Boiler Types Explained

Boiler Types Explained

Whether you’re moving house or just looking to make your existing home more efficient, you might be thinking about repairing or replacing your boiler.

That said, with three different types of boilers to choose from, it can be confusing to know where to start.

So to help you identify the different types of boilers out there and to get a better understanding of how each one works, we’ve put together this guide.

This can also be useful for choosing which boiler would be best for your property, should you wish to replace your existing one.

Read on as we explain the three different types of boiler you’re likely to come across.

1. Combination boiler

A combination boiler (also called a combi boiler) does what it says on the tin. It is a single unit that generates both your heating and your hot water, so it does a combination of the two. This means no hot water tank is needed.

This is because, unlike a traditional system, it does not need to heat and then store water in a tank. Instead, water is heated through a heat exchanger and then sent straight to the mains. This means you get hot water instantly without having to wait for it to warm up first.

With a combi boiler, everything is done through one unit, which is typically hung on the wall somewhere in your home.

So now we know how it works, let’s take a look at some of the advantages and disadvantages of this type of boiler system.


  • There is no need for a water tank and the smaller units mean these are a great way to save space
  • Combi boilers tend to have lower maintenance costs
  • You get hot water instantly




  • These boilers don’t work well in homes with poor water pressure
  • Water flow rates are reduced if two or more hot water outlets are being used at the same time

2. Regular (heat only) boiler

A regular boiler also referred to as a heat-only boiler, is one that only provides heating for your home. For these boilers, there is usually a feed and expansion tank in the loft and the boiler works by storing water in the cylinder before sending it directly to your radiators.

Hence why this is called a heat-only boiler.

These are often found in older properties and tend to be more compatible with older radiators. Once again, we’ll look at some of the advantages and disadvantages of these types of systems.



  • These are low cost to replace should your boiler break
  • These often come with a good cover/warranty from the manufacturer
  • They work well with older radiators for those in more dated properties


  • Water tanks can take up space in your home
  • Only the boiler is covered by the warranty; there are lots of other components that could break and cost money to fix

3. System boiler

The final of the three types of boilers is the system boiler. This has many of the same components as a combi boiler. However, it does not produce hot water but rather just does the heating. This means that like regular boilers, it works with a cylinder, but unlike regular boilers, there is no need for a large expansion tank in the loft.

What’s more, lots of the parts, for example, the pumps and valves, are integrated into the boiler and not outside of it like regular boilers. As such, this can be a bit of a space saver in comparison.

Essentially, a system boiler is a more modern version of a regular (heat-only) boiler. Below are the advantages and disadvantages of using this type of system over the others.


  • These are good for properties with high water demand as they can deliver hot water to multiple outlets at once
  • Generally, you’ll get good cover from the manufacturer warranty/guarantee


  • Hot water flow rates depend on your water pressure, so poor pressure means poor hot water flows
  • These systems require more space than a combi boiler so they might be better suited to larger properties rather than smaller ones

And there you have it, the three main types of boilers explained. Now you can decide which is going to be the most effective and space-saving solution for your property.