320 Electrical Power Systems Technology
Electrically energized comfort heating systems are widely used to-
day to produce heat for commercial, industrial, and residential build-
ings. Electrical energy is readily available at nearly any building site, and
it has a number of advantages over fuel-burning methods of producing
heat. Ecologically, any fuel needed to produce electricity is burned or
consumed at a power plant, which is usually located some distance from
the building where it is being used. With this method of heating, there is
less pollution than there would be if fuel were burned at each building.
Electric heat is also clean to use, easy to control, and highly efficient.
E lectric heating is important today because of its high level of ef-
ficiency. Theoretically, when electrical energy is applied to a system, vir-
tually all of it is transformed into heat energy. Essentially, this means
that, when a specified amount of electricity is applied, it produces an
equivalent Btu output. One thousand watts or 1 kW of electricity, when
converted to heat, produces 3412 Btus of heat energy.
Heating can be achieved in a variety of ways through the use of
electricity. Comfort heating systems contain an energy source, transmis-
sion path, control load device, and the possibility of one or more option-
al indicators. The primary difference between heat-pump and resistance
electrical systems is in the production of heat energy. Resistance heating
Figure 12-8. A simplified diagram of a room air conditioning unit