HEAT Test Flashcards
A slight glass would normally be located:
A) in the liquid line, ahead of the metering device
B) in the suction line, ahead of the compressor
C) either A or B
D) neither A or B
A) in the liquid line, ahead of the metering device
Bubbles in a sight glass could be an indication of:
A) an overcharged of refrigerant
B) a Low refrigerant charge
C) a restriction in the filter-drier (if the sight glass is after the filter-drier)
D) either B or C
D) either B or C
A clear sight glass could indicate:
A) all liquid refrigerant
B) no refrigerant
C) either a or b
D) neither a or b
C) either a or b
Which of the following is TRUE of a solenoid in a pump down system?
A) it is located after the metering device
B) it is located before the metering device
C) it is located after the evaporator
D) it is used instead of a metering device
B) it is located before the metering device
A Low pressure cut-off switch is used to:
A) establish a minimum operating pressure in the evaporator
B) prevent condensing pressure from reaching dangerously high levels
C) sense oil pressure in the lower portion of the compressor
D) all of the above
A) establish a minimum operating pressure in the evaporator
A good description of a how bi-metal fan switch operates the blower motor on a gas furnace is:
A) temperature on-time off
B) time on-temperature off
C) temperature on-temperature off
D) time on-time off
C) temperature on-temperature off
Redundant gas valves used on gas furnaces will shut down if the gas pressure exceeds:
A) 30.5 in W.C.
B) 60.5 in W.C.
C) 10.5 in W.C
D) 13.5 in W.C
D) 13.5 in W.C
Burning one cubic foot of Liquefied Petroleum gas will completely produce approximately _________ BTU’s
A) 2000-2500
B) 1500-2000
C) 1200-1500
D) 900-1100
A) 2000-2500
What is the purpose of a spoiler screw located on a burner, or adjustable-shutters?
A) mix combustion and dilution air
B) mix primary and secondary air
C) mix primary air and gas
D) mix dilution and excess air
C) mix primary air and gas
Furnace limit switches are wired in series with:
A) low speed fan
B) high speed fan
C) gas valve
D) heat anticipator
C) gas valve
A technician determines that a natural gas furnace has a defective heat exchanger. The technician should:
A) inform the homeowner
B) turn the thermostat off
C) turn the gas valve to the furnace off
D) all of the above
D) all of the above
A natural gas (standing pilot) furnace usually requires ______ gas pressure at the manifold and burners.
A) 3.5 in W.C
B) 4.2 in W.C
C) 5.0 in W.C
D) 7.0 in W.C
A) 3.5 in W.C
LP gas has a specific gravity of:
A) .4-.8
B) 1.0-1.1
C) 1.5-2.0
D) 2.5-3.0
C) 1.5-2.0
All condensing furnaces manufactured after 1992 must have an AFUE rating of at least:
A) 80%
B) 86%
C) 90%
D) 96%
A) 80%
The proper chemical name for natural gas is:
A) methane
B) propane
C) butane
D) octane
A) methane
A furnace nameplate specifies a temperature rise of 40-70 degrees. Temperature measurements indicate a rise of 80 degrees. The most appropriate action is to:
A) decrease fan speed
B) adjust the gas pressure regulator
C) increase fan speed
D) reduce burner size
C) increase fan speed
A BTU is the amount of heat required to raise the temperature of one pound of water:
A) one degree centigrade
B) one degree Fahrenheit
C) one degree Celsius
D) one degree kelvin
B) one degree Fahrenheit
Gas piping must be installed with a pitch of:
A) 1” per 15’ of run
B) 1/2” per 15’ of run
C) 1/3” per 15’ of run
D) 1/4” per 15’ of run
D) 1/4” per 15’ of run
Pipe joint compound should be applied to:
A) male threads completely
B) male threads less two end threads
C) both male and female threads
D) female threads
B) male threads less two end threads
A technician is installing a copper elbow on LP gas line; what type of solder is recommended?
A) rosin core solder
B) 95/5 solder
C) 0% silver
D) 15% silver
D) 15% silver
To burn one cubic foot of natural gas completely, at least _______ of combustion air must be available.
A) 5 cu ft
B) 10 cu ft
C) 15 cu ft
D) 20 cu ft
B) 10 cu ft
Air that is mixed with natural gas in the burner is called:
A) primary air
B) combustion air
C) excess air
D) dilution air
A) primary air
A natural gas furnace is operating properly. How many cubic feet of flue gas are needed for every one cu ft burned?
A) 5 cu ft
B) 10 cu ft
C) 20 cu ft
D) 30 cu ft
D) 30 cu ft
Fan time/temperature delay switches are used on gas furnaces to:
A) allow the vent to create proper draft
B) remove condensation from the manifold
C) allow the heat exchanger to warm up
D) both A and C
C) allow the heat exchanger to warm up
A technician needs to run the thermostat wire 75 feet. To avoid a voltage drop, the technician should use:
A) 16 AWG
B) 18 AWG
C) 20 AWG
D) 22 AWG
B) 18 AWG
A good thermocouple should read approximately________on a D.C. meter.
A) 12 volts
B) 24 volts
C) 18 milli-volts
D) 250 milli-volts
C) 18 milli-volts
What is current flow?
A) flow of voltage in a circuit
B) the impedance of a circuit
C) the inductive reactance of the circuit
D) the flow of electrons in the circuit
D) the flow of electrons in the circuit
What is impedance?
A) opposition to alternating current flow
B) electrical pressure
C) amperage
D) voltage applied to the circuit
A) opposition to alternating current flow
Any material that will readily release electrons is called?
A) an insulator
B) a conductor
C) a resistance
D) a neutron
B) a conductor
The symbol for current is:
A) E
B) I
C) R
D) W
B) I
Electricity can produce:
A) heat
B) light
C) magnetism
D) all of the above
D) all of the above
The safety ground conductor is usually color coded:
A) red
B) black
C) green
D) white
C) green
An electron has:
A) no charge
B) a negative charge
C) a positive charge
D) extra charge
B) a negative charge
What is resistance?
A) opposition to current flow
B) electrical pressure
C) amperage
D) voltage applied to the circuit
A) opposition to current flow
How are fused sized?
A) amps
B) volts
C) watts
D) both A and B
D) both A and B
Capacitors are rated in:
A) amperes
B) microfarads
C) volts
D) both B and C
D) both B and C
One horsepower is equal to how many watts?
A) 3.416
B) 746
C) 1200
D) 208
B) 746
In a series circuit, the voltage drop across each resistance (load) will:
A) always add up to equal the source voltage
B) depend on the value of each resistor
C) depend on the current flow in the circuit
D) all of the above
D) all of the above
Which of the following statements about current is true?
A) current flow is the same as voltage
B) current flow will increase when voltage increases
C) current flow will increase when resistance increases
D) current flow will decrease when voltage increases
B) current flow will increase when voltage increases
Which of the following statements is the correct formula for determining wattage in an electrical circuit?
A) W=E times I
B) W=E/R
C) W=I/R
D) W=E times R
A) W=E times I
Amperes can be calculated by:
A) E/R
B) W/E
C) The square root of W divided by R
D) all of the above
D) all of the above
Three resistors are wired in parallel. Two of the resistors have a value of 12 ohms; one resistor has a value of 6 ohms. What is the total resistance of the circuit?
A) 30 ohms
B) 18 ohms
C) 3 ohms
D) it is not possible to wire resistors of different values in parallel
C) 3 ohms
Capacitors are always connected to the start winding:
A) parallel
B) in series
C) through a relay
D) through a diode
B) in series
A device used to control a motor is a:
A) relay
B) contactor
C) line starter
D) all of the above
D) all of the above
This type of drawing illustrates where the components are located on the appliance:
A) pictorial
B) schematic
C) ladder diagram
D) outside
A) pictorial
When testing a capacitor with an analog ohmmeter, the needle on the meter should:
A) show no deflection and remain on an infinite reading
B) deflect towards zero then return to infinite reading
C) deflect to zero and stay there
D) deflect halfway between zero and infinity and stay there
B) deflect towards zero then return to infinite reading
Heat which causes a change in temperature of a substance is called:
A) latent heat
B) sensible heat
C) superheat
D) regular heat
B) sensible heat
Heat which causes a change in state of a material without a change in temperature is called:
A) latent heat
B) sensible heat
C) superheat
D) regular heat
A) latent heat
Heat which is added to a vapor after the change of state occurs is called:
A) latent heat
B) sensible heat
C) superheat
D) regular heat
C) superheat
A refrigerant gives up heat when:
A) it condenses
B) it evaporates
C) it is compressed
D) it vaporizes
A) it condenses
The state of the refrigerant in the suction line should be:
A) high pressure/high temperature liquid
B) high pressure/low temperature vapor
C) low pressure/low temperature liquid
D) low pressure/low temperature vapor
D) low pressure/low temperature vapor
The evaporator:
A) transfers heat from the refrigerated space to the refrigerant
B) transfers heat from the refrigerant to the refrigerated space
C) transfers heat from the refrigerant to the ambient air
D) transfers heat from the ambient air to the refrigerated space
A) transfers heat from the refrigerated space to the refrigerant
The order of stages in the vapor-compression process are:
A) expansion, condensation, compression, vaporization
B) vaporization, expansion, condensation, compression
C) compression, condensation, expansion, vaporization
D) expansion, compression, vaporization, condensation
C) compression, condensation, expansion, vaporization
Pressures lower than atmospheric are measured in:
A) inches of mercury (hg)
B) microns
C) PSIG
D) either A or B
D) either A or B
Heat can travel by:
A) conduction
B) convection
C) radiation
D) all of the above
D) all of the above
Zero PSIG is:
A) the same as atmospheric pressure
B) approximately 14.7 PSIG at sea level
C) a pressure which cannot be further reduced
D) both A and B
A) the same as atmospheric pressure
The temperature at which moisture will start to condense from the air is called:
A) dry bulb temperature
B) wet bulb temperature
C) dew point temperature
D) all of the above
C) dew point temperature
A compound pressure gauge measures:
A) pressure and vacuum
B) pressure and temperature
C) pressure and humidity
D) wet bulb and dry bulb temperatures
A) pressure and vacuum
Liquid slugging is:
A) a pounding noise caused by liquid refrigerant in the suction line at the point of restriction
B) noise caused by excessive liquid refrigerant in the condenser
C) liquid refrigerant in the compressor clearance space
D) excessive liquid refrigerant in the receiver
C) liquid refrigerant in the compressor clearance space
Which of the following will cause a change in compressor capacity?
A) suction pressure
B) discharge pressure
C) refrigerant vapor density
D) all of the above
D) all of the above
A customer tells a technician that his six month old furnace stops heating before the residence is warm. This happens only on very cold nights. The technician lights the furnace, tries to adjust the gas valve, but the flames do not change. He suspects:
A) a defective ignition module B) a defective gas valve regulator C) incorrect heat anticipator D) intermittent vent fan operation
B) a defective gas valve regulator
A standing pilot furnace has a bi-metal fan control. What are the factory setting?
A) Fan on 125F /Fan off 110F/ limit cut out 200F
B) on 125F/ off 80F/ limit 200F
C) on 95F/ off 110F/ limit 250F
D) on 95F/ off 80F/ limit 250F
A) Fan on 125F /Fan off 110F/ limit cut out 200F
The main function of the condenser is to A. Store liquid refrigerant B. Remove heat from the refrigerant C. Remove moisture from the refrigerant D. Add heat to the refrigerant
B. Remove heat from the refrigerant
The standard unit for measuring the quantity of heat in a substance is A. Degrees Fahrenheit B. Degrees Celsius C. Degrees rankin D. The British thermal unit
D. The British thermal unit
The heat removed from the refrigerant by the condenser is A. Sensible heat B. Latent heat C. Both sensible and latent heat D. Neither sensible or latent heat
C. Both sensible and latent heat
When testing the efficiency of an air cooled condenser, the refrigerant condensing temperature should be no more than\_\_\_\_\_\_\_\_\_ higher than the entering air temperature A. Approximately 30F B. Approximately 80F C. Approximately 100F D. Approximately 5F
A. Approximately 30F
The first function a condenser must perform is to\_\_\_\_\_\_\_\_\_ the refrigerant before condensing can occur A. Superheat B. De-superheat C. Compress D. Sub-cool
D. Sub-cool
A thermostatic expansion valve is designed to maintain A. Constant evaporator temperature B. Constant refrigerant flow C. Constant evaporator superheat D. Constant evaporator pressure
C. Constant evaporator superheat
The automatic expansion valve is designed to maintain A. Constant evaporator temperature B. Constant refrigerant flow C. Constant evaporator superheat D. Constant evaporator pressure
D. Constant evaporator pressure
An automatic expansion valve is best suited
A. When the system load remains fairly constant
B. When the system load varies greatly
C. When the compressor must start often
D. When multiple evaporators are used
A. When the system load remains fairly constant
The proper name of the tool used to cut the threads of a steel pipe is a:
A) pipe cutter
B) reamer
C) ratchet head cutter
D) die
D) die
A yellow flame indicates:
A) incomplete combustion is occurring. Soot may be created, which further hampers burner operation. Lack of primary air is the main cause.
B) the gas velocity is faster than the speed at which the gas can burn.
C) the gas flowing slower than the speed at which the burn is occurring.
D) incomplete combustion is the cause. Floating flames must me corrected. Carbon monoxide is present in the burner area, and this can create serious health and safety risks.
A) incomplete combustion is occurring. Soot may be created, which further hampers burner operation. Lack of primary air is the main cause.
A lifting flame indicates:
A) incomplete combustion is occurring. Soot may be created, which further hampers burner operation. Lack of primary air is the main cause.
B) the gas velocity is faster than the speed at which the gas can burn.
C) the gas flowing slower than the speed at which the burn is occurring.
D) incomplete combustion is the cause. Floating flames must me corrected. Carbon monoxide is present in the burner area, and this can create serious health and safety risks.
B) the gas velocity is faster than the speed at which the gas can burn.
A technician connects the electrical circuit to an 80000 BTU gas furnace with a 3 ton cooling system. The fan motor is rated @ 1/3 HP @ 120 VAC. What size conductor would normally be used?(copper conductors)
A) 8-10 AWG
B) 12-14 AWG
C) 16-18 AWG
D) 20-22 AWG
B) 12-14 AWG
How much current does a typical flame sensor produce?
A) 1-30 micro-amps
B) 30-200 micro-amps
C) 1-3 pico-amps
D) 300-200 pico-amps
A) 1-30 micro-amps
Flashback indicates:
A) incomplete combustion is occurring. Soot may be created, which further hampers burner operation. Lack of primary air is the main cause.
B) the gas velocity is faster than the speed at which the gas can burn.
C) the gas flowing slower than the speed at which the burn is occurring.
D) incomplete combustion is the cause. Floating flames must me corrected. Carbon monoxide is present in the burner area, and this can create serious health and safety risks.
C) the gas flowing slower than the speed at which the burn is occurring.
A customer complains that a 2 year old gas furnace will not light. The technician determines that the furnace locks out while attempting to light. He reads 19 VAC at the gas valve and concludes:
A) the electronic board is faulty
B) the gas valve is shorted
C) the transformer could be faulty
D) both B and C
C) the transformer could be faulty
Induced draft furnaces have a vent safety switch that should open at _________
A) 80F
B) 100F
C) 120F
D) 140F
D) 140F
To change the speed of a belt driven blower, the technician should:
A) adjust motor and blower wheel pulleys
B) adjust blower wheel pulley
C) adjust motor pulley
D) change blower wheel
A) adjust motor and blower wheel pulleys
A gas furnace has an electronic board. How is the fan cycled during heating?
A) heat relay
B) cooling bi-metal
C) temperature
D) time
D) time
Which of the following is NOT true of a capillary tube metering device?
A. They have no moving parts
B. They allow pressures to equalize after the compressor shuts down
C. They are not sensitive to system debris
D. They are sized to match system capacity
C. They are not sensitive to system debris
A decrease in superheat causes the thermostatic expansion valve to A. Open B. Close C. Fail D. None of the above
B. Close
In an air conditioning system that uses a thermostatic expansion valve, the temperature of the evaporator outlet will usually be A. Cooler than the evaporator inlet B. Warmer than the evaporator inlet C. The same as the evaporator inlet D. Unchanged by superheat
B. Warmer than the evaporator inlet
A rise in evaporator pressure causes the automatic expansion valve to A. Open B. Close C. Fail D. None of the above
B. Close
Refrigerant enters an evaporator as ______
A. Liquid only
B. Vapor only
C. A mixture of liquid with some flash gas
D. Superheated vapor only
C. A mixture of liquid with some flash gas
In the evaporator
A. Latent heat is transferred from the refrigerated space to the refrigerant
B. Latent heat is transferred from the refrigerant to the refrigerated space
C. The refrigerant changes from a vapor to a liquid
D. The refrigeration system reaches its highest pressure
A. Latent heat is transferred from the refrigerated space to the refrigerant
A liquid receiver is used
A. To prevent liquid refrigerant from reaching the compressor
B. To separate oil from the liquid refrigerant
C. To store liquid refrigerant
D. All of the above
C. To store liquid refrigerant
An accumulator is used
A. To prevent liquid refrigerant from reaching the compressor
B. To separate oil from the liquid refrigerant
C. To store liquid refrigerant
D. All of the above
A. To prevent liquid refrigerant from reaching the compressor
A floating flame indicates:
A) incomplete combustion is occurring. Soot may be created, which further hampers burner operation. Lack of primary air is the main cause.
B) the gas velocity is faster than the speed at which the gas can burn.
C) the gas flowing slower than the speed at which the burn is occurring.
D) incomplete combustion is the cause. Floating flames must me corrected. Carbon monoxide is present in the burner area, and this can create serious health and safety risks.
A) incomplete combustion is occurring. Soot may be created, which further hampers burner operation. Lack of primary air is the main cause.
A gas furnace has an induced draft fan. What switch must operate properly before ignition sequence?
A) fan limit
B) dilution air
C) rollout
D) different air pressure
D) different air pressure
Before working on an electrical furnace, the technician should:
A) review wiring diagram
B) remove jewelry and watches
C) follow safety procedures
D) all of the above
D) all of the above
A technician is using an extension ladder to work on a roof top unit. The top of the ladder should extend ________ beyond the support point.
A) 1 foot
B) 2 feet
C) 3 feet
D) 4 feet
C) 3 feet
When a pressure regulator handle becomes extremely hard to turn, the safest way to correct the problem is to:
A) use a high quality, light oil on the handle
B) take the regulator apart and repair it
C) have it repaired by a specialist, use no oil
D) use high quality white grease, never use oil
C) have it repaired by a specialist, use no oil
When using nitrogen and refrigerant trace for leak testing, you should always:
A) put the nitrogen in first and then the refrigerant
B) put the refrigerant in first, valve off and remove refrigerant cylinder, and then add nitrogen until stated test pressure is reached
C) you should use nitrogen only; refrigerant cannot be legally released after the pressure test
D) not necessary to valve off and remove refrigerant cylinder as additional trace refrigerant may need to be added to locate the leak
A) put the nitrogen in first and then the refrigerant
You are required to work on a system where the power supply is remotely located from the equipment, you should;
A) have a helper cut off the power to the circuit and remain at the panel until you compleat the required task
B) cut the power off to the equipment, tag the circuit and put your name, date and time on the tag
C) tag is not necessary if the electrical room is locked
D) lock and tag the electrical circuits in the off position before working on them. If work is interrupted, confirm that the circuits are deenergized before resuming work
D) lock and tag the electrical circuits in the off position before working on them. If work is interrupted, confirm that the circuits are deenergized before resuming work
A technician should never use an oxy-acetylene torch to remove a compressor or component from the refrigerant circuit because:
A) copper tubing could be damaged making compressor replacement more difficult
B) refrigerant oil could ignite, causing a fire, and create toxic fumes
C) acetylene when combined with refrigerant oil can create phosphorus gas
D) seldom enough space to use a torch without damaging other system components
B) refrigerant oil could ignite, causing a fire, and create toxic fumes
When using the wire brush on a hand held pedestal grinder, one should use the following eye protection:
A) safety glasses with side shield
B) safety goggles
C) safety glasses with full side shield and a full face shield
D) safety glasses with semi-side shield
A) safety glasses with side shield
Due to the nature of our work, technicians are subject to being caught outside during a thunderstorm. If caught in a thunderstorm, you should:
A) touch metal objects
B) go near trees, poles, hills, clothes lines, overhead wires, metal pipes, or water
C) congregate with others, there is safety in numbers
D) get into a building, vehicle, or under a covered porch
D) get into a building, vehicle, or under a covered porch
How do manufacturers of products inform their users of all potential hazard associated with using their products?
A) warning labels
B) directions for their intended use
C) material safety data sheets (MSDS)
D) toll free number to call in the event of an emergency
A) warning labels
Who is ultimately responsible for your personal safety?
A) the company owner accept responsibility
B) the immediate supervisor accept responsibility
C) the company safety officer accept responsibility
D) you must accept responsibility
D) you must accept responsibility
