Powered by natural gas or liquefied petroleum gas (LPG), like most boilers, a gas boiler burns fuel to heat water.

As boilers account for around 55% of the total cost of annual heating bills, a new energy efficient boiler can make a real difference to the average home.

With legislation passed in 2005 stating that all newly fitted gas boilers must be condensing; all new boilers burn fuel with increased efficiency, and work to reduce heat loss.

How does a gas boiler work?

When the boiler is switched on, a valve opens to allow mains gas to enter a sealed combustion chamber – this passes into a primary heat exchanger which is attached to a cold water pipe. The hot gas transfers its heat energy to the water, heating it up and circulating it through your pipes and radiators, powered by a pump.

As the water travels through the pipes, it gradually cools and then passes through 
a second exchanger where it is re-heated by the gases, producing a liquid known as ‘condensate’, which is then drained from the boiler system.

By this stage of the process, the hot gases have transferred their heat to the water and are no longer of use – so they pass out of
the system via the flue. The water which has already been heated and passed around your radiator system then flows back through the primary exchanger, where the process begins again, being re-heated so that the radiators can continue to send heat out into your home. The cycle continues until the thermostat detects that the temperature of your home has reached the pre-defined level, or until the boiler is switched off manually.

Types of gas boiler available:

What are the advantages of gas boilers?

  • Economical to run
  • Energy efficient
  • Reduced carbon dioxide emissions
  • Simple to control