There are three main types of boiler: Combi, System & Regular.
Combi boiler
A combi boiler is a simple unit which works by heating cold water directly from the mains whenever you turn on the hot tap. It does this using something called an integral heat exchanger.
A combi boiler delivers hot water to your taps and showers at mains pressure, and is ideal for small/medium sized homes. They are very popular in the UK and account for over 50% of all new boilers fitted.
Because a combi boiler heats water directly from the mains (with no hot water tank) it can deliver an unlimited supply of hot water. Since they don’t need a hot water storage cylinder or a cold-water storage tank in the loft, they are great for saving space.
Advantages of a combi boiler
- Space saving: Ideal for flats or small houses as you don’t need a hot water tank in the airing cupboard or a cold-water tank in the loft.
- Energy efficient: You only heat up the water you use, so no need to heat a full water tank just to wash the dishes. A combi boiler saves energy which translates to lower energy bills.
- Simple, cost-effective solution: Less complicated than traditional boilers and therefore are cheaper and easier to install.
- Unlimited, on-demand hot water supply: Since it is not dependant on any water tanks, you’ll never have a problem running out of hot water if you’re last in the shower in the morning!
Disadvantages of combi boiler
- You need good water pressure level at the mains: If you don’t have good mains water pressure then this type of boiler might not be suitable since it does not use storage tanks. The pressure you receive at the tap/shower will be restricted by your mains pressure.
- Not compatible with power showers: You won’t be able to use a power shower with a combi boiler as these showers use a built-in pump which needs to be connected to a hot water cylinder.
- Can’t run more than one bath/shower at the same time: You may find weak water flow or suddenly changing temperature when more than one tap/shower is being used at once.
- No backup water heater: Since there is no water tank, if your boiler breaks down, you’ll be without hot water and central heating. Though you can always reduce this risk by installing an electric shower which receives cold water directly from the mains.
System Boiler
A system boiler needs a cylinder for storing hot water but don’t require a cold-water storage tank in the loft.
With this type of boiler, some of the main heating and hot water system components are build into the unit itself which makes it quick and easy to install. It is ideal for homes with 2 or more bathrooms since it allows multiple showers to be ran at once.
Advantages of a system boiler
- No cold-water storage tank: Great for saving space, especially if you don’t have a loft.
- Easy to install: Many of the components of the central heating and hot water system are built into the boiler.
- Use multiple showers/taps: Since hot water if fed from a cylinder, there is no loss of water temperature of pressure when using more than one shower at the same time.
Disadvantages of system boiler
- Limited water supply: Because water if fed from a hot water cylinder, once the tank is empty, you’ll need to wait for it to heat up again.
- Takes more space than a combi: While they don’t need a cold-water storage tank in the loft, they do still require a hot water cylinder (usually in the airing cupboard) which could be an issue in flats or smaller homes.
- Less efficient than a combi: Heat can be lost while water is being stored in the hot water cylinder if it is not well insulated.
Regular/Traditional Boiler
Traditional boilers are the most commonly installed boiler type in the UK. However, they have become less popular in recent years as more people go for combi boilers.
A Traditional boiler requires a hot water cylinder and cold-water storage tank in the loft. They Ideal for homes where a lot of hot water is used at once. They are also perfect for low water pressure areas and central heating systems with old radiators.
Advantages of a Regular/Traditional Boiler
- Works with old heating systems: If your house has old radiators then a traditional boiler is more likely to be compatible than a combi or system boiler.
- Multiple showers/taps: As with the system boiler, because water comes from a hot water cylinder you can run multiple showers at the same time without losing pressure or having the temperature fluctuate.
- Works in low water pressure areas: Traditional boilers are able to function with lower water pressure than combi boilers.
Disadvantages of Regular/Traditional Boiler
- Takes up more space: A traditional boiler takes up the most space out of the three options as it needs both a hot water cylinder and also a cold-water storage tank.
- More expensive: Because traditional boiler systems are more complicated, they can take longer to install and can work out more costly.
- Heat loss: Since hot water is stored in a cylinder it can lose heat over time. This is especially true if the hot water cylinder is not well insulated.
What about condensing boilers?
A condensing boiler is a high efficiency, modern boiler which minimises heat loss and can achieve operating efficiencies of 90% or better under normal use.
If purchased after 2005 then it will be a condensing boiler as all new UK boiler installations since 1st April 2007 have to be condensing by Law.
Any new boiler which you buy today will have its output measured in kW (kilowatts) instead of BTU (British thermal units) as was used on old style less efficient boilers.
Advantages of a Condensing Boiler
- Much more efficient than old style boilers: Condensing boilers have 2 heat exchangers. The second captures exhaust gas heat from the first, which would usually be wasted in a non-condensing boiler.
- Lower cost over the long term: As condensing boilers are more energy efficient this results in lower bills.
Disadvantages of a Condensing Boiler
- Higher initial cost: While the initial purchase price is higher than non-condensing boilers this is made up for over the long term with lower energy bills.
What type of boiler do I have?
Ask these 2 questions:
Do you have a hot water cylinder?
| No: | Yes: |
|---|---|
| You have a Combi Boiler | You have a Regular or System Boiler |
Is there a pressure gauge on the boiler?
| No: | Yes: |
|---|---|
| You have a Regular/Traditional Boiler | You have a system Boiler |