Best 30kW Combi Boiler in 2026: Find the Best 30kW Combi Boiler For Your Home

A 30kW combi boiler is the workhorse boiler for average UK family homes, and every manufacturer has this boiler in their lineup. 30kW combi boiler options are endless in the UK, so it may be difficult to zero in on the right model for your home. Our team has assessed 15 30kW combis using a set of reliable boiler-selection criteria, and found four models that qualify as the best combis with a 30kW output.

The criteria our team has used to find the best 30kW combi boilers are as follows.

• Efficiency: The best 30kW combination boiler models should have energy-efficiency ratings that meet or exceed modern ERP and seasonal efficiency standards. The best 30kW combis we’ve picked have a seasonal heating efficiency of at least 93%.
• Durability: The top 30kW combi models must be durable enough to withstand over a decade of service-related wear-and-tear. All of the models we’ve picked in our guide have specific features that ensure their components’ reliability and longevity.
• Advanced features: The best 30kW-capacity combis stand out with their advanced features, which can range from functions that improve user-friendliness to those that prevent breakdowns and service disruptions. Each of the four 30kW combi picks below has advanced features that afford homeowners convenience and value.
  Controls: The best 30kW combi boilers have user-friendly controls and are compatible with the most popular thermostats. All four of our 30kW combis have straightforward control consoles and work with the best third-party thermostats on the market.
• Warranty: A 5-year warranty is the minimum you should consider when buying a replacement boiler. All of the 30kW combination boiler models we have found come with warranties that are 5 years or longer.
• Price: The 30kW combi is a common boiler for common people, and its price should not be exorbitant. All of the 30kW models we’ve listed are priced within the average, £2,000-3,000 range (including installation).

The five criteria above helped us narrow down the 30kW combination boiler choices to four models, of which Worcester Greenstar 4000 is the best. The Greenstar 4000 is our top pick for a 30kW combi for five reasons. First, the Greenstar 4000 offers the best value, as its price point matches its high performance, durability, and advanced features. Second, the Worcester 4000 has durable components, which are designed to last many years before developing faults. Third, the Greenstar 4000 is equipped with features that allow it to operate without disruptions in extreme weather conditions (which cannot be said for all 30kW combis). Fourth, the Worcester Bosch 4000 has a high energy-efficiency that translates directly into savings on gas bills. Finally the 4000 model from the Greenstar range comes with a long standard warranty of 10 years.

What is the best 30kW combi boiler in 2026?

The following are the four best 30kW combi boilers in 2026.

1. Worcester Bosch Greenstar 4000 30kW: Worcester Greenstar 4000 is the best overall 30kW combi because it offers top efficiency, durable components, quiet operation, and wide control compatibility all for a reasonable price.
2. Viessmann Vitodens 100-W 30kW: Viessmann Vitodens 100-W made our list because it’s the most efficient 30kW boiler available on the market, with a standard efficiency of 98%.
3. Ideal Logic Plus Combi 30: The Ideal Logic + 30 is one of the most budget-friendly 30kW combination boilers that still have a good track record for durability and A efficiency rating.
4. Baxi 630: The Baxi 630 is the best compact 30kW combination boiler. Its compact design means you’re able to fit it into a standard kitchen cupboard and save space at home.

Below is a more thorough description of the features and benefits of each of the aforementioned top 30kW combi picks.

1. Worcester Bosch Greenstar 4000 30kW – best overall value

Key benefits summary
Efficiency:	94% heating efficiency and 85% water heating efficiency.
Durability:	Durable heat exchanger protected by standard 10-year warranty.
Advanced features:	CondensureSiphon allows operation in temperatures as low as -15°C.
Controls:	Compatible with Worcester Bosch mechanical timer, Comfort + and Easy Control thermostats, as well as most smart third-party thermostats.
Warranty:	10 year guarantee when installed by a Worcester Bosch-accredited installer.
Price:	£2,500-£2,800, including installation.

Worcester Bosch Greenstar 4000 is the best overall 30kW combination boiler because it offers homeowners the following five benefits.

• Best overall value: The Greenstar 4000 offers top-grade energy efficiency, highly advanced features, durable components, and a long standard warranty for a very reasonable price. You get a feature-loaded boiler that exceeds in all aspects of performance for a mid-range price point of £2,500-£2,800 with installation.

• Durable components: Worcester Bosch use tough, reliable components in their boilers. Reliable internal parts mean that the boiler is able to withstand many years of heat and pressure-induced stress without starting to break down. Worcester’s 10-year standard warranty on their heat exchangers is a testament to the company’s faith in their boilers’ most burdened parts.
• Works in subzero temperatures: The Greenstar 4000 is equipped with Worcester’s CondensureSiphon feature, which keeps the condensate pipe from freezing over in cold weather. Frozen condensate pipes are the primary cause of boiler lockouts during periods of frigid weather, and CondensureSiphon ensures that the Greenstar 4000 is safe from such lockouts. The system makes the boiler drain condensate in short bursts, which stops the pipe from freezing over in temperatures as low as -15°C.
• High energy efficiency: The Greenstar 4000 has an efficiency of 94% for central heating and 85% for domestic hot water. Such a high efficiency translates into notable savings on energy bills when the boiler is operating in condensing mode. For example, at peak efficiency your Greenstar will convert 94p and 85p into heat and hot water, respectively, for every pound you spend on gas.
• Long warranty: Worcester Bosch Greenstar 4000 comes with a standard 10-year guarantee if you get the boiler installed by a Worcester-accredited installer. Unlike a traditional warranty, Worcester’s guarantee comes free of charge and protects all of the boiler’s components without expecting you to pay callout fees.

The installation cost of a Greenstar 4000 depends on where you live, whom you use to install the boiler, and a host of other site-specific factors. However, you can get an instant online quote for a new Greenstar 4000 by filling in Heatable’s anonymous form here.

2. Viessmann Vitodens 100-W – most efficient 30kW combi boiler

Key benefits summary
Efficiency:	94% ERP efficiency and up to 98% seasonal heating efficiency.
Durability:	Corrosion-resistant stainless steel heat exchanger and proprietary internal parts.
Advanced features:	Weather compensation feature keeps a steady interior temperature and reduces boiler fuel use by proactively adjusting the heating output.
Controls:	Compatible with Viessmann’s ViCare thermostat and most well-known third-party thermostats.
Warranty:	5 year warranty with an additional 7 years available for a fee.
Price:	£3,000-£3,300, including installation.

Below are the four reasons Viessmann Vitodens 100-W has made our list of the best 30kW combination boilers.

• Industry-leading energy efficiency: Viessmann Vitodens 100-W has one of the highest energy efficiency ratings on the market. The model’s seasonal heating efficiency (the ratio of heat produced to the total fuel consumption over the heating season) is a staggering 98%. This ultra-high efficiency means you only waste 2p for every pound you spend on gas during the heating season.
• Proactive heating output: The Vitodens 100-W has a weather compensation feature that regulates the boiler’s heating output based on the weather conditions. The compensation function proactively adjusts the boiler’s heating output as the weather outside changes, so that the boiler doesn’t have to wait for the indoor temperatures to change before adjusting its output. This proactive heating process allows the boiler to operate at peak efficiency and ensures a consistently comfortable indoor climate.
• Quality parts: Viessmann ensure the quality and longevity of their Vitodens 100-W by outfitting it with tough components that withstand the constant burdens brought on by intense heat, pressure, and corrosion. The heat exchanger on this 30kW combi boiler is made from stainless steel instead of the customary aluminium. This choice of material increases the longevity of a part that’s integral to the boiler’s operation and costs at least £450 to replace when damaged.
• User-friendly controls: The Viessmann Vitodens 100-W 30kW combi boiler has a user-friendly LCD touchscreen display that allows straightforward navigation through the boiler’s functions. However, the Viodens 100-W 30kW combi is smart thermostat-compatible, so you don’t need to operate it from the boiler display under most circumstances.

On the downside, Viessmann Vitodens 100-W is significantly more expensive than our #1 pick – it costs roughly £3,000 to get this boiler installed. You’re able to get your own fixed-price quote for the Vitodens 100-W by filling in a quick online form at Heatable.

3. Ideal Logic Plus Combi 30 – best budget 30kW boiler

Key benefits summary
Efficiency:	Seasonal space heating efficiency 94%, water heating efficiency class A.
Durability:	Heat exchanger protected by a 10-year warranty.
Advanced features:	Frost protection prevents condensate from freezing.
Controls:	Compatible with Logic’s RF programmable thermostat and weather compensation kit (sold separately) and third-party thermostats.
Warranty:	7 year standard warranty on parts and labour.
Price:	£2,100-£2,300, including installation.

Below are the four reasons we’ve chosen the Ideal Logic Plus for our list of the best 30kW boiler models.

• Low cost: Ideal Logic Plus Combi 30 is the best budget boiler you can get, with installation costing as little as £2,100. However, the low cost is not an indicator of poor quality – the Logic Plus is efficient, reliable, and offers most features its higher-priced counterparts do.
• Durable boiler: An Ideal 30kW combi boiler is a durable boiler that stands the test of time despite its low cost. Ideal use fewer mechanical parts in their boilers, including the Ideal Logic Plus, to minimise the risk of components failing. Logic’s philosophy is that fewer internal components means fewer parts that may break due to wear and tear.
• Quiet operation: The Ideal Logic Combi 30kW boiler is quiet mark accredited and, as such, is guaranteed to keep noise pollution low.
• Warranty: An Ideal Logic Plus 30 has a 7-year warranty, which is a very generous term considering the boiler’s purchase price.

Note that the fitting costs of a Logic Plus combi range depending on the geographic location and the installer you employ. Use Heatable’s online calculator to get a near-instant, fixed-price quote for an Ideal Logic Plus 30kW combi on your screen.

4. Baxi 630 – best compact 30kW combination boiler

Key benefits summary
Efficiency:	Seasonal space heating efficiency 93%, water heating efficiency class A.
Durability:	Compact dimensions allow this boiler to fit into a kitchen cupboard.
Advanced features:	Easy-Fill filling link simplifies the topping up process for homeowners.
Controls:	Compatible with uSense smart control (sold separately) and third-party thermostats that operate on the OpenTherm protocol.
Warranty:	7 year standard warranty on parts and labour.
Price:	£2,100-£2,400, including installation.

Baxi 630 has made our list of the best 30kW combination boilers for the three reasons below.

• Compact size: Baxi 630 measures just 390mm (W) x 700mm (H) x 285mm (D). Its tiny size allows the 630 to handily fit into a standard cupboard in the kitchen. Hanging a boiler in a kitchen cupboard saves homeowners valuable space and helps keep the boiler noise down in the living quarters.
• Easy-Fill feature: Baxi 630 comes with the Easy-Fill function, which gives homeowners a simple way to top up their boiler if it’s lost water pressure.
• Low cost: Baxi 360 is reasonably priced, especially for a compact boiler. Compact dimensions usually command a premium, yet the Baxi 360 is priced on the lower end of the range. Typical installation costs for a Baxi 360 are in the £2,100-£2,400 range.

How do I choose the best 30kW combi boiler?

Follow the four steps below to choose the best 30kW combi boiler.

1. Determine whether a 30kW combi boiler is the right size and type for your property. A 30kW combi boiler is likely not the right choice for larger homes or those with pre-existing system boilers.
2. Choose the correct brand of 30kW combi boiler for your needs. 30kW boilers are popular, and all leading brands have their own offerings.
3. Consider the warranty applicable for each boiler. A lower upfront might be tempting. However, if the warranty is less than five years, there are more sensible options for the long term.
4. Factor in the prices. Not every 30kW combi boiler costs the same amount, and finding one that fits your budget is crucial.

Below we take a closer look at the four aforementioned steps for choosing the best 30kW combination boiler.

1. Do you need a 30kW combi boiler?

First, determine whether you need a 30kW combi boiler by answering the two following questions.

• Is a 30kW output suitable for the size of the home? A 3-bedroom home with one or two bathrooms produces the average demand for a 30kW boiler.
• Is a combi boiler the correct type of boiler for the home? A combi is a suitable replacement boiler if you’ve already got a combi boiler installed or if you have low-to-moderate demand for hot water.

We take an in-depth look at the questions (and how they influence your boiler selection) below.

Is 30kW the right size boiler for you?

A 30kW combi boiler is the right size for you if you live in a traditional 3 or 4-bedroom family home. A 30kW combi boiler is perfectly adept at heating a 4-bedroom house with up to fifteen radiators and two bathrooms. However, a large home with up to 20 radiators and two or more bathrooms needs a 35-42kW boiler. Similarly, a smaller property needs a smaller boiler – 30kW costs too much to buy and operate if you’ve got a single bedroom and bathroom in your home.

Is a combination boiler the most suitable boiler type?

A combination boiler is suitable in two situations. First, a replacement combination boiler is an appropriate choice if you already have a combi, since changing boiler types always costs more but isn’t always worth it. Second, a combi boiler is an efficient boiler choice if your family has modest water demand and seldom runs multiple taps concurrently. Combis do not generate a powerful supply of domestic hot water, so they’re less suitable if your family has a high water demand.

What boiler types are alternatives to combination boilers?

Below are the two boiler types that are alternatives to combination boilers, and both types generally come in a 30kW size.

• System boilers: System boilers are ideal for larger homes with multiple bathrooms, but require a hot water cylinder to operate. A system 30kW boiler is a fitting choice for 3-bedroom homes with high hot water demand.
• Regular boilers: Regular boilers (also known as “heat-only” boilers) are tank-fed boilers that are great for large properties with low water pressure. Replacement regular boilers are the most cost-efficient choice for homes that already have a regular boiler because the cost of removing the pipework and water tanks is often high.

Below are the best 30kW system and regular boiler options if you deem that a combi is not ideal for your home.

System 30kW boiler options

The following are the two best system 30kW boiler models.

• Alpha E-TEC 30s: The Alpha E-TEC 30s is a quality 30kW system boiler at an affordable price. An Alpha E-TEC 30s can be purchased and installed for as little as £1,900 and often includes a standard ten-year warranty.
• Worcester 30CDi Classic System: A premier 30kW system boiler, the Worcester 30CDi Classic System is a compact boiler that delivers plenty of heat and hot water. Worcester is one of the most reputable boiler brands, and as such, a Worcester 30CDi Classic System costs approximately £2,600 to buy and install. Read more about the best Worcester system boilers to see if the investment is worth it for you.

Regular 30kW boiler options

Below are two of the best regular 30kW boiler options.

• Worcester Bosch Greenstar Ri 30kW Boiler: Much like the 30CDi, the Worcester Greenstar Ri 30kW boiler is a compact system that can be placed inside a cupboard and kept out of sight. Worcester Greenstar Ri 30kW boiler costs approximately £2,300, including installation costs.
• Vaillant ecoFIT Pure 430 30kW Boiler: Another dependable brand name, the Vaillant ecoFIT pure 430 30kW boiler, is a great option for any home looking to replace an existing regular boiler. Vaillant ecoFIT Pure 430 30kW boiler costs approximately £2,300, including installation and a 10-year warranty.

The cost of boilers is constantly changing, and one of the simplest ways to get an accurate quote for a 30kW combi, regular, or system boiler is to use Heatable’s online calculator.

2. Find the best 30kW combi boiler brand and model

The four best brands producing 30kW combi boilers are Worcester, Ideal, Viessmann, and Baxi. The four best 30kW combis we’ve recommended above are manufactured by these four brands. Each of the four brands builds durable, efficient boilers, offers long warranties, and has a bulletproof reputation on the UK market. Going with a 30kW combination boiler from any of these four brands is a wise choice, as you can expect the boilers to perform well and last long.

3. Consider the warranty term that comes with the 30kW combi boiler

A 30kW combi boiler should have at least a five-year warranty, although a seven or 10-year warranty is preferable.

The warranty length is an essential factor to consider when you’re shopping for a 30kW combi boiler for two reasons. Firstly, the warranty length is an indicator of the boiler model’s reliability. Manufacturers provide short warranties (often as short as two years) on cheaper models, because they know these boilers are vulnerable to wear-and-tear after a short time in service. Conversely, boiler makers offer long warranties of up to 10 years or more on boiler models they know will last a while without defects. Secondly, a longer warranty protects your boiler investment for a longer time. A 30kW combi is not a cheap investment, costing in the region of £2,200-£3,000. The last thing you want is for your boiler to start requiring costly out-of-pocket repairs after only two years of service.

Three of the four best 30kW combis we’ve listed above come with 5-7-year warranty terms as standard. Worcester Greenstar is an exception, with the longer, 10-year standard warranty. However, there are two ways in which you’re able to extend the length of a boiler warranty. First, you’re able to get a longer warranty by paying more for a manufacturer-accredited installer to fit the boiler. Second, you always get at least a 10-year warranty when you install your new boiler using Heatable.

4. Factor in the prices of the available 30kW combi boilers

The 30kW combi boiler prices change depending on the brand and the model. Budget ranges such as a Baxi 630 or the Ideal Logic Plus Combi 30 boilers cost approximately £900 to buy. Meanwhile, the Worcester Bosch 8000 30kW combi boiler is priced at around £1,500. These prices exclude fitting costs and any extras, such as extended warranties, additional filters, or service plans.

What are the 30kW combi boiler installation costs?

The 30kW combi boiler installation costs vary in the same way as the individual boiler prices do. For example, the total cost of buying and installing a new Worcester Bosch 4000 30kW combi boiler is approximately £2,700, while the Viessmann Vitodens 100-W costs approximately £3,500. Budget-friendly 30kW combi boilers like the Ideal Logic Combi C30 come in at £1,600. However, this boiler often comes with a shorter warranty, typically just two years.

These prices are based on a like-for-like boiler replacement, with the assumptions that the new 30kW boiler goes in the same location as the previous unit. Use the Heatable’s online boiler cost calculator to get an accurate estimate of what a 30kW combi will cost to get installed at your home.