UNIT 59 REVIEW QUESTIONS ANSWER KEY
List three advantages of a warm air electric furnace as compared to an oil or gas
It is more compact than the equivalent gas or oil furnace.
Due to cooler surface temperature, it has “zero” clearance requirements on
all sides. It may, therefore, be located in small spaces such as closets.
Since there is no combustion process, there are no requirements for venting
pipes, chimney, or makeup air. This reduces building costs and simplifies
What material are electric heater coils often made from?
Nickel chrome alloy wire.
An electric furnace rated at 240 volts and 30 amps would have an output
capacity of how many kW?
240 V x 30 A = 7,200 W, which is 7.2kW
What happens to the current draw as an electric heating element warms up?
As the electric heating element temperature increases, its resistance also
increases and the current draw decreases.
When would the blower come on in an electric furnace?
The blower must come on before the first heating element and must remain on
until the last heating element has been de-energized.
Why is nickel chrome alloy used for electric furnace heating elements?
Nickel chrome alloy has a high electrical resistance and also resists oxidation.
How are electric heating elements rated?
Electric heating elements are rated by their kW capacity.
How would a multistage thermostat operate for a heat pump system with
supplemental electric heat?
For heat pumps the first stage brings on the heat pump and the next stage brings
on the electric strips as needed.