How Forced Air Heating Works
Fuel that is burned in a furnace releases heat into the air that is circulating through it to create a forced air heating system. A fan in the unit blows this heated air to work in time with the on and off cycles of the furnace. The fan timing is crucial to the effectiveness and efficiency of the furnace as the fan prevents heat from backing up. It also prevents cold air from being blown through a room when the furnace stops. A forced air heating system can be found with a furnace that is either variable-speed or dual-stage, but most are single stage. The following article will explain how a forced air heating system works.
Distribution of Heat
Warm air from the forced air heating system is pushed through main duct work, a trunk and several branches of duct work. These ducts branch off and lead into individual rooms. Dampers control the heat by closing or opening to block or release the hot air. Dampers are normally motorized and controlled by a thermostat for each zone in the home. You can also have individual registers that can be opened or closed, but these are not as effective.
A forced air heating system needs a furnace of proper size in order to be effective. If your home is cold, you might feel that you need a larger furnace, but this is not the case. Instead, the solution is a better distribution. A larger furnace in a forced air heating system will create a surplus of heat and an inadequate way of distributing it. This can cause undue wear on the furnace as well as noises, cracking, noxious fumes and clogging. The duct work and furnace need to be right for the space to be heated by the forced air heating system.
Supply and Return
A forced air heating system needs to have the supply and return equal to prevent loss. An ideal forced air heating system will have one register and one return for each room. A furnace will attach itself to the home in order to draw air into itself in order to fuel it. If there is an improper supply of air to return this sucking on the home will cause negative pressure. When this happens noxious fumes can backup in the system which will eventually be released into the home. If the vents are not properly spaced a draft can occur as air will race to the furnace.
Forced air heating system return air runs are easy to install because, unlike supply runs, don't have to be contained in metal. The return can be cut directly into the floor as you would for a register. Returns can be found behind staircases, wall studs and in stacked closets. For a forced air heating system to work there should be space under doors so when registers are closed the furnace can still suck in air. It will retrieve air from anywhere in the home where air can freely circulate.