Central Heating Provides One Unit For Entire Building
Most homes and buildings use the concept of central heating to keep the buildings warm, which has some advantages in cost over individual space heating, as well as some disadvantages. In most buildings, central heating uses a single heating source to heat air, which is then forced by a fan through heating ducts into the rest of the building. This eliminates the need for a separate heating unit in each room, but typically relies on a single thermostat to set the temperature throughout the entire building.
In single family homes, a furnace is usually located in the basement of the home, with duct work from the central heating furnace's heat exchanger routed to the different rooms in the home. A centrally located thermostat reads the temperature in that room and signals the furnace to come on when it reaches a predetermined temperature. The fault here is that other rooms in the house may by colder and not affected by the heat from the furnace.
Although it is the most common type of heat, central heating is at best inefficient by not maintaining a constant temperature throughout the entire home. If the thermostat is set high enough to warm the coldest room, the one in which it is located will become too hot.
A Lot Of Space Lost To Ducts
Additionally, central heating not only requires duct work, usually placed between floor joists leading to the separate rooms, it also requires cold air return ducts to take the cold air back to the furnace. When the force air fan is running it can spread allergens in the air throughout the house, causing problems to people with allergies. Additionally, it has been known that mold can grow inside the ducts, which is spread when the fan blows.
In some homes, electric radiant heat is used as a supplemental heating source to the central heating unit to help keep colder rooms more comfortable. This increase the overall cost of heating a home with central heating. A few systems, with separate duct work, allows for individual room thermostats to control the duct openings, allowing heat to flow through only when needed. With these systems a family can keep unused rooms in the house cooler than the ones they use they most.
Most central heating furnaces operate on gas, oil or natural gas depending on the fuel availability and although somewhat inefficient, are the most convenient source of home heating in use today.
