The Best Boilers For Large Homes

The energy crisis has been tough for us all, especially for those in the chillier regions of Scotland like Braemar and Aviemore. With fuel poverty now hitting around 6.3 million households across the UK, finding the most efficient way to heat our homes has never been more important.

Because Envirohomes Renewables knows the ins and outs of home heating, we understand the unique challenges you face. That’s why we’ve put together this comprehensive guide to pinpoint the best boiler for a large house in Scotland. From combi boilers to the trusty system boiler, we’ve got insider tips to help you make an informed, wallet-friendly decision.


Combi, Regular or System Boilers?

Finding the right boiler for your home can be a headache, especially without the proper knowledge. So, let’s start off with the basics: Exploring the types of boilers. We’ll look at the three main types – combi boilers, regular boilers and system boilers – and explore their basic functions, environmental impact and safety considerations.

Combi boilers

A combi boiler is a popular choice for many homeowners. It’s a compact unit that provides both heating and hot water directly from the mains, eliminating the need for a separate hot water storage tank. This means you get hot water on demand, which is perfect for smaller households.

However, for larger homes, especially in colder regions like Braemar and Aviemore, a combi boiler may struggle to meet high hot water demands simultaneously.

Environmental impact: Combi boilers are generally energy efficient as they heat water directly from the mains, reducing heat loss. This means lower carbon emissions and a smaller carbon footprint.

Safety considerations: Modern combi boilers come with safety features like pressure relief valves and thermostats. However, regular maintenance is essential to prevent issues like gas leaks, especially with gas boilers.


  • Space-saving due to no need for storage tanks.
  • Instant hot water on demand.
  • Energy-efficient, leading to potential savings on energy bills.


  • Might struggle to supply multiple outlets simultaneously.
  • No backup hot water source if the boiler breaks down.


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Regular Boilers

Regular boilers, often called traditional or conventional boilers, require a hot water cylinder and a cold water storage tank, usually fitting in the loft. They supply water to radiators and a hot water storage tank, ensuring a steady supply even for larger homes.

Environmental impact: Regular boilers can be less efficient than combi boilers, especially if older models. But, when they’re paired with solar water heating systems, their carbon footprint can be reduced significantly.

Safety considerations: When it comes to safety, regular boilers are no exception to the rules. They need annual servicing by Gas Safe registered professionals. The reality is that their safety features can fail or become faulty, so regular checks are a must.


  • Suitable for homes with multiple bathrooms.
  • Can work in tandem with solar water heating systems.
  • Provides a steady supply of hot water.


  • Requires more space due to the hot water cylinder and storage tank.
  • Potentially less energy-efficient than combi boilers.
boiler installation

System Boilers

Think of system boilers as a middle ground between combi and regular boilers. They need a hot water cylinder but don’t require a cold water storage tank. They get their water supply directly from the mains, like a combi boiler, but store hot water in a cylinder for later use.

Environmental impact: System boilers are generally more energy-efficient than regular boilers but slightly less so than combi boilers. The way that they store hot water can lead to some heat loss, but newer models are designed to minimise this.

Safety considerations: System boilers, like the other types, should be serviced every year by Gas Safe registered engineers. They also come with built-in safety features like timers, but the hot water cylinder still needs regular checks to ensure it’s functioning correctly.


  • Provides a steady supply of hot water, suitable for larger homes.
  • Doesn’t require a cold water storage tank, saving some space.
  • Can handle high hot water demand.


  • Requires space for a hot water cylinder.
  • Potential for some heat loss from the stored water.

Ultimately, the best type of boiler for your home depends on your household’s size, hot water needs, and available space. For example, combi boilers are compact and efficient, but regular and system boilers are better suited for homes with higher hot water demands. Always consider the environmental impact and safety of your chosen boiler, as well as government initiatives targeted at a greener future.

gas boiler

Which Boiler Type Is Most Cost Effective to Install?

If you’ve got a large house (5+ bedrooms) then you’ve probably felt the pain of having to deal with high energy bills. So, when you’re shopping for a boiler, not only do you need to consider the boiler’s efficiency and performance, but also the installation costs. Here’s a look at the cost-effectiveness of installing different types of boilers.

Combi boilers

Combi boilers are compact and don’t need a separate tank or cylinder, which can reduce installation costs. This is why combi gas boilers are generally seen as the cheapest to install, especially gas combi boilers. For a large 5-bedroom house with around 15 radiators, the average cost of installing a combi boiler can range from £2,500 to £4,500.

Although the initial installation might be cheaper, combi boilers might not always be the best choice for homes with high hot water demands, as they can struggle to supply multiple outlets at the same time.

System boilers

A system boiler, when paired with a hot water cylinder, can efficiently cater to a large house’s demands. For a similar 5-bedroom house with a central heating system comprising around 15 radiators, the installation cost for a system boiler can be slightly higher, ranging from £3,000 to £5,000. This includes the price of the boiler and the hot water cylinder.

The advantage here is the steady supply of hot water, even if multiple taps are on.

Regular boilers

If you’re considering a system or regular boiler, know that the regular boiler setup is more complex. It requires both a hot water cylinder and a cold water storage tank. For our example of a 5-bedroom house, the installation cost for a regular boiler can range from £3,500 to £6,000, considering the additional components.

This might be a suitable choice for homes with multiple bathrooms and a higher number of radiators.

Other factors to consider

There’s no denying that a boiler’s price is a significant chunk of the installation cost but other factors can also influence the total price. Here are a few:

  • Complexity of the installation: Some homes can have intricate layouts or older systems. This means that the installation process can be more challenging and potentially increase the costs involved. These costs can be offset by handling minor tasks yourself.
  • Rates charged by the heating engineer: Different engineers have varying rates based on their experience, expertise, and demand. The best thing to do in this case is to get multiple quotes to find a balance between cost and quality. Regardless of whoever you pick, make sure they’re a Gas Safe registered professional.
  • Any required modifications to the property: Older homes normally have old fittings and might need adjustments or upgrades to accommodate a new boiler. This could involve updating pipework or enhancing ventilation, which can add to the overall expense.

Don’t get too caught up on the initial installation costs, as the long-term running costs and potential savings on energy bills also matter. Although combi boilers may seem like the most cost-effective option upfront, a system or regular boiler might be a more practical choice for larger homes with a higher number of radiators and greater hot water demands.

Try to get multiple quotes and consider both the immediate and long-term costs when making your decision.

oil boiler

What Size Does a Boiler Need to Be for a Large House?

Choosing the right boiler size for a large house is a bit like picking the perfect pair of shoes. It needs to fit just right. Too small, and it won’t meet your heating and hot water needs. Too big, and you’re overpaying for energy you don’t use.

Always bear in mind that the type of boiler and its size should align with your home’s specific needs. So, don’t try to eyeball this if you’re unsure. The best thing to do is to consult with a heating expert to get tailored advice. The last thing that you want is to take a wild guess and end up having a home that’s perpetually cold or consuming way too much energy.

Let’s break it down.

Understanding boiler size

When we talk about the ‘size’ of a boiler, we’re referring to its power output, measured in kilowatts (kW). This determines how much hot water and warmth it can provide to your home.

For a (large) 5-bedroom house

A 5-bedroom house typically has more bathrooms and a larger living space, which means more radiators and greater hot water demands. For such homes, you should likely be looking at boilers with an output ranging from 35 kW to 42 kW, depending on specific needs.

Combi boiler sizing

Combi boilers are all about instant hot water. For a large house, you need a combi boiler that can deliver a higher flow rate. This ensures that even when someone’s enjoying a hot shower upstairs, there’s still enough hot water for the kitchen tap.

The most suitable combi boiler for a 5-bedroom house would typically have an output of 35-42kW, matching the demands of the number of radiators and frequent hot water usage.

System or regular boiler sizing

With system boilers and regular boilers, it’s a tad different. Since they store hot water in a cylinder, their size doesn’t solely depend on instant demands. For spacious 5-bedroom homes, a system or regular boiler with an output of 30kW – 35kW should suffice. But, you also need to ensure the hot water cylinder is large enough to store water for baths, showers, and other needs.

Factor in your radiators

The number of radiators in your home plays a pivotal role. More radiators mean you’d need a boiler with a higher output. As a rule of thumb, count your radiators and then multiply by 1.5 kW. This gives you a rough estimate of the boiler output you’d need for your central heating system.

How Many kW Does a Boiler Need for a Large House? (5 to 7 bedrooms)

With boilers, your primary concern should be the fit and, in this case, the fit is measured in kilowatts (kW).

Although the kW ranges below are a good starting point, don’t forget that every home is unique. Factors like insulation, the age of the property, and even the number of occupants can influence your boiler needs. So, always chat with a heating expert before making a decision.

24-27 kW boilers

For the smaller end of large homes, say a 5-bedroom property with a couple of bathrooms, a boiler in this range might do the trick. It can comfortably handle domestic hot water and heating needs without breaking a sweat. But remember, if your home is on the larger side of this bracket or has more than two bathrooms, you may want to consider a more powerful option.

28-34 kW boilers

These boilers are designed for homes that are just a bit more demanding. Think around 6 bedrooms, multiple bathrooms, and perhaps a couple of en-suite facilities. They ensure that your heating system runs smoothly, even when multiple taps and showers are in use.

35-42 kW boilers

We’re talking about the big guns here. For those grand 7-bedroom homes with several bathrooms, a boiler in this range is what you should be eyeing. It ensures that every corner of your home stays toasty and that there’s always enough hot water to go around.

Power calculators

If you’re still scratching your head, wondering which kilowatt bracket your home falls into, don’t fret. Some handy websites offer power calculators. Just pop in a few details about your home, and voila, you get an estimate of the kW you will need for your new boiler. It’s like having a personal stylist but for your heating system!

Best Combi Boiler for a Large House

If you’ve decided that a combi boiler is the best solution for your large home, then here are some options that you may want to consider:

Worcester Bosch Greenstar 8000 Life 50

The Worcester Bosch Greenstar 8000 Life 50 kW stands out as the most powerful combi boiler in its range. Here’s why it’s the best fit for a large house:

  • Power and efficiency: With a 50 kW domestic hot water (DHW) output rating, it’s ideal for properties with multiple bathrooms and an ensuite. Plus, its central heating (CH) output rating of 35 kW is perfect for homes with around 15 radiators. Its seasonal efficiency rating of 94% also ensures you get top-notch performance without hefty energy bills.
  • Reliability: The Greenstar 8000 Life 50 comes with a standard 5-year warranty, which can be extended to a whopping 12 years when installed by a Worcester Bosch Accredited Installer.
  • Price point: While quality comes at a price, the Greenstar 8000 Life 50 offers value. Its total cost, including VAT, sundries, and installation, typically ranges from £2,900 to £3,400.


  • DHW output: 50 kW
  • CH output: 35 kW
  • Efficiency: 94%
  • Warranty: 5 years (extendable to 12 years)
  • Price range: £2,900 to £3,400

Good alternatives

  1. Vaillant ecoTEC Plus 938: A powerful combi boiler with an integrated hot water storage device, it can deliver up to 20 litres of hot water per minute. With a CH output of 30.9 kW and a DHW output of 38.7 kW, it’s suitable for homes with up to 15 radiators and 2 bathrooms. Its efficiency stands at 94%.
  2. Ideal Vogue Max C40: This wall-mounted condensing combi gas boiler boasts a CH output of 32 kW and a DHW output of 40 kW. It’s best suited for homes with 2 bathrooms and around 15 radiators. With an efficiency of 93%, homeowners can expect savings on their energy bills.

Although the Worcester Bosch Greenstar 8000 Life 50 takes the title for the best combi boiler for a large house, you should always take a long look at all the options available, as the ‘best boiler’ for one large house may not be the best for other houses. This is where understanding your specific needs and budget becomes important.

boiler fitter

Best System Boiler for a Large House

If you choose wisely, system boilers can work well for a large house, even better than a combi boiler in some cases. Here are some of the best system boilers available.

ACV E-Tech W 36 Tri

The ACV E-Tech W 36 Tri stands out as a top-tier electric system boiler, perfect for homes seeking a gas alternative. Here’s why it’s the best of its kind for a large house:

  • Eco-friendly: As gas and oil resources deplete, electricity emerges as a sustainable option for home heating. The E-Tech W 36 Tri offers zero emissions and no risk of carbon monoxide leaks, making it an environmentally friendly choice.
  • Efficiency: With an efficiency rating of 37%, it might seem lower than gas and oil boilers. However, remember that electricity is carbon-intensive, which affects these ratings. Despite this, the boiler’s quick response to the heating system being turned on ensures efficient heating.
  • Flexibility: This boiler doesn’t need flues, which means it’s pretty flexible when it comes to installation. Its compact design also ensures it doesn’t hog too much space in your house.
  • Key features: The E-Tech W 36 Tri works well with both radiators and underfloor heating. It comes with modulation based on heating demand, 10-litre water storage, and a built-in controllable circuit that is protected by a 3 amp internal miniature circuit breaker.


  • Efficiency: 37%
  • Warranty: 1 year (standard)
  • Features: 10-litre water storage; modulation based on demand; built-in control circuit
  • Price range: £2,600 to £3,100

Good alternatives

  1. Baxi Platinum Plus 32: A gas system boiler with an efficiency of 93%. It’s suitable for homes with up to 20 radiators. One of its standout features is the Adey Micro2 magnetic filter, which captures debris in the system, preventing blockages. It comes with a generous 10-year warranty.
  2. Ideal Vogue Max S32: This gas system boiler boasts an efficiency of 93.2%. Suitable for homes with 15-20 radiators, it’s the most powerful in the Vogue Max range. It’s designed for larger homes with multiple bathrooms, ensuring strong water pressure across all outlets. The boiler is covered by a 10-year warranty, extendable to 12 years with a Max Accredited installer.

The ACV E-Tech W 36 Tri takes the top spot for the best system boiler for a large house, but the alternatives we’ve mentioned also offer lots of features and solid performance. As mentioned earlier, always weigh up the respective pros and cons of your options.


Best Regular Boiler for a Large House

Last but certainly not least, we have regular boilers. As you would expect, there are more than a few options out there. Luckily, in terms of your search, some boilers stand out from the rest in terms of efficiency, performance, and value for money. Let’s take a look at the best system boilers for a large house.

Ideal Logic Max Heat H30

The Ideal Logic Max Heat H30 is a regular gas boiler that has gotten a lot of attention for its impressive features and reliability. Here’s why it’s the top choice for a large house:

  • Efficiency: With a 93% efficiency rating, the H30 is not only environmentally friendly but also ensures you get the most out of every pound spent on heating. This could translate to significant savings on energy bills over time.
  • Output Rating: The H30 boasts a central heating output rating of 30 kW, making it an ideal choice for larger properties with around 20 radiators. This ensures consistent heating throughout the home, even during the coldest months.
  • Warranty: One of the standout features of the H30 is its generous 10-year warranty, which can be extended to 12 years with a Max Accredited installer. This offers homeowners peace of mind knowing they’re covered for a long time.


  • Efficiency: 93%
  • Central Heating Output: 30 kW
  • Warranty: 10 years (extendable to 12 years)
  • Price range: £1,920 to £2,420

Good alternatives

  1. Worcester Bosch Greenstar 8000 Life 35: This regular gas boiler with an efficiency rating of 94% is suitable for medium-sized homes with up to 20 radiators. It offers a central heating output of 35 kW and comes with a standard 5-year warranty, which can be extended to 12 years with a Worcester Bosch Accredited Installer.
  2. Vaillant ecoTEC plus 430: This boiler offers an efficiency rating of 94% and has a central heating output of 30.5 kW, making it suitable for homes with as many as 20 radiators. It comes with a 5-year warranty, which can be extended to 7 or 10 years. A key feature is its two-stage frost protection, ensuring the boiler’s smooth operation during cold months.

If you’re torn between the Ideal Logic Max Heat H30 and the alternatives we’ve mentioned, then the solution is simple: Just get in touch with a heating professional and let their expertise guide you. They’ll look at the boring aspects like efficiency and output rating while you contemplate how much you’re able or willing to spend on a new boiler.


Lots of homeowners, especially those with larger properties, struggle to get consistent hot water and heating, so some large houses do install two boilers to meet their heating demands. A dual-boiler setup can be a more efficient heating solution. If one boiler struggles or fails, then the other can take over, which will keep your central heating system operational.

Although this approach can provide a steady supply of hot water and heating, it’s important to consider the cost implications.

Yes, there are grants available to help people with the costs of installing a new boiler. One of the most notable schemes is the ECO4 (Energy Company Obligation 4) scheme. Under this scheme, low-income households can get financial assistance to improve their energy efficiency. Another key part of ECO4 is major energy suppliers funding the installation of energy-saving measures, including new boilers.

To qualify for the ECO4 scheme, you need to be on certain benefits, such as Universal Credit. Your total household income and the type of property you live in can also influence your eligibility. The best thing to do is to contact Envirohomes Renewables to check your eligibility.

Yes, heat pumps can be a viable alternative. In fact, nowadays heat pumps are becoming a popular alternative to traditional boilers, especially for larger homes.

Heat pumps work by extracting heat from the outside air or ground and using it to heat your home. One of the main problems with heat pumps is that they can be quite costly to install, particularly compared to a new boiler. However, heat pumps can save you a lot in the long run, making them a good option for those wanting to cut their carbon footprint and energy bills.

If we focus only on running costs, then modern gas boilers will generally be the most cost-efficient. Electricity in the UK is over three times more expensive than gas, so gas boilers are still unbeatable when it comes to efficiency and combating rising energy prices.

This is where using renewable technologies, like solar panels to power an electric boiler, can be helpful in reducing running costs.

In most cases, no. This is because electric boilers tend to have a lower power output compared to gas or oil boilers. They normally work well for smaller homes and flats, but not as much for larger homes.

For example, an electric boiler rarely exceeds 15 kW, but a gas boiler can have an output of up to 35 kW. If you’re considering an electric boiler for a large home (5+ bedrooms), do your best to calculate the ideal size based on the number of radiators and other factors like insulation and glazing.


If you own a large house in Scotland, then choosing the right boiler is a decision that can’t be taken lightly, as it can greatly affect how your energy bills will look in the future. Don’t forget that it’s ultimately about ensuring comfort and warmth for you and your family.

With the energy crisis impacting so many Scots, it’s vital to start making informed choices that will give both efficiency and reliability. Whether you’re considering a combi boiler, system boiler or regular boiler, each has its own unique advantages which can suit different needs.

Remember that a warm home is a happy home. Although what you may have to pay initially for a new boiler may be daunting, you will have peace of mind and reap the benefits in the long term. Plus, grants like the ones provided by the ECO4 scheme can also provide financial relief, making energy-efficient upgrades more accessible to everyone.

In the end, it’s about finding the perfect balance between cost, performance, and environmental impact. So, take your time and weigh your options. If you make smart decisions, your home will stay cosy throughout the year.