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Worcester Bosch Greenstar 30i vs Worcester Bosch Greenstar 29CDi Classic Combi Boiler – Review

Welcome to the latest battle of the boilers. This time it’s a contest between two extremely popular Worcester Bosch combination (or ‘combi’) boilers: the Worcester Bosch Greenstar 30i combi and the Worcester Bosch Greenstar 29CDi classic combi.

When trying to decide between Worcester Bosch combi boilers, you’ll need to factor in price, size, control and energy efficiency. Remember, combi boilers are more suitable for small to mid-sized properties with less demand for hot water and heating in comparison to larger homes with multiple bathrooms. Here’s a useful guide on the types of boilers if you need a refresher. Before we head into the review, let’s take a quick look at the manufacturer.

Worcester Bosch manufactures heating and hot water products. As a brand, Worcester Bosch has a high customer satisfaction score, which is no surprise given their experience that spans over five decades. The company was also founded in the United Kingdom, with energy-saving goods being its primary focus.

Are you ready to take a closer at the boilers?
The table below shows the basic stats for each boiler model:

 Worcester Bosch Greenstar 30iWorcester Bosch Greenstar 29CDi Classic Combi
Other outputs available2534, 38, 42
ErP rating (energy efficiency)A (93%)A (89.1%)
Size (HxWxD in mm)710x400x330760x440x360
Heating output (kW)2430
Hot water output (kW)3030
Flow rate (litres/min)12.312.3
Standard warranty (years)5 (extended warranties available)5 (extended warranties available)


Both boilers offer the standard on-board controls you’d expect on a combi boiler, with the notable difference that the control panel of the 29CDi has more buttons and dials to play with but has a smaller display. The 30i, however, offers a larger screen with fewer buttons to tinker with. The controls for each boiler do pretty much the same thing – they switch the boiler on or off, decrease and increase output, and display an error code if your boiler encounters a problem.

To maximise your control over the boiler, you are best to look at thermostats. It is very rare for homes not to have controls installed for their boiler, whether it’s mechanical or digital. Mechanical controls offer the most basic control of your boiler, whereas digital controls will allow you to programme and control your boiler across 7 days.

Boiler Plus was introduced in April 2018 to improve the energy efficiency of homes nationwide by only installing gas boilers with a 92% energy efficiency rating, as well as time and temperature controls. Due to Boiler Plus, mechanical thermostats are no longer compliant as they only control temperature.

For combi boilers, there are four additional requirements to be compliant with Boiler Plus. Only one of the four measures will need to be met by the homeowner. The requirements are as follows:

  • Weather compensation – The ability to alter the water temperature from the boiler based on the outdoor temperature.
  • Load compensation – The ability to alter the temperature of the hot water from the boiler based on the room temperature.
  • Smart control – A control that automates and optimises your central heating system.
  • PFGHRD (Passive Flue Gas Heat Recovery Device)

Besides mechanical and digital thermostats, you should also consider the newest generation of heating controls, that is smart thermostat options. Worcester Bosch offers their entry into the smart thermostat market with the Worcester Wave, which allows you to control your boiler remotely via your smartphone and analyse your heating and hot water use. Alternatively, you could go for the popular Nest Learning Thermostat, which learns from your heating routine, as well as the times you’re most likely to be in or out of the house and adjusts the setting accordingly.

By the way, each Hometree boiler installation comes with a Honeywell T6 Lyric smart thermostat for no additional cost.

To round the ‘Control” category off, the 30i has the edge over the 29CDi due to the simpler and easier-to-use onboard control panel. The 29CDi seems to be a little more complicated to navigate, which could be tricky for some. A point to the 30i, 1-0.


When comparing the two boilers, the Worcester Bosch Greenstar 29CDi is slightly larger than the Greenstar 30i. The 29CDi comes in at 760mm x 440mm x 360mm, while the 30i measures 710mm x 400mm x 330mm. If you’re looking for a boiler that can be installed in a kitchen cupboard, neither of these boilers will be suitable. Worcester Bosch offers some more compact alternatives, including the Greenstar 30Si Compact, which has a similar output in terms of kW.

It’s a point for each as neither of the two models fits into a standard kitchen cupboard. 2-1.

Energy Efficiency

To prevent energy from being wasted and reduce your carbon footprint, the ErP (Energy-related Product) directive, which has been introduced in 2015, is designed to test and improve the energy efficiency of all energy products before they’re sold to the public. The ErP’s goal is to raise awareness around a product’s carbon footprint and help you make savings on energy bills.

Each boiler is rated based on their heating and hot water performance. Both appliances have been given an ‘A’ rating for efficiency, although the 30i has a slightly better energy efficiency rating of 93% compared to the 29CDi’s energy efficiency rating of 89.1%. In this category, the 30i remains in the lead over the 29CDi.

The Worcester Bosch Greenstar 30i boiler takes another point over the 29CDi! It’s now 3-1.


Worcester Bosch offers a standard 5-year warranty with each of their boilers. Each warranty, however, can be extended to a further 10 years if you decide to have your installation completed by a Worcester Accredited Installer.

At Hometree, you can enjoy extra peace-of-mind with 5-year warranties available with all our installations. We also offer 10-year warranties for an extra charge.

It’s a point for each boiler in this category again – 4-2. It looks like the 30i may already be our winner.


Worcester Bosch have received Which? Best Buy awards for their combination gas boilers for seven years running. Their boilers have also had a great run of 6 years being rated at 92% for customer satisfaction and engineer recommendations.

Given the multitude of awards for all Worcester Bosch gas boilers, each boiler earns a point in this category.

The verdict

We now have a winner – the Worcester 30i wins the battle by 2 points, making the final score 5 – 3.

To conclude this edition of ‘battle of the boilers’, the 30i appears to be the clear winner. The Greenstar 29CDi is a bulkier boiler, which can’t compete with the 30i’s energy-efficiency rating and modern control panel. You’ll still enjoy the brand reliability of Worcester Bosch with the 29CDi Classic, however, for a more energy efficient experience; the 30i is the better choice of the two.

To get your Worcester Bosch Greenstar 30i price, we offer this boiler complete with installation and a range of extended warranties along with a free smart thermostat. If you are still browsing, we can also recommend a selection of boilers that are suitable for your home just by asking a few questions.

 Worcester Bosch Greenstar 30iWorcester Bosch Greenstar 29CDi Classic Combi
Energy Efficiency10

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