Eco Happy (Solar Expert)

Published February 23, 2024

As many households are trying to become more energy efficient and reduce their energy bills, it makes sense to install a condensing boiler.

For a start, these new-age systems play a crucial role in the UK government’s national energy strategies. In line with the 2005 Boiler Plus regulations, they help reduce greenhouse gas emissions, enhance energy security, and lower energy consumption. 

The best condensing boiler currently on the market is the Worcester Bosch Greenstar 4000 gas condensing boiler. It is highly efficient with modern features and a great warranty.

This article will look at the 6 best condensing boilers available in the UK and explore their many benefits.

The Top 6 Condensing Boilers Of 2024

These are the top-selling and best condensing boilers currently available on the UK market:

1. Worcester Bosch Greenstar 4000 gas condensing boiler

  • Efficiency rating: Up to 94%
  • Key features: Modern design and an easy-to-use full-colour text display. Controllable via a mobile phone app.
  • Unique selling point: Bosch has excellent customer service and a reputation for reliability.
  • Pricing and warranty: Priced from £1,200 to £2,500, the Worcester Bosch Greenstar 4000 comes with a standard five-year warranty. If installed by a Bosch-accredited installer, it comes with a 10-year guarantee.
  • Best for: Small- to medium-sized homes with one bathroom.


The Worcester Bosch Greenstar 4000 is one of the top-selling condensing boilers in the UK, and our top pick for the best condensing boiler.

This gas boiler is ideal for small-to-medium homes with a single bathroom. Thanks to its design, it works well in low water-pressure areas. It is highly efficient and comes with a Quick Tap function which helps you to save water.

It can also connect wirelessly with the Bosch EasyControl, making temperature management a breeze.

2. Viessmann Vitodens 050-W gas condensing boiler

  • Efficiency rating: Up to 92%
  • Key features: Boasts an attractive price/performance ratio with low emission levels.
  • Unique selling point: This system boiler offers easy operation and a web-enabled WiFi interface.
  • Pricing and warranty: Starts at around £2,150 and comes with a seven-year standard warranty. An extended warranty of up to 10 years is available.
  • Best for: Smaller homes or apartments with limited space.


The Vitodens 050-W is a wall-mounted gas boiler that is perfect for smaller homes or apartments. It has an LED display and touch buttons, making it easy to use. 

What we really like about this boiler is how quietly it runs. This, coupled with its compact size makes it perfect for installation in living spaces. 

It is compatible with Viessman boiler smartphone apps through its wireless capabilities, making home heating control easier than ever before. 

3. Viessmann Vitodens 100-W gas condensing boiler

  • Efficiency rating: Up to 95%
  • Key features: Features a Mobile ViCare app and WiFi connectivity. It also boasts easy installation and service and multiple venting options.
  • Unique selling point: Suitable for conventional and combi systems. The Vitodens 100-W has a preheating function for rapid hot water availability.
  • Pricing and warranty: Pricing starts at around £2,100, with a standard 10-year warranty.
  • Best for: Homes with a high demand for hot water.


This gas-fired, wall-mounted boiler is made of high-quality stainless steel. The Viessmann Vitodens 100-W is ideal for homes or apartments with limited space.

Considering the quality of the boiler and its warranty, it is an affordable option. It can be integrated with smart technology so you can optimise your heating while reducing your energy bills. 

Thanks to its compact size and silent operation it can be installed inside the bathroom or another living space without causing disruption to your routine – it will simply (and silently) do its job. 

4. Baxi 800 gas condensing boiler

  • Efficiency rating: Up to 93%
  • Key features: Easy installation and maintenance. The Baxi 800 has a range of outputs to suit different home sizes.
  • Unique selling point: Certified to work with 20% Hydrogen. Affordable price point without compromising performance.
  • Pricing and warranty: Pricing starts at around £1,050, with a standard 10-year warranty.
  • Best for: These cost-effective home boilers are perfect for budget-conscious homeowners and smaller homes with moderate heating demands.


Easy to install and available in 24kW, 30kW and 36kW, the Baxi 800 runs on natural gas and LPG. This low-cost boiler features a heated condensate trap to prevent frozen condensate pipes in winter.

It’s compatible with Baxi uSense, the brand’s smart control that can be paired with your Baxi app. This allows you to operate your heating no matter where you are. 

We also really like the EasyFill function, which allows you to top up your boiler to restore pressure without having to call a heating engineer. 

The reason it is fourth on our list is its lower efficiency, however, its other features make it a strong contender.

5. Vaillant ecoTEC plus gas condensing boiler

  • Efficiency rating: Up to 89.3%.
  • Key features: Has a 15-litre reservoir for reliable hot water delivery.
  • Unique selling point: Compact design, eliminating the need for a separate hot water cylinder. It also recharges fully in just two minutes.
  • Pricing and warranty: Starts at around £1,350, with a standard, 5-year warranty.
  • Best for: Larger homes with limited space or a need for instant hot water.


This ErP A-rated condensing boiler features stainless steel heat exchangers and premium high-quality components.

It can be wall-hung in almost any room thanks to its silent operation and compact design. 

The ecoTEC plus gas boiler can withstand fluctuating gas quality thanks to its IoniDetect function. This means it will continue to operate optimally, even when gas quality drops. 

It can connect with the sensoCOMFORT system control, allowing homeowners or tenants to take charge of their home’s temperature. This control system will also ensure that the boiler is always running efficiently, which can save you money on your electricity bill. 

It has a lower efficiency rating than other boilers on our list, but its affordable price has earned it fifth place.

6. Alpha Combi E-TEC Plus NX gas condensing boiler

  • Efficiency rating: Up to 93%
  • Key features: Built-in frost protection. Has a large, backlit display for easy temperature adjustment.
  • Unique selling point: Simple and intuitive controls. Ideal for those who prefer a straightforward interface.
  • Pricing and warranty: Starts around £1,600 to £2,100, with an extended 13-year warranty.
  • Best for: Medium-sized homes with moderate hot water or central heating demands.


Featuring a unique stainless steel heat exchanger, this condensing combi boiler has a combined condensate and pressure relief valve connection. It also features a zinc-plated expansion vessel to prevent corrosion.

It’s been approved by Good Homes, so you can rest easy knowing it’s a quality boiler. 

This boiler is very easy to use thanks to the large LCD screen and touch button controls, allowing you to set your heating preferences at the push of a button.

Alpha boilers are premium quality at affordable prices, and the E-TEC Plus NX is no exception. 

How We Chose the Best Condensing Boilers

Here’s a quick breakdown of the factors we considered when selecting the 6 top condensing boilers.


We looked for boilers and boiler brands with a proven track record of reliability and durability. This involved researching brand reputation, warranties, and failures. 

We only selected the top boiler brands in the UK, as well as their most reliable models.


Different boilers boast different features, which is why we evaluated the features of the top condensing boilers on the market. We considered factors like:

  • Efficiency rating
  • Output
  • Control options
  • Compatibility with smart home tools

Customer Reviews

Customers are a valuable source of information. To substantiate our research, we investigated customer reviews from various online sources to better understand real-world experiences with our top boilers. This helped us gauge operational noise, user-friendliness, and satisfaction with the boiler. 

Value for money

Just because a boiler has a premium price, doesn’t mean it is a premium boiler. 

We considered the value that each boiler offers, weighing up the initial cost and cost of installation against the efficiency and maintenance requirements. 

How to Choose the Right Condensing Boiler for Your Needs 

Choosing the right condensing boiler for your home will depend on several factors:

  • Home size and heating requirements: Consider how many bathrooms and faucets you have, as well as the number of radiators. This will greatly influence which boiler you select as you’ll have to consider the boiler output.
    A well-insulated home will require less heating than an older, draughty home. 
  • Boiler efficiency rating: You want a boiler with a high ErP rating as the more efficient a boiler is, the lower your energy bills will be since less heat is being lost. 
  • Budget: You should not only consider the cost of the boiler, but also the installation costs, maintenance costs, and how an efficient boiler can help you save in the long run. 
  • Features: Are you looking for a user-friendly boiler that you can simply install and start enjoying hot water, or are you looking for something compatible with smart home devices like a smart thermostat? The features you want in a boiler will determine which is right for you. 

Costs of Condensing Boilers

As is evident from our list of the top 6 condensing boilers above, they can cost from £1,050 to £2,500.

Several factors affect the cost of condensing boilers, including:

  • Brand and model: Top-tier condensing boiler brands with advanced features cost more than “regular” boilers.
  • Boiler output: Boilers with higher output and capable of heating large spaces come with a higher price tag.
  • Installation: Labour costs and additional materials and add-ons will increase the final price of these systems.

Condensing boilers tend to be more expensive than traditional boilers when initially purchased.

However, homeowners see a significant return on their initial investment after installing these energy-efficient heating options. Some studies show that, on average, homeowners recoup their initial investment over three or five years in the form of cost savings.

Financing options

UK homeowners have access to several financing options to make installing a condensing boiler more affordable, including:

  • Government grants and incentives. Homeowners can take advantage of the UK government’s Boiler Upgrade Scheme to fund the installation of a new condensing boiler. The Warmer Homes Scotland initiative also provides funding to replace old, energy-hungry radiators.
  • Green energy loans. Some UK banks and lenders offer preferential loan rates for energy-saving home improvements.
  • Boiler scrappage schemes. These schemes provide homeowners with funding to install environmentally friendly heating devices.


What are the disadvantages of condensing boilers?

  • Higher upfront costs. Generally, the initial purchase prices of condensing boilers are higher than other types of boilers.
  • More complex installation. Condensing boiler installations can be more complicated and require additional wiring, plumbing, and labour.
  • Higher maintenance requirements. Condensing boilers require more regular maintenance.

Why are condensing boilers considered the safer option?

A non-condensing boiler is designed to take air from within the room, which can cause loose objects to potentially be sucked into it. On the other hand, modern condensing boilers get their air directly from the outside, reducing this risk. Additionally, condensing boilers are designed to remove all their wastewater via condensation water pipes, reducing the risk of exposure to harmful vapours.


Many UK households have started installing condensing boilers for their home heating needs.

These boilers, available in regular, combi, or system boilers, capture the heat of their exhaust flue gases to supply households with warm water and central heating. These energy-friendly boilers boast energy efficiency of 90% or above. Helping UK households use less energy, these boilers also help the environment and reduce monthly energy bills.

Consider your household heating needs and budget to choose the condensing boiler that best fits your heating system requirements. Contact Eco Happy for a free, no-obligation quote on a condensing boiler installation and start reaping the benefits today.

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