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Worcester Bosch Greenstar 34CDi Classic Combi Boiler – Review

Next up, we have the Worcester Bosch 34CDi Classic Combi boiler. Here you will find a full review of its features to help you decide whether it’s the right boiler for your household.

Before we get into the details, let’s first tell you a little bit about the manufacturer, Worcester Bosch. Established in 1962, the company was originally known as ‘Worcester,’ until it became part of the Worcester Bosch Group in 1996. Today, Worcester Bosch is the leading domestic boiler manufacturer in the UK and has built up a reputation for producing boilers of the highest standard, from its headquarters in, you guessed it, Worcester. The brand is also highly competitive on a European scale, with its main competitor being the German brand Vaillant.

Worcester manufactures an extensive range of domestic boilers to suit all homes, so you’re bound to find one to meet your needs. Let’s get cracking and see if it’s the 34CDi Classic!

Will the Greenstar 34CDi Classic be suitable for my home?

With a central heating output of 30kW and the ability to heat up to 20 radiators, the Worcester Bosch 34CDi will be a great asset to 3 to 4 bedroom houses with 1 or 2 bathrooms. It has a great flow rate of 12 l/min, so if you need hot water fast, it won’t let you down. As with all combi boilers, we’d advise having your mains pressure checked by an expert, before installation. Combi boilers require a fair bit of power, so you need to make sure your water pressure can handle it.

If your home is smaller and has just one bathroom, you can probably get away with a slightly less powerful boiler than the 34CDi Classic. Take a look at the Worcester Greenstar 25i instead. It’s still a very popular combi boiler from Worcester Bosch, but it offers a slightly lower central heating output of 24kW and flow rate of 9 l/min. If that flow rate seems a little low, the Worcester Bosch Greenstar 30i model from the same range offers 10.8 l/min.

Busy households or those with 4-6 large bedrooms may benefit from an even higher hot water flow rate than that offered by the Worcester Greenstar 34cdi classic. The Worcester Bosch Greenstar 38CDi Classic Combi has a flow rate of 14 l/min and the 42CDi classic, 15 l/min. As we said before, there’s something for everyone.

A good equivalent boiler from another brand is the Vaillant ecoTec Pro 30 combi boiler. This offers the same 30kW central heating output as the 34CDi and a similar flow rate of 12.3 l/min.

Worcester Bosch 34CDi Controls

As far as combi boiler controls go, the ones on the Worcester 34CDi are pretty basic. There’s a clear temperature display and knobs so you can increase or reduce the heat to your liking. You’ll also be able to program various modes, such as ‘holiday mode,’ which will turn your central heating off and ‘eco mode,’ to save energy.

In April 2018, new industry regulations came into force, known as Boiler Plus. These regulations basically determine the level of energy efficiency boilers should offer as a minimum. They also require all boilers to have time and temperature controls working correctly.

The 34CDi is a combi boiler, so it must also have 1 of the 4 following features, in order to comply with Boiler Plus:

Weather compensation: Water temperature can be changed based on the temperature outside

Load compensation: Water temperature can be changed based on the temperature of the room

Smart control: Boiler can be linked to a smart app or device for increased automation and improved efficiency

Passive Flue Gas Heat Recovery Device: Boiler is fitted with a device that prevents otherwise redundant flue gas from being wasted, using it to heat water instead.

The best way to make sure your Worcester 34CDi is compliant is to link it with a digital or smart controller. Worcester Bosch offers two fantastic options:

Greenstar Comfort Twin Channel Programmer – Choose different time programmes for your heating or hot water. New settings can be applied for each day of the week.

Bosch EasyControl – A smart thermostat you can link to your mobile phone. Use it to pre-heat rooms (never walk into a cold house again,) turn the heating off in unused rooms (saving money) and check your energy usage from any location (it’s always good to be in the know!).

The 34CDi is also compatible with other popular smart thermostats including the Nest and the Hive. Both offer greater control over your heating system, with smartphone apps for easy programming and monitoring, from any location.

Another alternative is the Honeywell Lyric T6 Smart Thermostat. The controls on the device are fairly basic but paired with the smartphone app it offers fantastic functionality, much like the Nest and Hive. What’s even better is that by choosing Hometree to install your new boiler, you can receive this smart thermostat for free! Who doesn’t love a freebie?

Greenstar 34CDi Size

We’ll get straight to the point and say, unfortunately, this combi boiler will not fit into your average size kitchen cupboard. The trouble is, because the 34CDi is so powerful, it’s hard to make it compact. At 760mm x 440mm x 360mm it’s pretty hefty but if you’re struggling for location ideas, feel free to get in touch with our expert engineers for more guidance.

If slimline is a must, you may be better off looking at the CDi Compact range of combi boilers from Worcester Bosch. All of the boilers in this range are designed to fit into a standard kitchen cupboard. Keep in mind, you’ll have to compromise on power. The Greenstar Compact models only have a central heating output of 24kW, which won’t be powerful enough to heat 20 radiators. Count up and see how many you have before making any decisions.

Worcester Greenstar 34CDi Warranty

Every new Worcester boiler installation carried out by Hometree (Worcester Accredited Installers no less) comes with a free 5-year warranty. This can be extended to a 10-year warranty for a small, additional charge.

Worcester 34CDi Energy Efficiency

You’ll be pleased to hear the Greenstar 34CDi has a fantastic ErP rating of A, with 92% energy efficiency. As long as it’s better than the rating of your current boiler, you will see a reduction in your energy bills just by installing the 34CDi instead. Choosing a more energy efficient boiler will also help to reduce your carbon footprint, so you can feel good about that too!

Verdict – Is the Worcester Bosch 34CDi the right boiler for you?

If you are looking for a top of the range, powerful boiler from one of the UK’s most trusted boiler brands, the Worcester Bosch 34CDi Classic Combi ticks all of the boxes. Its powerful 30kW output makes it suitable for large, family homes and the 12 l/min flow rate is pretty decent.

If size is an issue, the 34CDi may not be the best option for your home. However, you need to consider what’s more important – a boiler powerful enough to heat all your radiators or one that fits neatly into your kitchen?

We hope you’ve found our Worcester Bosch review useful. For more information, feel free to get in touch with our expert team of Gas Safe engineers.

 Worcester Bosch Greenstar 34CDi Classic
ErP rating (energy efficiency)A (92%)
Size (HxWxD in mm)690x390x280
Heating output (kW)30
How water output (kW)34
Flow rate (litres/min)12
Standard warranty (years)5 (extended warranties available)
Other available sizes (kW)29, 38, 42

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 34CDi 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 34CDi Classic combi boiler manual

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