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Different Types Of Boilers [Explained] And Which One You Need

Welcome to our 5-minute guide to the different types of boilers available, and which one you’re going to need. After reading this guide, you’ll know the most suitable type of boiler to install in your property.

We’ll also explain when it’s viable to switch to a different type of boiler from your current setup, and why.

The Different Types Of Boilers Available

Back Boilers

We’re starting this guide, with a boiler type that’s not popular at all; back boilers (yuck!).


Because if you have a back boiler, we’d advise switching and upgrading to a new central heating system, most likely one that incorporates a combi boiler.

What Is A Back Boiler?

If you’ve purchased a new property, you’ve looked for your boiler, and you’re stumped, there’s a good chance it’s hidden in the fire; that’s a back boiler.

These types of boilers were introduced in the 1960s and were fitted up until around the 1980s.

Needless to say, if you have a back boiler installed in your property, it’s going to be REALLY old. And with age, comes an incredible amount of inefficiency. Being ridiculously inefficient, it’s no coincidence that the big manufacturers no longer produce back boilers.

If you think you have this type of boiler, jump straight over to our guide to back boiler replacement here.

Or, you can get a heating engineer to help decide what the best route forward is, with a free on-site visit and quote here.

Combi Boilers

Combis are by the far the most popular types of boilers.

And, that’s because they’re most suited to small-averaged sized properties. So, that’s a 1-bedroom flat, a 4-bedroomed detached house, and pretty-much everything in between.

What Is A Combi Boiler?

Combination boilers are an extremely efficient way to heat your home, and hot water.

They heat hot water on demand. So, as you turn up the thermostat, or turn on a tap or shower, the boiler heats water, just enough to supply you with what need.

The great thing about this? You won’t need any kind of water storage facility. And, that’s going to save space. After all, cylinders aren’t exactly small; they’ll take up the majority of space in an average airing cupboard.

The popularity of combi boilers has meant that most airing cupboards are now redundant. If there’s capped off pipework in your airing cupboard, it’s likely the central heating system has been upgraded from one of the boilers below; a system or conventional boiler. After it’s been upgraded, the cylinder would have been removed.

We’ve created a couple of guides, including one on combi boiler prices, and the best combi boilers currently available.

And, you can get a boiler installation company to offer you free expert advice, with an on-site quote here.

Advantages Of A Combi Boiler

  • Instant hot water and heating
  • Many brands produce compact combis that can fit in a small kitchen cupboard
  • No need for a hot water cylinder, saving you space
  • Energy efficient, saving you up to £305 per year on your utility bills
  • No cold feed in the loft, meaning no risk of pipes freezing during winter
  • Cheap to replace

System Boilers

Whilst most homes either have a combi boiler, or upgrade to one, that doesn’t mean there isn’t a place for other types of boilers, including system boilers.

What Is A System Boiler?

A system boiler doesn’t work like a combi; it doesn’t heat hot water on demand. Instead, it fills up a cylinder.

Although there’s an obvious disadvantage to having to find space to install a hot water cylinder, there are some major advantages too.

In large properties with huge hot water demand, it comes to a point where it’s no longer viable to fit a combi boiler. We’re talking about properties where multiple taps and/or showers are running at once.

You’re really going to struggle to get the output from a combi, because sometimes, they just can’t keep up.

So, if you have a system boiler with a hot water cylinder, and have high hot water demand, it’s unlikely it’s a viable option to switch to a combi; keep your current setup.

Sound like the type of boiler you need?

Check out our guide to system boilers, which covers everything you need to know, including prices

Advantages Of A System Boiler

  • No need for a cold water tank in your loft
  • Ability to provide large volumes of hot water, via multiple taps and showers
  • Perfect for properties with multiple bathrooms
  • Can be used with an existing cylinder (when in good condition), meaning replacement costs are similar to combi installations (cheap!)

Conventional Boilers

You’ll hear conventional boilers being called a few different things. That includes heat-only, and traditional.

What Is A Conventional Boiler?

Essentially, the conventional boiler, is an old-school version of a system boiler. But, instead of a simple water storage facility, it also needs a tank (usually located in your loft), to feed the boiler. Of course, that’s extra space.

Most popular boiler manufacturers still produce conventional boilers.

Whilst a system boiler might be a more viable option, it’s likely a straight swap for a conventional is the most cost-effective option, that is, if you don’t plan to alter pipework in your central heating system (i.e. lots of additional cost).

That’s because, an old and traditional central heating system might not be able to cope with the additional output and pressure, given out by newer system boilers.

But, this isn’t a one-size fits all approach. My suggestion, would be to get a heating engineer to spec your property, consider what’s currently installed (in terms of the boiler and the pipework), consider your demand for hot water, and then help you decide. You can go and get a site visit and quote here.

If there’s no risk of a system or combi boiler putting current pipework under too much pressure, it’s likely one of these will be a better fit than a conventional boiler.

We’ve created a guide to conventional, heat-only and traditional boilers here.

Advantages Of A Conventional Boiler

  • Ideal for properties with low water pressure
  • Due to water storage facilities, it can provide high volumes of water to multiple taps and showers
  • Not essential to upgrade to a combi or system, so no need to replace your full heating system

Condensing Boilers

You’ll see some older properties with what’s known as a non-condensing boiler. This is a generic term and isn’t directly related to a specific boiler type (i.e. back, combi, system or conventional boiler).

What Is A Condensing Boiler?

Due to new building regulations, boilers need to meet certain energy efficiency requirements. Many of which, aren’t met by non-condensing boilers, due to their inefficiency.

When a non-condensing boiler is firing, it wasted lots of energy, via heat that’s expelled out of the flue. A condensing boiler recycles these gases, and heat. Essentially, it’s making use of energy, that would otherwise be wasted.

We’ve already written a detailed guide to condensing boiler prices here. As well as flicking through that, you can get free on-site boiler installation quotes, from a qualified engineer here.

Installation Costs For Different Types Of Boilers

Now you know which type of boiler you need, the next question is, how much will it cost to install?

We’ve created a range of guides to help you. Also have a look at our new boiler deals.

If you own a back boiler, you’re most likely going to need to upgrade, check out our back boiler cost guide here.

For a typical gas boiler installation, including combi, system and conventional boilers, we’ve written a guide to boiler installation here.

But, if you’re off the grid and run on oil, check out our oil boiler installation guide.

Finally, if you have no central heating in your property currently (you’re using storage heaters, for instance), we’ve also created a guide to the central heating installation.

What’s Next?

Still confused about the types of boilers, or have a complex central heating system, and have questions?

Check out our guides to getting a new boiler here. Or, we’d be happy to help, you can drop us a line via our contact page.



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