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1. If a lockout relay becomes defective, it should be replaced with an exact duplicate, sometimes called a(n) ________.

control relay

impedance relay

time-delay relay

induced-draft relay

Question 1 of 20

2. To increase furnace efficiency, the startup of the furnace blower is delayed using a ________.

time delay relay

thermocouple

limit control

short-cycle time

Question 2 of 20

3. Thermostats with bimetal sensing elements typically use a combination of copper or brass and ________.

Elinvar®

Invar®

nickel

aluminum

Question 3 of 20

4. NEC Article 440, Part V covers ________.

digital control systems

resistors and reactors

requirements for motor compressor controllers

the control and protection of fixed electric space heating equipment

Question 4 of 20

5. In a cooling system, the heat absorbed by the refrigerant is transferred to the cooler outdoor air in a heat exchanger known as a(n) ________.

evaporator

condenser

compressor

expansion device

Question 5 of 20

6. If lighting units and other appliances are also supplied, the rating of cord- and plug-connected room air conditioners must not exceed what percentage of the branch circuit rating?

80%

90%

70%

50%

Question 6 of 20

7. Multi-stage thermostats provide energy savings by cycling on stages of heating or cooling based on ________.

time delay relays

pump size

demand

preset timers

Question 7 of 20

8. A freezestat is a ________.

normally closed bimetal switch

digital control

normally open bimetal switch

thermostat that has seized

Question 8 of 20

9. Automatic changeover thermostats have a minimum interlock setting, also known as the ________.

evaporator

differential

compensator

deadband

Question 9 of 20

10. Conventional line-voltage thermostats do not provide precise temperature control because ________.

the sensor must be routed through a delay switch

occupants often use the override controls

the bimetal elements are heavier and do not respond as quickly

they have staggered startup

Question 10 of 20

11. The thermostat terminal that connects to the reversing valve control in a heat pump is ________.

Question 11 of 20

12. Connecting a 120V heating cable to a 240V circuit will ________.

cause the system to operate within acceptable standards, but at less than full efficiency

produce only 25% of the rated cable wattage

melt the cable

enable the system to operate most efficiently

Question 12 of 20

13. When the bimetal coil in a cooling-only thermostat heats up and unwinds, the mercury switch ________.

closes its contacts and starts the cooling system compressor

opens its contacts and stops the cooling system compressor

closes its contacts and shuts down the system

opens its contacts and initiates defrost

Question 13 of 20

14. Which of the following is an example of an external analog device?

Switches

Relays

Thermistors

Lights

Question 14 of 20

15. A conventional thermostat should not be thrown into the regular trash because it ________.

is easy to repair

contains sulfuric acid

may contain mercury

has a 10-year warranty

Question 15 of 20

16. The tubing that carries heat-laden refrigerant gas from the evaporator to the compressor is known as the ________.

suction line

liquid line

discharge line

hot gas line

Question 16 of 20

17. If a mercury thermostat seems out of adjustment, the first thing to do is ________.

adjust the setting lever

check for accurate leveling

reset the system switch to Off

recalibrate the thermostat

Question 17 of 20

18. Which of the following principles states that heat is created in one place and carried to another by means of air or water?

Heat-movement principle

Heat-creation principle

Heat-transfer principle

Heat-transplant principle

Question 18 of 20

19. A device that uses dissimilar metals to control electron flow is known as a(n) ________.

firestat

thermocouple

thermistor

freezestat

Question 19 of 20

20. The purpose of the defrost cycle in a heat pump is to ________.

remove frost buildup throughout the system ductwork

warm the unit circuits for optimum electrical operation

prevent ice buildup on the indoor coil

prevent ice buildup on the outdoor coil

Question 20 of 20

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