Follow and like us on our Facebook page where we post on the new release subject and answering tips and tricks to help save your time so that you can never feel stuck again.
Shortcut

Ctrl + F is the shortcut in your browser or operating system that allows you to find words or questions quickly.

Ctrl + Tab to move to the next tab to the right and Ctrl + Shift + Tab to move to the next tab to the left.

On a phone or tablet, tap the menu icon in the upper-right corner of the window; Select "Find in Page" to search a question.

Share Us

Sharing is Caring

It's the biggest motivation to help us to make the site better by sharing this to your friends or classmates.

# Heating, Ventilation, Air Conditioning and Refrigeration

Covers the principles, design, installation, and maintenance of HVACR systems to ensure optimal indoor comfort and air quality in various environments.

## thermostats

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

• Isolation
• Diagnosis
• Localization
• Sectionalization

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)

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

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

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

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

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

What mode of control corrects the problem of offset?

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

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

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

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

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

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

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

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

• Ammeter
• Voltmeter
• Ohmmeter
• Anemometer

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

• Large
• Medium
• Small
• Micro

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

• A2
• A1
• B1
• B3

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

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

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

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

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

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

• Open compressors
• All types of compressors
• Hermetic compressors

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

Air conditioning window units for homes were first available in

• 1950s
• 1960s
• 1940s
• 1970s

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

Copper tubing that comes in rigid, straight lengths is called

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

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 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.

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

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

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

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

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

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

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

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.

A major problem of proprotional control is

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

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

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

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

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

Three forms of energy used in heating and air conditioning include

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

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

The preferred tool for cutting PVC pipe is

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

The absolute temperature scale for Celsius is

• Kelvin
• Rankine
• Celsius absolute
• Fahrenheit

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

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 three basic methods of heat transfer are

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

Above what temperature do most refrigerant oils begin to fail?

• 150oF
• 300oF
• 200oF
• 250oF

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

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

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

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

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 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 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

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.

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

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

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

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

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

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

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

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

The chemical in CFCs that contributes to ozone depletion is

• Carbon
• Flurine
• Chlorine
• Hydrogen

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

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

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

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

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

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

• Condenser
• Compressor
• Expansion device
• Evaporator

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

What units are used to measure vacuum?

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

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)

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)

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 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

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)

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

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

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

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

Pressure is defined as

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

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

Soft copper tubing can be joined by

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

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

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

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

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
• Convection
• Sublimation

Saturated steam is steam

• At a temperature below boiling water
• At a temperature above boiling water
• At the temperature of boiling water

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

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 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

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

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

• Isolation
• Diagnosis
• Localization
• Sectionalization

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.

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

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

Two materials that are considered good thermal conductors are

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

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

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

New residential air conditioning systems now primarily use

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

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

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

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

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

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 chemical components of CFC refrigerants are

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

• Disconnecting the pistons in the unloaded cylinders
• Flooding the unloaded cylinders with oild
• Making the valves in the head inoperative

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

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

• B1
• A2
• B3
• A3

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

• Saturation
• Subcooling
• Superheat
• Glide

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

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

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

• Fahrenheit
• Kelvin
• Rankine
• Celsius

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

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

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

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

The temperature of the water formed by melting ice is

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

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

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

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

The three common states of matter are

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

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

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

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

Small appliances such as household refrigerators and freezers now primarily use

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

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

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

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

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.

The curved oval metal tube inside a gauge is called

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

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

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

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

Two types of fixed metering devices are

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

Anything that has weight and takes up space is

• Energy
• Matter
• Motion
• Atoms

The substance being cooled by a refrigeration system is called

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

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

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 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

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

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

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

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

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

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

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

• BTUs
• Degrees Fahrenheit
• Joules
• Kilocalories

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

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

• Differential-pressure
• Mechanical
• Centrifugal
• Ultrasonic

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

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.

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

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

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

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.

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

• Kilocalories
• Joules
• BTUs
• Degrees Fahrenheit

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

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

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

• Sensor
• Controller
• Controlled device

Which saturation temperature is used to determine refrigerant operating pressure temperature

• 50oF
• -58oF
• 0oF
• 104oF

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

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

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

The absolute temperature scale for Fahrenheit is

• Fahrenheit absolute
• Rankine
• Celsius
• Kelvin

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

Thermostatic expansion valves respond to changes in

• Temperature
• Superheat
• Pressure
• Subcooling

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

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

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

• Open
• Closed
• Combination
• Reverse reset

What material is used for air conditioning drain lines?

• Galvanized iron pipe
• CPVC
• Copper
• PVC

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

• Conduction
• Convection

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 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.

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

• Control fire, smoke, and freezing
• Fire and freeze suppression
• Emergency fan shutdown

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

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)

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
• Set point dial

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

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

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

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

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.

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

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

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

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

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

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

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

• Stabilizes
• Decreases
• Increases
• Stays the same

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

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

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

• Month
• Three months
• Six months
• Year

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

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

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 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

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

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

Campers being heated by a fire outside is an example of

• Sublimation
• Convectin
• Conduction

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

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

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

Which Air Force publication gives you electrical safety requirements?

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

The air circulating inside a refrigerator is an example of

• Convection
• Sublimation
• Conduction

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

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

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

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 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

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.

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

• Calories
• Tons
• Joules
• Therms

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
• Turn the integral control action off
• Replace the sensor with a variable resistor

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

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

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

• Latent heat process
• Sensible heat process
• Moisture injection process

Examples of halogenated refrigerants include

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

A hydroscopic lubricant

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

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

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 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

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

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

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

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

What physical change of state is the opposite of evaporation?

• Melting
• Sublimation
• Freezing
• Condensation

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

Heat content i plotted on the psychometric chart by extending the

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

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

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.

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

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

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

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

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.

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

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

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

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

Refrigerants with the highest ozone depletion potential are

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

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

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

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.

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

Rotary compressors are commonly used in

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

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 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

Contaminants that can be found in recovered refrigerant include

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

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

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

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

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

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.

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 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

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

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

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

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

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.

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

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

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 two general categories of metering devices are

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

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

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

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

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

Who developed the first modern air conditioning system?

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

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

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

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

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

• Oil
• Air
• Electricity
• Nitrogen

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

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

• Any ladder that is structurally sound is safe as long as the power tool is properly gounded

Which one do you like?

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

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

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

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

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.

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 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

Hard copper tubing can be joined by

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

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

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

• A broken diaphragm
• A short in the controller
• An open in the motor windings

How many watts equal one horsepower of work?

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

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

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

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

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

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 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

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

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 rear pot in the series controller controls the

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

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

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

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

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

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

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

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

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

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

Capillary tube metering devices are commonly used today in

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

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

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

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

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

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

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

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

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

The refrigerant inside most refrigerant cylinders is a

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

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

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 gases are safe to use for refrigerant system pressure testing?

• Compressed air
• Acetylene
• Oxygen
• Dry nitrogen

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

• Commercial
• Residential
• Industrial
• All of the above

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

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.

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.

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

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

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

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

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

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

• Pneumatic
• Electronic
• Self-contained
• Electromechanical

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
Paypal Donation

To keep up this site, we need your assistance. A little gift will help us alot.

- The more you give the more you receive.

Related Subject

Air Conditioning and Refrigeration Service

Nursing Interventions: Ineffective Breathing Pattern

Respiratory Care Science

Refrigeration Service

Kitchen and Bath Specialty

Pneumatics and Hydraulics Technology, Design and Control