The Best Combi Boilers For Small Properties [Flats, Apartments & Houses]

If you’ve already been looking for boilers, you’ll know it’s not exactly a clear cut process. Two different properties with the same number of bedrooms, might not require the same type or size of boiler as the other. And, that’s because heating and hot water demand is going to differ.

This guide focuses on small combi boilers; suitable for properties with one bathroom and shower, and up to two bedrooms.

If you’re looking for anything larger than this, we’d suggest jumping over to our generic guide covering the best combi boilers on the market.

How Much Does Installation Cost For Small Boilers?

If you want to jump straight to it and check out on-screen prices for recommended boilers, you can use this clickable form (takes around 90 seconds, no need for any contact details) from HEATABLE, one of the most trustworthy companies in the market.

Depending on size, brand and the complexity of the install, we’d expect the average small boiler installation cost to be in the £1,800-2,000 range.

Compact & Small Combi Boilers

They might sound like the same thing, but in the case of boilers, small and compact mean two different things.

You’ll need to determine whether you need a compact boiler before reading the rest of the guide.

Small Combi Boilers

When we refer to “small” gas boilers, in general, we’re talking about output. Essentially, they’re designed to power small properties, such as a 1 bedroom flat, through to a small 2 bedroomed terrace house.

Compact Boilers

But you can have a small boiler that is also compact.

A compact boiler refers to dimensions, and usually, a unit that’s going to fit in a small space such as a kitchen cupboard. So, if you want to move your boiler from being wall hung in your kitchen, out of the way into a cupboard, a compact boiler is for you.

It’s worth noting that buying a compact appliance can add anything from 5-20% onto the purchase price. In the case of boilers suitable for smaller properties, you could be talking around £50-200 on top of the total installation cost, in comparison to a standard unit.

What Size Boiler is “Small”?

Typically, you’ll be looking at gas boilers labelled under 25kw in output for flats, apartments and small houses.

In some scenarios, a 25kw boiler can easily power a 3 bedroomed property, so you may be able to go with something smaller depending on your hot water demand, and the number of radiators you have in your property.

Remember, each boiler is spec’d based on flow rate and CHW (central heating output) in KW. If you have more than the average number of radiators for your property size, or regularly run taps/showers at the same time, you’ll want DHW (domestic hot water) and CHW at the high end.

We could go through BTU calculations and so on, but it’s much easier to use this multiple choice form to work out which boiler you need.

Click the options relevant to your property, and you’ll get suggested boilers on screen, and a total price including installation.

The Best Small Boiler Manufacturers

There are literally dozens of boilers brands being supplied in the UK. That just adds to the confusion, as a suitable small boiler could be £400 from one manufacturer (price for the boiler only), and £800 or more from another.

Typically, the difference in price is going to be down to a few things, including:

  • Brand reputation
  • Customer service
  • Online reviews
  • Supply & demand
  • Warranty

Brand and warranty are the two most important things to consider.


We always say if a small boiler manufacturer offers a short/long warranty, there’s most likely a reason. If you invest in a boiler with a short warranty just to save £100 or so on a potential installation cost of £1,800+, it could come back to bite you.

We’d always aim for the longest warranty possible, and 5 years as minimum. You’ll get that as standard from the likes of the Ideal Logic Plus (7 years) and the Worcester Bosch range (up to 10 years) here.

Choosing A Brand

In terms of brands, one local installer might prefer a certain brand, with another installer leaning elsewhere. However, it’s likely the majority will agree the top brands include the likes of:

  • Worcester Bosch
  • Ideal Boilers
  • Baxi
  • Potterton

We’ve written a full guide covering the best boiler makes being supplied in the UK, and that’s worth a quick read.

The Best Small Combi Boilers

As we’ve already mentioned, some installers will prefer one brand over another. Typically, that’s because in their experience, they are the most reliable, and offer excellent value for money.

If that’s the case, it’s likely they install them in volume, and get a volume based discount from their supplier (which they can then pass onto you, getting you a better deal).

Here are two boilers worth mentioning…

Worcester Bosch Greenstar 25i

At my time working in a plumbing merchant, this was one of the most popular boilers we sold. And, it’s MORE than adequate for smaller properties. In fact, you’d be able to power an average 3 bedroomed house with a boiler like this.

You can get on screen prices, up to 10 years warranty and other juicy extras by clicking here — that’s HEATABLE, and prices for installation from these guys, are extremely competitive.

You can also read our full review of the Worcester 25i here.

Ideal Logic Plus 24kw

The Ideal Logic Plus 24kw is comparable to the Worcester Bosch 25i. When using a local installer, it’s likely the Worcester is likely to be £100-200 more expensive. However, as we mentioned above, HEATABLE provide small Worcester boilers at extremely competitive prices.

Typically, the cost from HEATABLE for the Ideal and Worcester are the same, as you can see here.

If you’re using a local installer and looking to save a little, it’s worth a look. The warranty is strong at 7 years (so already above what we recommend), and Ideal Boilers are fast becoming one of the most popular boiler manufacturers in the UK.

One thing worth noting too; the Logic Plus is compact. So, that means it’s going to fit into a kitchen cupboard. The 25i won’t. If you want a Worcester boiler that’s compact, you’ll need to go for the CDi Compact.

Want to read more about Ideal Boilers? We’ve reviewed the Ideal Logic Plus 24kw here.

What’s Next?

Thanks for reading our guide to the best small combi boilers.

Got questions or need some advice relating to an upcoming boiler purchase? Drop us a line via our contact page, and we’ll get back to you as soon as possible.



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