What are the different types of boilers?

There are three main types of boilers that you can get in your home:

• Combi or combination boilers.

• System boilers.

• Regular boilers (also called heat only boilers or conventional boilers).

Each boiler type has advantages and disadvantages and the one that’s best for you will mostly depend on your current heating and hot water demands.

If it’s time to get a new boiler then it’s a good idea to consider whether you should stick with the type of boiler system you have or swap to a different type of central heating boiler.

How does a combi boiler work?

A combi boiler uses an integral heat exchanger to heat water directly from the cold mains. This means it’s able to provide instantaneous hot water for your home.

Because combi boilers don’t require a separate water tank, they take up less space than the other two boiler types.

What are the advantages of a combi boiler?

• Instant heating and hot water. You get it when you need it.

• Space saving as no separate hot water tank. Ideal for smaller properties.

• Easy installation. You only need to have one unit fitted.

• High energy efficiency. Combi boilers are over 90% efficient.

• Easier to maintain.

What are the disadvantages of a combi boiler?

• Reduced water flow rates when you’re using hot water at two or more outlets. For example, two showers at the same time.

• Don’t work well in homes with poor water flow rates and/or poor water pressure.

• Not compatible with solar water heating systems.

How does a regular boiler work?

Similar to a combi boiler, a regular or conventional boiler has a heat exchanger that warms water and then uses a pump to transport the water to a water storage tank. The hot water then flows through to the radiators to heat them or into your tap when you switch them on.

The cold water is supplied to your home using the cold water tank, which is typically in the loft/attic. It fills the boiler with the help of gravity.

Biomass fired reciprocating grate steam boiler

What are the advantages of a regular boiler?

• Work well with older heating systems as they don’t rely on mains pressure.

• Suitable for homes with greater hot water demands as they provide a higher flow rate.

• Lower replacement costs as regular/conventional boilers are generally the cheapest type of boilers to buy.

• Can work with solar water heating systems to help lower your bills.

What are the disadvantages of a regular boiler?

• Hot water isn’t always available on demand so you may need to wait to have a shower.

• Regular boilers aren’t as efficient as combi boilers as heat is lost when the water is stored in the cylinder.

• You’ll need plenty of space in your home to house the hot water cylinder and cold water tank.

• May not be compatible with some newer central heating systems.

How do system boilers work?

System boilers work with a hot water cylinder. They’re not “open vented”, which means there are no tanks in the loft and are essentially an updated version of regular boilers.

What are the advantages of a system boiler?

• Good for properties that need a lot of hot water at the same time, for example multiple bathrooms.

• No need for a cold water tank.

• You don’t need any components in the attic, perfect if you’re looking to convert it.

• Work well with underfloor heating.

What are the disadvantages of a system boiler?

• The water flow rate depends on the main pressure. So if there’s low pressure in your area the water flow rate throughout your home will be worse.

• You’ll need to have space for the hot water cylinder, for example an air cupboard.

• If you use up all the hot water in the cylinder then it’ll take a while to reheat.