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Identify your central heating boiler
Do you have cold water storage tanks in your home (usually in the loft)?
If you do, you probably have a conventional boiler or a condensing boiler.
If you don't have water tanks in the loft, you probably have a combination boiler.
The following descriptions provide further information to help you identify your boiler.
Conventional boiler
In a conventional heating system water is fed from cold water tanks situated high up in your home, usually in the loft, to a hot water storage cylinder, usually situated in an airing cupboard, heated by the boiler. A supply of hot water is pumped from the storage tank to radiators and taps.
The feed from the cold water tank keeps the hot water storage tank topped up, but if all of the water in the hot water storage cylinder has been used, or has cooled overnight, the heating process has to be restarted to produce a fresh supply of hot water.
Conventional boiler key features
- Needs cold water storage tanks, usually two tanks in the loft
- Requires a hot water storage tank, usually in the airing cupboard
- You sometimes have to wait for a fresh supply of hot water
Combination boiler
A combination boiler (or 'combi' boiler) heats water directly from the mains supply. Via a pump, the boiler provides 'instant' hot water directly to taps when they are turned on, as well as supplying hot water to heat radiators.
Combination boiler key features
- Provides 'instant' hot water heated directly from the mains supply, so no hot water storage cylinder or airing cupboard
- Doesn't require separate water storage tanks
- You only get a decent flow of hot water from one tap at a time
- Using a hot tap while the heating is on interrupts the flow of hot water to radiators
Condensing boiler
Condensing boilers can be either 'conventional' or 'combination', as described above. However, they work more efficiently by using some of the heat from flue gases which are normally lost to heat additional water.
Condensing boiler key features
- Reusing heat from flue gases is energy efficient, so fuel bills are lower with a condensing boiler
Since 1 April 2005 Building Regulations have specified that new, or replacement gas-fired boilers, installed in England and Wales should be condensing boilers. If your boiler has been installed since then, it is likely to be a condensing boiler.
Thermal storage cylinders
A thermal storage cylinder stores hot water which is used to heat mains water that's passed through a heat exchanger in the cylinder when a hot tap is turned on.
The hot water stored in the cylinder can be pumped to radiators to heat rooms. This water never leaves the system, returning to the thermal storage cylinder to be re-heated.
The water in the thermal storage cylinder can be heated with an electric coil or with a gas or oil boiler.
Thermal storage key features
- Hot water supplied to taps at mains pressure
- Provides hot water to taps and showers at the same time
Back boiler
A back boiler is installed behind an existing heat source, like a gas fire or wood burning stove. The back boiler heats water which is fed to a hot water storage cylinder and to radiators.
Back boiler key features
- Usually fitted behind a gas fire
- Needs cold water storage tanks, usually two tanks in the loft
- Needs a hot water storage cylinder, usually in the airing cupboard
Boiler summary
- Conventional boiler
Uses cold water tanks with hot water stored in a cylinder, usually in an airing cupboard - Combi boiler
No storage tanks required, uses the mains water supply - Condensing boiler
Can be conventional or combination and uses flue gas to heat additional water, improving efficiency - Thermal storage
Provides mains pressure hot water - Back boiler
Fitted in a fireplace, usually behind a gas fire
If you need help identifying your boiler, or have any questions about cover for your boiler, please call us on 0800 197 0610.