🕑 13 minutes read
[Explained By Serviceteam Experts]

Upgrading your boiler can significantly transform your home experience. In the UK, there are three types of boilers, each with its own way of working. Understanding these differences helps you find the best fit for your home.

If you own or live in a large house, finding the right boiler is crucial to keep everyone warm and provide enough hot water. Whether you have a big family or share your home with several people, it's essential to have a powerful central heating system that can handle heating and hot water for multiple bathrooms, bedrooms, and living spaces.

Regular boilers might struggle to meet your hot water needs, so investing in a more powerful boiler becomes necessary to ensure everyone can enjoy a hot shower. The finest combination boilers not only cut down your household expenses but also ensure an energy-efficient central heating system that delivers hot water whenever you need it. These boilers, known as combi boilers, remove the necessity for a water tank, decrease carbon emissions, and are conveniently compact to fit into a cupboard. Although the initial cost for a new boiler is approximately £1,900 - £2,500, the potential savings of up to £540 on annual energy bills quickly make it a worthwhile investment. This makes combi boilers a favoured choice among homeowners.

By evaluating factors such as power output, pricing, manufacturer reputation, and customer reviews, our analysis aims to assist you in selecting the optimal new boiler for your home, ensuring a blend of efficiency and cost-effectiveness.

What Is a Combi Boiler?

A combi boiler is a system that efficiently delivers both central heating and hot water for your home. It operates by directly heating water from the mains, ensuring a quick warm-up when you turn on your taps or shower. What makes it unique is that it doesn't require a separate hot water storage tank or cylinder. This feature makes it a perfect choice for smaller homes.

A residential area of Victorian style houses in London

Surprisingly, more than 80% of boilers in the UK are combi boilers, showing that they are very popular and practical.

What Is The Best Combi Boiler For Your Property?

Before we talk about finding the best combi boiler for your home, let's first understand what’s the difference between a combi boiler and a system boiler. Keep reading to find out which option is best for your home.

Combi Boiler vs System Boiler
A Worcester Bosch Combi boiler

Worcester Bosch Combi boiler

A Vaillant System boiler

Vaillant ecoTec System boiler

Choosing the right boiler for your home means deciding between a system or combination (combi) boiler. You need to think about factors like your hot water needs, available space, and how efficient each type of boiler is.

“SYSTEM boilers and COMBI boilers might look similar, but they work differently.”

For example, a system boiler must be installed with an unvented hot water cylinder to store hot water until you use it. On the other hand, a combi boiler has all the necessary components built into the unit itself, providing both heating and hot water for your home.

The main difference is in how much hot water they can provide. A combi doesn't have a tank, so it has less hot water, especially when many bathrooms are used. This is important, especially if you have a big house.

What Is The Best Combi Boiler For a Small Flat?

We suggest getting a small combi boiler with an output of less than 24kW. After carefully comparing gas combi boilers from reliable brands, our experts suggest the Ideal Vogue Max C26 and Vaillant ecoTEC Plus 825 are recommended for small homes or flats.

A new Ideal Vogue Max C26 combi boiler

Ideal Vogue Max C26 combi boiler

A new Vaillant ecoTEC Plus 825 Combi boiler

Vaillant ecoTEC Plus 825 Combi boiler

“If you have a small flat or home with just one bathroom, go for a COMBI Boiler.”

These boilers are excellent because they don't need a big space for a hot water cylinder or a large cold water tank. This means they won't take up much room.

What Is The Best Boiler For a 1-Bathroom House?

Combi boilers are ideal for homes with a single bathroom as they conserve hot water. However, keep in mind that using two showers or taps simultaneously may impact the flow of hot water. High-flow combi boilers efficiently handle the demands of homes with 2 bathrooms.

What Is The Best Combi Boiler For a 3-bedroom House With 1-2 Bathrooms?

Most 3-bedroom homes typically don't have more than 2 bathrooms. Therefore, the recommended boiler for heating a 3-bedroom house with 1-2 bathrooms is likely a combi boiler. For those looking for the top combi boilers for a 3-bedroom house, consider the, Worcester Bosch Greenstar 8000 Style 30kW, and Baxi Duotec Combi 33 gas boilers. These are our top picks for the best combi boilers.

A new  Viessmann Vitodens 100W 35 kW Combi boiler

Viessmann Vitodens 100W 35 kW

A new Worcester Bosch Greenstar 8000 Style 30kW Combi Gas Boiler

Worcester Bosch Greenstar 8000 Style 30kW Combi Gas Boiler

A new Baxi Duotec Combi 33 gas boiler

Baxi Duotec Combi 33 gas boiler

If you have a 3-bedroom house, check out these recommended boiler brands.

Best Combi Boilers Best System Boilers Best Regular Boilers
Worcester Bosch Greenstar 8000 Style Worcester Bosch Greenstar 4000 21kW System Gas Boiler Vaillant ecoTEC plus 424 Regular Gas Boiler
Baxi Duotec Combi 33 Ideal Logic Max S24 System Gas Boiler Ideal Logic Max Heat H24 Regular Gas Boiler
Viessmann Vitodens 100W Alpha E-TEC 20S System Gas Boiler Baxi 424 Heat 24kW Regular Gas Boiler
A new Worcester Bosch Greenstar 8000 Style combi boiler

Worcester Bosch Greenstar 8000 Style combi boiler

A new Worcester Bosch Greenstar 4000 21kW System Gas Boiler

Worcester Bosch Greenstar 4000 21kW System Gas Boiler

A new Vaillant ecoTEC plus 424 Regular Gas Boiler

Vaillant ecoTEC plus 424 Regular Gas Boiler

However, we suggest installing a system boiler for a 3-bedroom home with more than 2 bathrooms.

This will efficiently cater to the increased demand for hot water, ensuring your household's needs are met with optimal performance.

What Is The Best Combi Boiler For a 3-bed Semi-Detached Home?

The Viessmann Vitodens 100-W and Vaillant ecoTEC Plus 832 are highly suitable combi boilers for a 3-bed semi-detached house with a single bathroom.

A new Viessmann Vitodens 100-W combi boiler

Viessmann Vitodens 100-W Combi boiler

A new  Vaillant ecoTEC Plus 832 combi boiler

Vaillant ecoTEC Plus 832 Combi boiler

Both models offer nearly identical outputs for central heating (CH) and domestic hot water (DHW), making either option fully capable of meeting your requirements. Rest assured, these systems are designed to provide reliable and efficient performance for your home.

However, choosing the right boiler for your 3-bedroom home involves considering factors like the number of bathrooms and the insulation of your property.

"If you live in a 3-bedroom semi-home with 2 bathrooms, an 18kW system boiler is a good fit. For a home with 3 bathrooms, a 26kW boiler is more appropriate."

Also, it's essential to consider insulation factors such as cavity wall insulation, loft insulation, and windows and door sealing quality. In cases where your home lacks these insulation features, you may experience heat loss, necessitating a higher-output boiler unless you plan to implement insulation improvements. This ensures your heating system aligns perfectly with your home's unique requirements, providing optimal comfort and efficiency.

What Is The Best Combi Boiler For a 4-bedroom House?

If you're searching for a combi boiler, we suggest opting for one with an output in the range of 35-43kW for a 4-bedroom house.

If you reside in a medium-sized home with around 15 radiators, a 35kW combi boiler is likely suitable. However, for larger houses with up to 20 radiators, opting for a 43kW boiler would be more fitting.

Usually, a 4-bedroom house has multiple bathrooms, making a system boiler the perfect option. However, choosing a boiler with a high output rating is essential to achieve effective heating in a 4-bedroom house.

A new Baxi EcoBlue Advance Combi 33 boiler

Baxi EcoBlue Advance Combi 33 boiler

System boilers with a maximum central heating (CH) output rating suitable for a 4-bedroom house generally range from 18kW to 26kW.

To simplify your search, we've curated a list of the best boilers for 4-bedroom houses in 2024. This includes top-notch combi, system, and regular boilers from renowned brands. All listed boilers are robust enough to heat 10 and 15 radiators efficiently. Beyond their output rating, we meticulously considered various factors in our research and analysis of the available models in the market.

Combi Boilers System Boilers Regular Boilers
Baxi EcoBlue Advance Combi 33 Ideal Logic Max S24 Baxi 825 Heat
Worcester Bosch Greenstar 8000 Life 30kW Vaillant ecoTEC plus 624 Ideal Logic Max Heat H24
Ideal Vogue Max C32 Baxi 818 Vaillant ecoFIT Pure 425

Keep in mind that a higher output rating allows the boiler to support a greater number of radiators efficiently. Rest assured that choosing the right boiler with the appropriate output rating will provide optimal heating performance for your home.

What is The Best Combi Boiler For a 5-bedroom House?

Typically, for larger homes with 2 or more bathrooms, a system or regular boiler proves to be the optimal choice. These boilers can store hot water in a cylinder, ensuring an ample supply for your household needs.

Excitingly, there are also advanced combi boilers with high power capabilities. If you're outfitting a 5-bedroom house, top-notch choices for combi boilers include models like Worcester Bosch Greenstar 8000 Life 50, Ideal Vogue Max C40, and Vaillant ecoTEC Plus 938.

A new Worcester Bosch Greenstar 8000 Life 50 boiler

Worcester Bosch Greenstar 8000 Life 50 boiler

A new Ideal Vogue Max C40 combi boiler

Ideal Vogue Max C40 combi boiler

A new Vaillant ecoTEC Plus 938 boiler

Vaillant ecoTEC Plus 938 combi boiler

What Is The Best Combi Boiler For a Large House?

Combi boilers are specifically designed to deliver a reliable and ample hot water supply without any disruptions. However, it is generally not recommended to use a combi boiler in large houses with multiple bathrooms and high-demand hot water. Fortunately, some exceptional combi boilers excel in meeting these demanding requirements while ensuring a consistent water flow.

A new Worcester Bosch Greenstar 8000 Life Combi boiler 50kW

Worcester Bosch Greenstar 8000 Life Combi boiler 50kW

The key factors to consider in a boiler for a large house

  • Efficiency: This is a top priority, as the most efficient boilers minimise energy costs; new models are typically A-rated for high efficiency of 95% or more.
  • Proper sizing by output: This is essential for meeting the home's heating and hot water demands based on factors like radiators, bathrooms, and usage.
  • Warranty length and coverage: This can vary by manufacturer but significantly impacts peace of mind; the best warranties ensure the most extended duration.
  • Price: While price alone should not be decided, total cost, including installation, is worth considering if significant savings can be found between boiler options.

For a detailed comparison of these factors, use our boiler selection tool to make the right choice to meet the needs of a large home.

Best Combi Boiler For A Larger House

COMBI Efficiency Central Heating Max Output
Worcester Bosch Greenstar 8000 Life 50 94% 35kW
Ideal Vouge Max C40 93% 32kW
Vaillant eco TEC Plus 938 94% 30.9%kW

We've pinpointed some top system boilers and regular boilers that work best for larger homes. Let's explore your options!

Best System Boiler For a Larger House

SYSTEM Efficiency Central Heating Max Output
Vaillant eco TEC Plus 630 94% 30.4kW
Ideal Vogue Max S32 93% 32kW
Baxi Platinum Plus 32 92% 32kW

Best Regular Boiler For a Larger House

REGULAR Efficiency Central Heating Max Output
Ideal Logic Max Heat H30 93% 30.3kW
Worcester Bosch Greenstar 8000 Life 35 94% 35kW
Vaillant eco TEC plus 430 94% 30.5kW
“The best choice for homes with more than 5-bedrooms or 2-bathrooms is a system or regular boiler. Even the best combi boilers might not provide enough hot water if your house has 7-bedrooms or more. If your home doesn't have an attic or loft, a system boiler is the best choice, as regular boilers need expansion tanks. “

If you're uncertain about whether a combi boiler suits your needs, don’t worry! Instead of looking into extensive research and spending hours contacting installers, serviceteam is here to assist you effortlessly in obtaining dependable advice and quotes from certified gas & heating engineers. Regardless of your home's size, rest assured that all our partnered boiler engineers are Gas Safe registered and thoroughly vetted by us.

In conclusion, take a look at this condensed version of the information to get a clear idea when picking your new boiler.

A combi boiler in the kitchen of a small flat
Property Type Boiler Type
Small Home/ Flat - 1-bathroom Combi boiler
Small Home - 3 bedrooms with 2 bathrooms Combi boiler
Average size - 1 bathroom Combi boiler
Average size - 3 bedrooms with 3 or 3+ bathrooms Regular / System boiler
Large Home - 1 bathroom Combi boiler
Large Home - 4 bedrooms with 3 or 3+ bathrooms Regular / System boiler

A large house built in red bricks in London
"Do you have a large house with more bathrooms?
Don't get a Combi boiler. Go for a System or Regular boiler."

What Is The Best Combi Boiler For a Hard Water Area?

A bath tap of a property in hard water area

Hard water consists of calcium and magnesium salts. This situation creates pesky insoluble salts of calcium and magnesium that form scales on the inner walls of boilers. And guess what? These scales are efficiency busters, reducing the heating prowess of boilers. There's more! Hard water doesn't stop there – it's also a culprit for causing corrosion in boilers, leading to heating problems.

According to our recommendations, the top picks for combi boilers in hard water areas are:

1. Worcester Bosch Greenstar 8000 Life Combi Gas Boiler
2. Ideal Logic Max Combi Gas Boiler
3. Vaillant ecoTEC Plus Combi Gas Boiler

Modern combination boilers are more resistant to hard water issues, though it's still wise to proceed with caution. If you're keen on using showers without any modifications, the standard boiler might be your top choice. However, if you're considering an unvented hot system, ensure you have sufficient pressure and, most importantly, ample flow.

As per Part L of The Building Regulations, it is highly recommended to treat the cold mains supply to combi boilers with a scale prevention device in hard water areas. This is essential for preventing limescale buildup, which can obstruct the heat exchanger in your combi boiler and consequently reduce both flow rates and the hot water temperature. This proactive measure ensures optimal performance and efficiency of your combi boiler system.

What Is The Best Shower For a Combi Boiler?

It's crucial to choose the right shower for your combi boiler; among various options, a thermostatic mixer shower stands out as the top choice. This type of shower is especially beneficial for busy households, ensuring a steady and consistent water temperature, even when others are using hot water simultaneously.

Bathroom Thermostatic Mixer Shower Set

A new Bathroom Thermostatic Mixer Shower Set

One key advantage of a thermostatic mixer shower is its ability to prevent sudden and uncomfortable temperature fluctuations, offering a more enjoyable and pain-free shower experience. Considering this, it is undoubtedly the best option to pair with a combi boiler. While there are alternative choices to explore, the thermostatic mixer shower stands out for its reliability and ability to cater to the demands of a bustling household.

Regrettably, power showers are not compatible with combi boilers since they are designed to work with low-pressure water systems. Consequently, they are not a suitable choice for combi boilers.

Things To Consider When Choosing a Good Combi Boiler

Faulty Gas Valve A radiator in a hallway

Assess how many radiators are present in your home. This count will guide you in determining the power your boiler needs to heat your space effectively.
- For up to 10 radiators: 24kW to 27kW
- For 10 to 15 radiators: 28kW to 34kW
- For 15 to 20 radiators: 32kW to 40kW

If you experience any problems with your existing radiators, contact serviceteam immediately. We do provide radiator replacement, central heating powerflush and system maintenance all across London.

Showers and Hot Water Demand A-hot-water-shower

Consider the number of showers in your home and your overall hot water requirements. This information helps ensure that your boiler can meet the heating and hot water demand.

Call Serviceteam Combi Boiler Installers

Consult a pro for tailored guidance and new boiler installation in your home. Finding the right installer can be tough, but we've made it easy. We are here to assist you if you are unsure which combi, system, or regular boiler is the right match for your home.

Get personalised quotes, compare the offer, and secure the best deal for your London home. It's a simple way to cut costs and avoid potential overcharges.

Contact serviceteam for a free quote, compare, and choose the best deal – no obligation!