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53 Cards in this Set
- Front
- Back
- 3rd side (hint)
The type of material used for resistance wire in electric heat is
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Nichrome.
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Portable or small space heaters with glowing coils transfer heat by
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Radiation.
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Base board heaters transfer heat by
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convection.
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A disadvantage of a central forced air electric furans is that. A. There is no zone control for individual rooms., B. A thermostat must be installed in each individual room, C. Only line voltage thermostat can be use, D. It is difficult to add air conditioning
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A : There is no zone control for individual room.
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Three common controls used in central electric heat applications are thermostat, contactors, (or relay) A. Capacitor B. sequencer C. Cool anticipator
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B : Sequencer
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The low voltage thermostat is used for central electric heat because it is compact, it is responsive, and A- it provides fuse protection B- It acts as a limit switch. C- it is safe
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C : it is safe.
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The heat anticipator setting is determined by A- Adding all the current draw in the 24-Volt circuit that passes through the thermostat control bulb and heat anticipator. B- Using the amperage of fan motor. C- Using the total of high- voltage amperage of the circuit.
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A : Adding all the current draw in the 24 Volt circuit that passes through the thermostat control bulb and heat anticipator.
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The sequencer uses _________ (high or low) voltage control power to start and stop the electric heaters.
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Low
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True or Falls: A package sequencer can start or stop only one stage of strip heat.
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False.
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Two type of wiring diagrams are the pictorial and_________.
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Schematic ( line or ladder)
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The limit switch shuts off the unit if: A- High temperature occurs. B- The furnace is unable to maintain the correct heat. C- The heat anticipator does not function properly. D- The cool anticipator does not function properly.
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A : High temperature occurs.
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The ________ wire from the transformer furnishes power to the thermostat. A-Red. B-Blue. C-Orange. D- Yellow.
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A : Red
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State the formula used for determining the cubic feet per minute (CFM) air flow across the furnace heating elements.
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CFM = Qs/1.08 x TD.
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Power consuming devices are wired in _________ (series or parallel).
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Parallel.
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Power passing devices are wired in ___________ (series or parallel).
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series.
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The resistance wire often used in an electric heating element is made of: A- Copper. B- stainless steel. C- Nickel chromium. D- magnesium.
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C : Nickel chromium
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Radiant heat is transferred by: A- Ultraviolet rays. B- Infrared rays. C- Ionization. D- Diffraction.
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B : Infrared rays.
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Most electric baseboard units are ________ heaters. A- Natural draft convection. B- Forced draft convection. C- Forced draft conduction. D- Radiant.
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A : Natural draft convection
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Central forced air electric furnaces frequently use _________ to start and stop multiple heating circuits. A: Capacitor. B: Sequencers. C: Limit control. D: Cool anticipators.
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B : Sequencers.
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A sequencer utilizes a __________ to initiate its operation. A: Bimetal heat motor. B: Bimetal snap disc. C: capacitor. D: Nichrome resistor.
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A : Bimetal heat motor.
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The component location in the thermostat that shuts off the electric furnace down prematurely so that the space will not be overheated is the. A: sequencer. B: Cool anticipator. C: Heat anticipator. D: Mercury bulb.
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C : Heat anticipator.
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The disadvantage in using a contactor to open and close the circuit to the electric heating element is the. A: Noise it makes. B: Low control voltage. C: heating element would all be started at the same time unless separate time delay relay were used. D: both A and C.
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D : A and C
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A limit switch or control is used to: A: Start the furnace if the thermostat malfunction. B: Insure that the fan stop when the furnace cool down. C: start the furnace prematurely on a cold day. D: Open the circuit to the heating elements if the furnace overheats.
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D : Open the circuit to the heating elements if the furnace overheats.
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Electric unit heaters are usually installed: A: Hanging from the ceiling. B: As baseboard heat. C: As forced air furnaces. D: For hot water systems.
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A : Hanging from the ceiling
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Electric ceiling panel heat: A: easily adapts to central air conditioning. B: Is radiant type heat. C: Uses circulating hot water. D: Can easily have humidify equipment added to the system.
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B : Is radiant type heat
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The _____________ thermostat is commonly used for forced air electric furnace installations. A: Low voltage. B: All voltage. C: No voltage. D: High voltage.
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A : Low voltage.
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The _____________ thermostat is commonly used for baseboard electric installations. A: Low voltage. B: All voltage. C: No voltage. D: High voltage.
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D : High voltage.
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The control voltage for the controls on a sequencer are typically: A: 24V. B: 208V. C: 460V. D: 12V.
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A : 24 V.
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An electric furnace is operating on 225 V and is drawing 83 amps. What heat capacity is this furnace putting out? A: 55,787 Btu/h. B. 33,467 Btu/h. C: 98,953 Btu/h. D: 63,738 BTU/h.
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D : 63,738 BTU/h.
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83amp x 225 v = 18,675 watts x 3.413 BTU/Watts
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The kw rating of an electric of an electric heater is the ____________(temperature rating, power rating, voltage rating, or name of the power company)
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Power Rating
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The Btu rating is a rating of the _________ (time, wire size, basis for power company charges, or heating capacity)
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Heating capacity
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The factor for converting watts to BTU is ________
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BTU/h = Watts X 3.413.
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A kw is _______ (1000 watts, 1200 watts. Or 10000 watts)
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KW = 1000 watts
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The typical air temperature rise across an electric furnaces normally considered (high or low) compared to a gas furnace.
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Low
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The air temperature at the outlet grilles of an electric heating system is considered (hot or warm) compared to a gas furnace.
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warm
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The circulating fan motor normally runs on (high or low) speed in the heating mode
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Low
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What is the current rating of a 7.5 kw heater operating at 230 volts?
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32.61 Amps
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I = P/E
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A 12 kw heater will put out _______Btu per hour.
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40,956Btu/h
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Btu/h = watts x 3.413
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Most heat anticipators are _______ (fixed resistance or variable resistance)
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Variable resistance
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A heat anticipator that is set wrong may cause _______ (no heat, excessive temperature swings, or noise in the system)
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Excessive temperature swings
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If the service technician momentarily shorted across the sequencer heater coil, it would cause which of the following? (blown fuse, burned heat anticipator, the heat turned on, or the cooling turned on)
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Burned heat anticipator
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All heating thermostats have heat anticipator. (true or False)
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False.
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When system has several sequencers that would cause too much current draw through the heat anticipator, which of the following could be done to prevent the anticipator from burning up ? A Install a higher amperage rated thermostat. B Wire the sequencer so that all of the coils did not go through the anticipator. C Change to a package sequencer. D B or C
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D : B or C.
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The heat anticipator differs from the cooling anticipator (True or False)
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TRUE
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When the furnace is two stage, there are how many heat anticipator
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Two if two stage thermostat is used.
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The heat anticipator is located in which component? (Thermostat or sub base)
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Thermostat
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If the heat anticipator was burned so that it was in two parts, the symptoms would be which of the following? A : No heat B : Too much heat. C : The cooling would come on. D : The residence would overheat
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A : No heat
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Low voltage controls are used for which of the following reasons? A : Less Expensive. B : Easier to troubleshoot. C : More Reliable D : Safety
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A and D
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Low voltage wire has an insulation value for which of the following? A : 50 V B : 100 V C : 500 V D : 24 V
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A : 50 V
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Wire size determined by which of the following? A : Voltage. B : Amperage. C : Ohms. D : Watts.
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B : Amperage.
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The gage of wire that is normally used in residential low voltage control circuits is which of the following? A : No. 12 B : No. 18 C : No. 14 D : No. 22
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B : No. 18
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Low Voltage wire always has to be run in conduit. (True or False)
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False.
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The normal low voltage for control circuits is which of the following? A : 50 V B : 24 V C : 115 V D : 230 V
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B : 24 V
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