Central heating systems are one of the more common standard heating systems used in public buildings and homes. These heating systems are typically used in colder climates. The components of the system usually includes a heating unit such as a heat pump, furnace or boiler in a central location.
The fuel for the heating unit can be oil, coal, electricity, natural gas or other fuels. The central unit heats air, steam or water and disperses it throughout the structure. Units in the outlying spaces such as ductwork, piping or radiators may be part of the system.
In larger buildings, the furnace or boiler is placed in a central location, usually a furnace room, boiler room or mechanical room. Private homes may have basement unit or closet called the furnace room. Heat pumps may be located inside or outside the home or building. They are sometimes placed on the flat roof of a building.
From the furnace or the boiler, piping or ductwork is carried to all parts of the structure. If the system is a forced air unit, ductwork carries the heated air to the rooms. A fan or blower circulates the air through the ducts and into the rooms. Often, the amount of heat is controlled by a thermostat set within a room or area. There is usually filters or air cleaners attached to the system to prevent blowing or forcing dust or mold into the rooms.
When the system uses hot water to transfer the heat, the water is heated and sent through piping to the rooms where there are radiators. The radiators heat by convection rather than radiant heat. Radiators are placed on walls or they may be placed within the floor to heat the floor surface. When the weather is hot, the same ductwork can be used to distribute air conditioning results throughout the building.
When the heat is circulated by means of fluid, there is nearly always a pump to equalize the distribution of heat throughout the structure. A hot water heat system is usually combined with hot water for the household. There is usually a secondary heat exchanger within a storage container so that the household is supplied with hot water for bathing and dishes.
The placement of radiators or vents is important in the optimum efficiency of the heating system. The radiator should be placed next to windows and in the part of the room that is coldest. When the radiator is near the windows, condensation is minimized. The heat near the window sets up the proper air flow to make best use of the heating element. Contrary to popular belief, directing the heat away from windows defeats the positive air currents that are required for best efficiency.
The invention of central heating systems is credited to the ancient Romans. Their system of air ducts was designed to provide hot air ducts in private homes and public baths. The later systems are not that much different in distribution although the heating method is quite different today.