Something about the boiler

A central heating system has a primary heating appliance such as a furnace or boiler located in an out-of-the-way place such as a basement or garage. It delivers heat throughout the house either by pumping warmed air through a system of air ducts or sending hot water or steam through pipes to room radiators or convectors. The boiler is the most important part of a central heating system. It’s like a big fire that has a continuous supply of natural gas streaming into it from a pipe that goes out to a gas main in the street. When you want to heat your home, you switch on the boiler with an electric switch.

How does home central heating work?

We can think of a central heating system as a continuous circuit moving hot water out from the boiler, through all the radiators in turn, and then back again to pick up more heat. In practice, the circuit is usually more complex and convoluted than this. Here’s how the whole central heating works:

1. Natural gas enters your home from a pipe in the street. All the heat that will warm up your home is stored, in chemical form, inside the gas.
2. The boiler burns the gas to make hot jets that play on a heat exchanger. The heat energy from the gas is transferred to the water.
3. An electric pump pushes the heated water through the system.
4. The water flows around a closed loop inside each radiator, entering at one side and leaving at the other. After it’s passed through all the radiators, the water has cooled down significantly and has to return to the boiler to pick up more heat.
5. 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.
6. Waste gases from the boiler leave through a small smokestack called a flue and disperse in the air.