When an electric furnace delivers heated air blown by a fan through a network of ducts, it is called a forced-air system. Because the fan is literally forcing air into each room in the house, this type of system does not depend on natural convection to distribute heated air evenly throughout your house.
If electricity is your only energy source, unused chimney flues can be closed off, insulated, and sealed. Closing off the chimney flues can have an effect on drafts and humidity levels in the house, and will reduce heat loss.
To accommodate different types of houses, there are three main furnace designs for use with forced-air systems. The designs are named according to the way air travels through the system.
- Upflow furnaces are recommended for basement floor locations.
- Horizontal flow furnaces are particularly suited for crawl space installations.
- Downflow furnaces are recommended for installations in mobile homes or on the main floor of houses on concrete slabs.
If you replace your forced-air furnace with a new electrical furnace, you can usually use the existing ductwork with very few modifications.
Electric plenum heaters can be added to forced-air systems to boost capacity or create dual-energy systems. The plenum heater, consisting of one or more heating coils, is placed in the hot air plenum of the heating system (the plenum is that part of the ductwork immediately downstream from the furnace). The furnace circulating fan blows air through these coils on the way to the warm air registers.
Uneven heat distribution is sometimes a problem, which often results in the inability to heat some rooms in the house, such as upstairs bedrooms. This can be due to leakage of warm air out through joints in the heating ducts, or heat loss from ductwork passing through the basement or, even worse, through unheated areas such as a crawl space, an attic, or a garage.
Balancing the heat delivered to different areas of the house is as important with hydronic heating as it is with a forced-air system. Radiators are often fitted with simple manual valves that can be used to control the amount of water flowing through them. Such valves can be used to vary the heat delivered to different rooms in the same way that balancing dampers are used in a forced-air system.
Electric room heaters can be installed in each room and individually controlled. The thermostat controls can be located in the units themselves or be mounted on a nearby wall. All room heaters have built-in controls to prevent overheating if airflow is restricted. A wide variety of moderately priced room heaters are available.
