A central heating system is a continuous circuit of moving hot water leaving the boiler and passing through all the radiators in turn, and then back again to the boiler to pick up more heat.

The central heating water is permanently sealed inside the central heating system and the same water circulates continuously around your home every single day.

Here’s how it works:

1. Natural gas enters your home to the boiler from a pipe in the street.
2. The boiler burns the gas and a flame heats up a heat exchanger that contains the water.
3. The heat energy from the gas is transferred to the water.
4. An electric pump pushes the heated water through the whole system including upstairs.
5. The water flows around the radiator system , entering at one side and leaving at the other. Because each radiator is giving off heat, the water is cooler when it leaves a radiator than it is when it enters.
6. After the water has passed through all the radiators it will have cooled down significantly and then returns to the boiler to pick up more heat.
7. A thermostat mounted in one room monitors the temperature and switches the boiler off when it’s hot enough, switching the boiler back on again when the room gets too cold.
8. Waste gases from the boiler leave through a flue and disperse into atmosphere.