The concept of central heating dates back to the rudimentary hypocaust system of ancient Rome that used hot air and flue gases travelling upward through wall cavities to provide heat for an inside space. However, it has not been until the last century or so that technological advances have added efficiencies and more availability to the mix.
Central heating systems for home use have evolved dramatically. At one time coal burning furnaces heated water either to circulate through a number of connected radiators to bring warmth to rooms remote from the furnace location, or to create steam to accomplish the same purpose. Then as natural gas pipe lines were built, natural gas displaced coal as fuel. In some cases, oil replaced coal. Natural gas and oil are still used as fuels for home heating systems.
Electric Central Heating Systems
Electric central heating has not been used nearly as much as natural gas, although that may change. The need for well insulated, energy efficient housing started gaining greater recognition after the oil shortages of the early 1970′s. For quite some time after that, use of electricity to heat a home was limited by its high operating cost because using electricity required using an electric resistance furnace in a forced air system. Such a furnace blows air across a thick, glowing wire, to create warm air. It is quite inefficient. However, new technology using electricity more efficiently is constantly coming to market, making electricity a very efficient alternative to natural gas.
Central Heating Installation
Central heating installation takes place at the construction site but planning begins with the architect and engineer. A system distributes heat. It does this by means of duct work in a forced air system, or pipes in a hot water or steam system. The duct work is connected to a furnace while the pipes attach to a boiler. A gas furnace has a burner with numerous flames of burning gas that heat the air as it passes over and through them in a forced air system, while in a hot water or steam system, fuel is burned to heat water, which passes through pipes to a radiator, or it creates steam to do the same thing. Duct work is typically run through interior wall cavities to strategically placed outlets. Pipes for a system using a boiler also are easy to conceal and lead to a radiator, or to radiant tubes concealed in a sub floor, to warm indoor living spaces.
Central heating boilers available now are smaller than previous models and use fuel–gas or oil–more efficiently. Central heating radiators for use with such boilers may be the vertical, iron style that has been in use over a hundred years, or they may be a copper tube with closely space, thin metal fins attached to distribute heat. The latter style intrudes less into a room space, weighs less and is easier to handle than a traditional style radiator.
Gas Central Heating
Gas central heating, particularly a forced air system, is the most widespread system in the United States. A forced air system circulates air through a vertical furnace. The air is heated by the burner and passes through duct work to the various rooms of the house. Forced air furnaces that can achieve 96% efficiency by rapidly cycling off and on are available for this type system. A gas fired central heating system may also use a boiler to create hot water or steam which moves through a system of radiators to heat rooms.
Newer building techniques that take advantage of the sun as a source of heat are being used more often on a wider front than ever before. The economic and environmental advantages of this approach are numerous. However, despite increasingly higher levels of thermal efficiency in building and new technologies to make use of sunlight for heating, it is quite likely that there will always be a need for a central heating system in public and private buildings.