Heating, Ventilation, Air Conditioning and Refrigeration

When should you reqd a product's safety Data Sheet (SDS)?

• Whenever an OSHA inspector is on the job site
• After completing the job so you can file all the required safety reports
• Whenever you accidentally contact the material to find out what treatment is recommended
• Before using the material so you are aware of its hazards

What difference is there between handling zeotropes and azeotropes?

• Zeotropes can be flammable and azeotropes are non-flammable
• Zeotropes must leave the cylinder as a liquid but azeotropes may leave the cylinder as either a liquid or a vapor
• Azeotropes must leave the cylinder as a liquid but zeotropes may leave the cylinder as either a liquid or a vapor
• There is no difference in how Zeotropes and azeotropes are handled.

The temperature of a boiling liquid

• Is set by the physical properties of the liquid and does not change
• Is set by the chemical properties of the liquid and does not change
• Is controlled by the pressure on the liquid
• Is controlled by the rate that heat is applied to the boiling liquid

A heat process that causes a substance to change state is called

• Latent heat
• Total heat
• Sensible heat
• Specific heat capacity

The purpose of an airflow switch in a humidity control subsytem is to

• Shut the fan off
• Lower the relative humidity in the duct
• Protect the humidifier if the fan stops
• Protect against putting water in the ducts

Most materials that are good electrical conductors

• Will transfer heat by convection, but not by conduction
• Also tend to make good thermal conductors
• Will transfer heat by radiation, but not by conduction
• Are poor thermal conductors

How does a fluorescent dye leak detector work?

• It is applied evenly to the outside of an area suspected of a leak
• It dyes the refrigerant, so that escaping gas leaved a visible cloud
• It dyes the refrigerant oil so that escaping oil leaves traces of dye
• It is used in conjunction with ultrasonic detectors to improve that resolution of the mechanical ultrasound

The match of the motor and compressor inside a hermetic compressor

• Is generally not critical, allowing a single compressor to cover a wide range of applications
• Is made in the field by the installing technician
• Is specific for the application of the compressor
• Is typically 1 horsepower per ton for nearly all applications

How many BTUs will a 10-kilowatt heater produce if operated for an hour?

• 10 kw/3410 BTUs = 2.93 BTUs
• 10 kw x 1000w/kw x 1 hour x 3.410 BTUs = 34100 BTUs
• 10 kw 1 hour = 10,000 BTUs
• (10 kw / 3410) x 60 = 176 BTUs

A compressor with a suction pressure of 120 psig and a discharge pressure of 480 psig compression ratio of?

• 480/120 = 4 to 1
• (480 * 120)/(480+120)=57,600/600 = 96 to 1
• (480 + 15)/(120 + 15) = 495/135 = 3.67 to 1
• (480 -15)/(120 - 15) = 465/105 = 4.4 to 1

A mechanical refrigeration system cools a room by

• Adding cold to the room until the level of cold reaches the proper level
• Removing heat from the room
• Realigning the air molecules in the room
• Radiating cold energy into the room

Atmospheric pressure is created by

• The weight of the air in the atmosphere
• Centrifugal force created by the spinning of the earth
• The earth's magnetic field
• There is no such thing as atmospheric pressue

Where isthe best place to mount the components of a pneumatic control system?

• Close to the equipment it is controlling
• On a steady base away from vibration
• On the side of an air handler
• Close to main air supply

Air conditioning window units for homes were first available in

• 1950s
• 1960s
• 1940s
• 1970s

Heat flows from the product into the evaporator because

• The refrigerant in the evaporator has fewer Btus/lb than the product
• The refrigerant in the evaporator has a lower specific heat than the product
• The evaporator is at a lower temperature than the product
• The evaporator is at a lower pressure than the product

What adjustment should you make if you find that the output voltage of a dual-input electronic controller is not what you predicted it would be?

• Ratio dial
• Throttling range
• Decade box
• Set point dial

What is the main difference in calibration between a single-input controller with remote sensor and one with a built-in sensor?

• The dials must all be set to the specified values
• The temperature must be measured at the sensor
• A temperature simulator cannot be used in calibration
• You must allow extra time for the system to stabilize

Tube in tube, shell and coil, and shell and tube are all different types of

• Water cooled condensers
• Evaporative condensers
• Natural draft condensers
• Air cooled condensers

A compressor crankcase heater is used to

• Prevent off cycle refrigerant migration to the compressor crankcase
• Maintain the crankcase pressure above a vacuum
• Encourage refrigerant to return to the compressor crankcase for the next start up cycle
• Keep the motor winding warm for improved energy effciency

The failure of a control circuit to respond after calibration could be due to

• A broken diaphragm
• A short in the controller
• The linkage out of adjustment
• An open in the motor windings

What units are used to measure vacuum?

• In reciprocal psi (1/psi)
• In inches of mercury
• In negative psi (-psi)
• In negative pascals (-p)

The difference between a liquid receiver and a suction accumulator is that

• Receivers only allow liquid to leave while accumulators only allow vapor to leave
• An accumulator is located on the low side just before the compressor
• A liquid receiver is used after the condenser on the high side
• All of the above

The temperature difference between the bubble point and the dew point of a zeotropic refrigerant

• Saturation
• Subcooling
• Superheat
• Glide

Fan cycling, fan speed control, damper control, and condenser flooding are different types of

• Condenser low ambient controls
• Energy efficiency improvements
• Protection against excessively high condenser pressures
• System capacity control

What is used in a humidity control subsytem to keep the humidity in the ductwork from getting to high?

• Airflow switch
• Normally closed humidifier
• Low-limit humidity controller
• High-limit humidity controller

When the pressure to the control point adjustment port of a pneumatic controller increases,the setpoint

• Stabilizes
• Decreases
• Increases
• Stays the same

Matter is defined as

• Anything that has mass and takes up space
• Physical objects that can be seen
• Anything that has weight, can be seen, and emits energy
• Physical objects that emit energy

The heat that changes water at 212* F to steam at 212*F is known as

• Latent heat of vaporization
• Latent heat of condensation
• Sensible heat of vaporization
• Sensible heat of condensation

What size energy monitoring and control system (EMCS) system has 50 to 600 points?

• Large
• Medium
• Small
• Micro

Calculate the amount of heat required to change 5 lbs of 32o ice to water.

• No extra heat is required because the ice is already at the melting temperature.
• 5 lbs x 144 BTUs/lb = 720 BTUs
• 5 lbs x 32oF x 0.5 BTU/lb = 80 BTUs
• The amount of heat required cannot be calculated without knowing the ending temperature of the water.

The difference between brazing and soldering is that

• Brazing melts the base metal and soldering does not
• Soldering occurs at higher temperatures than brazing
• Brazing occurs at higher temperatures than soldering
• Brazing never requires flux

The mixed-air section for a variable air volume (VAV) system is identical to the one on a single-zone system, unless the

• Cooling discharge temperature rises
• Outdoor-air temperature is too low
• Ventilation requirement drops
• Ventilation load is constant

What is an oil lift?

• An oil lift is an electric oil pump that moves collected refrigerant oil up against gravity
• An oil lift is the increase in pressure created in the suction line due to the presence of refrigerant oil
• An oil lift is a trap at the bottom of a vertical suction riser
• An oil lift helps return oil up a vertical riser using an integral orifice tube which creates a Bernoulli effect, forcing oil up the line

Whis test is essentially the same as the performance verification test?

• Basic field test
• Opposite season test
• Operation of outputs test
• Surge protection verification test

The major safety concern with R-410A is that

• R-410A operates at much higher pressures than most conventional refrigerants
• R-410A is flammable
• R-410A is toxic
• All of the above

What form of heat transfer most commonly used in the HVAC indusrty is

• Conduction
• Convection
• Radiation
• Radiant

Why is a large refrigerant leak potentially dangerous?

• Most common refrigerants used in residential systems are highly flammable
• Most common refrigerants used in residential are highly toxic
• Most common refrigerants used in residential systems are highly corrosive
• Asphyxiation can result from refrigerant displacing the air

Water vapor in the air condenses on the evaporator coil

• Whenever the evaporator is below dewpoint temperature of the air
• Whenever there is moisture in the refrigerant
• Whenever the system is operating
• All the time, even when the system is not operating

What physical change of state is the opposite of evaporation?

• Melting
• Sublimation
• Freezing
• Condensation

To the closest tenth, what is normal atmospheric presure sea level?

• 11 psi
• 14.7 psi
• 110 psi
• 340 psi

Campers being heated by a fire outside is an example of

• Radiation
• Sublimation
• Convectin
• Conduction

What would the resistance be for an electronic controller with a reference tempetature of 70*F, a reference of 100 ohms, and a rate of change of 2.2 ohms/degree that is sensing 65*F?

• 989 ohms
• 999 ohms
• 1011 ohms
• 1022 ohms

A system with a loose TEV sensing bulb would most likely

• Have a low superheat
• Have a high superheat
• Have a lower than normal evaporator pressure
• Need adjusting to compensate for the poor bulb installation

Perform recalibration procedures on direct digital control (DDC) systems according to the

• Applicable air force instruction
• Manufacturer's instruction
• Local building codes
• Craftsman's discretion

Use the following information to answer the question:Honeywell 908BTotal change set point = 10*FTotal change CPA pressure = 5 psiSpan of sensor = 100*F (0* to 100*F)If you used the second port of a pneumatic dual-input controller as a control adjustment, what should the authority setting be to obtain the desired performance?

• 6 percent
• 12 percent
• 24 percent
• 48 persent

The separation of the refrigerant components in a zeotropic refrigerant when the refrigerant evaporates or condenses is know as:

• Fractionation.
• Refinement.
• Separation.
• Concentration.

What basic components make-up the diret digital controls (DDC) loop?

• Controller area network (CAN),inputs and outputs
• Personal computer, BAC network, and DCC controller
• Process information, input parameters, and customer needs
• Input from a sensor or device, a building automation controller, and controlled device

The major types of compressors listed by mechanical design are

• Air cooled, water cooled, and refrigerant cooled
• Hermetic, semi-hermetic, and open
• Forward curved, backward curved, radial, in-line
• Reciprocating, rotary, scroll, screw, and centrifugal

Which of the following metering devices can respond to changes in system conditions?

• Fixed restriction
• Orifice
• Thermostatic expansion valve
• Capillary tube

Which statement accurately describes heat flow between two objects?

• Heat travels from the object with the higher BTU quantity to the object with the lower BTU quantity.
• Heat travels from the object with the lower temperature to the object with the higher temperature.
• Heat travels from the object with the higher temperature to the object with the lower temperature.
• Heat travels from the object with the lower BTU quantity to the object with the higher BTU quantity.

Optional components found on the low side of a refrigeration system include

• Discharge line muffler, oil separator, liquid receiver, and liquid line filter-drier
• Suction to liquid heat exchanger, economizer, oil level regulator
• Suction line filter, accumulator, and evaporator pressure regulator
• All optional components can be used on the low side of the system

In the compression refrigeration cycle the refrigerant is superheated

• The refrigerant contains some superheat throughout the cycle
• Leaving the evaporator, through the compressor, up to the condenser
• Leaving the compressor, through the condenser, up to the metering device
• The refrigerant is not superheated anywhere in the compression cycle

How many BTUs are required to raise the temperature of 15 pounds of water from 100o F to 130o F?

• 15 lbs x (130oF - 100oF) = 450 BTUs
• 15 lbs x (130oF + 100oF) = 3450 BTUs
• (130oF/15lbs) - (100oF/15lbs) = 2 BTUs
• The BTUs required cannot be determined using the information given.

What is the maximum reading on a typical R410A high pressure gauge?

• 120 psig
• 300 psig
• 800 psig
• 500 psig

Refrigerants release heat

• By converting refrigerant molecules into heat energy
• By condensing from a vapor to a liquid
• By evaporating from a liquid to a vapor
• By rearranging their molecular structure to form a new compound

What happens to the temperature of boiling water once it starts to boil?

• It increases above the boiling point in proportion to the amount of heat added during the boiling process.
• The water temperature decreases after the water begins to boil.
• The water temperature stays the same once the water begins boil.
• It increases to 1o F above the boiling point.

Oversized suction lines:

• Can cause poor oil return because of low refrigerant velocity
• Can reduce system efficiency because of a low pressure drop
• Can cause poor oil return because of high refrigerant velocity
• Can reduce system efficiency because of a high pressure drop

To begin a plotting procedure on the psychometric chart, you must know the

• Grains of moisture and specific heat
• Dewpoint and wet-bulb temperatures
• Wet-bulb and dry-bulb temperatures
• Dry-bulb and dewpoint temperatures

Capillary tube metering devices are commonly used today in

• Large spit system air conditioning systems
• Window units
• Commercial refrigeration rack systems
• Low pressure chillers

A device used to evenly distribute mixtures of liquid and vapor refrigerant leaving the TEV to multiple evaporator circuits is called a

• Refrigerant distributor
• Refrigerant manifold
• Refrigerant junction
• Refrigerant header

A compressor which compresses gas between a fixed spiral and an orbiting spiral is a

• Centrifugal compressor
• Screw compressor
• Scroll compressor
• Rotary compressor

Compressor cylinder unloading reduces the capacity of a reciprocating compressor by

• Disconnecting the pistons in the unloaded cylinders
• Blocking off the discharge port in the unloaded heads
• Flooding the unloaded cylinders with oild
• Making the valves in the head inoperative

The two general categories of metering devices are

• Fixed and modulating
• High pressure and low pressure
• Copper and brass
• Pressure reducing and pressure increasing

What is the first step in cleaning up a contaminated pneumatic air supply?

• Calibrate the instruments
• Use a degreasing compound
• Stop the contamination at the source
• Retrofit the compressor air supply equipment

Oil accumulation in the evaporator:

• Helps lubricate the walls of the evaporator
• Acts as an insulator reducing the heat transfer of the coil
• Can lead to leaks because refrigerant oil is corrosive to the metal used in evaporator coils
• Improves heat transfer in the exaporator

What is the main purpose of the fins on finned tube evaporators?

• Fins increase the surface area of the coil
• Fins direct the condensed water to the drain pan
• Fins protect the coil from being punctured by projectiles
• Fins direct the air more smoothly across the coil

How do ultrasonic flow meters measure flow?

• By measuring a free moving element into the flow
• By measuring the difference across the orifice plate
• By measuring the vertical plane of a venturi tube
• By detecting changes in sonic paths within the fluid

Soft copper tubing can be joined by

• Flare fittings
• Compression fittings
• Soldering and brazing
• All of the above

Which of the following modifications would need to be made in a long-line system?

• Reducing refrigerant charge
• Using a piston-type orifice at the evaporator
• Adding a compressor hard-start kit
• Removing any compressor crankcase heaters

When gas exerts pressure on its container, the pressure is

• Distributed equally on all surfaces of the container
• Higher at corners and converging surfaces
• Higher near the middle of the container than towards the outside
• Higher on the larger surfaces

What function of the energy management software ensures that a minimum amount of heating or cooling energy is used to satisfy zone temperature requirements?

• Zero energy band
• Optimum start
• Optimum stop
• Load reset

To the lowest level of supervision, who can authorize you to work on energized circuit, if mission critical?

• Chief of operations flight
• HVAC foreman
• Electrical foreman
• Base civil engineer or equivalent

The operation of a thermostatic expansion valve can best be described as

• Evaporator pressure=evaporator pressure + bulb pressure
• Spring pressure = bulb pressure + evaporator pressure
• Bulb pressure = evaporator pressure + spring pressure
• Bulb pressure = evaporator pressure = spring pressure

Which of the following refrigerant safety designations indicate the refrigerant is highly flammable?

• A2
• A1
• B1
• B3

The pointer on a dial type thermometer is moved by a

• Lever which is moved by a column of mercury
• Bi-metal element
• Volatile fluid
• Heat motor and gears

Use the following information to answer this question about a single-input pneumatic controller:What is the ouput of the contoller at 70*F?

• 3 psi
• 8 psi
• 10 psi
• 13 psi

Which troubleshooting step are you using when you divide the section in half to locate the trouble?

• Isolation
• Diagnosis
• Localization
• Sectionalization

How many degrees higher than the expected heating season maximum temperature should you set a supply duct firestat?

• 100*F
• 75*F
• 50*F
• 25*f

Which type of condenser generally operates with a lower discharge pressure?

• Natural draft air cooled condensers
• Forced draft air cooled condensers
• Water cooled condensers
• The discharge pressure is not affected by the type of condenser used.

Hot-water reset is an example of what type of contol loop?

• Open
• Closed
• Combination
• Reverse reset

When can a saturation pressure-temperature chart be used to accurately predict the temperature of a refrigerant if its pressure is known?

• Only when both vapor and liquid are present
• Only when liquid is present
• Only when vapor is present
• Always

If the refrigerant is recovered improperly from a water cooled condenser

• All the water may drain out of the condenser
• The oil dissolved in the refrigerant may crystalize
• The water may freeze
• The water may boil

When the primary variable set point of a pneumatic dual-input controller decreases as the reset variable increases, what is the reset?

• Counter
• Straight
• Direct
• Reverse

What classification would a 100,000 Btuh furnace most likely be?

• Commercial
• Residential
• Industrial
• All of the above

A metal rod is heated on one end and heat travels from that end to the cooler end through the rod. This is an example of

• Conduction
• Radiation
• Convection
• Sublimation

A compressor that uses a high speed impeller to throw the refrigerant outwards is called a

• Screw compressor
• Reciprocating compressor
• Centrifugal Compressor
• Rotary compressor

How does pressure affect the boiling temperature of a liquid

• The pressure cannot change once a liquid begins to boil.
• Increasing the pressure increases the boiling point.
• Decreasing the pressure increases the boiling point.
• Pressure has no effect on the boiling temperature of a liquid.

If desired to maintain a constant temperature in the air leaving a coil, what type of coil control is used?

• Zone control
• Reset control
• Reheat control
• Discharge control

Saturated steam is steam

• With more heat added
• At a temperature below boiling water
• At a temperature above boiling water
• At the temperature of boiling water

What is absolute 0?

• The coldest temperature possible where all molecular motion stops
• The freezing point of water on an absolute temperature scale
• The theoretical starting temperature for quantum physics experiments which is derived by measuring the average rotational velocity of the molecules
• The hottest possible temperature where matter is indistinguishable from energy

The four major components of the compression refrigeration cycle in order are

• Condenser, metering device, compressor, evaporaor
• Compressor, condenser, metering device, exaporator
• Compressor, evaporator, condenser, metering device
• Metering device, condenser, evaporator, compressor

Convert 55 psig to absolute pressure.

• 55 psig - 30 = 25 psia (rounded)
• 55 psig - 15 = 40 psia (rounded)
• 55 psig + 30 = 85 psia (rounded)
• 55 psig + 15 = 70 psia (rounded)

Why are copper fittings cleaned before soldering or brazing?

• To create enough clearance so that the pipe will fit into the fitting
• To remove oxides
• To enhance the aesthetic appearance of the completed joint
• To make it easier to see the junction between the fitting and the pipe.

Calculate the amount of heat required to change 5 pounds of 212o water to steam.

• No extra heat is required because the water is already at the boiling point.
• 5lbs x 212oF x 1 BTU/lb = 1060 BTUs
• 5 lbs x 970 BTUs/lb = 4850 BTUs
• The amount of heat required cannot be calculated without knowing the starting temperature of the water.

What is an absolute temperature scale?

• A temperature scale with no negative temperatures and 0o equal to absolute 0
• A temperature scale that uses sensitive wireless sensors to detect the vibrational frequency of the molecules in a substance to determine its temperature to a high degree of accuracy
• A theoretical temperature scale that only applies to quantum physics
• A thermometer that has been NIST calibrated to be absolutely correct

After you have adjusted the proportinal band and percent authority on a dual-input controller, your next step is to

• Draw performance graph
• Find the sensor pressures
• Disconnect both sensors and connect the simulator
• Measure the output pressure

The pressure of a refrigerant cylinder containing saturated refrigerant

• Is determined entirely by the temperature of the refrigerant
• Is determined entirely by the amount of gas in the cylinder
• Is determined by the amount of liquid in the cylinder
• Is determined by both the amount of refrigerant in the cylinder and the cylinder temperature

Why does the compression refrigeration cycle have a high pressure side and a low pressure side?

• So the refrigerant can evaporate at a low pressure and temperature and condense at a high pressure and temperature
• The pressure difference is not intentionally created, but simply the result of circulating refrigerant with the compressor
• The pressure difference is the result of polar molecular alignment due to the intense magnetic field created by the compressor motor
• So the refrigerant can condense at a low pressure and temperature and evaporate at a high pressure and temperature

What mode of control corrects the problem of offset?

• Proportional-plus-integral
• Proportional-with-reset
• Proportional
• Floating

When you troubleshoot a pneumatic control system, the first component you check is the

• Sensor
• Controller
• Adapter
• Controlled device

What is the purpose of the Refrigeration Service Engineer's Society, RSES?

• To regulate who can work in the refrigeration service field
• To establish standards and codes for good refrigeration engineering practices
• To educate refrigeration service technicians and service managers
• To train engineers who design refrigeration systems

What kinds of pressures are expressed in inches of water column?

• Saturation pressures on a saturation pressure-temperature chart
• Atmospheric pressure or vacuum
• Air pressure in ductwork or a gas line pressure
• Refrigeration system high and low side pressures

An efficient multizone system controls the coils by using the

• Furthest of the zone controllers
• Zone controllers through a discriminator
• Hot-deck controller with the reheat controllers
• Mixed-air controller through a high-pressure selector

What units are most commonly used to measure heat quantity in the United States?

• BTUs
• Degrees Fahrenheit
• Joules
• Kilocalories

What is the maximum reading on a typical R22 high pressure gauge?

• 120 psig
• 500 psig
• 300 psig
• 800 psig

How can a thermocouple tip be used to get an accurate line temperature measurement?

• The thermocouple wire must be wrapped around the line several times to insure good contact
• It must be held firmly against the line and insulated from the surrounding air
• The thermocouple tip must be temporarily soldered to the line
• Thermocouples can not be used to measure line temperatures

The three basic methods of heat transfer are

• Specific, sensible, and latent
• Endothermal, exothermal, and isothermal
• Anterior, inferior, and superior
• Conduction, convection, and radiation

Which saturation temperature is used to determine refrigerant operating pressure temperature

• 50oF
• -58oF
• 0oF
• 104oF

Sensible cooling

• Reduces the air temperature
• Is an interesting theory that has not been proven
• Removes water from the air
• Reduces the air temperature and removes water

Refrigerant leaves the metering device

• In the same physical state that it entered
• As a saturated mixture of liquid and vapor
• As a subcooled liquid
• As a superheated gas

When calibrating a dual-input pneumatic controller, you adjust sensors oneand two to the set point value. Your next step is to adjust the

• Action
• Proportional band
• Percent authority
• Output pressure to equal calibration pressure (Pcal)

To increase latent cooling capacity

• Reverse the direction of airflow over the evaporator
• Raise the evaporator pressure
• Reduce the airflow over the evaporator
• Increase the airflow over the evaporator

In the United States, the cooling capacity of air conditioning equipment is expressed in?

• Calories
• Tons
• Joules
• Therms

The rear pot in the series controller controls the

• Face and bypass dampers
• Reheat value
• Temperature
• Steam coil

What are the chemical components of HFC refrigerant?

• Helium, Freon, and Chlorine
• Hydrogen, Freon, and Chromium
• Hydrogen, Fluorine, and Carbon
• Helium, Fluorine, and Chlorine

The purpose of HI in the terminal reheat system is to pass the signal from the

• Mixed-air controller
• Coil controller
• Warmest zone
• Coldest zone

A low pressure refrigerant has a pressure at the reference saturation temperature

• Between 170 psia and 355 psia
• Below 45 psia
• Above 355 psia
• Atmospheric pressure

When the temperature increases above the set point in series 90 controller controlling a face andbypass damper cooling system, the motor will

• Operate clockwise
• Close the face dampers
• Open the face dampers
• Open the chilled water

Which is the correct formula for converting Fahrenheit to Celsius?

• F = (C x 1.8) + 32
• F = (C x 1.8) - 32
• C = (F - 32) / 1.8
• C = (F + 32) / 1.8

Examples of halogenated refrigerants include

• CFCs, HCFCs, and HFCs
• CFCs and HCFCs only
• CFCs only
• All refrigerants are halogenated

How many watts equal one horsepower of work?

• 746 watts = 1 horsepower
• 1 watt = 1 horsepower
• 1000 watts = 1 horsepower
• 3410 watts = 1 horsepower

Anything that has weight and takes up space is

• Energy
• Matter
• Motion
• Atoms

Types of copper tubing in order of wall thickness from light to heavy are

• L, M, and K
• M, L, and K
• L, M, and L
• K, L, and M

Thermostatic expansion valves respond to changes in

• Temperature
• Superheat
• Pressure
• Subcooling

A heat process that causes a change in a substance's temperature is called

• Latent heat
• Sensible heat
• Total heat
• Specific heat capacity

What material is used for air conditioning drain lines?

• Galvanized iron pipe
• CPVC
• Copper
• PVC

How does an ultrasonic type leak detector work?

• It uses sonar to look for imperfections in the tubing and fittings
• It hears the high pitched sound of escaping gas
• It sees the disturbance in the air surrounding the leak
• All of the above

What is the relationship between atoms and molecules?

• Atoms are made up of molecules
• Molecules are made up of atoms
• They are both weightless
• They are two words for the same thing

Use the following information to answer this question about a single-input pneumatic controller:What is the proportional band required to obtain the desired performance?

• 5 percent
• 10 percent
• 15 percent
• 20 percent

The heat rejected by the condenser

• Equals the heat added by the compressor
• Equals the heat absorbed by the evaporator plus the heat added by the compressor
• Equals the heat absorbed by the evaporator
• Has no relationship to either the evaporator or compressor

What equipment should always be used when using nitrogen?

• An expansion valve to insure that no liquid nitrogen enters the compressor
• A fire extinguisher in case the nitrogen catches on fire
• A pressure regulator and relief valve
• All of the above

The purpose of the high-limit controller in a mixed-air control system is to

• Open the return-damper when outdoor-air temperature is below its setpoint
• Close the return-air damper when the outdoor-air temperature is above its setpoint
• Close the outdoor-damper to minimum when the outdoor-air temperature is above its setpoint
• Open the outdoor-damper to minimum when the outdoor-air temperature is below its setpoint

After you have drawn the performance graph for calibrating a single-input controller, what must you do next?

• Find the transmitting pressure for both corners and the set point
• Use a simulator in place of both sensors
• Set the proportional
• Adjust the controller P cal

A major problem of proprotional control is

• Offset
• Sensitivity
• The throttling range
• The position of the final element

Why are HCFCs not as harmful to the atmosphere as CFCs?

• HCFCs are more chemically stable than CFCs because the contain hydrogen
• HCFCs contain less carbon.
• HCFCs contain less chlorine
• HCFCs are less chemically stable than CFCs because they contain hydrogen.

What sould you do after installing a new eletrical control?

• Give it a complete operational checkout
• The resistance should be dropped
• Handle control carefully
• Replace the cover

When the hand wheels on the gauge manifold are turned counter clockwise

• The pressure in the hoses is shut off from the gauges and no reading can be made
• The pressure is the hoses is allowed to travel up to the gauges for a reading
• Refrigerant flow between the outer hoses and the center hose is shut off
• Refrigerant can flow between the outer hoses and the center hose

When special requirements are line voltage, two-position, and "fail-safe," the type of electrical control motor you should use to operate a damper isthe series

• 40
• 60
• 80
• 90

While calibrating a direct-acting electronic controller with a built-in sensor, if you increases the set point dial to equal half the amount of the throttling range, you provide an output voltage that

• Decreases to half of the actuator range
• Increases to half of the actuator range
• Decreases to the full amount of the actuator range
• Increases to the full amount of the actuator range

Azeotropes are mixtures of two refrigerants

• That do not separate when changing state
• That separate when changing state
• That are chemically bonded to form a new refrigerant
• That are electromagnectically bonded to form a new refrigerant

When selecting an evaporator for an air conditioning system the evaporator should be

• The same nominal size in tons as the condensing unit
• An AHRI match for the condensing unit
• Manufactured by the same manufacturer as the condensing unit
• All of the above

In the compression refrigeration cycle the refrigerant is saturated

• In the compressor and condenser
• In the evaporator and condenser
• Only in the metering device
• Only in the compressor

Suppose you are calibrating an electronic controlling with integral control. After you have obtained the controller performance, what is the next thing you should do?

• Calibrate the controller
• Adjust the controller output
• Turn the integral control action off
• Replace the sensor with a variable resistor

The fins on finned tube coils increase heat transfer by

• Increasing the laminar air flow through the coil
• Increasing the surface area exposed to the air
• Increasing the laminar refrigerant flow through the coil
• Directing the air smoothly across the coil

An evaporator in which refrigerant enters as a saturated liquid vapor mix and leaves as a superheated vapor is a

• Flooded evaporator
• Direct expansion evaporator
• Saturated evaporator
• Carbureting evaporator

To test the integral action of an electronic controller, you should turn off the integral action and increase the V out. If the integral action is working, what will happen when you turn it back on?

• The V out will stay the same
• The V out will increase also
• The V out will decrease
• The V out will cycle

Which sensor is used to measure temperature changes caused by stratification?

• Ceiling diffuser
• Averaging bulb
• Insertion sensor
• Humidity sensor

What meter should you use to check a two-posistion control without power?

• Ammeter
• Voltmeter
• Ohmmeter
• Anemometer

The law of conservation of matter states that

• Matter should not be wasted.
• Matter cannot be created or destroyed.
• Only "green" matter should be used for installing HVACR systems.
• An equal amount of matter is always created somewhere whenever matter is destroyed.

Use the following information to answer this question about a pneumatic sensor:What is the output pressure of a pneumatic sensor with a range of 50* to 100* F if the temperature measured is 80*F?

• 3.0 psi
• 8.6 psi
• 9.4 psi
• 10.2 psi

Who developed the first modern air conditioning system?

• Willis Carrier
• James Trane
• Harold Goodman
• Dave Lennox

The halogen family of chemicals includes

• Carbon and hydrogen
• Chlorine, fluorine, and bromine
• Oxygen, carbon, and hydrogen
• All the chemical elements found in refrigerants are halogens

The absolute temperature scale for Fahrenheit is

• Fahrenheit absolute
• Rankine
• Celsius
• Kelvin

What are the four basic methods of control in a direct digital contol (DDC) system?

• Digital or analog outputs and digital or analog inputs
• Digital outputs and digital or analog inputs, only
• Digital or analog outputs and digital inputs, only
• Digital outputs and digital inputs, only

The basic purpose of the mixed-air control system is to control the amount of

• Return air brought into the system
• Supply air brought into the system
• Outside air brought into the system
• Exhaust air brought into the system

What is the ICE exam?

• Industry Competency Exam given to students to test their knowledge of fundamentals
• Instantaneous Calibration Exam used to check the accuracy of test instruments
• A performance test all the ice machines must pass to become EPA certified
• Industrial cooling Efficiency is a test performed to check industrial cooling equipment

What components in a compression refrigeration system maintains the pressure difference in the system?

• The compressor and condenser
• The metering device and evaporator
• The condenser and evaporator
• The compressor and the metering device

The purpose of the trap in a condensate drain is to

• To keep snakes and insects from crawling up the drain into the coil
• To insure that some water is always standing in the evaporator drain pan
• Provide a place for coil slime to collect so that it can be easily cleaned out
• Offset the negative pressure on the drain which can prevent the water from draining

If a gas with a specific gravity of 1.3 is released in a room, will it be more likely to be found near the ceiling or near the floor?

• It would be found at both the ceiling and the floor because a gas with a high specific gravity would fill up the room
• The specific gravity of a gas does not affect its position in a room relative to other gases
• Near the floor because it's specific gravity is greater than 1
• Near the ceiling because it's specific gravity is greater than 1

What units are most commonly used to measure heat intensity in the United States?

• Kilocalories
• Joules
• BTUs
• Degrees Fahrenheit

On a variable air volume system uses a differential-pressure transmitter, what special component do you need to convert its signal to a proportional velocity pressure for an input signal to the controller?

• Low-pressure selector
• Square-root extractor
• High-pressure selector
• Velocity-pressure extractor

Which type of ladders are safest to use in any working conditions?

• Aluminum ladders
• Any ladder that is structurally sound is safe as long as the power tool is properly gounded
• Fiberglass ladders
• All steel folding ladders

What are the two most common sizes of acetylene cylinders used in the HVAC/R trades?

• Disposable 5 lb and refillable 27 lb
• 22ft3 and 55ft3
• MC and B cylinders
• AC-1 and AC-2

As the refrigerant passes through the condenser, the refrigerant is

• Condensed from a gas to a liquid, and then superheated
• Superheated, condensed from a liquid to a vapor, and then sub-cooled
• Condensed from a gas to a liquid, and then subcooled
• De-superheated, condensed from a gas to a liquid, and subcooled

Three forms of energy used in heating and air conditioning include

• Electrical, Magnetic, Mechanical
• Solid, liquid, and gass
• Preheat, setpoint, postheat
• Saturation, subcooling, superheat

The curved oval metal tube inside a gauge is called

• A pressure transducer
• A strain gauge
• A bourdon tube
• A pressure tube

Copper tubing that comes in rigid, straight lengths is called

• ACR copper
• Soft copper
• Tempered copper
• Hard copper

In which troubleshooting step would you identify the type of system?

• Isolation
• Diagnosis
• Localization
• Sectionalization

The absolute temperature scale for Celsius is

• Kelvin
• Rankine
• Celsius absolute
• Fahrenheit

How does a mimimum-poisition pneumatic adapter relay work?

• It will not allow output pressure to fall below a preset value
• It selects both the high and low signal
• It changes the signal from direct-acting to reverse-acting
• It will not allow the output pressure to go above a preset value

If a refrigeration system's high side pressure is unusually low

• The compressor amp draw may increase
• The evaporator pressure may increase
• The metering device may not supply enough refrigerant to the evaporator
• All of the above

Hard copper tubing can be joined by

• Soldering and brazing
• Flare fittings
• Compression fittings
• All of the above

Small appliances such as household refrigerators and freezers now primarily use

• HFC - 134a
• CFC-12
• HCFC-22
• HFC-410A

Which test includes a sequence of operation demonstration and a control loop stability and accuracy demostration?

• The basic field test
• The performance verification test
• The actuator range adjustment test
• The application software test

As refrigerant passes through the metering device it

• Drops in temperature but not in pressure
• Increases in pressure and temperature
• Drops in pressure and temperature
• Drops in pressure, but not in temperature

The two main types of switches used in electronic controls are

• Double pole, double throw and double pole, single throw
• Single pole, double throw and single pole, single throw
• Snap acting and mercury switch
• Thermostatic and mercury

Why is it dangerous to use gauges only designed for R22 on a R410A system?

• Because R410A can dissolve the lining of the hoses used on R22 systems
• Because the system pressures can exceed the design limit of the R22 gauges
• Because R410A and brass form an explosive new chemical compound on contact
• All of the above

Which Air Force publication gives you electrical safety requirements?

• AFP 91-12
• AFI 32-1064
• AFI 32-1999
• AETCI 32-101

At what point in the refrigeration cycle does the refrigerant lose the most heat?

• In the middle of the condenser where it changes from a gas to a liquid
• In the end of the condenser where the liquid is sub cooled
• In the middle of the evaporator where the cold liquid turns to a cold gas
• In the metering device where it goes in as a warm liquid and leaves as a cold saturated mixture

What is the purpose of annealing copper tubing?

• To harden the tubing and improve its strength
• To remove impurities from the copper
• To prepare the tubing for brazing
• To allow the tubing to be formed without cracking or buckling

You can check the voltage span of most electonic actuators by

• Watching the system work
• Operating the actuator from start to stop
• Adjusting the set point dial
• Changing the voltage output of the contoller

The purpose of subcooling the liquid refrigerant is to

• Increase the system capacity
• Insure a solid stream of liquid to the metering device
• Increase system efficiency
• All of the above

What material is used for refrigerant piping heating, air conditioning, and refrigeration system?

• Galvanized pipe
• Iron pipe
• Aluminum tubing
• Copper tubing

Single-zone systems are typically used where space conditions can be properly controlled with

• One sensor
• Two sensors
• Three sensors
• Four sensors

What is the maximum reading (including retard) on a typical R22 compound gauge?

• 120 psig
• 800 psig
• 500 psig
• 350 psig

What advantages do orifice type metering devices have over capillary tubes?

• They adjust to changing operating conditions.
• They are more efficient.
• They are easy to change
• They equalize during the off cycle.

What is the purpose of flux?

• Promotes wetting of the base metal with the filler metal
• Prevent formation of new oxidation
• Remove light surface oxidation
• All of the above

What type of compressors contain the compressor and motor together inside a welded steel housing?

• Open compressors
• All types of compressors
• Semi-hermetic comprssors
• Hermetic compressors

The preferred tool for cutting PVC pipe is

• A circular saw
• A hack saw
• A plastic tubing shear
• A pocket knife

A very high pressure refrigerant has a pressure at the reference saturation temperature

• Between 170 psia and 355 psia
• Below 45 psia
• Above 355 psia
• Atmospheric pressure

Two materials that are considered good thermal conductors are

• Thermoplastic and rubber
• Copper and aluminum
• Glass and ceramic
• Paper and wood

The heat balance in a compression cycle refrigeration system can be shown as

• The heat picked up by the condenser + the heat of compression = the heat rejected by the evaporator
• The heat picked up by the evaporator + the heat of compression = the heat rejected by the condenser
• The heat picked up by the evaporator = the heat rejected by the condenser
• The heat picked up by the condenser = the heat of compression + the heat rejected by the evaporator

Refrigerants with the highest ozone depletion potential are

• CFCs - chlorofluorocarbons
• HCs - Hydrocarbons
• HFCs - hydroflorocarbons
• HCFCs - hydrochloroflorocarbons

What gases are safe to use for refrigerant system pressure testing?

• Compressed air
• Acetylene
• Oxygen
• Dry nitrogen

Above what temperature do most refrigerant oils begin to fail?

• 150oF
• 300oF
• 200oF
• 250oF

The air circulating inside a refrigerator is an example of

• Convection
• Radiation
• Sublimation
• Conduction

The term for temperature control that uses no external source of energy is

• Pneumatic
• Electronic
• Self-contained
• Electromechanical

An advantage of open drive compressors is that

• They are smaller and more compact than hermetic compressors
• They require no type of regular maintenance
• The motor and compressor can be replaced separately
• They are generally less expensive then comparable semi-hermetic compressors

The first law of thermodynamics states that

• Energy cannot be created or destroyed
• The molecular energy band is directly proportional to the thermal activity of the molecule
• Whenever energy is created, an equal quantity of energy must be destroyed to maintain thermal equilibrium
• All objects contain some energy

What functions of the energy management software cycles HVAC equipment so only stored energy handles building load, but still maintains an occupancy comfort level?

• Zero energy band
• Optimum start
• Optimum stop
• Load reset

Contaminants that can be found in recovered refrigerant include

• Oil and non-condensavles
• Carbon and particulates
• Water and acid
• All of the above

The shaft seal on a open compressor is more complicated than the gaskets and seals on other parts of the compressor because

• It must seal a shaft that is turning.
• It must seal in a vacuum
• It is subjected to both refrigerant and oil while other seals and gaskets are not.
• It must seal against higher pressure

Which of the following refrigerant safety designations indicate the refrigerant is non-flammable?

• B1
• A2
• B3
• A3

Rotary compressors are commonly used in

• Large central split systems
• Window units
• Commercial refrigeration systems
• All of the above

A compressor that squeezes gas between two rotating screws shaped like augers is called a

• Scroll compressor
• Rotary compressor
• Reciprocating compressor
• Screw compressor

What measurements are necessary for a test instrument to measure suction superheat?

• High side pressure and discharge line temperature
• Low side pressure and high side pressure
• High side pressure and liquid line temperature
• Low side pressure and suction line temperature

What units are used to measure pressure in HVAC/R systems in the United States?

• Pounds per square inch absolute (psia)
• Newtons
• Pounds per square inch gauge (psig)
• Kilopascals (kPa)

The primary cause of high condensing temperatures in water cooled condensers is

• Excessive water flow
• Oversized condenser water circulating pumps
• Scaled and fouled condenser surfaces
• Restricted metering devices

The refrigerant in a mechanical compression refrigeration system absorbs and releases heat by

• Changing its temperature
• Changing its molecular composition
• Changing its physical state
• Converting energy to mass

Ozone is an oxygen molecule formed with

• Chlorine to produce a new compound
• 3 oxygen atoms instead of the normal 2
• 2 oxygen atoms instead of the normal 3
• Freon to produce a new compound

In an air conditioner with a fixed metering device, a decrease in the outdoor ambient causes

• Increased system superheat
• Increased system capacity
• Decreased system superheat
• No appreciable change in either system capacity or superheat

A compressor that uses a roller that rotates in an orbital motion to squeeze gas between the roller and a spring-loaded vane is called a

• Screw compressor
• Scroll compressor
• Rotary compressor
• Reciprocating compressor

What is the easiest way to calibrate a pneumatic controller with a control point adjustment port?

• Allow the system time to stabilize; then calibrate
• Disconnect the control point adjustment pressure and calibrate the controller
• Adjust the control point adjustment to maximum pressure; then, use the dual-input calibration procedures
• Return the control point adjustment port to the calibration pressure; then, use the single-input calibration procedures

What would the output pressure of the temperature controller be if the sensor were sensing 70*F?

• 5 psi
• 8 psi
• 10 psi
• 13 psi

The substance being cooled by a refrigeration system is called

• The product
• The cooling medium
• The refrigerant
• The source

Which one do you like?

• Option 1
• Option 2
• Option 3
• Option 4

What is the specific volume of one pound of dry air at standard conditions?

• 13.33 cubic feet
• 0.016 cubic feet
• 29.92 inches mercury
• 62.4 pounds/cubic foot

What is the primary difference between air cooled condensers on standard efficiency systems and air cooled condensers on high efficiency systems?

• The condenser coils are made from steel instead of copper or aluminum
• The coil size is decreased to raise the head pressure and increase the temperature difference.
• The number of fins per inch are reduced to reduce the restriction to airflow
• The coil size is increased to increase the heat transfer area.

Sensible heat added to a substance will be indicated by a

• Drop in temperature of that substance
• Change in physical state of the substance
• Stable temperature of that substance
• Rise in temperature of that substance

Refer to figure 1-10. If the wet-bulb temperature is 57*F and the dry-bulb temperature is 65*F, what is the relative humidity?

• 57 percent
• 61 percent
• 65 percent
• 70 percent

Upon calibrating a single input electronic controller with a decade box to simulate proper resistance, you notice that the voltage output isn't correct. What controller adjustment will remedy the problem?

• Action
• Set point
• Throttling range
• Variable resistance

The second law of thermodynamics states that

• Heat travels from higher temperature to lower temperature
• The molecular energy band is directly proportional to the thermal activity of the molecule
• All objects contain some energy
• Heat travels from the higher specific heat capacity to lower specific heat capacity

The chemical in CFCs that contributes to ozone depletion is

• Carbon
• Flurine
• Chlorine
• Hydrogen

A hydroscopic lubricant

• Is used primarily with water cooled systems
• Is an oil whose composition is based on water
• Absorbs water readily
• Is water repellant

Hydraulic pressures will develop and break compressor parts if

• Liquid refrigerant enters the compressor cylinders
• The system operates with too high a superheat
• The compressor oil is contaminated with moisture
• Vapor refrigerant enters the compressor cylinders

What is the advantage of timed, two-position control?

• The final control elements moves to a position equal to the amount the controlled variable moved
• The controller never catches up with the controlled condition
• It greatly reduces the swings in the controlled variable
• The thermal timer will cool

What opens and closes the valves in a reciprocating compressors?

• Hydraulic valve lifters
• The piston pushes them open
• Pressure difference across the valves
• A cam shaft

The difference between a series 60 and a series 40 two-position motor is that the series 40 is

• A line voltage circuit
• A fail-safe control circuit
• Used mainly where hazardous conditions exist
• Unusable when single-pole,double throw control of line voltage is required

Assuming they both have the same condenser temperature, which application requires more horsepower to produce a ton of cooling: a 0oF evaporator or a 40oF evaporator

• The 0oF evaporator because of the higher pressure difference
• The 40oF evaporator because of its higher pressure
• The horsepower requirement per ton of cooling is not affected by the evaporator temperature
• The horsepower requirement is too complicated a calculation to make any valid comparison based only on evaporator and condenser temperatures

What is the purpose of SDS sheets?

• To provide information on what types of material a product is compatible with
• To communicate the substance's hazards and how they can be avoided
• To provide instructions on possible uses of a product
• To prevent lawsuits by including injury disclaimers and liability waivers

What is the purpose of low ambient controls for air cooled condensers?

• To control the ambient temperature
• To increase the fan speed to compensate for low barometric pressure
• To maintain a maximum head pressure, even at lower than normal operating conditions
• To maintain a minimum head pressure, even at lower than normal operating conditions.

An air conditioner with refrigerant R-410a has a high side pressure of 340 psig and a temperature of 95oF. According to the pressure temperature chart

• It is superheated
• It is subcooled
• It is saturated
• Its condition cannot be determined knowing just the pressure and temperature

Why are wastewater systems no longer allowed in some areas of the country?

• Concerns about possible health issues of using sewage water to cool condensers.
• Water resources are becoming increasingly scarce.
• Solids found in waste water can clog up the condensers.
• Heating the waterwater interferes with the sewage treatment.

The three basic types of condensers used with HVAC/R systems are

• Standard, metric, and transitional
• Condensing, non-condensing, and static
• Air cooled, water cooled, and evaporative
• External, internal, and cross-charged

Explain how a non-toxic, nonflammable refrigerant can be dangerous.

• Most common refrigerants decompose on contact with air to form toxic substances
• Most common refrigerants decompose on contact with air to form flammable substances
• Concentrated refrigerant can cause euphoric highs that lead to irrational and dangerous behavior
• The refrigerant can replace all the air in a space, depriving you of oxygen

A high pressure refrigerant has a pressure at the reference saturation temperature

• Between 170 psia and 355 psia
• Below 45 psia
• Above 355 psia
• Atmospheric pressure

The presence of non-condensables in a refrigerant recovery cylinder can be detected by

• Comparing the cylinder pressure and temperature to a PT chart
• Comparing the actual cylinder weight to the cylinder water capacity
• Checking the acidity of the refrigerant with litmus paper
• Testing to see if the gas on top of the cylinder will burn

Which type of condenser requires the most maintenance?

• Condensers do not require maintenance
• Water cooled condensers
• Air cooled condensers
• The maintenance requirements for air cooled condensers and water cooled condensers are comparable.

HVAC fans noramlly provide firestats or smoke detectors and freezestats that provide for

• Notification of emergency personnel
• Control fire, smoke, and freezing
• Fire and freeze suppression
• Emergency fan shutdown

The definition of a fluid is

• A liquid with a viscosity equal to or greater than the ANSI requirement for standard fluid
• A substance that deforms and flows under pressure
• Any liquid which cannot become a vapor at system pressure and temperature
• Any substance in liquid form

Use the following information to answer the next question:Controller = barber colmanVcal = 7.5 VDC (at midpoint)Span c = 3 VDC (6-9 direct current voltage (VDC)Tsp = 70*FTRc = 4*FAction = directWhat should the output voltage (Vout) be if the sensor is sensing 68*F?

• 0 direct current voltage (VDC)
• 3 direct current voltage (VDC)
• 6 direct current voltage (VDC)
• 9 direct current voltage (VDC)

One operating advantage of fixed restriction metering devices over expansion valves is

• Improved system control
• Can be used with low starting torque compressor motors
• Easier to adjust
• Higher operating efficiency

In the compression refrigeration cycle the refrigerant is subcooled

• Leaving the condenser up to the metering device
• Leaving the metering device, through the evaporator, up to the compressor
• Leaving the evaporator up to the compressor
• The refrigerant is not subcooled anywhere in the compression cycle

An air conditioner with refrigerant R-22 has a low side pressure of 70 psig and a temperature of 55oF. According to the pressure temperature chart

• It is subcooled
• It is saturated
• It is superheated
• Its condition cannot be determined knowing just the pressure and temperature

The refrigerant inside most refrigerant cylinders is a

• Homogeneous mixture of liquid and vapor
• Saturated liquid-vapor mix
• Subcooled liquid
• Superheated vapor

ACR copper tubing is

• Type M, dehydrated copper tubing
• Type L, dehydrated copper tubing
• Any type of copper tubing so long as it has been dehydrated
• Copper tubing with added metallurgical alloys which resist corrosion from the refrigerant

The chemical components of CFC refrigerants are

• Chlorine, Freon, and Chromium
• Chlorine, Fluorine, and Carbon
• Carbon, Freon, and Chlorine
• Carbon, Frankincense, and Chlorox

The chemical components of HCFC refrigerants are

• Helium, Carbon, Freon, and Chlorine
• Helium, Carbon, Frankincense, and Chlorox
• Hydrogen, Chlorine, Freon, and Chromium
• Hydrogen, Chlorine, Fluorine, and Carbon

Liquid lines need to be insulated:

• For systems using HFC refrigerants
• If they travel through an unusually hot space
• They are run close enough to hot suction line to pick up heat from it
• Always

Optional components on the high side of a refrigeration system include

• Suction line filter, accumulator, and evaporator pressure regulator
• Discharge line muffler, oil separator, liquid receiver, and liquid line filter-drier
• All optional components can be used on the high side of the system
• Suction to liquid heat exchanger, economizer, oil level regulator

What procedure is used when heating a brazed copper joint?

• Heat the fitting first and then heat the pipe after the fitting is hot
• Concentrate the flame on the line where the pipe slips into the fitting
• Heat the pipe first and then the fitting
• Use a fanning motion to heat the fitting evenly and slowly

Refrigerants absorb heat

• By rearranging their molecular structure to form a new compound
• By evaporating from a liquid to a vapor
• By converting heat energy into additional refrigerant molecules
• By condensing from a vapor to a liquid

The refrigeration system component that absorbs heat out of the product is the

• Condenser
• Compressor
• Expansion device
• Evaporator

The function of the compressor in the refrigeration cycle is

• Raise the pressure and temperature of the refrigerant in the condenser
• Move the refrigerant vapor through the system
• Lower the pressure and temperature of the refrigerant in the evaporator
• All of the above

With a multizone system, what controls the temperature to each zone?

• The output of the hot-deck controller
• The output of the cold deck
• The mixed-air section
• Zone mixing dampers

The purpose of the condenser in a refrigeration system is to

• Absorb heat into the refrigerant
• Reject heat from the refrigerant
• Reject heat from the condensing medium
• Increase the pressure and temperature of the refrigerant

Why are vertical suction risers often smaller than the horizontal runs on the same suction line?

• The risers are sized smaller to minimize noise
• The risers are sized smaller to increase the pressure drop for improved control
• The risers are sized smaller to minimize pressure drop
• The risers are sized smaller to maintain a minimum velocity to lift the oil

The standard industry number designation for each refrigerant is assigned by

• ASHRAE - American Society of Heating Refrigeration and Air Conditioning Engineers
• AHRI - Air Conditioning Heating and Refrigeration Institute
• RSES - Refrigeration Service Engineer's Society
• NIST - National Institute for Standards and Testing

All refrigeration compressors are designed to pump

• Only vapor
• Mostly vapor plus small quantities of liquid
• Mostly liquid with small quantities of vapor
• Only liquid

Pressure is defined as

• The product of density and specific volume
• The average applied force
• Applied force
• Force per Unit Area

Two types of fixed metering devices are

• Copper and brass
• Pressure reducing and pressure increasing
• Capillary tubes and orifices
• High pressure and low pressure

Why are the mixed-air controller (MAC) and the temperature controller cooling (TCC) integrated to operate the controlled device (CD)?

• If the zone temperature is low, TCC will override MAC and close dampers
• If the zone temperature is low, TCC will override MAC and open dampers
• If the zone temperature is high, MAC will override TCC and open the cooling valve
• If the zone temperature is high, MAC will override TCC and close the cooling valve

What flow meter measures volume rate by inserting its free moving element into the water flow?

• Differential-pressure
• Mechanical
• Centrifugal
• Ultrasonic

If you are calibrating a contoller with a built-in sensor and you have adjusted the controller calibration screw to equal Pcal, your next step is to adjust the

• Set point dial up by one-half the TRc
• Sensitivity slides
• Calibration screw
• Pressure span

You adjust the primary loop variable resistance of a dual-input electronic controller to each end point of the performance graph and check the output voltage at each end. What calibration step are you performing?

• Setting and or checking the throttling range
• Current condition check of the output voltage
• The ratio is set correctly
• Current conditions check of the decade box

Which electronic controllers may combine temperature and humidity measurements to measure heat content?

• Electric to pneumatic controllers
• Relative humidity controllers
• Temperature controllers
• Enthalpy controllers

What type of coil control provides for control of the coil from the controlled space?

• Zone control
• Reset control
• Mixed-air control
• Economizer control

Heat content i plotted on the psychometric chart by extending the

• Relative humidity line
• Dew point line
• Dry-bulb line
• Wet-bulb line

Why do some commercial buildings need air conditioning in the winter?

• Commercial buildings are maintained at lower temperatures to improve productivity.
• The complexity of control systems for commercial buildings often cause a system to cool a building even when cooling is not needed.
• Lower temperatures reduce the spread of bacteria.
• Commercial buildings often have large internal heat loads from people, lights, and machines.

Define a vacuum.

• A vacuum is any pressure less than atmospheric pressure
• A vacuum is a negative pressure.
• Vacuum is the reciprocal of pressure. For every pressure there is a reciprocal vacuum.
• A vacuum is anti-pressure created by counter clockwise molecular rotation.

Refrigerant piping must be able to adequately carry both refrigerant and:

• Oil
• Air
• Electricity
• Nitrogen

In critical buildings or locations, senors for differential-pressure flow meters should be calibrated every

• Month
• Three months
• Six months
• Year

A compressor that squeezes gas in between the piston and a valve plate at the top of the cylinder is called a

• Scroll compressor
• Rotary compressor
• Screw compressor
• Reciprocating compressor

The coil discharge temperature for a mulitzone system is based on the

• Zones that have the smallest heating and cooling loads
• Zones that have the largest heating and cooling loads
• Temperature of the hot decks and cold decks
• Number of zones the system is operating

Conduction is the transfer of heat

• Similar to that of light waves and radio waves
• By the movement of a fluid such as air or water over a substance
• Where a fan is used to propel the air across a hot or cold surface
• Through a substance or from one body to another when the bodies are in direct contact

The ratio or authority as used with the reset loop of a dual-input electronic controller determines the

• Influence of the reset loop over the primary
• Amount of integral control needed
• Hot water reset performance
• Calibration instructions

What should you do after you remove the vapor degreasing compound from a pneumatic system?

• Turn on the fans
• Calibrate the controller
• Change the filters in the controller
• Flush the system with a clean air supply

At what point in the refrigeration cycle does the refrigerant absorb the most heat?

• In the compressor where it changes from a low temperature gas to a high temperature gas
• At the end of the evaporator where the gas is superheated
• In the condenser where it changes from a gas to a liquid
• In the middle of the evaporator where the cold liquid turns to a cold gas

Refrigeration oils must be miscible with the system refrigerant because

• The system depends on the refrigerant to carry the oil throughout the system to lubricate all the refrigeration components
• The system depends on the oil to refrigerant to return the oil to the compressor
• The system depends on the refrigerant to return the oil to the compressor
• The compressor cannot operate properly without liquid refrigerant in the crankcase

To calibrate a timed two-postion control system, adjust the

• Linkage
• Differential
• Limit stops in the motor
• Resistance heater in the thermostat

A general definition of refrigerant is

• A hydrocarbon based chemical with noble elements replacing some of the hydrogen atoms
• A fluid that is naturally cold
• The fluid used in a refrigeration system for transferring heat
• A fluid that can turn heat into mass

The temperature of the water formed by melting ice is

• 32 F
• 33 F
• 31 F
• It can be any temperature above 32 F

Which process follows the line of constant enthalpy or has no heat change?

• Latent heat process
• Sensible heat process
• Moisture injection process
• Adiabatic saturation process

What is the maximum reading (including retard) on a typical R410A compound gauge?

• 300 psig
• 120 psig
• 800 psig
• 500 psig

To allow the passing of data to a local operator terminal or another controller, zone and system level controllers should be equipped with

• Input/output boards
• An analog/digital converter
• A communications or access port
• EEPROM

The preferred method of cutting copper tubing for a refrigeration system is with

• A circular saw
• A hack saw
• A tubing cutter
• A cutting torch

What is one type of controlled device used in pneumatice system?

• Actuator
• Switching relay
• Square root extractor
• Minimum position switch

What is the relationship among matter, energy, and heat?

• Energy is made up of atoms, which consists of electrons kept in motion by matter, which is a form of heat
• Heat is made up of molecules, which consists of electrons kept in motion by energy, which is a form of matter
• Matter is made of atoms, which consists of electrons kept by heat, which is a form of energy
• Energy is made up of molecules, which consists of electrons kept in motion by heat, which is a form of matter

The rate of heat transfer is faster if

• The molecular energy bands are in synchronous alignment
• The temperature of the two objects are very close to the same
• The two objects are exactly the same temperature
• There is a large difference between the two objects

Why is it illegal to operate a torch with an acetylene pressure greater than 15 psi?

• Acetylene becomes unstable and can explode above 15 psi
• Hoses cannot be built to handle pressures exceeding 15 psi
• Acetylene is a rare and precious resource that must be used sparingly to insure a supply in the future
• The torch cannot be manufactured to contain pressures exceeding 15 psi.

Which of these statement about absolute pressure is true?

• The absolute pressure scale starts at a prefect vacuum.
• Absolute pressure is a pressure reading that is 100% accurate.
• Absolute pressure is the metric system of reading pressure.
• Absolute pressure is pressure measured above atmospheric pressure.

Why are acetylene cylinders only used in the upright position?

• To take advantage of natural convection
• The upright position is more convenient because they take up less space
• To prevent acetone from being pulled out of the cylinder
• The acetylene cylinders will roll around if they are laid sideways on the floor

What function does spring range have in a pneumatic system?

• The pressure range over which a high/low selector operates
• The pressure range over which a program switch operates
• The pressure range over which a actuator operates
• The pressure range of a controller's internal parameters

What is the last step in the calibration of a single-input pneumatic controller?

• Adjust the calibration screw to equal the predicted output pressure
• Adjust the sensors to the predicted output pressures
• Disconnect the sensor simulators
• Readjust the the proportional band

Why do acetylene cylinders contain acetone?

• Acetylene gas is dissolved in the acetone liquid
• Acetone helps keep the cylinder weight balanced by evenly distributing the liquid
• Acetone chemically reacts with the filler in the tank to produce acetylene gas
• The acetone liquid boils off to form acetylene gas

Operating a hermetic compressor in a vacuum

• Can cause the motor to arc out because of the change in electrical resistance
• Can cause a dangerous increase in the motor current draw
• Is the most efficient operation because of the reduced pressure on the compressor mechanism
• Can cause a dangerous increase in the discharge pressure

On a pneumatic dual-input receiver controller, one sensor measures the primary variable. What does the second sensor measure?

• Desired variable
• Reset variable
• Set point
• Offset

Where would you likely find the fasest moving air within a duct?

• Along the walls
• At the top
• At the bottom
• In the center

What is the AHRI "A" performance testing condition for air cooled air conditioning equipment?

• 90 degrees F outside ambient, 85 degrees F indoor dry bulb, 70 degrees F indoor wet bulb
• 100 degree outside ambient, 75 degree F indoor dry bulb, 72 degree F indoor wet bulb
• 95 degrees F outside ambient, 75 degrees indoor dry bulb, 75 degrees indoor wet bulb
• 95 degrees outside ambient, 80 degree F indoor dry bulb, 67 degree F indoor wet bulb

What sources of reheat do variable air volume (VAV) boxes use?

• Steam and hot water
• Hot water and electric
• Electric and steam
• None of the above

New residential air conditioning systems now primarily use

• CFC-12
• HCFC-22
• HFC-134a
• HFC-410A

Latent cooling

• Reduces the air temperature and removes water
• Reduces the air temperature
• Is an interesting theory that has not been proven
• Removes water from the air

Use the following information to answer this question about a pneumatic sensor:What is the output pressure of a pneumatic sensor with a range of 0* to 100* F if the temperature measured is 24*F?

• 3.52 psi
• 5.88 psi
• 9.20 psi
• 11.60 psi

Zeotropes are mixtures of two or more refrigerants

• That do not separate when changing state
• That are electromagnetically bonded to form a new refrigerant
• That are chemically bonded to form a new refrigerant
• That separate when changing state

What is a typical application of floating control?

• Static pressure in a variable air volume system
• Controlling temperature in a laboratory
• Hot water reset from outdoor air
• Room and discharge

What is the purpose of adding fins on the tubing used for heat transfer?

• Fins protect the coils from dirt.
• Fins straighten the air flowing over the coils so that it flows more easily.
• Fins increase heat transfer by increasing the surface area.
• Fins keep small animals out of the unit by closing the gaps between the coils.

Use the following information to answer the next question:Controller = barber colmanVcal = 7.5 VDC (at midpoint)Span c = 3 VDC (6-9 direct current voltage (VDC)Tsp = 70*FTRc = 4*FAction = directWhat should the output voltage (Vout) be if the sensor is sensing 72*F?

• 0 direct current voltage (VDC)
• 3 direct current voltage (VDC)
• 6 direct current voltage (VDC)
• 9 direct current voltage (VDC)

Flash gas in the liquid line can be identified by:

• The bright flashes of light that accompany the flash gas
• A drop in the liquid line temperature
• A significant temperature increase in the liquid line temperature
• The popping sound the refrigerant makes every time a new flash explodes

Besides improving efficiency, insulating the suction line:

• Serves as a backup sealing system to prevent refrigerant loss
• Prevent stray electrical current from traveling down the pipe
• Reduces mechanical vibrations set up by the compressor
• Prevents moisture from condensing on the line

Why is it recommended that an acetylene cylinder valve never be opened more than 1/4 turn?

• To allow rapid shutoff in the case of an accident
• To regulate the pressure to the torch handle
• To prevent the valve from getting stuck in the fully opened position
• To minimize the strain of the high cylinder pressures on the valve threads

What is the purpose of air conditioning?

• To control the humidity in a building
• To clean the air in a building
• To control the temperature in a building
• All of the above

The three common states of matter are

• Radiant, conductive, and convective
• Sensible, latent, and specific
• Solid, liquid, and gas
• Sub-atomic, atomic, and molecular

An air conditioner using refrigerant R-134a has a low side pressure of 35 psig and a temperature of 40oF. According to the pressure temperature chart

• It is subcooled
• It is saturated
• It is superheated
• Its condition cannot be determined knowing just the pressure and temperature

What temperature scale uses 0o as the freezing point of water and 100o as the boiling point of water?

• Fahrenheit
• Kelvin
• Rankine
• Celsius

When controlling coils, it is sometimes desireable to use discharge control and reset the setpoint of the control loop as a function of another conditions. What might this condition or conditions be?

• Mixed-air temperature
• Return-air temperature
• Outdoor-air or space temperature
• Return-air or mixed-air temperature