Best Combi Boiler For A Large 4 Bedroom House UK

Written by

Jennifer Warren

Last updated: November 15, 2023

Wanting to know what the best boiler for a large house is? A house with four bedrooms or more needs a powerful boiler, but which?

The best boiler for a large 4-bedroom home will come down to whether you have one or more bathrooms.

A combi boiler can get the job done if you have one bathroom, and some high-power models can effectively heat your home if you have two bathrooms or more.

If your 4-bedroom house has more than two bathrooms, you can also turn to a system or regular boiler.

If you’re unsure which boiler you need, keep reading for a rundown of the best boiler for a large four-bedroom plus house.

Best Combi Boiler for Large House Key Takeaways:

  • The boiler size you require is largely determined by the number of radiators, bedrooms and bathrooms in your home.
  • Combi boilers are generally suitable for small and average-sized homes, while system and regular boilers (boilers with a tank) are more suitable for larger properties. 
  • To get an accurate quote for the boiler size you need, you can start your application with Which? approved boiler installers Heatable here.

Combi, System, or Regular Boilers?

Combination boilers provide heating and hot water from a single wall-mounted unit.

They’re best suited for homes with one bathroom because they heat water on demand without storing it, weakening the water flow if more than one person wants a shower or bath.

Combi boilers can sometimes be suitable for homes with two bathrooms or more, but the boiler size, also known as the output rating or the measure of the boiler’s power, needs to be high enough.

Large houses with more than two bathrooms should consider a system or regular boiler.

System and regular boilers store hot water in a separate cylinder, meaning more hot water to go around.

Only consider a regular or heat-only boiler if you already have one installed. They’re complex heating systems that need extra pipework and additional water feed tanks that can increase your installation costs.

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You can modernise your heating system by changing from a regular to a system boiler and free up some loft space!

A system boiler is an upgraded or modern version of the heat-only boiler.

It takes water from the mains water supply instead of a tank installed in the loft or above the boiler.

Learn all about the different types of boilers, including condensing boilers, LPG boilers, oil boilers, Opentherm boilers and calculating boiler size in our guide.

Boiler erp label

Comparing The Best Boilers For A Large House

Some vital things to consider when choosing a boiler for your 4-bedroom plus house include the following:

Boiler Efficiency

Thanks to condensing technology, all modern boilers are highly efficient.

By law, all new boiler installations in the UK must be condensing.

As boilers burn fuel, they produce water vapour or steam, which contains heat that contributes to warming up the central heating.

Before condensing boiler technology was developed, the heat went straight out of the flue pipe, losing up to 30% of the heat from the boiler and requiring more fuel to make up for the loss.

Condensing boilers use a flue gas recovery system where the heat from the steam is recycled and not lost.

The system makes condensing boilers more efficient than ever, and the same amount of hot water and heat can be delivered to your home using much less fuel than non-condensing boilers.

All boilers have an efficiency rating based on an ABC banding scale, with A being the most efficient.

Many new boilers are A-rated, and you can check the efficiency rating out of 100%.

The closer the rating is to 100%, the lower your bills and carbon footprint.

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How old is your boiler? Should you consider a boiler repair or start looking at the latest boiler prices? It’s no secret that boiler efficiency deteriorates over time.

Sizing (Power Output)

Boiler size refers to the boiler’s power instead of its physical dimensions. It’s the output rating and is measured in kilowatts (kW).

The correct boiler size for your house will depend on the hot water demands and the number of bathrooms and radiators you have.

Generally, the higher your demand for heat and hot water, the higher the output you’ll require.

Each type of boiler measures kW outputs differently, so you should choose the appropriate kW for the type of boiler you’re buying.

What Type Of Boiler Is Best For A Large Home?

Here we review the types of domestic boilers and the size you will typically require based on the size of the property and number of bathrooms:

Combi Boilers

Output in kWBedroomsBathroomsRadiators
24-281-21Up to 10
28-353-41-2Up to 15
35-434+2+Up to 20

For a large house with 4+ bedrooms, you’ll require a combi boiler with an output between 35-43 kW.

System Boilers

Output in kWBedroomsBathroomsRadiators
12-151-2110
18-243-41-215
30+4+2+20

A house with 4+ bedrooms will need a system boiler with an output of between 24kW to 30kW.

If your home has 1-2 bathrooms, a 24kW system boiler can be enough, but if it has 2+ bathrooms, you’ll need a 30kW boiler.

Regular Boilers

Output in kWBedroomsBathroomsRadiators
10-181-2110
18-262-32-315
27-404+3+20

Your 4+ bedroom house will need a regular boiler with an output of 27kW to 40kW.

Boiler Guarantee/Warranty

Different boiler manufacturers have different warranties and guarantees for their boilers.

They can differ based on how long they last and whether they’re standard or extended.

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You can find different warranties for different boilers in a manufacturer’s range.

Boiler Guarantee Vs Warranty

A boiler with an extended warranty can ensure your peace of mind for as long as possible.

You can get a replacement or repair at no extra cost should you face any breakdown or faults within the warranty period, provided it falls in line with the manufacturer’s terms and conditions.

Ideally you want the boiler warranty to be as long as possible, the likes of Worcester and Alpha both offer a 10 year warranty as standard.

We also covered the boiler brands to avoid and the most reliable boilers currently available.

Boiler Prices

The cost of a new boiler consists of the cost of the boiler and installation costs. You’ll find huge or negligible differences between boiler prices.

Although it shouldn’t be the only deciding factor, it’s worth considering if you can save a decent amount of money upfront.

Most expensive doesn’t always mean the most performance, and you can find some budget-friendly brands that are technically brilliant.

Who offer the best boilers deals in the UK? Check out our review of online boiler installation companies, boiler brands and the best UK boilers that topped our list concerning new boilers in the current year.

Best Combi Boilers For A Large 4 Bedroom+ House

  • Worcester 8000 35kW combi boiler.
  • Viessmann Vitodens 100 35kW combi boiler.
  • Alpha E-Tec 38kW combi boiler.

Best System Boilers For A Large 4 Bedroom+ House

  • Vaillant ecoTEC plus 630 System Gas Boiler 30.4 kW.
  • Ideal Vogue Max S32 System Gas Boiler 32kW.
  • Baxi Platinum Plus 32kW System Gas Boiler.

Best Regular boilers For A Large 4 Bedroom+ House

Only consider regular boilers if you already have one installed in your home. The best ones include:

  • Worcester Bosch Greenstar 8000 Life 35kW.
  • Ideal Logic Max Heat 30.3kW.
  • Valliant ecoTEC plus 430 30.5kW.

Best Boiler for a Large Home Conclusion

System and regular boilers are excellent choices for a large house with four bedrooms+ and more than two bathrooms.

The technology in combi boilers has also improved, making combi boilers a realistic prospect for larger homes, which is good news for the environment and your pocket!