What type of boiler do I have?

‘Types of Boiler’ doesn’t refer to the sort of fuel you’re using like gas or oil, but the kind of boiler and heating system that’s been installed. This usually falls under one of the three main boiler types: combi boilers, regular boilers or system boilers.

For any homeowner, choosing your next type of boiler can be a confusing task. Because of this, it’s important to know what ‘types of boiler’ actually means.

There are very clear distinctions about how each type works, and for which property they would suit best. But it’s important for homeowners who aren’t industry-savvy to understand the different types of boiler available.

By the end, we want you to be ready to decide which boiler is best. If this is the case, then you can also get a quote, which you can do for free by using the link below. Otherwise, let’s dive right in!

Types of Boiler – Combi Boiler

combi boiler

Combi or ‘Combination’ boiler is the most popular out of the three types of boiler featured.

Unlike the other types, a combi boiler houses the components for central heating and hot water within the unit itself. This means that you no longer need a hot water cylinder cylinder or cold water storage tank in the loft.

Your cold water will be provided from the mains supply, but any DHW (Domestic Hot Water) will be heated from the boiler itself, and provided only when you need it. Combi boilers don’t have hot water stored, so their efficiency is maximised.

Because of this, combi boilers such as those in the  Viessmann Vitodens range are the most popular type of boiler today and are considered very reliable.



  • No need for hot water cylinder or cold water storage tank – If you’re converting from a regular boiler to combi, this frees up a lot of space that can be used for storage.
  • Compact size – You’re given more options for where the boiler can be positioned in the property.
  • Hot water on demand – It’s provided as and when it’s required.
  • Energy bills are lowered – Because of the way the water is supplied, no waste is created from unnecessarily heated water.


  • Not ideal for homes with more than 2 bathrooms – Combi boilers are a good option for properties with up to 2 bathrooms. There are still many combi boilers available in the Viessmann Vitodens range that can provide the water that you need. Alternatively, storage combis are also an acceptable alternative, and are the most efficient way of storing water.

If you would like to know more about how a combi boiler works, read this article.

Types of Boiler – Regular Boiler

regular boiler

Also known as ‘Conventional’ or ‘Open Vent’ boilers. These types of boiler require a hot water cylinder that’s fed by a cold water storage tank in the loft.

They may take up the most space out of the three, but one strength of open vent boilers is their ability to supply hot water across several bathrooms. This means they’re also a fantastic choice for larger households.

If you have a large family, then you’ll need a boiler that can provide for you. In the morning for instance, multiple bathrooms are likely to be needed, and since the hot water is readily stored in the hot water cylinder, it’s ready and waiting to be supplied.

A good example of a reliable regular/open vent boiler is the Vitodens 100-W Open Vent Boiler from Viessmann.




  • Ideal for homes where hot water supply is needed from multiple outlets simultaneously.
  • Constant supply of hot water – Cold water for the heating system comes from the attic tank into the boiler. After the boiler heats this up, it’s stored in the hot water cylinder ready to be supplied to the rest of the house through the radiators. The hot water cylinder is padded with insulation to ensure the water stays hot.
  • An acceptable choice if your mains water pressure is low.


  • Cold water storage tank and hot water cylinder – These can take up a lot of space. Hot water cylinders are often kept in an airing cupboard while cold water storage tanks are kept in the attic.
  • More energy is wasted to keep the water hot – Regular boilers are the least efficient of the three, because regular boilers have a constant supply of hot water backed up, so use a lot of energy to ensure it’s always ready.

Hot water can run out – If you require a larger amount of hot water, the size of the storage will determine how extensive your supply is. When it empties, you’ll have to wait until the boiler can heat up more water.

Types of Boiler – System Boiler

system boiler

System boilers have the best of both worlds. While they do still require a hot water storage cylinder, there’s no need for a cold water storage tank or expansion tank.

Your mains supply will send water to the boiler which is heated up. Then depending on where you want it, this hot water is either sent through your central heating system (radiators) or into the hot water cylinder to be stored for when you need hot water out of the taps.

Installations for system boilers can often be straightforward – especially if you’re converting from a regular boiler. Because there’s no need for a cold water storage tank, you can free up a lot more space and eliminate any concerns for leaks.

Out of these three types of boiler, system boilers are considered ideal if there are plans for an attic conversion or space is minimal.

Viessmann Vitodens 100-W System Boiler

Viessmann Vitodens 100-W System Boiler


  • Hot water supply is near-constant – This gets stored in the hot water cylinder. Until it’s empty, you’ll have hot water ready for whenever you need it.
  • Multiple Taps – The hot water supply can be used straight away over several taps. Because it’s coming from the hot water cylinder, there won’t be a drop in temperature between taps.
  • No need for cold water storage tank – This frees up a lot of space, allowing more options for expansion/conversion.
  • Ideal for properties with more than one bathroom Because the hot water is stored in the hot water cylinder, it’s ready to be supplied across multiple bathrooms. This can make life a lot easier for families in the morning that need to use more than 1 bathroom.


  • Space for installation The hot water cylinder takes up more space, which is often housed in an airing cupboard or a similar storage area.
  • Hot water cylinder size – This determines how much hot water you have stored ready to be used. Like other types of boiler with a hot water cylinder, if it’s empty, you’ll have to wait for the boiler to heat up more before it’s ready.


With any boiler you need to look beyond short-term solutions, and think about the long-term benefits as well.

The truth is, if you’re not industry savvy you can be easily confused by boiler and central heating terminology. Be careful not to confuse ‘boiler type’ with ‘boiler fuel’.

It’s easy to see how much of a difference it can make to know more about your boiler. For example, according to the Energy Saving Trust, heating accounts for around 55% of your annual energy bills.


saving money

If you’re still curious about different fuel types and boiler sizes, you can also read the following articles:

As well as this, Boilerhut can provide you with valuable advice that can give you that much-need reassurance. To find out more, get a free online quote by filling in the box below, or call us on 02920 099898 to speak to one of our knowledgeable heating experts!

0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *