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The Best 30kw Combi Boiler [And What It Costs To Install]

Are you looking for a new 30kW combi boiler? Then you’re in the right place! In this guide, we’ll discuss brands that produce 30kW boiler models, warranties, and prices you should expect to pay.

Do You Need a 30kW Boiler?

First up, you need to determine if you actually need a 30kW combi boiler. Typically, this much heating output will suffice for anything up to a 3 bedroom house. That said, there are plenty of variables involved in sizing boilers, so you might need something bigger; or, be able to get away with something smaller.

To ensure you get the exact boiler you need, jump over to this boiler size calculator. It will account for details about your property, central heating system and hot water demand, and list the most suitable boiler models at the top of the screen.

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Brands Producing 30kW Combi Boilers

Given a 30kW boiler has enough heat output to provide central heat and hot water for anything up to a 3-bedroom property (and sometimes larger), the size is exceptionally popular. Consequently, most boiler brands will produce them.

And honestly, any leading brand will work. We’ve detailed some of the best boiler makes here, which include the likes of Worcester Bosch, Ideal, Vaillant, Baxi and Potterton.

Now, there are a few factors that will help you narrow down to a specific 30kW combi, and we’ve mentioned these below.


You should budget somewhere in the region of £2,000-£2,300 for a 30kW combination boiler installation. Naturally, you want the longest warranty possible.

Typically, we’d suggest a minimum warranty of 5-years; ideally higher. There are combi boilers that might be £100 or so cheaper, but these are typically backed by a pitiful warranty of 2 years or less, and we’ll urge you to avoid them. The last thing you want is a big boiler breakdown that leads to a costly replacement just 2 years down the line.

Looking for a 5-year warranty as a minimum still gives you plenty of choice from the likes of Vaillant, Ideal, and Worcester Bosch. For example, Worcester 30kW boilers that are installed by Heatable come with a juicy, 10-year warranty.

30kW Combi Boiler Prices

So, you’ve got plenty of natural gas boilers from a range of brands in the 5-10 year warranty range. Now, it’s just a matter of price. And as we suggested above, the average boiler cost tends to hover around the £2,000-£2,300 mark.

As a starting point to compare boiler prices, we’d suggest looking at Heatable. It might not be obvious by looking at their website, but Heatable put technology above salespeople to bring you the best value for boiler installs, which means they get some of the most premium brands, such as Worcester, at ridiculously low rates. And, as you’ll see by using this boiler cost calculator, these savings are passed onto the end consumer: you!

The Best 30kw Combi Boiler

Now, we did say that just about any 30kW boiler from a leading brand will do. But in our opinion, the pick below is still your best bet — especially if you want a known boiler brand with plenty of features, stellar energy efficiency, a solid warranty, and a reasonable price.

Our Pick: Worcester Greenstar 4000 30kW

When we first wrote this article, the best 30kW combi on the market was the Worcester 30i. However, at the time of writing (January 2022) it’s since given up the top spot to the new and improved Worcester Bosch Greenstar 4000 30kW.

The Greenstar 4000 30kW is powerful, with up to 12.3L flow rate, and incredibly reliable — Worcester uses the best internal parts in their boilers, which is how it fully guarantees their heat exchanger for a period of 10 years. It’s also efficient, Quiet Mark certified, and relatively small with a lift weight of 34.9kg.

That said, it’s not compact — this means you won’t be able to fit it into a kitchen cupboard. If you’re looking to tuck your boiler away, you’re going to need something like the 32CDi Compact, which provides ample central heat and hot water in a much smaller package.

Worcester Greenstar 4000 Warranty

As we’ve mentioned above, you want to make parts & labour warranty the focus of your search. With the Worcester 4000 30 kW boiler, it’s about as good as it gets, with a solid 10-years warranty on offer.

It’s worth noting with Worcester Bosch, the warranty is only given when using an accredited installer and certain branded products. And that’s why we suggest heading straight for Heatable, as they offer the 10-year coverage as standard due to their relationship with Bosch.

Worcester 4000 30kW Price

Around £2,200 is what you should be budgeting for a standard 30 kw boiler installation, from a local Gas Safe engineer, and for a reasonable brand. You’ll be able to fit almost any boiler you want from Baxi, Vaillant, Ideal or Worcester Bosch at around the £2.2-2.5k mark.

And, this is probably why Heatable are currently so popular. Not only are they able to install a combination boiler (like the Worcester Bosch Greenstar 4000)  for less than this estimate, they also come with a system cleanse, magnetic filter to protect your boiler, and even a smart thermostat!

It’s a deal that’s hard to beat, especially when you consider national household names will charge you closer to £3,000 rather than £2,000.

Worcester Bosch Greenstar 4000

Winter Protection

One of the best features of Worcester boilers is the CondenseSure Siphon.

During the winter months, boilers are prone to locking out thanks to the condensate pipe freezing over.

The ConsenseSure Siphon eliminates this problem by releasing the condensate in short bursts, which reduces the risk of them freezing. It’s able to keep your boiler up and running for 48 hours at -15°C. Not only does this frost protection mean zero downtime for your boiler, it also means no expensive emergency call out charges, too.

Suitable Controls

You’ll have a lot of flexibility when it comes to the type of controls you can use with the Worcester 4000 30kW combi boiler. Obviously, you can go with a basic (and cheap) thermostat, or the Worcester Wave smart thermostat with LCD display.

However, the Heatable promise is you’ll be getting upgraded controls installed as standard, without additional charges.

Our Verdict

When considering the essentials, such as the price, warranty, and winter protection, the Worcester 4000 30kW is one of the best 30kW combi boilers on the market. And you can get your on-screen fixed price quotes for one here. You don’t need to supply any personal information, such as a phone number or email address, nor do you need to join a mailing list, to get a fixed price quote.

Top 30kW Combi Boiler Alternatives

Not sure about the Worcester Greenstar 4000 30kW? No problem — here’s a quick summary of other 30kW combi boiler models we’ve reviewed (all have similar flow rates and outputs for central heating and water):

  • Viessmann Vitodens 100-W — premium, German brand and model with premium pricing that’s similar to Worcester’s, and a 10-year warranty. The boiler comes in a variety of outputs, including 30kW, which should set you back around £2,200.
  • Ideal Logic Combi 30 — another premium model with all the bells and whistles you’d expect from Worcester. You’ll save around £300 by opting for the Ideal Logic Combi 30 over a Worcester or a Viessmann equivalent, but you’ll only get a 7-year warranty.
  • Baxi 630 — excellent budget option for a 30kW boiler, and the cheapest on this list. Baxi is still very much a premium UK brand, so you can rest assured that it’s reliable. But, there’s also a 7-year warranty to put your mind at ease. Best of all, this boiler is compact — you can easily sneak it into your kitchen cupboard.

There are other 30kW options available, such as those from Glow Worm, but the ones above offer a better balance between cost and quality.

Whilst Heatable don’t install Baxi (you can find them here), you can use their online calculator to get a range of fixed price quotes on Viessmann and Ideal 30kW models.

System 30kW Boiler Options

Are you looking for a system 30kW boiler instead of a combi? If you already have a hot water cylinder and a system boiler, it might make sense to keep your central heating system setup just as it is. Here are our top picks for system boilers with a 30kW output:

  • Alpha E-TEC 30s — this is definitely one of the cheapest boiler options you’ll find on the market. In fact, you could get most Alpha models installed for as little as £1,675 at the time of writing. And despite the incredibly appealing price, you’ll still be getting a quality boiler.  Note — of course, your prices may differ from the estimates we got — so go ahead and use Heatable’s calculator to see what they’ll quote you on an Alpha system boiler.
  • Worcester 30CDi Classic System — this is a compact system boiler, so you’ll be able to fit it into a kitchen cupboard. Seeing how it’s made by Worcester, however, there’s no surprice that the price tag weighs in at around £2,600, including installation.

You can explore your system boiler options further in our detailed guide here.

Need a 30kW Regular Boiler? Consider the Worcester Greenstar Ri 30kW

If you already have a regular boiler (aka conventional, or heat-only boiler) at home, you may be reluctant to convert it to a combi. This is especially true if you’ve got a larger household, or one with plenty of demand for heat and hot water. Unlike a combi, a regular boiler allows you to store hot water in a hot water storage cylinder — this way, you’ve always got plenty at your disposal.

So, if you’ve got a regular boiler and want to replace it with a 30kW boiler that’s also regular, Worcester’s Greenstar Ri 30kW is an excellent option. Like the 30CDi Classic System, the Greenstar Ri is compact, meaning you can tuck it away into a kitchen cupboard. The price point reasonable — you should be able to get one installed by a Gas Safe engineer for around £2,300 (prices change often, so don’t take our word for it — check out Heatable’s online calculator to get a quote).

Best 30kW Combination Boilers: Wrapping Up

Thanks for reading our guide to the best 30kW combi boilers. Still confused about which boiler is right for your property’s specific hot water and central heating needs? Drop us a line below, and we’ll do our best to help you out.




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