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Worcester Bosch Combi Boiler: Homeowners’ Buying Guide for 2023

When people think of boilers, there’s usually one brand that pops into their head: Worcester Bosch.

And in this quick guide, we’ll link out to boiler reviews, show prices, and let you know what we think of Worcester’s lineup of combi boilers.

Worcester Bosch combi boilers

Worcester combi boilers are by far the most popular brand in the UK. And, their success has led to the company employing over 2,000 people.

If you’re looking for a new combi boiler from Worcester, one of the best places to start looking first is Heatable.

Heatable are one of the biggest installers of Worcester boilers in the UK. They’re a strong online installation site for boilers, and they offer some of the most competitive prices around. You can get a fixed price boiler quote on-screen in only 90 seconds.

Worcester Bosch Greenstar 4000

Which Worcester Bosch Combi Boiler Do You Need?

Buying a heating boiler is confusing, and Worcester boilers are no exception: different models will suit different properties. The type of combi boiler you will require depends on several factors, including:

  • Number of bedrooms
  • Number of bathrooms
  • Quantity of radiators
  • Demand for hot water (i.e. the number of taps and showers on at the same time)

Below, we’ve put together a table with several common Worcester combis. The table shows the models’ output, flow rates, and properties for which they’re suitable.

Boilers Available From Worcester Bosch

Model Heating Output (kw) Flow Rate for hot water (lpm) Suitable For:
Greenstar 4000 25 24kw 9 Smaller properties with 1-3 bedrooms and 1 bathroom.
Greenstar 4000 30 24kw 10.8 Smaller properties with 3-4 bedrooms and 1 bathroom.
25I 24kw 10.2 Smaller properties  with 1-3 bedrooms and 1 bathroom.Read our 25I review here.
30I 24kw 12.3 Medium-large properties with 3-4 bedrooms and 1 bathroom.

Read our 30I review here.

25SI Compact 24kw 10.2 Smaller properties  with 1-3 bedrooms and 1 bathroom.


The Compact is usually used when installation needs to take place in a small area, such as a kitchen cupboard.

30SI Compact 24kw 12.3 Medium-large properties with 3-4 bedrooms and 1 bathroom.


The Compact is usually used when installation needs to take place in a small area, such as a kitchen cupboard.

28CDI Compact 24kw 14.7 Medium-large properties with 3-4 bedrooms and 1 bathroom.
32CDI Compact 24kw 13.1 Medium-large properties with 3-4 bedrooms and 1-2 bathrooms.


Read our take on the 32CDI Compact here.

36CDI Compact 24kw 14.7 Medium-large properties with 3-5 bedrooms and 1-2 bathrooms.
29CDI 30kw 12.3 Medium-large properties with 3-5 bedrooms and 1-2 bathrooms.
34CDI 30kw 14.3 Medium-large properties with 4-5 bedrooms and 2 bathrooms.
38CDI 30kw 16.4 Large properties with 4-6 bedrooms and 2 bathrooms.
42CDI 30kw 17.2 Large properties with 5-6 bedrooms and 2-3 bathrooms.

Please only use this table as a guide. A qualified Gas Safe engineer will be able to work out the correct boiler for your property, so you should consult one before making a boiler purchase.

Alternatively, you can use this 90-second form from Heatable. It doesn’t just recommend the perfect boiler; it also gives you a fixed price online.

Heatable boiler installations

Types and Range of Worcester Combi Boilers For Every Lifestyle

Worcester Bosch have created several ranges of combi boiler to suit several types of properties. In each gas boiler range, they have boilers with different central heating system and hot water outputs. Below is a quick guide to each of the 5 ranges.

Worcester Greenstar 4000

One of Worcester’s newest ranges, the Greenstar 4000 is an update to the popular Greenstar i. This new boiler range features a sleek design, compatibility with solar panels, and the Quick Tap water-saving function. These boiler are also incredibly quiet, boasting the Quiet Mark as proof of their noiseless operation.

Boilers in the Greenstar 4000 range are an excellent option for small-to-medium sized homes with average water demand.

Worcester Greenstar i Boiler

The Worcester Bosch Greenstar i boiler is still the most popular range in the Worcester lineup. Typically, properties using a 25i or 30i don’t have a particularly high demand for hot water or central heating output. For instance, these boilers work well for 3-4-bedroom semi-detached houses with just 1 bathroom.

Worcester Greenstar Si Compact Boiler

As you can see from the heating and hot water output in the table above, the 25Si and 30Si match the 25i and 30i boilers.

The difference is in the physical dimensions. 

Essentially, the Si range is ideal when you’re looking to preserve as much space as possible. For example, a 25i boiler might be installed in a garage, whereas a 25Si boiler will easily fit into a kitchen cupboard.

Worcester Bosch offers its Si gas boilers in both natural gas and LPG.

Worcester Bosch CDI range

Worcester Greenstar CDi Compact Boiler

When the power output of the Si boiler just doesn’t cut it, but the installation area is still extremely small, the Worcester Greenstar CDI Compact boiler is going to best option. There are three sizes including the 28CDi Compact, 32CDi Compact and the 36CDi Compact.

Like the Si, the CDi Compact boiler is available in 2 fuel types — natural gas and LPG.

Worcester Greenstar CDi Classic Combi

If you’re looking for a Worcester combi at the top-end with exceptional heating and hot water output, you’ll find that the CDI Classic boiler is where you’ll want to focus your attention.

Worcester Bosch offers a 29CDI, 34CDI, 38CDI and 42CDI; so, there’s a range of boiler options depending on the size of your property.

Typically, these boilers are either used in large houses where the demand for hot water is extremely high (i.e. lots of radiators, or multiple bathrooms). If the output still does not suffice, you’ll have to consider different boiler types — a system boiler or a regular boiler may be a better fit.

Again, natural gas and LPG models are available.

Worcester Combi Boiler Prices — Boiler Only

Worcester Bosch are by no means the cheapest brand available, with boiler prices varying between £800-2,000 for a combi. You’ll notice that compact models, and those in the CDi range tend to cost more.

Combi Boiler Model Price for Boiler Only (inc VAT)
Greenstar 4000 25 £1,200
Greenstar 4000 30 £1,250
Greenstar 25i £950
Greenstar 30i £1,100
25Si Compact £1,100
30Si Compact £1,175
28CDi Compact £1,150
32CDi Compact £1,250
36CDi Compact £1,400
29CDi £1,200
34CDi £1,300
38CDi £1,400
42CDi £1,700

Worcester Combi Boiler Prices — With Installation

Typically, boiler prices including installation will start at around £1,800 (for a budget boiler) and go as high as £3,500. Worcester Bosch boiler installations tend to start in the region of £2,000.

However, Heatable offer competitive installation prices, along with 10-year warranties and flexible financing options when you get a Worcester through them. Quotes take around 90 seconds to process, and you can get yours here.

Worcester Bosch Greenstar 4000

Remember, the price of a Worcester Bosch boiler isn’t the only thing you should take into account. Most heating systems will need a new filter, clock, flue, flue extensions and a full system drain down and flush. All of these extras add lots of time and increase the cost of boiler installation.

Worcester Combi Boiler Alternatives

Worcester Bosch have always had competition from a range of brands. Some of the most popular competitors include Baxi, Viessmann, and Vaillant.

Of course, there are budget boiler brands out there, such as Glow-Worm and Vokera. The budget brands tend to appeal to a different market, suitable for a different lifestyle and home size.

A boiler brand that is hot on the heels of Worcester right now is Ideal. Ideal Boilers give customers a similar (and in many cases, longer) warranties, and they usually blow Worcester Bosch boiler prices out of the water.

Installing an Ideal boiler can cost between £100 and 400 less than fitting an equivalent Worcester combi.

Currently, Ideal Boilers Offer 3 Ranges:

  • Logic, with a 2-year warranty
  • Logic Plus, with a 7-year warranty
  • Ideal Vogue, with a 10-year warranty

Before installing a Worcester Bosch boiler, speak to your local Gas Engineer and try to get at least 2 quotes. They’ll also be able to advise which boiler is better suited to your property and central heating system.

Alternatively, you can just jump here and get a fixed price on screen.

Worcester Bosch Boiler Service Cost

With anything mechanical, the cost of a service is something worth taking into consideration. Luckily, most combi boilers cost the same to service. The cost of a Worcester Bosch service should be in the region of £75-100.

The cost of boiler service will depend on a few things, including:

  • Access
  • Type of boiler
  • Location

Finding Cheap Worcester Combi Boilers

One of the cheapest ways to get a Worcester combi boiler installed, is via Heatable. Streamlined sales helped them get Worcesters at low prices, and passing on those savings directly to you.

There’s a range of boiler options on offer. All you need to do, is to fill out this 90-second clickable form, and you’ll get your fixed price on screen. You won’t need to supply any personal details until you want to make a purchase.

What’s Next For Your Boiler System?

Hopefully this article has given you a good overview of the different Worcester combi boilers, prices, alternatives, and places to find them at the cheapest possible price.

Remember, always consult a qualified Gas Engineer before making a boiler purchase.

Is there anything we missed? Or, do you have a question about Worcester combi boilers? Please leave us a comment below and we’ll get back to you as soon as possible.

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