Central heating is a way of heating in which the heat is generated centrally in a central heating boiler and by means of a system of pipes which lead to radiators which heat the required spaces.
In the Netherlands, water is the most commonly used medium to transport heat. The boiler heats the water that flows through pipes to radiators or underfloor heating which release the heat. The cooled water then flows back to the boiler, where it is reheated. Most radiators have their own forward and return channel so that each radiator can be controlled separately by means of a radiator valve.
In addition, a water-filled heating system has an expansion tank which prevents excessive pressure differences. Without an expansion tank, the pressure in the system would be rise so high that a channel or other component in the system could crack. A pressure relief valve prevents a central heating system which has been too far filled from getting damaged even when the boundary of the range, over which the expansion tank can cope with the differences in pressure, is exceeded.
The temperature of the main room is often controlled by a room thermostat. The radiators in this are not rot regulated separately, but are always on. In other rooms so-called thermostatic valves can be mounted. These valves control the heat of the radiator, depending on the set temperature and will respond to the set temperature and shut off when reached.
The temperature can also be controlled by a weather-dependent regulation, whereby the heat output of the boiler is dependent on the temperature of the space, the required temperature and the outside temperature.