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Last updated: 1 April 2025

Best Combi Boiler For 3 Bed House in the UK: Expert Picks 2025

Best Combi Boiler For 3 Bed House
  • The Ideal Logic Max, Worcester Bosch Greenstar 4000, and Viessmann Vitodens 050-W are the best boilers for a 3 bedroom house.
  • On average, you can expect to pay between £1,200 to £1,500 for a high-quality boiler (before installation).
  • A 24kW to 35kW combi boiler is sufficient for the average 3 bedroom house.

Combi boilers are a great way to heat your home with high efficiency and on-demand hot water. When it comes to 3-bedroom homes, they can cater to most homes with within-average water consumption, i.e. homes that do not need more than two simultaneous hot water taps running or do not have more than two bathrooms.

We’ve created a selection of the best combi boilers available in the UK and compared them to provide you a list ideal for 3 bedroom houses. Let’s dig deeper into what makes them the best home heating appliances.

While this list is extensive, it may not cover precisely what you need since each home is different. That’s why you should consult a reliable installer. Finding one can be a tough task. There are many options, but you’ll never know if they suit your pricing needs or can provide quality service and the best boiler for your property. Thankfully, we can help with that using our network of qualified engineers.

We’ve personally vetted the best installers in the UK, so you don’t have to. Fill out a 30-second survey, and we’ll provide you with up to 4 free, non-binding quotes. Click the button below to get started.

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What are the best combi boilers for 3 bedroom houses?

We surveyed over 50 prominent boilers to arrive at this final top 5. They are all best suited to 3-bedroom homes and have outstanding specifications.

Best combi boilers for a 3-bed house
Model Output Efficiency Price (excl. installation) Warranty Fuel type
Worcester Bosch Greenstar 4000 25kW - 30kW 94% £1,100 - £1,400 10 years Gas or LPG
Ideal Logic2 Max 24kW - 35kW 94% £1,200 - £1,400 10 years Gas or LPG
Viessmann Vitodens 050-W 29kW - 35kW 92% - 97% £900 - £1,300 7 to 10 years Gas or LPG
EHC Mercury Electric Combi 12kW - 26kW 99% - 100% £1,300 - £1,700 5 years Electricity
Alpha E-Tec NX 28kW 28kW 93% £750 - £1,050 7 to 10 years Gas or LPG
  • Worcester Bosch Greenstar 4000: Best all-around boiler, matching a good price with a quality brand and high-performance stats.
  • Ideal Logic2 Max: Best output range for 3 bedroom homes with higher water consumption.
  • Viessmann Vitodens 050-W: The Vitodens have the best build quality, being quiet, compact, and still having a low weight. This can be a great boiler for those who are looking for a quiet 
  • EHC Mercury Electric Combi: The EHC Mercury is the best solution for homes with high gas prices or ones that are not on the gas grid.
  • Alpha E-Tec NX 28kW: Alpha’s NX is the best budget boiler for matching quality with value for money.

All of these entries have also popped up on numerous best combi boiler lists and have stellar reviews. We cover our selection criteria in depth below the list.

What size combi boiler do you need for a 3 bed house?

A 24kW to 35kW combi is best for three-bedroom households. The upper range is best for larger 3-bedroom houses with multiple bathrooms, while the lower end of the output spectrum covers smaller homes with lower water consumption. These rates can vary for electric combi boilers, which need between 12kW and 26kW.

Both conventional and system boilers can also be suitable for 3-bedroom houses, but they may have higher running costs. They also take up less space since they do not have any additional components, which can free up room in a storage, loft, or other area.

However, homes that need multiple simultaneous running taps or multiple bathrooms may do better with system and conventional boilers. The best combi boiler for a large house (5+ bedrooms) will have to be above 30kW at minimum.

Worcester Bosch Greenstar 4000

Worcester Bosch Greenstar 4000

Worcester Bosch usually tops the bill with their boilers, and this list is no different. The Greenstar 4000 has a lot of variants in terms of outputs and type of boiler, but the best one for a 3 bedroom house is in the 25kW - 30kW combi range.

Worcester Bosch Greenstar 4000
Output 25kW - 30kW
Efficiency 94%
Warranty 10 years
Dimensions 724mm x 400mm x 310mm
Price £1,100 - £1,400

There are many things that make this one the best mix of all the necessary qualities you would need. The Greenstar 4000 is one of the most efficient boilers on this list, has great heat output, and offers a 10-year warranty. On top of that, it is still reasonably priced, especially for a Worcester Bosch boiler considering the company tends to be on the pricier side.

Pros
  • Great value for money: At the £1,100 – £1,400 price level, there are very few premium companies making such a good offer.
  • Comprehensive boiler guarantee: The warranty can be extended to 10 years and covers all parts of the boiler, ensuring a good level of performance.
Cons
  • Occasional supply shortages: 2024 and 2025 both had their fair share of chip shortages, which affected the supply of the Greenstar 4000 boilers.

The Greenstar is the best boiler for a 3 bedroom house due to its mix of performance, efficiency, warranty measures, and value for money.

Ideal Logic Max

Ideal Logic2 Max

The Ideal Logic2 Max is a great addition to an already stellar series of boilers, providing improvements in many different areas, such as better troubleshooting and connectivity. Ideal’s boiler range is great for 3 bedroom homes of all sizes, from those with minimal water consumption to those with multiple bathrooms and simultaneous taps.

Ideal Logic2 Max
Output 24kW - 35kW
Efficiency 94%
Warranty 10 years
Dimensions 700mm x 395mm x 278mm
Price £1,200 - £1,400

The Logic Max is also fairly compact, having the lowest dimensions of any gas combi on this list. Despite this, it can be a powerhouse in terms of output, going up to 35kW (which could be good for heating even a 4-bedroom property with one bathroom). To complement its output, it also has great efficiency, matching the Worcester Bosch Greenstar, which ensures that your home will get the most of the fuel you burn.

Pros
  • Excellent output: The boiler is great for 3-bedroom homes of all sizes and water consumption levels.
  • Relatively compact: The boiler is a fair bit smaller than many other boilers on this list while still maintaining a great level of quality and output. This makes it easier to fit in tighter spaces.
Cons
  • Unsuitable for multi-bathroom homes: Ideal combi boilers tend to have lower water pressure and are thus unsuitable for homes with multiple bathrooms.

With the combination of output and efficiency, it can be a great option for homes with higher water consumption while also minimising fuel consumption. It could also potentially be a contender for the best boiler for a 4 bedroom house.

Viessmann Vitodens 050-W

Viessmann Vitodens 050-W

Viessmann’s Vitodens series has various outputs. The 050-W model best suits homes with 3 bedrooms, providing a great output at a very reasonable price. The boiler also has the highest potential efficiency with the right seasonal conditions and proper maintenance.

Viessmann Vitodens 050-W
Output 29kW - 35kW
Efficiency 92% - 97%
Warranty 7- 10 years
Dimensions 707mm x 400mm x 350mm
Price £900 - £1,300

With a stainless steel Inox heat exchanger that has its own individual warranty, Viessmann is offering a long-lasting heating system. Aside from the internal features, it also has a nifty interface with great ease of use features. All of this comes in a fairly compact build that can fit in some smaller spaces.

Pros
  • Great features: The ease of use and connectivity features of the Vitodens are a great addition.
  • Longlasting parts: The materials are well-built, and the company offers an extendable warranty contingent on installation from an approved installer.
Cons
  • Low standard warranty: While the extended warranty is great, it could be an issue if you can’t find a company-approved installer in your area. It’s advisable to find one before opting for a purchase.

Viessmann runs a tight ship, and the Vitodens line is one of their finest. That’s why this boiler is best for homes looking for a reliably built boiler with some great features.

EHC Mercury Electric Combi

EHC Mercury

The Electric Heating Company has been making some reliable electric boilers for quite a while, garnering quite a lot of positive customer reviews on platforms like Trustpilot (where it has a 4.8 out of 5). The Mercury is one of their most popular models due to its high efficiency and wide heat output range.

EHC Mercury
Output 12kW - 26kW
Efficiency 99% to 100%
Warranty 5 years
Dimensions 690mm x 451mm x 258mm
Price £1,300 - £1,700

Mercury also offers “Weather Compensation & Advanced Service Diagnostics,” which is a fancy way of saying it can adapt the temperature to external conditions. While the low-output versions, like the 12kW edition, can be suitable for homes with a shower, the 26kW version can manage bathrooms with higher water consumption (like those with a large tub).

Pros
  • Great external compatibility: The heater can be plugged into underfloor heating and can adjust temperatures for winter and summer times automatically.
  • High energy efficiency: Electric boiler efficiency works differently than gas boiler efficiency.
Cons
  • Low warranty: Electric boilers often have short warranties, so 5 years is quite common. However, compared to the rest of the list, it can pale in comparison.

As the lone electric heating appliance on this list, it can be a great addition to homes off the gas grid or ones with solar panels. The 12kW to 26kW range is ideal for electric boilers that need to provide hot water for 3-bedroom homes.

Alpha E-Tec NX 28kW

Alpha E-Tec NX

Alpha’s E-Tec line has a number of great entries, and the NX is no different. With a 28kW output, it can comfortably supply water to the average UK home. It has a decent flow rate while having fairly compact dimensions and some novel design choices in the heat exchanger. The efficiency is also on the higher side (93%), especially considering the price.

Alpha E-Tec NX
Output 28kW
Efficiency 93%
Warranty 7 - 10 years
Dimensions 712mm x 440mm x 269mm
Price £750 - £1,050

The boiler maintains a high efficiency by adjusting heat flows in real time and is compatible with external sensors that can improve weather detection. Open Therm and Alpha BUS controls allow for better connectivity as well. While the boiler comes in a variety of sizes, the 28kW system is the best bang for your buck.

Pros
  • Affordability: The most affordable quality boiler on this list. With a decent warranty (if installed by an approved installer), it also shows the company’s faith in their product.
  • Easy part access: It’s also made for easier installation and replacement of parts, which can cut the installation time down.
Cons
  • Limited availability in some regions: Judging by online stores in our research, some regions of the UK might have a limited supply.

Alpha is a great company with a solid reputation which is why this boiler is best for homeowners looking for a reliable boiler at a generous price.

How did we compare the best boilers for 3 bedroom houses?

Boiler comparison factors
  • Output: The output is the main factor that determines what size home a boiler can handle. The higher the output, the more heating it can provide and is thus more suitable for larger homes. The best boiler for a 3-bed house will have between 24kW to 35kW output for combis, while system and conventional boilers will require 12kW to 26kW. This can also depend on the number of radiators in your home.
  • Efficiency: Efficiency denotes the amount of fuel that is turned into energy versus the amount that is lost. Most condensing gas boilers have over 90% efficiency, which is considered an A-rated heating appliance. Electric boilers can have over 98% efficiency, however, this may not translate into lower heating bills if the price per kWh of electricity is higher than that of the price per kWh of gas.
  • Price: Balancing affordability and quality is very important when choosing a boiler, as there are many heating appliances available at a reasonable price. Most good combi boilers are priced between £1,200 and £1,500, but some can be as low as £750.
  • Warranty: A good warranty shows that the manufacturer has faith in their products. Longer warranties and guarantees can ensure proper functionality. A good combi boiler warranty is generally 7 to 10 years.
  • Manufacturer: The reputation of the manufacturer and how prominent they are is a great sign of quality. A well-established manufacturer also provides wider accessibility for its boilers and the parts that come with it.
  • Reviews: Word of mouth, professional reviews, and Trustpilot scores were crucial to getting a read on which boilers to pick. We ensure that every boiler company we review has at least a 4 out of 5 on Trustpilot.

Find the best combi boiler for your 3 bedroom house

If you’re still asking yourself, “What size boiler do I need for a 3-bed house?” or “Which of these will suit my home?”, then it might be best to call an installer. A reliable one can be a great resource for in-person knowledge as they assess your property and give you the best advice.

Finding a reliable installer on your own can take hours of research, and you may still not find the best offers. That’s why our service is a far better alternative. All you need to do is fill out a 30-second form, and we’ll handle the rest as you get the best prices in your area from installers we’ve personally vetted.

Click the button below to receive up to 4 free, non-binding quotes from reliable installers.

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