50kW Combi Boiler Review & Price Guide 2025

When buying a new boiler, the output should easily cope with your hot water demands. And, if you have a large home, a smaller boiler won’t be enough.

Introducing the best 50 kW boilers—the perfect high-output option for a large home with multiple bathrooms.

50kW boilers feature powerful performance and advanced technology to ensure they can meet your needs and maintain a warm and comfortable home.

Due to their high output, 50kW combi boilers are less common in the market. However, there’s still a sufficient range to find the perfect fit for your home.

In this article, we’ll present our expert round-up of the best 50kW combi boilers you can buy.

50kW Combi Boiler Prices

Here’s a quick reference guide to our top choices:

Boiler brand	Approx cost of boiler	Approx cost of boiler plus installation
Worcester Bosch 8000+	£2,278	£3,500
Vaillant EcoTec Plus 48kW	£2,264	£3,500
Flexiheat 50kW	£2,000	£3,300

Prices are correct as of January 2025.

Please note that these are approximate prices and certain factors can affect the final cost, like where your boiler is located or if you require any additional equipment.

The Best 50kw Combi Boilers

When it comes to the best combi boilers, we look at the main things homeowners want. 

Reliability and energy efficiency top the list to ensure you get a high-performing boiler as well as save money on your energy bills.

Given the limited choice, here are the best 50kw combi boilers we could find. If you want a wide range of combi boilers to choose from, read our guide on the best combi boilers.

Worcester Bosch Greenstar 8000+ 50kw

We can confidently say that the Worcester Bosch Greenstar 8000 50kW combi boiler is one of the best on the market. 

This trusted household name is renowned for its quality, so you can be confident you are choosing a top-of-the-range option.

The powerful wall-hung boiler is perfect for larger homes. With its advanced technology, high efficiency, and ease of use, it’s our top recommendation for a reliable and efficient heating solution.

Worcester Bosch 8000+ 50kw main features

The Worcester Bosch 8000+ has a lot to offer, including:

• A-rated 94% energy efficiency helps lower energy bills and carbon emissions through its innovative controls and unique heat exchanger design
• Measures 440mm (w) x 780mm (h) x 365mm (l)—although slightly larger than average, it will still fit into compact spaces
• Long 12-year warranty
• Smart weather-responsive controls maintain the optimum temperature economically
• High direct hot water flow rate of up to 16 litres per minute
• 10% power modulation (so you only use the energy you need)
• LCD display with smart controls and built-in wifi for remote monitoring and diagnostics

Vaillant EcoTec Plus 48k

This model is not quite 50kW, but at 48kW, it can still pack a punch in a larger home.

The Vaillant EcoTec Plus is a high-performing combi boiler created to offer dependable heating for your home. It stands out thanks to its high-performance heating system that combines efficiency, dependability, and cutting-edge technologies.

Vaillant is recognised for its top-notch customer service and extended warranties—crucial for your peace of mind.

Valliant EcoTec Plus Main Features

The Vaillant EcoTec Plus has several standout features:

• A-rated 94% energy efficiency for lower energy bills (without compromising comfort)
• 440mm (w) x 720mm (h) x 352mm (l)
• Lengthy 10-year warranty
• Revolutionary “quiet mark” certification, which certifies that it’s one of the quietest boilers
• Durable stainless steel heat exchanger, which is designed to last for the lifetime of the boiler
• Sophisticated control system, which enables accurate temperature control and monitoring

Flexiheat 50kW Combi Boiler

Flexiheat UK is a subsidiary of German boiler manufacturer Kroll Energy. It provides a wide range of heating and cooling solutions to domestic and commercial properties.

Its 50kW combi boiler just had to make this list because of its impressive energy rating and huge flow rate.

While Flexiheat UK is a lesser-known brand, it is the most powerful boiler on this list. Plus, its long 10-year warranty should give you some peace of mind.

Flexiheat 50kW Combi Boiler Main Features

• A-rated 97% energy efficiency—the highest on this list!
• Generous 10-year warranty
• Increased burner modulation ratio of 1:10, preventing on/off cycling
• High flow rate of 20.30 litres/min
• Inbuilt intuitive controller for control and troubleshooting
• Advanced remote control with full-colour display and built-in wifi
• Suitable for mains gas or LPG

50kW System Boilers

Given the limited choice of 50kW combi boilers, you might prefer to look at a system boiler instead.

System boilers are a type of central heating boiler that provides hot water for both heating and domestic use. They are a popular choice for big properties due to their efficiency, ease of installation, and ability to deliver hot water to multiple taps at once.

Their efficiency is thanks to the separate hot water storage tank that is kept ready and waiting for when it’s required. 

A couple of cons to consider:

• If the tank becomes empty, you have to wait for it to fill up and become warm again, making it a slightly less convenient option than a combi boiler.
• Additionally, you should consider the extra space required to house the hot water tank.

What Is The Best 50kw System Boiler?

Here’s a quick list of what we consider the best system boilers sized at 50kW:

Boiler brand	Fuel type	Approx cost of boiler	Approx cost of boiler plus installation
Worcester Bosch GB162 50kW	Gas	£2,000	£2,750
Worcester Bosch Greenstar 8000+ System	Gas	£2,300	£3,000
Viessmann Vitorondens 200-T 53kW	Oil	£6,241	£7,450
Vaillant ecoTEC Plus 48kW	Gas	£2,300	£3,300

Prices are correct as of January 2025.

We have a more detailed article on system boilers you can check out.

Advantages and Disadvantages of Having a 50kW Combi Boiler

It’s important to carefully consider the advantages and disadvantages of having a 50kW boiler before making a decision.

The advantages of having a 50kW boiler include:

• High heating output: 50kW boilers are capable of producing a large amount of heat, making them well-suited for large homes.
• Energy efficiency: These boilers are designed to be energy efficient, which can help to lower running costs and lower carbon emissions.
• Easy to operate: Many 50kW boilers come with digital controls, making them easy to operate and troubleshoot.
• Long-term warranty: Most manufacturers offer long-term warranties for their 50kW boilers, which can provide added peace of mind.

Disadvantages of having a 50kW boiler include:

• Increased size: 50kW boilers are slightly larger than average, so you may need to make additional room for them.
• Increased maintenance: Because of increased usage, 50kW boilers require more maintenance than smaller boilers. You will have to pay the same boiler service cost every year too, to maintain the warranty.
• Noise: Some models may be fairly loud, which may be a problem if your boiler is installed in certain rooms of your home.

Understanding 50kw Combi Boilers for Central Heating and Domestic Hot Water Supply

You’ll find that a 50kw boiler is a reliable solution for both central heating and hot water supply for a medium to large property or building.

When it comes to domestic hot water, a 50kw boiler can provide an abundant supply to meet the demands of a family.

The central heating system can also be effectively managed to ensure a comfortable and warm living environment. 

Most 50kW combi boilers can handle 15 radiators on top of usual hot water demand. However, they can heat 20+ radiators if hot water demand is low.

A 50kw boiler system can work independently or as part of a multi-boiler cascade system (where multiple boilers work together to meet the heating and hot water demand of a large property).

You’ll tend to find cascade systems used on commercial properties. For domestic properties, an independent system is usually sufficient.

FAQs

What is a 50 kW combi boiler?

A 50 kW combi boiler is a normal combi boiler with a higher output rating, meaning it can produce a significant amount of heat compared with smaller models.

50kW boilers are commonly used in larger homes containing multiple bathrooms or with high heating demands.

Who can use 50 kW boilers?

50kW boilers are ideal for medium-to-large homes containing more than one bathroom. 

This is because they can run all your radiators effectively while providing your water outlets with higher volumes of pressurised hot water.

What is the difference between a 50 kW boiler and a smaller boiler?

A 50kW boiler is better for larger homes, and a smaller boiler is better for average to small-sized homes.

A 50kW boiler is capable of heating larger spaces and meeting increased hot water demands when compared with smaller boilers.

Is a boiler with a higher kilowatt better?

A boiler with a higher kilowatt is capable of producing more heat, so it’s considered better for larger homes with higher demands.

Choosing a boiler with the correct kilowatt output is important. Picking one that is too powerful for your needs leads to increased running costs and wasted energy.

To understand the best kilowatt size for your property, read our what size kw boiler for my home guide here.

How much space is required for a 50 kW boiler?

Although boiler brands vary in size, a 50kW boiler typically requires 70cm (width) x 40cm (depth) x 70cm (height) of space. 

The clearance for ventilation and servicing must also be factored in, which should be around 5cm on all sides.

What is the lifespan of a 50kW boiler?

The average lifespan of a 50kW combi boiler is around 15-20 years.

However, this can vary depending on the manufacturer and model and how well you keep on top of your boiler’s maintenance schedule.

What is the efficiency of a 50kW boiler?

A modern 50kW condensing combi boiler has an efficiency rating of between 94% – 97%, making it an A-rated option.

It should be noted that gas boilers tend to have the highest efficiency among the available fuel sources. 

What are the servicing requirements for a 50kW boiler?

The maintenance requirements for a 50kW boiler can vary depending on the manufacturer and model; however, you should typically get the following checked via an annual boiler service with a qualified technician:

• Combustion checks
• Fluw inspection
• Heat exchange inspection
• Water pressure monitoring
• Safety valve test
• Filter cleaning

What are the safety concerns with a 50kW boiler?

As with any heating device, it’s important to follow the manufacturer’s safety guidelines and have regular safety inspections performed by a professional. 

Potential safety concerns include gas leaks and carbon monoxide emissions.

How many radiators can a 50kw combi boiler run?

A 50kW combi boiler is capable of running over 20 radiators if it’s not simultaneously delivering hot water to the home.

A more realistic number would be around 15 radiators because this also accounts for hot water usage.

As an example, the Worcester Bosch Greenstar 8000 Life 50 kW combi boiler is perfect for properties with around 15 radiators.