Eco Happy (Solar Expert)

Published February 23, 2024

If you want to find the best boiler for your 3-bedroom house for 2024, you’re in the right place!

A combi boiler is the best boiler for a 3-bed house – if you have 1 to 2 bathrooms that is. Statistically, 80% of UK homes have combi boilers installed. However, if you have 2+ bathrooms you’ll likely need a system or regular boiler to keep up with your heating and hot water demands.

There are other factors to consider too when it comes to picking the right size boiler for your home, such as house size and lifestyle routines. Not to mention the abundant options of boiler models on the market.

But don’t fret, our article is here to help!

Today, we’ll be discussing the right size boiler for a 3-bedroom house along with other handy tips and tricks. We’ve scoured the boiler market – so you don’t have to – and have reviewed 6 of the best boilers, for 2024, helping you make a more informed decision.

Sit back, relax and within a few minutes you’ll have your “heating solutions for three-bedroom houses” answer!

Our Top 6 Boilers For A 3-Bed House

If you’re looking for the best boilers for your 3-bedroom home – whether it be the best system boilers or combi boilers – we’ve got you covered. Check out this fantastic boiler model comparison list:

1. Viessman Vitodens 111-W combi boiler

  • Dimensions: 950 mm (h) x 600 mm (w) x 500 mm (d)
  • Fuel type: Gas boiler
  • Power output size: 25 kW; 35 kW
  • Efficiency rating: Up to 98% (35 kW model)
  • Price: Around £1,976 incl. VAT (35 kW size)

The Viessman Vitodens 111-w is a highly efficient boiler known for its reliability, rapid heating and compact size. Available in two power output sizes – 25 kW and 35 kW – it’s one of the best combi boilers currently on the UK market.

  • 25 kW = 17 litres per minute flow rate (up to 20 radiators)
  • 35 kW = 18.1 litres per minute flow rate

As mentioned, combi boilers are essentially “2-in-1” systems, having both a central heating system and a boiler in one compact unit.

Specifically, this Viessman boiler has a 46-litre stainless steel pressurised water cylinder that can supply up to 18.1 litres per minute flow rate to three water outlets. This larger cylinder size is equivalent to a 150-litre cylinder in terms of heating performance!

Other notable features of this boiler model include:

  • WiFi compatibility – connecting to smart technology like Hive or Nest for thermostat control from afar.
  • Is hydrogen-ready – with a 20 hydrogen:80 gas ratio
  • LCD touchscreen
  • A-rated energy efficiency rating of up to 98%. This means it generates 98p of heating for every £1 spent!
  • Easy-to-use control panels
  • Standard 5-year warranty period (extended to 10 years when installed by Viessman fitters)
  • They’re the best boilers for medium-sized homes!

Fun fact: This boiler model is an upgrade to the Viessmann Vitodens 100 w boiler.

2. Worcester Bosch Greenstar 8000 Lifestyle 30 kW combi boiler

  • Dimensions: 780 mm (h) x 440 mm (w) x 365 mm (d)
  • Fuel type: Gas boiler
  • Power output size: 30 – 50 kW
  • Efficiency rating: Up to 94%
  • Price: Around £1,200 incl. VAT (30 kW size)

The Worcester Bosch Greenstar 30 kW combi boiler is ideal for homes with up to 15 radiators and more than 1 bathroom. This gas-fueled combi boiler uses advanced condensing technology to generate heat and reduce heat loss. With a 94% energy efficiency rating, these boilers produce 94p of heat for every £1 spent; saving on your energy bills.

Domestic hot water is supplied at a 12.3 litre per minute flow rate (with a central heating output of 30.2 kW), which is ideal when multiple taps are used.

Worcester Bosch is a reputable, long-standing boiler brand that has a strong market presence – meaning you won’t be disappointed with their products or service! A few notable aspects of this gas boiler include:

  • Intelligent filling system
  • Easy-to-use LCD touchscreen controls
  • Easy access to internal parts when it comes to servicing and repair
  • Compatible with smart technology
  • On/off cycling prevention for system longevity
  • Standard warranty of 5 years (extended to 12 years with accredited Worcester Bosch fitters)

3. Ideal Vogue Max C26 combi boiler

  • Dimensions: 740 mm (h) x 445 mm (w) x 330 mm (d)
  • Fuel type: Gas boiler
  • Power output size: 26 kW; 32 kW; 40 kW
  • Efficiency rating: 90%
  • Price: Around £1,500 incl. VAT (26 kW size)

The Ideal Vogue Max C26 kW combi boiler is perfect for a 3-bedroom house; covering all your heating needs. This proud UK-built brand is a wall-mounted gas boiler unit that uses advanced condensing technology; known for its reliability and top-class engineering.

Being a sealed combi boiler, it provides heating and hot water from one compact unit; operating with a single spark ignition and fan-assisted combustion chamber. Notable features of this boiler include an LCD touch screen, stainless steel heat exchanger, quiet operation (47 decibels), the ability to convert to LPG and a standard 8-year warranty.

  • Central heating output = 26 kW
  • Domestic hot water output = 28 kW
  • Flow rate = 10.61 litres per minute

4. Vaillant ecoTEC Plus 938 storage combi boiler

  • Dimensions: 720 mm (h) x 440 mm (w) x 624 mm (d)
  • Fuel type: Gas boiler
  • Power output size: 38 kW
  • Efficiency rating: 89.4%
  • Price: Around £1,664 incl. VAT

The Vaillant ecoTEC Plus storage combi boiler is a powerful gas boiler ideal for a 3-bedroom house with 2+ bathrooms. Its advanced condensing technology is just shy of a 90% efficiency rating for both heating and hot water. But its innovative built-in hot water storage cylinder delivers up to 20 litres per minute and can supply hot water within 5 seconds!

With its larger storage cylinder, this Vaillant boiler delivers more hot water than traditional combi boilers. Other notable features of this boiler include:

  • Easy-to-use controls
  • Includes ‘step-by-step wizard’ for easy set-up
  • Range of thermostat controls – to keep energy costs down!
  • Standard 5-year warranty (with the option of 2 additional years when installed by Vaillant-accredited boiler fitters)
  • Quiet operation (46 decibel)
  • Perfect for larger homes with 3 to 4 bedrooms or 2 – 3 bathrooms
  • LPG models are available for off-the-grid properties

5. Viessman Vitodens 200-w 11 kW system boiler

  • Dimensions: 700 mm (h) x 450 mm (w) x 360 mm (d)
  • Fuel type: Natural and LPG gas boiler
  • Power output size: 11 kW
  • Efficiency rating: Up to 98%
  • Price: Around £1,591 incl. VAT

The Viessman Vitodens 200-w 11 kW system boiler is the perfect size boiler for a 3-bedroom house or one with mega hot water demands! Don’t let its compact size fool you though as this highly efficient boiler certainly brings the heat, is wall-mounted and fits perfectly into kitchen or bathroom cabinets.

It has a powerful Inox-Radial heat exchanger, known for its reliable high condensing efficiency of up to 98% – you simply can’t get better than this in terms of the best bang for your buck!

Key features of this fantastic boiler include:

  • WiFi compatibility
  • Built-in 2-stage frost protection
  • Compatible with air-to-water heat pump hybrid systems
  • MatriX-Plus burner and Lambda Pro Plus automatic combustion controller for efficient operation
  • Movable 7-inch display screen for convenient eye-level operation
  • Hydrogen-ready (20:80 blend)
  • Standard 7-year warranty (12-year extended warranty available)
  • Super environmentally friendly

For a smaller, equally efficient and incredible boiler, you can also consider the Viessman Vitodens 100-w boiler.

6. Worcester Bosch Greenstar 8000 Life 30 kW system boiler

  • Dimensions: 780 mm (h) x 440 mm (w) x 365 mm (d)
  • Fuel type: Natural and LPG gas boiler
  • Power output size: 30 – 50 kW
  • Efficiency rating: 94%
  • Price: Around £1,236 incl. VAT

The Worcester Bosch Greenstar Life 30 kW system boiler size is great for a 3-bed house with 20 radiators and 2+ bathrooms. Its unique condensing technology generates 94p of heat from every £1 spent (94% efficiency rating). This boiler model has a central heating output of 30 kW and a 10.7 litre per minute flow rate – up to 20 litres per minute with the 50 kW model!

It’s LPG compatible and offers a wide range of other benefits and features, namely:

  • LCD touchscreen
  • Compatible with smart technology and solar power
  • On/off cylinder protection – for extended boiler longevity
  • Improved fuel efficiency
  • Intelligent filling system
  • Easy to access internal components for quick installation and repairs
  • Standard 5-year warranty (with the option to extend to 12 years)
  • Available in two high gloss colours: white or black

Combi, System, Or Regular: What Suits Your Lifestyle?

Choosing boiler types for your home can be tricky but the main thing you needs to consider are: lifestyle routine and hot water demands. These aspects are the deciding factor in your boiler-type quest.

We’ve made it easier for you and have put together a boiler comparison list:

Combi boilers

A combination boiler – or combi boiler for short – is an energy-efficient boiler and central heating system in one compact unit. As mentioned, around 80% of UK homes have been fitted with combi boilers.

Key features

  • Combi boilers provide excellent energy-efficient heating for 3-bed homes, supplying instant heating and hot water.
  • They are space-savvy options as there’s no need for separate hot water cylinders or cold water storage tanks.
  • Their compact size is ideal to install in small spaces – for example, inside your kitchen cupboard.
  • New combi boilers range between £1,500 – £2,500 (including installation).
  • Spoiler alert: One of the best combi boilers (in our opinion) is the Viessman Vitodens 111-w boiler!


  • Space-saving option due to no additional tanks or cylinders.
  • Provides instant hot water.
  • Combis are energy-efficient boilers – lowering your energy costs.
  • Lower installation costs as the system has fewer parts.


  • Limited hot water flow rate for homes with multiple bathrooms.
  • Hot water supply can be affected during high demands (i.e. when more than 1 hot water outlet is used at the same time).
  • Not suitable for properties with low water pressure.

System boilers

A system boiler uses a hot water cylinder to provide heating and hot water to our homes. Essentially, it is a “hybrid” between a combi and a regular boiler.

Key features

  • Works with a hot water cylinder but no need for a separate cold water storage tank.
  • System boilers are ‘sealed systems’ which means they draw water directly from the main supply.
  • These boilers have more components than combi boilers (e.g. circulating pump, expansion vessel).
  • Can store hot water for later use – providing optimal heating for 3-bed homes or those with higher hot water demands.
  • A new system boiler ranges between £1,700 – £3,600 (including installation costs).


  • Can supply hot water to multiple bathrooms and taps simultaneously.
  • No need for a storage tank in the loft.
  • More energy-efficient than regular boilers – especially when the hot water cylinder is well-insulated.
  • Compatible with green energy (i.e. solar power).


  • Requires more space than combi boilers because of hot water cylinders.
  • Hot water isn’t instant as it depends on the capacity (size) of the heating cylinder.
  • If the cylinder runs out of hot water, you’ll need to wait for it to reheat again.

Regular boilers

Regular boilers – also known as conventional or heat-only boilers – are the bulkiest boiler type on our list as they require both a hot water cylinder and a storage vessel.

Key features

  • Requires both a heating cylinder and a cold water storage tank.
  • Ideal for homes with traditional radiator systems.
  • Suitable for bigger properties with multiple bathrooms and very high water demands.
  • A new conventional boiler ranges between £1,700 – £3,000 (including installation costs).


  • Can supply hot water to multiple taps without losing water pressure.
  • Compatible with older heating systems and radiators.
  • Good for areas that have low water pressure.


  • Takes up more space due to the need for a cylinder and storage cylinder (usually placed in the loft).
  • Hot water isn’t instant based on the size of the storage cylinder.
  • Less energy efficient when compared to other boiler types on our list due to heat loss from the cylinder.

How to Choose the Right Boiler

Now that you’ve seen the best boiler sizes available for a 3-bedroom house, let’s look at the next part of your boiler size decision: How to choose the right boiler for your home.

While some might think that the most expensive boiler is the best option to go for, it’s not always the case.

Opting for a boiler and heating system that is too big for your property can lead to wasted energy, in terms of heating and money spent. Whereas, choosing a heating system that is not compatible with the number of bathrooms you have can lead to insufficient hot water recovery time and supply.

The factors mentioned on Eco Happy‘s list play an important role in your “3-bedroom house decision-making process”, so you should definitely give them a read!

House size

Boilers come in all shapes and sizes. Depending on how many radiators and bathrooms you have in your 3-bedroom house, will determine which unit size you’ll ultimately need. A rule of thumb is that larger homes typically need a bigger boiler to meet heating demands – but it’s not always the case.

Boilers are measured in kilowatts (kW), which shows the power output they draw to generate enough heat and hot water. These boiler kWs are typically suitable for a 3-bed house:

  • Combi boiler = 20 – 35 kW
  • System boiler = 10 – 25 kW
  • Conventional (heat only) boiler = 10 – 25 kW

In saying this, if you have a home with more than 2 bathrooms, it’s best to go for a system (e.g. Viessman Vitodens 200-w 11 kW) or a conventional boiler. This will ensure the boiler provides enough heating and water when multiple taps are in use.

While a combi boiler is a great option, it might struggle to meet (and maintain) your hot water demand needs. However, if you have a single bathroom then a combi boiler should be fine.

Other factors to consider in terms of house size include:

  • Location
    • What is the water pressure like where you live?
    • Do you live in an urban or rural area?
    • Hint: Regular boilers work best in low-pressure areas.
  • Type of home
    • Do you have a terraced or semi-detached 3-bed house?
    • Have you moved or bought a new build or are you using a more traditional heating system?
    • What fuel type is compatible with your postcode area? While a gas boiler might be a more cost-effective fuel type, your area may not have a reliable gas supply.
    • Hint: A conventional boiler works well with older radiators and central heating systems.

Insulation levels

  • Heating retention: Well-insulated homes retain heat more effectively than poorly-insulated homes. Insulation reduces the amount of heat lost to the environment. Depending on the size of your house, a smaller boiler system may suffice as less energy is needed to maintain a comfortable temperature.
  • Energy efficiency: Homes with poor insulation lose heat more quickly, as mentioned before. This means your boiler has to work harder (i.e. use more fuel) to keep your house warm. This extra effort on your boiler’s part not only leads to higher energy bills but your home will have a bigger carbon footprint as well!
  • Impact on boiler cycling: Boiler cycling is an automatic ‘on-off’ feature that happens when our boilers experience fluctuating temperatures. When the boiler turns off, the water inside loses heat to the surroundings, causing the thermostat to detect a drop in temperature and trigger the boiler to turn on again. This cycle repeats when the temperature falls below the set point.Poorly insulated homes may experience more boiler cycling which can affect your boiler longevity.

Hot water demands

  • The number of bathrooms: A 3-bedroom house with 2+ bathrooms requires bigger boilers – often leading more towards system or regular boilers. Whereas a combi boiler will suffice for a 3 bedroom house with one bathroom.
  • Usage patterns: Your household’s lifestyle and habits play a major role in boiler size. High water demands such as frequent showers or baths increase the demand for the boiler.

While combi boilers are a space-saving option, they may (or may not) be the best option for your 3-bed house. Choosing the right boiler size is a balancing act between sufficient heating supply and energy efficiency. Overestimating boiler size can lead to increased energy bills, while underestimating can result in insufficient heating and supply.

Top tip: According to a 2022 Statista report, the average person (in England and Wales) per household uses 146 litres of water per day – including domestic hot water.


  • Look for brands, like Ideal or Viessmann, that have a strong track record of reliability and customer service. Top brands that consistently deliver quality products are more likely to offer boilers that meet – and exceed – your expectations.
  • Check out the brand’s official website to see if the brand has received any industry awards. Recognition from industry professionals is a key indicator of quality.
  • Check customer reviews and testimonials – these provide valuable insights into boiler performances.


  • A longer warranty period indicates the manufacturer’s confidence in their product. Look for warranties that cover an extended period, ideally between 7 to 10 years.
  • Understand what the warranty covers. Is it a parts and labour warranty? Or are you eligible for a new boiler replacement should the boiler be faulty?
  • Take note of service and maintenance requirements within your boiler warranty. You should know how often should a boiler be serviced to ensure you don’t lose your warranty. Some warranties may be invalid if an annual boiler service is not done.


  • Choose a boiler with a high energy efficiency rating (A-rated) to reduce your energy bills and carbon footprint.
  • Most new boilers are equipped with condensing technology; using as little fuel as possible to generate the maximum amount of heat.
  • Consider noise levels per boiler type – opt for quiet operation mode models.
  • If smart technology is important to you, choose boilers with WiFi compatibility for a range of smart features, like temperature control.


Is a 24 kW boiler big enough for a 3-bedroom house?

A 24 kW combi or system boiler is big enough for a 3-bedroom house with 2+ bathrooms. If you only have one bathroom, you can opt for a smaller size boiler.

What are a plumber’s installation costs to fit a new boiler?

Plumbers and heating professionals usually charge around £50 – £100 per hour for new boiler installations. As a guideline, replacing an old combi boiler with a new boiler typically takes 4 to 8 hours to install (± £200 – £800).

Is a higher kW boiler better?

It depends. The number of radiators and bathrooms you have in your 3-bedroom house will determine the kW on your boiler. Opting for a boiler that is too big (i.e. higher kW) could result in wasted energy and higher energy bills.


As we end this ‘best boiler for a 3 bedroom house’ roadshow, we hope you’re more inspired to make better boiler choices. Whether you opt for combi, system or conventional boilers – the main thing to consider is house size and hot water demand. This makes choosing the right boiler for your home a breeze.

As the UK moves towards a greener future – with an ambitious goal of reaching net zero carbon emissions by 2050 – energy efficiency ratings are key. If your 3-bed house only has one bathroom, then a combi boiler is your best bet. But, if you have multiple bathrooms, consider conventional or system boiler options.

Either way, after reading this guide, you’ve become a boiler guru and we’re certain you’ll make the best boiler choice for your home’s heating needs! Or if you want more info, chat with the Eco Happy team today.

Leave a Reply

Your email address will not be published. Required fields are marked *