Updated: 6th August, 2024
When shopping for a boiler, many people forget to check the physical dimensions of each model before purchasing and can sometimes end up with a brand new boiler that won’t fit in their kitchen cupboard.
If you're looking to install a new combi boiler into a tight space such as a kitchen cupboard or small utility room, you'll need a model with smaller dimensions.
After carrying out extensive research into the best (physically) small-sized combi boiler, system and regular boilers and checking out reviews from both customers and engineers, we have compiled a list of the top compact boiler models on the market. So let's get into it!
Get a quote in 60 seconds, fitted as fast as next day!
0% APR finance available.
Get a free fixed price quote for a new boiler installed fast! - Find the perfect boiler!
Combi boilers are the most compact type of boiler as they combine both a water heater and central heating into a single unit, meaning there's no need for additional hot and cold water tanks that take up lots of space, making them ideal for fitting in kitchen cupboards.
Here are our top compact combi boilers and why we love them so much:
Models | Dimensions (H x W x D) | Maximum Output Ratings |
Worcester Bosch Greenstar CDi Compact | 680mm x 390mm x 280mm | 28kW, 32kW, 36kW |
Ideal Logic + Combi | 700mm x 395mm x 279mm | 24kW, 30kW, 35kW |
Viessmann Vitodens 100-W | 700mm x 400mm x 350mm | 25kW, 30kW, 35kW |
Viessmann Vitodens 050-W | 707mm x 400mm x 350mm | 25kW, 30kW, 35kW |
Alpha E-Tec | 712mm x 440mm x 275mm | 28kW, 33kW |
Dimensions: W 390mm, D 280mm, H 680mm
The Worcester Bosch Greenstar CDi Compact is a bite-size combi boiler that was specifically designed to fit within a standard kitchen cupboard. Despite its compact size, this combi boiler still delivers incredible heating and hot water, with various outputs available to suit different homes.
Winner of the Which? Best Buy Gas and Oil Boilers award in September 2021 and produced by one of the most reliable boiler manufacturers on the market, you can count on this boiler to deliver effective and efficient heating for a long time, keeping your home warm with much lower running costs.
When talking about combi boiler size, we usually refer to the power output in kW. Generally, the larger your home and the higher demand for heating and hot water, the higher the boiler power output you will require.
The Greenstar CDi Compact is available in the following power output sizes:
Hot water output | Suitable for | Flow rate |
28kW | The Worcester Bosch Greenstar 28CDi is best suited for smaller families living in an apartment or bungalow with one to two bedroom(s), one bathroom and up to ten radiators. | 11.4l/min |
32kW | The Worcester Bosch Greenstar 32CDi is ideal for medium sized families living in a medium terrace, bungalow or semi detached house with three to four bedrooms, one to two bathrooms and up to fifteen radiators. | 13.1l/min |
36kW | The Worcester Bosch Greenstar 36CDi large family with a high demand for hot water living in a large semi-detached or detached house with over four bedrooms, over two bathrooms and up to twenty radiators. | 14.7l/min |
One of this model's key features is its efficiency. The entire Worcester Bosch Greenstar CDi Compact Combi range is ErP A-rated thanks to its impressive 91% efficiency.
By replacing an old, inefficient combi boiler with this new combi, you could save up to £380 a year on your energy bills.
If you purchase a Worcester Bosch Greenstar CDi through iHeat, our fixed price includes the new combi boiler and complete installation from our Gas Safe engineers, delivering the full package.
Prices for the Worcester Bosch Greenstar Compact range plus installation begin at £2,085 and are available with several finance options to help you spread the cost.
Although there are cheaper options on the market, the Worcester Bosch price tag is high for a reason.
Firstly, they offer 10-year guarantees (not warranties). Guarantees typically cover the whole product, and Worcester Bosch won't charge you for a guarantee call-out visit providing that your boiler is serviced annually.
Winner of multiple Which? Best Buy awards
High TrustPilot ratings
Huge brand name thanks to reliability
Made in the UK
Get a quote in 60 seconds, fitted as fast as next day!
0% APR finance available.
Dimensions: W 395mm, D 279mm, H 700mm
The Ideal Logic Plus Combi boiler is a fantastic little appliance, scoring highly on efficiency and delivering speedy heating and hot water, all whilst being able to tuck away neatly into a kitchen cupboard.
The boiler is supported by the Queen’s Award for Enterprise 2013 and the Good Housekeeping Reader Recommended Status in 2013 and 2017, so you can be sure it’s a good choice!
The Ideal Logic+ is available in the following power output sizes:
Hot water output | Suitable for | Flow rate |
24kW | The Ideal Logic + 24kW is best suited for smaller families living in a flat or bungalow with one to two bedroom(s), one bathroom and up to ten radiators. | 9.9l/min |
30kW | The Ideal Logic + 30kW is perfect for medium sized families living in a medium terrace, bungalow or semi detached house with three to four bedrooms, one to two bathrooms and up to fifteen radiators. | 13.1l/min |
35kW | The Ideal Logic + 35kW is best suited to a large family with a high demand for hot water living in a large semi-detached or detached house with over four bedrooms, over two bathrooms and up to twenty radiators. | 14.7l/min |
The Ideal Logic + isn’t quite as efficient as the Worcester Bosch CDi Compact, however, it still offers a fantastic 90% energy efficiency, delivering more cost-effective heating and hot water, helping to keep your central heating bills low.
If you purchase an Ideal Logic Plus through iHeat, you can get a fixed price for the combi boiler and installation by our Gas Safe installers. Prices for the Ideal Logic + Combi boiler range plus installation begin at £1,895 and are available with several finance options to help you spread the cost.
Included in our prices is a fantastic 10-year warranty that we offer exclusively with all our combi boilers here at iHeat.
Dimensions: W 400mm, D 350mm, H 700mm
Efficient, compact, quiet and affordable, the Viessmann Vitodens 100-W combi boiler is the most popular solution available at iHeat. Reviewed as a Which? Best Buy in 2019, the Vitodens 100-W features innovative technology and services combined with reliability and longevity.
This combi helps you to optimise your heating and save on energy costs and can all be done from inside your kitchen cupboard.
The Viessmann Vitodens 100-W is available in the following power output sizes:
Hot water output | Suitable for | Flow rate |
25kW | The Viessmann Vitodens 100-W 25kW is perfect for smaller families living in a flat or bungalow with one to two bedroom(s), one bathroom and up to ten radiators. | 10l/min |
30kW | The Viessmann Vitodens 100-W 30kW is perfect for medium sized families living in a medium terrace, bungalow or semi detached house with three to four bedrooms, one to two bathrooms and up to fifteen radiators. | 14l/min |
35kW | The Viessmann Vitodens 100-W 35kW is best suited to a large family with a high demand for hot water living in a large semi-detached or detached house with over four bedrooms, over two bathrooms and up to twenty radiators. | 14.3l/min |
Up to 94% of the fuel used by the Viessmann Vitodens 100-W is converted into heat, making it an incredibly efficient boiler. According to Viessmann, this could help you to save up to 40% off your energy bills when replacing an old inefficient model.
If you purchase a Viessmann Vitodens 100-W combi boiler through iHeat, you can get a fixed price for both the boiler itself plus installation by our Gas Safe installers.
Prices for the Vitodens 100-W range plus installation start at £2,395 and are available with several finance options to help you spread the cost.
Although this boiler is on the slightly pricier side, you can be sure to get your money’s worth.
Viessmann recently updated the 100-W for 2021, featuring all-new innovative technology and services combined with reliability and longevity ready for smart technology, helping you optimise your heating and save on energy costs.
Dimensions: W 400mm, D 350mm, H 707mm
With compact dimensions, low weight and quiet operation, the attractively priced Vitodens 050-W combi boiler is a low-cost gas combi boiler that will integrate effortlessly into any living space and does not compromise on quality; making it ideal for both new build homes and modernisations.
The Vitodens 050-W 29 kW Combi boiler was also reviewed as a Which? Best Buy in 2019.
Get a quote in 60 seconds, fitted as fast as next day!
0% APR finance available.
The Viessmann Vitodens 050-W is available in the following power output sizes:
Hot water output | Suitable for | Flow rate |
25kW | The Vitodens 050-W 25kW is perfect for smaller families living in a flat or bungalow with one to two bedroom(s), one bathroom and up to ten radiators. | 10l/min |
30kW | The Vitodens 050-W 30kW is perfect for medium sized families living in a medium terrace, bungalow or semi detached house with three to four bedrooms, one to two bathrooms and up to fifteen radiators. | 14l/min |
35kW | The Vitodens 050-W 35kW is best suited to a large family with a high demand for hot water living in a large semi-detached or detached house with over four bedrooms, over two bathrooms and up to twenty radiators. | 14.3l/min |
Like the 100-W, 94% of the fuel used by the Viessmann Vitodens 050-W is converted into heat, so this model is equally as efficient, with an A rating, helping you to cut hundreds off your heating bill each year.
If you purchase a Viessmann Vitodens 050-W through iHeat, you can get a fixed price for both the combi boiler itself plus installation by our Gas Safe installers.
Prices for the Vitodens 050-W range plus installation start at £2,055 and are available with several finance options to help you spread the cost to make it more affordable.
At nearly £200 cheaper than its 100-W counter model, you may wonder what separates them.
One of the key differences between the two is that the Vitodens 050-W has a smaller depth than the 100-W, being just 350mm deep, which is 50mm shallower than the 100-W, making it a more suitable choice for those who are tight for space.
The depth of the combi boiler is particularly important because there needs to be an open space of at least 60mm for an engineer to access it during its annual service properly.
Another difference is the size of the LED screen on the front of the unit. The 100-W does have a much larger screen, making it easier to see and operate; however, for many, this isn’t a great enough difference to justify paying for the more expensive model.
Dimensions: W 440mm, D 275mm, H 712mm
The entire E-Tec range is Alpha’s smallest yet, designed to fit into a unit with small dimensions. Compactness allows an easy fit in a standard kitchen cupboard, and annual servicing is made easy with front access.
The Alpha E-Tec combi boiler is available in the following power output sizes:
Hot water output | Suitable for | Flow rate |
28kW | The Alpha E-Tec 28kW is perfect for smaller families living in a flat or bungalow with one to two bedroom(s), one bathroom and up to ten radiators. | 12.1l/min |
33kW | The Alpha E-Tec 33kW is best suited to a large family with a high demand for hot water living in a large semi-detached or detached house with over four bedrooms, over two bathrooms and up to twenty radiators. | 14.1l/min |
Much like the rest of this list, the Alpha E-Tec has an incredibly high energy efficient rating of 89%, so you can rest easy knowing your energy bills won’t be any higher than necessary.
The Alpha E-Tec combi boiler is our most affordable boiler at iHeat, but don’t expect it to compromise quality.
It might not be the flashiest of boilers, but it’s certainly robust and reliable and sure to last you a long time with fantastic heating results.
If you purchase an Alpha E-Tec combi boiler through iHeat, you will pay a fixed price for both the boiler itself and installation by one of our Gas Safe installers.
Prices for the Alpha E-Tec range plus installation start at £1,675 and are available with several finance options to help you spread the cost.
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.
Boiler costs 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 |
The best compact combi boiler often depends on specific needs, including the size of your home, water usage, and energy efficiency requirements. Brands like Worcester Bosch, Vaillant, Ideal, and Baxi are well-regarded for their compact combi boilers, offering models that are efficient, reliable, and designed to fit in small spaces. Models such as the Worcester Bosch 4000 series or Vaillant ecoTEC plus are popular for their performance and compact design.
Yes, you can get small combi boilers. Many manufacturers design compact combi boilers specifically for small homes, apartments, or where space is at a premium. These boilers are designed to fit inside kitchen cabinets or in other tight spaces without compromising on heating and hot water performance.
Combi boilers are not being phased out; instead, there's a push towards more energy-efficient and environmentally friendly boilers .
Yes, a combi boiler can be installed in a cupboard, as long as there's enough space for installation and maintenance, and it meets the manufacturer's clearance requirements for safe operation. Proper ventilation and access for servicing are also essential considerations.
Yes, a combi boiler in a cupboard needs ventilation to ensure safe operation and to prevent overheating. The specific ventilation requirements will depend on the boiler model and installation guidelines provided by the manufacturer. It's essential to follow these guidelines to ensure the boiler operates safely and efficiently.
It's not illegal to have a combi boiler in a bedroom, but there are strict regulations and safety standards that must be met, such as ensuring adequate ventilation and carbon monoxide detectors. It's important to consult with a qualified heating engineer to ensure compliance with local building codes and safety guidelines.
Whether you need a fire door on your boiler cupboard depends on local building regulations and the specific installation scenario. While not always required, fitting a fire door can be a safety enhancement, especially if the boiler is located near potentially combustible materials. Consulting with a professional installer or local building control for guidance based on your specific situation is advisable.
06th December, 2024
Understanding the various reasons why a boiler may not switch on can save homeowners time...
05th December, 2024
An electric combi boiler is a compact unit that provides both central heating and hot wate...
05th December, 2024
What happens when your boiler pressure goes too high, some possible causes and how to fix...