An Introduction to Gas Boilers

Gas boilers are central heating systems that act like a mini fire, continuously heating water. This heated water is then pumped around the property through pipes and radiators in order to heat space, and either pumped directly to taps and showers as with a combi boiler, or stored in a hot water tank for future water usage. The boiler uses either on-grid gas or bulk LPG stored on site. This gas is then burned in the boiler’s combustion chamber and warms the water to around 70°C through a heat exchanger.

Are gas boilers dangerous?

Importantly, when natural gas is burned without enough oxygen it burns yellow. This creates a dangerous toxic gas called carbon monoxide, which can be lethal if inhaled for long periods. This is why you should always have a carbon monoxide detector and regularly ensure the boiler is burning blue.

Are there different types of boiler available?

There are four main types of gas boiler that are installed up and down the UK:

Combination, or combi boilers, do not use a water tank to store the hot water but produce instant hot water direct from the boiler for taps and showers.

System boilers store hot water in an insulated water tank and have one cold water tank.

Regular boilers in essence work in much the same way as system boilers, but can be vented (one cold water tank) or unvented (two cold water tanks).

Finally, combined heat and power (CHP) boilers, which act as micro power plants by providing your hot water like the previous three but also generating electricity to use around the home.

Are they efficient?

We recommend replacing your boiler every 12 years or so; this is to compensate for both the loss of efficiency and the lack of available spare parts for repair. If your boiler is pre-2002 the chances are that it is a non-condensing model, which are up to 80% efficient with new condensing models reaching into the 90s%.

Boiler controls

Gas boilers can be programmed to come on at specific times of the day, to ensure that you never pointlessly heat your home when no one is in. Also, to avoid overheating and under-heating your property, thermostats can be installed to make sure that the required temperature is reached and maintained. For larger properties with rooms that are often uninhabited, thermostatic radiator valves may be installed on each radiator to minimise wasted heat.