Unit 30 Electric Heat

A.) there is no zone control for individual rooms

A disadvantage of a central forced-air electric furnace is that: A.) there is no zone control for individual rooms B.) a thermostat must be installed in each room. C.) only line-voltage thermostats can be used D.) it is difficult to add air-conditioning (cooling)

D.) Rh & Rc

An isolating thermostat subbase is easily identified because it has which of the following terminals? A.) W, Yc, & C B.) R, Wc, Y, & C C.) R, C, & Gh D.) Rh & Rc

B.) Convection

Baseboard heaters transfer heat by _____________. A.) conduction B.) convection C.) evaporation D.) radiation

D.) Gypsum board

Ceiling-mounted radiant heating panels are typically constructed of _________. A.) 3/4-in. plywood B.) Gypsum board C.) 1/2-in. balsa wood D.) select pine board

C.) reduced airflow and increased internal appliance temperature

Dirty air filters on an electric forced-air furnace can cause: A.) reduced airflow and low internal appliance temperature. B.) increased airflow and increased internal appliance temperature C.) reduced airflow and increased internal appliance temperature D.) increased airflow and low internal appliance temperature.

A.) remotely located line-voltage thermostats

Electric baseboard heaters are typically controlled by: A.) remotely located line-voltage thermostats B.) heater-mounted line-voltage thermostats C.) remotely located low-voltage thermostats D.) heater-mounted low-voltage thermostats

D.) Less Expensive to purchase and more expensive to operate than fossil fuel heating equipment.

Electric heating equipment is typically. A.) Less expensive to purchase and less expensive to operate than fossil fuel heating equipment. B.) More expensive to purchase and more expensive to operate than fossil fuel heating equipment. C.) More expensive to purchase and less expensive to operate than fossil fuel heating equipment. D.) Less Expensive to purchase and more expensive to operate than fossil fuel heating equipment.

A.) are often controlled by individual thermostats.

Electric radiant heating elements: A.) are often controlled by individual thermostats. B.) are often installed as part of a ducted, forced-air heating system. C.) must be installed in the walls of a structure. D.) must be installed by a licensed electrician in all jurisdictions.

A.) flue or vent piping

From an installation standpoint, electric boilers have the benefit of not requiring: A.) flue or vent piping B.) pressure relief valves C.) aquastats D.) limit controls

A.) 54000 Btu/h

How much heat is being put out by an electric furnace if the airflow is 1000 cfm and the temperature difference across the furnace is 50°F? A.) 54000 Btu/h B.) 40500 Btu/h C.) 27000 Btu/h D.) 13500 Btu/h

D.) the limit control

If a fusible link is found to be defective, which other system component must be replaced as well? A.) the space thermostat B.) The furnace blower motor C.) the heating sequencer D.) the limit control

C.) One-quarter of the amount of heat sensed at the initial location.

If the distance between a heat source and the heat target is doubled, the amount of sensed heat at the target location will be ____________ A.) equal to the amount of heat sensed at the initial location. B.) one-half of the amount of heat sensed at the initial location. C.) one-quarter of the amount of heat sensed at the initial location. D.) twice the amount heat sensed at the initial location.

A.) the circuit breaker needs to be reset

If the proper voltage is supplied to an electric heating element and it does not get hot, A.) the circuit breaker needs to be reset B.) the fusible link has melted C.) the heater is defective D.) the limit switch is open

B.) The supply voltage to the appliance is too low.

If the thermostat is calling for heat, but the appliance is providing insufficient heat, which of the following is the most likely cause for system malfunction? A.) The main disconnect switch is off. B.) The supply voltage to the appliance is too low. C.) The thermostat is defective. D.) The control transformer is defective.

C.) Reduced airflow and increased internal appliance temperature

On furnaces that are equipped with belt-driven blower assemblies, which of the following can result if the belt is too loose? A.) Reduced airflow and low internal appliance temperature B.) Increased airflow and increased internal appliance temperature C.) Reduced airflow and increased internal appliance temperature D.) Increased airflow and low internal appliance temperature

D.) Radiation

Portable or small space heaters with glowing coils transfer heat by ______. A.) Conduction B.) Convection C.) Evaporation D.) Radiation

a control that causes a staging of events in electrical heat.

Sequencer

C.) Mica or ceramic

The electric resistance strip heaters in an electric furnace are insulated from the rest of the appliance using which materials? A.) Ceramic or iron B.) Iron or Copper C.) Mica or ceramic D.) Aluminum or mica

A.) one-time, safety device

The fusible link is best described as a(n): A.) one-time, safety device B.) one-time, operational device C.) resettable safety device D.) resettable operational device

A.) adjustable device that is wired in series with the thermostat's heating contacts

The heat anticipator is a(n): A.) adjustable device that is wired in series with the thermostat's heating contacts B.) non-adjustable device that is wired in series with the thermostat's heating contacts. C.) adjustable device that is wired in parallel with the thermostats heating contacts. D.) non-adjustable device that is wired in parallel with the thermostat's heating contacts.

C.) is safe

The low-voltage thermostat is often used to control an electric heating system because it is compact, quick to respond to load changes, and it: A.) provides fuse protection B.) acts as a limit switch C.) is safe D.) acts as a fusible link.

B.) nickel chromium (nichrome)

The material often used to manufacture electric strip heater element wire is: A.) nickel cadmium (nicad) B.) nickel chromium (nichrome) C.) cadmium sulfate (calfate) D.) cadmium dioxide (cadoxide)

B.) staggering the starting and stopping of multiple stages of electric heat.

The sequencer is responsible for: A.) cycling the furnace blower on and off during call for heat. B.) staggering the starting and stopping of multiple stages of electric heat. C.) protecting the limit switch and fusible links. D.) ensuring that the space temperature remains within 1 degree of the thermostat's set point.

D.) pictorial diagram

The wiring diagram that shows the location of each system component is the: A.) ladder diagram B.) line diagram C.) schematic diagram D.) pictorial diagram

A device used to control the temperature.

Thermostat

B.) thermostats, contactors and sequencers

Three common controls used in central electric heat applications are: A.) capacitors, thermostats, and contactors. B.) thermostats, contactors and sequencers C.) cool anticipators, relays, and contactors D.) capacitors, cool anticipators, and sequencers

D.) 100%

What is the approximate efficiency of an electric furnace with respect to its ability to convert electrical energy to heat energy? A.) 25% B.) 50% C.) 75% D.) 100%

B.) It prevents the heaters from coming on if the blower is not energized.

What is the purpose of an interlock circuit on an electric forced-air furnace? A.) It prevents the blower from coming on if the heaters are not energized. B.) It prevents the heaters from coming on if the blower is not energized. C.) It prevents the equipment owner from receiving and electric shock. D.) It prevents all of the system's heaters from turning on at the same time.

A.) The fusible link melts at a temperature that is higher than the temperature at which the limit switch opens.

Which of the following states is true regarding the limit switch and the fusible link? A.) The fusible link melts at a temperature that is higher than the temperature at which the limit switch opens. B.) The fusible link melts at a temperature that is lower than the temperature at which the limit switch opens. C.) The fusible link melts at the same temperature at which the limit switch opens. D.) There is no direct relationship between the opening temperature of the te limit switch and the melting temperature of a fusible link.