really, of course you would! Choose Hometree to perform your boiler installation and we’ll give you the Honeywell Lyric T6 Smart Thermostat free of charge. The controls on the device itself are quite basic, however, paired with the smartphone app, it offers extensive functionality, very similar to the Nest and Hive.

42CDi Worcester Boiler Size

If you’re looking for a boiler that fits inside your kitchen cupboard, the Worcester 42CDi probably isn’t it. At 760x440x360mm it’s not the most compact boiler on the market but unfortunately, that’s a compromise you may have to make if you want a powerful model like this. If you’re struggling for wall space in your kitchen, feel free to get in touch with our expert engineers, who may be able to suggest alternative locations.

If the size of the Worcester Bosch Greenstar 42CDi has put you off and you require something more slimline, the CDi Compact boilers from Worcester Bosch may prove a better fit. As the name suggests, they are compact in size and have been designed to fit in a standard kitchen cupboard (but it’s always worth measuring up first, just to be sure!) The downside is you’ll have to compromise on power. The Worcester Bosch 36 CDi Compact Combi boiler only has a central heating output of 24kW.

Worcester Greenstar 42CDi Combi Warranty

Hometree is proud to be Worcester Accredited Installer and can offer a free 5-year warranty with every boiler installation. If you’d like to increase this to 10 years, we can do so for a small additional charge.

Worcester 42CDi Energy Efficiency

Today all boilers have an ErP rating, which determines how energy efficient they are. The Worcester Bosch 42CDi Classic Combi has an A-rated ErP of 92%. If your older boiler has a lower ErP and you swap it for the 42CDi, you can expect to see a reduction in your energy bills. We thought you’d like the sound of that!

Verdict – Is the Worcester Bosch 42CDi Classic the right boiler for you?

If you are looking for a powerful combi boiler, capable of heating a large spacious home, the Worcester Bosch 42CDi is definitely one to consider. In addition to its powerful outputs, its hot water flow rate of 15 l/min will prove very beneficial to those with high hot water demands.

Unfortunately, some will be put off by the size of the 42CDi but here’s what you need to ask yourself. Do you need a powerful boiler that can heat up to 20 radiators or do you need one that fits seamlessly into your kitchen? Only you can decide that.

We hope we’ve provided you with enough information about the Worcester Bosch 42CDi to make a smart purchasing decision but if you have any questions, please don’t hesitate to get in touch.

 Worcester Bosch Greenstar 42CDi Classic
ErP rating (energy efficiency)A (92%)
Size (HxWxD in mm)690x390x280
Heating output (kW)30
How water output (kW)42
Flow rate (litres/min)15
Standard warranty (years)5 (extended warranties available)
Other available sizes (kW)29, 34, 38

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 42CDi Classic 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%

Boiler manual

Worcester Bosch Greenstar 42CDi Classic combi boiler manual

We Beat or Match Any Quote

Call 0330 912 4843 and we’ll beat or match any quote.

Serious About Service

24/7 claims support & rated Excellent on Trustpilot

Cover Match Guarantee

Get a £50 gift card if you find something we don’t cover

All Gas Boilers Covered

All makes and models, regardless of age