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An electric forced air system is a single heating unit controlled by a single thermostat that supplies heat to the entire house by fan-forced air through duct work. Ducts are often concealed in crawlspaces, attics or walls and deliver heat through an adjustable register. The volume of air within the house is continually cycled through the system by return air ducts.

How do electric forced air systems work?
Electric forced air systems generate heat through high resistance wires called heating elements. Electricity flowing through the elements generates heat that is distributed throughout your home by a fan or blower which forces air through the elements, and directs the heated air into the ductwork.

How to operate electric forced air systems
A single thermostat controls the heating unit which turns the unit On or Off according to the set temperature. When the system turns on, electricity generates heat in the elements and the furnace fan forces air over the elements and distributes the heated air out the ducts and through the registers.

Usually, registers have built-in adjustable louvers to control the amount and direction of air flow.

The flow of electricity to the elements stops when the set temperature is reached. The fan shuts off once the unit cools down.

A technician should inspect and service your system annually. A service check should focus on:

• blower motor bearings for lubrication.
• belts (if any) for wear and tension.
• electrical connections for burned or frayed wires.
• calibration of the thermostat anticipator.
• operating amperage on motor and elements.
• overheat limit sensors.
• pressure balance of the system so that it will work at its optimum by delivering heat at every register.

Create greater system efficiency by sealing the plenum (where the ducts attach to the furnace) and ductwork at all seams and joints. By doing so, you could prevent a 15 - 40 percent loss of delivered air.

Electric forced air system options
Going away for a while? If so, programmable thermostats are available to automatically "set back" the temperature while you are gone and while you sleep. You also can choose from several different types of air filters that reduce the amount of pollens and mold spores in the air.

Cost to operate electric forced air systems
The cost of operating the system is affected by many variables, for instance:

• leakage from air ducts affecting efficiency.
• insulation of the duct work.
• the size of the system compared to the size of your home.
• outdoor temperature and desired indoor temperature.
• the age of your home and the forced air system.
• whether or not your home is insulated.
• maintenance of the system.

Nevertheless, an example of an annual heating cost for a "typical" 1500 square foot, well-insulated house in Eugene heated by an electric forced air system is about $783 a year for heating only. This example assumes a 70 percent delivery efficiency of the system, and a $.04015 rate per kWh (kilowatt hour.)

• check to make sure the thermostat is on.
• check to make sure the service breaker is on.
• check for a clogged filter.
• check to see if the registers are open.

Call your service technician in cases where only cool or cold air is delivered, the system cycles on and off continually, the fan runs constantly, or the system breaker keeps "popping."