AC Final Flashcards
Comfort can be described as the gentle balance between ______.
a. temperature, humidity, air movement, and air cleanliness
b. air velocity, air cleanliness, humidity, and air movement
c. air speed, air velocity, temperature, and humidity
d. acceleration, air cleanliness, filtration, and humidity
a
Of the heat produced in the human body, which is by perspiration?
a. Conduction
b. Convection
c. Radiation
d. Evaporation
D
If the dry bulb temperature is 93 F and the wet bulb temperature is 60 F, what is the specific volume of the air?
a. 14.0 ft 3/lb
b. 14.0 lb/ft 3
c. 12.0 lb/ ft 3
d. 12.0 ft 3/ lb
a
The generalized comfort chart can be used as a basis to _____.
a. determine combinations of temperature and humidity to produce comfort in summer and winter
b. study air and its properties
c. determine the amount of fresh air make up necessary for comfort
d. none of the above
a
The density of air is the _____.
a. amount of moisture in the air
b. amount of movement in the air per cubic foot
c. weight of the air per cubic foot
d. combination of the temperature and pressur of the air
c
The density of water is _______.
a. 61.3 lb/ft 3
b. 62.0 lb/ft 3
c. 62.4 lb/ ft 2
d. 62.4 lb/ ft 3
d
What is the relative humidity if the dry bulb temperature is 100 F and the wet bulb temperature is 62 F?
a. 13 %
b. 28%
c. 43%
d. 58%
a
If the wet bulb and dry bulb are both 80 F what is the humidty?
a. 0%
b. 35%
c. 70%
d. 100%
D
The dry bulb temperature is the ______.
a. same as the wet bulb temperature
b. total of the sensible and latent heat
c. sensible heat level of the air
d. sensible heat less the humidity
c
The reading from a wet bulb thermometer ______.
a. is the same as the wet bulb depression
b. is the saturation pressure
c. takes into account the moisture content of the air
d. is always higher than the dry bulb temperature
c
The wet bulb depression is ____.
a. the difference between dry and wet bulb temperatures
b. the same as the wet bulb temperatures
c. the same as the dry bulb temperatures
d. when the air is saturated with moisture
a
What is the dew point temperature if the wet bulb temperature is 65 F and the dry bulb temperatures is 100 F.
a. 40 F
b. 50 F
c. 60 F
d. 70 F
a
The dew point temperature is the _______.
a. temperature when the air is saturated with moisture
b. temperature at which moisture begins to condense out of the air
c. difference between the dry bulb and wet bulb temperature
d. temperature of the air at 50% relative humidity
b
Infiltration is the term used when referring to the air entering a stucture _____.
a. through an air make up unit
b. around doors and windows
c. through ventilation
d. because of street traffic
b
A small amount of air is induced from the outside into the conditioner to keep the air from becoming _______.
a. too humid
b. superheated
c. oxygen starved and stagnant
d. too dry
c
T/F The human body is comfortable when the heat produced in the body is equal to the heat lost to the surroundings.
T
T/F The rate at which water will evaporate from the wick on the wet bulb thermometer is determined b the moisture content of the surrounding air.
T
T/F Introduction of forced ventilation in the winter heating season helps to raise the humidity level.
F
The average core body temperature is ______ F.
98.6 F
Typically when the body is at rest (sitting) and in surrounding of _______ F and 50% humidity with a slight air movement, the body is close to being comfortable.
75 F
Air consists of approximately 78% ______, 21% oxygen and 1% other gases.
nitrogen
Water in the form of low pressure vapor is suspended in the air and is called ______.
Humidity
The mositure content in air (humidity) is measured by weight and expressed in pounds or ______.
Grains
The closer the wet bulb and dry bulb temperature are to each other, the higher the ______.
relative humidity
If the dry bulb temperature is 76 F and the wet bulb temperature is 68 F, the wet bulb depression is ______ F.
8
When the dry bulb and wet bub temperature are the same, the relative humidity of the air is ________.
100%
The ______ of air is the measure of heat content in Btu per pound of air.
Entholpy
When fresh air is introduced through the air handling system, the process is called fresh air intake, or _________.
Ventilaton
The total heat content of infiltrated air of the same dry bulb temperature may vary from one part of the country to another because of the difference in _______.
a. solar load
b. sensible heat
c. humidity
d. convection currents
c
A homeowner plans to bulid a house out in Las Vegas, Nevada, in the middle of the desert. It would be in his/ her best interest to lower the solar load to lacate most of the windows on the _____ sides of the house.
a. north and east
b. east and west
c. north and south
d. south and west
C
The solar load on a structure is the heat gain resulting from the _____.
a. heat from the surrounding air conducted through the materials of the structure
b. air infiltration
c. heat form the radiation of the sun
d. dry bulb inside the sturcture
C
More than one evaporator coil circuit is used when ______.
a. the evaporator is located outside the conditioned area
b. there would be excessive refrigerant pressure drop in the coil circuit
c. a distrbutor would not be pratical
d. a slant coil is at an angle more than 60 degrees
b
A popular material combination used in air conditioning evaporators and condensers is _____.
a. copper tube stainless steel fin
b. copper tube copper fin
c. copper tube aluminum fin
d. stainless steel tube aluminum fin
c
In reciprocating compressor used in air conditioning, the motor is mainly cooled by ______.
a. air over the shell of the assembly
b. discharge gas from the compressor
c. suction gas returing to the compressor
d. Both a and c
D
In rotary compressor, the motor is cooled by _____.
a. air over the shell of the assembly
b. discharge gas from the compressor
c. suction gas returning to the compressor
d. liquid refrigerant by passsed from the liquid line
b
A dirty condenser coil can lead to _______.
a. increased efficiency
b. reduced efficinency
c. reduced head pressure
d. increased subcooling
b
High efficiency condensers _______.
a. cna withstand higher pressures than standard condensers
b. have more surface area than standard condensers
c. have stainless steel coil
d. are located in serparate cabinets
b
When exposed to salt air, ______ should be used for the screws to secure the sheet metal of cabinets of air conditioning equipment.
a. copper
b. stainless steel
c. iron
d. tin
b
The package air conditioning system is ______ than the split system beccause it is completely factory assembled and charged with refrigerant.
a. less efficient
b. slightly less efficient
c. slightly more efficient
d. more efficient
D
On a package air conditioning system which refrigerant lines must be field installed?
a. discharge and suction
b. liquid and suction
c. discharge and liquid
d. no lines to be field installed
d
Appearance is a major drawback with what type of air conditioning equipment?
a. ductless split systems
b. ground level package units
c. rooftop package units
d. multi position package units
a
The air temperature of the air off an evaporative cooler is ______.
a. warmer than the entering air
b. cooler than the enetering air
c. the same as the entering air
d. made up of sensible heat only
b
T/F The moisture content of the air in different locations of the country must be taken into account when selecting air conditioning equipment.
T
T/F After being threaded many times the screw holes in condenser cabinets may become oersized if so replace the srews with new ones of the same size.
F
T/F If a structure has no attic, there should be sufficient sinsulation in the roof to minimize the heat gain in the occupied space.
T
T/F Air conditioning equipment will perform at its best effciency when running at full load.
T
T/F If a residential split air conditioning system has a compressor equipped with a start capacitor and relay, it is probably using a thermistatic expansion valve as a metering device.
T
T/F The supply duct portion of an air handling system needs to be insulated when run through an unconditioned space.
T
T/F The return duct portion of an air handling system never needs to be insulated.
F
There are three kinds of attic ventilation power, natural and _______.
solar
When an A coil is used in a horizontal application, the coil is laid on its side and a special ________ pan is required.
Condensation drain
Slant coils for downflow application are designed with coil slant of usually _______%.
60
A compressor that uses a stationary vane is the _______ type.
rotary
Three types of expansion devices are used in residential air conditioning systems. They are TXV, capillary tube and ______.
Orifice
The pressure in a duct system is measured in ________.
a. psig
b. psia
c. in Hg
d. in WC
D
The ______ provides the pressure difference needed to force the air into the duct system, through the heat transfer surfaces in the conditioning equipment, through the grilles and registers, and into the room.
a. blower
b. forcer
c. compressor
d. condenser
a
The ______ provides the pressure difference needed to force the air into the duct system, through the heat transfer surfaces in the conditioning equipment, through the grilles and registers, and into the room.
a. blower
b. forcer
c. compressor
d. condenser
a
The atmosphere exerts a pressure of ______ at standard atmospheric conditions.
a. 12.696psi
b. 14.696psi
c. 16.696psi
d. 18.696psi
b
A ____ can be connected to measure the velocity pressure of the air moving in a duct.
a. ammeter
b. manometer
c. pyrometer
d. speedometer
b
An instrument that is commonly used on air distribution systems is the anemometer or _____.
a. velometer
b. manometer
c. pyrometer
d. ammeter
a
Airflow pressure in ductwork is measured in inches of _______.
a. mercury pressure
b. water column
c. air pressure
d. mercury column
b
The simple way to check for airflow is to see if you cna feel the airflow at a distance of about ______ from each register.
a. 2 to 3 feet
b. 3 to 5 feet
c. 5 to 8 feet
d. 8 to 10 feet
a
The reason for using a reducing plenum system is to _______.
a. reduce maintenance costs
b. reduce the operating cost of the system
c. provide easier means of fastening the takeoff fittings
d. maintain a constant pressure throughout the length of the trunk duct
d
One reason for using an extended plenum system is to ____.
a. save materials
b. reduce the velocity of the air as the air reaches the a last takeoffs on the extended plenum
c. prolong the main plenum closer to the farthest supply register
d. keep the noise level low
c
A ______ F temperature difference from the inside to the outside of the duct is considered the amximum difference allowable before insulation is necessary.
a. 10
b. 15
c. 18
d. 20
b
If the equivalent length of a transition piece of ductwork is 10 feet and the main duct is series with it is 20 feet, what is the length used to estimate the total frictional loss?
a. 10 feet
b. 20 feet
c. 30 feet
d. 60 feet
c
T/F The forced air system is different from a natural draft system, where the air passes naturally over the conditioning equipment.
T
T/F The duct pressure equals the velocity pressure plus staitc pressure.
T
T/F Adjusting the tension on the belt will alter the rate at which air is moving through the system but does not affect the amperage draw of the motor.
F
T/F Canvas collors are generally made of canvas rather than other materials such as rubber.
F
T/F Duct systems can be plenum, extended plenum, reducing plenum, or perimeter loop.
T
T/F Oversized duct systems cost more to fabricate and install and will also result in the slowing of the air as it flows through the duct.
T
T/F The main drawback of the extended plenum system is that the velocity of the air is lower as the air reaches the last takeoffs on the extended plenum.
T
T/F A device used to put trunk duct or extended plenum sections together is called a drive clip.
T
T/F Friction due to air rubbing the walls of the ductwork can be eliminated.
F
Baseboard hot water heat is an example of _______ heat.
radiant
Galvanized sheet metal comes in several different thicknesses, called the _______ of the metal.
gauge
Flexible round duct comes in sizes up to about ______ in in diameter.
24
Each foot of duct offers a known resistance to airflow which is called ______.
Friction loss
If the velocity of air through an 8 * 20 duct id 700 fpm, how many cfm of air is being carried by the duct?
777cfm
One drawback of using custom made, pre fabicated duct sections is that ______.
a. if the measuring was not done correctly, the job may not go together
b. altering a duct section at the job site results in lost time
c. altering a duct section at the job site is extemely cost ineffective
d. all of the above
d
What two fasters are used with sheet metal square and rectangular duct?
a. s fasteners (slips) and drive clips
b. staples and tape
c. self tapping screws and draw bands
d. tabs and adhesives
a
What fastener is commonly used with round flexible duct?
a. s fasteners (slips) and drive clips
b. staples and tape
c. self tapping screws
d. tabs and adhesives
d
What two fasteners are used with fiberglass ductboard?
a. s fasteners (slips) and drive clips
b. staples and tape
c. self tapping screws and draw bands
d. tabs and adhesives
b
_______ used at the end of a metal duct run will help reduce any noise that may be traveling through the duct.
a. fiberglass ductboard
b. aluminum duct
c. insulated metal duct
d. flexible duct
d
A boot in a duct system is a fitting used ________.
a. at the plenum
b. between the trunk duct and the branch duct
c. between the branch and the supply register
d. to eliminate vibration between the unit and the duct
c
A trap in the condensate line prevents _______.
a. air from being drawn up into unit from the end of the drain
b. foreign particles from being pulled into the condenser
c. the pump turning on if the float fails
d. both a and b
a
An auxiliary drain pan under the unti is recommended when the evaporator is installed ______.
a. near a dry well
b. at the end of the house
c. above the conditioned space
d. next to a driveway or patio
c
After refrigerant lines have been installed, they should be evacuated to a _______ vacuum.
a. average
b. low
c. moderate
d. deep
d
T/F One purpose of a flexible duct connector in a duct system is to reduce the transmission of noise and virbration.
T
T/F Application of acoustical lining to the interior of a duct is accomplished by using tabs, glue, or both.
T
T/F Power to the control trnasformer is controlled by the conditioned area thermostat.
F
T/F When hanging a horizontal air handler, it should be pitched toward the drain port for proper condensate.
F
T/F The sun shining on the panels and coils of the condensing section will lower the efficiency of the unit.
T
T/F When installing a split air conditioning system with a remote condensing unit, the line set may be altered if the standard length was incorrect for installation.
T
T/F When removing the rubber plugs from a line set, the hiss indicates that the tubing is not leaking.
T
T/F When the length of quick connect presharged line sets is altered, the charge will not normally have to be altered.
F
T/F Once the power has been connected to the condensing unit of a package air conditioner, it is a good idea to start the compressor immediately to make certain it runs.
F
A fitting used to change the size of a square or rectangular duct is called ______.
transistion
A round to rectanguar fitting is called a ________.
Square to round tansition
A split central air conditioning system is installed with the control trnasformer located in the attic hung air handler and the condensing unit located outside. The low voltage wire from the thermostat is run to the _________.
air handler
The typical gauge wire that is used in low voltage control circuits is _________ gauge.
18
Before a system is evacuated, all piping should be filled with nitrogen and a samm amount of refrigerant, in order to be _________ checked.
leak
Homeowner can cut utility bills by _______ % or more by following energy audit recommendations.
a. 15
b. 20
c. 25
d. 30
a
According to the United States Department of Energy (US DOE) 43% of the energy used by the average home goes toward _____.
a. heating water
b. refrigeration
c. space heating and space cooling
d. lighting
c
The home’s exterior is also known as the _______.
a. core
b. shell
c. structure
d. case
b
Flexible products made from mineral fibers, such as fiberglass and rock wool are known as ______.
a. rigid fill insulation
b. roll in place insulation
c. loose fill insulation
d. rolls and batts
d
The higher the ______ value, the better your walls and roof will resist the transfer of heat.
a. S
b. T
c. P
d. R
D
Cavity insulation can be installed at levels up to _______ in a 2 in * 4in wall.
a. R-5
b. R-6
c. R-15
d. R- 21
C
________ streaks in a flame are dust particles burning.
a. Yellow
b. Orange
c. Blue
d. Red
B
______ is a colorless and oderless gas which can sicken or kill persons residing in the home.
a. Hydrogen
b. Nitrogen
c. Carbon dioxide
d. Carbon monoxide
D
A ____ furnace has a postive vent pressure and operates with a vent gas temperature at least 140 F above its dew point and is known as a mid efficiency furnace.
a. Category I
b. Category II
c. Category III
d. Category IV
C
_____ is the force that allows air to travel into the combustion chamber of a combustion appliance and force the combustion gasses out through a vent or chimney.
a. Dampening
b. Thrust
c. Draft
d. Force
C
______ draft is taken in the vent stack between the combustion device and the draft diverter.
a. over the fire
b. chimney
c. vent
d. combustion
b
_______ minimizes the interaction of the furnace with other combustion appliances.
a. Heat venting
b. Pressurized venting
c. Indirect venting
d. Direct venting
d
T/F The US DOE says that 12% of the home’s total energy bills usually goes toward heating water for hosuehold use.
T
T/F The terms residential energy audit and home energy audit are often used interchangeably.
T
T/F Diagnostic testing and evaluation of the home and it systems is perhaps the least important phase of a residential audit.
F
T/F Numerical analysis and review of the homes energy consumption history, which will include both electrical and heating fuel bills is an important part of a residential audit.
T
T/F Sealing and insulating the envelope of shell of a home is often the most cost effective way to improve energy efficiency and comfort.
T
T/F Ventilation has little effect on moisture control.
F
T/F Adding insulation to the attic is fairly difficult but very cost effective.
F
T/F Gas equipment preventive maintenance consists of servicing the air side components: filter, blower, belt and drive, and the burner section.
T
T/F Cad cells or photo cells are usually used in conjunction with a primary control and are most often found on electric furnaces.
F
T/F Furnace manufacturers use standard pressure settings for their pressure switches.
F
T/F Making sure heating, cooling, refirgeration, water heating and humidification systems are all working properly and efficiently greatly affect the energy usage of the residence.
T
A preliminary evaluation of the homeowner’s needs is known as _______.
home audit
A _______ Insulation Calculator tools can provides insulation levels for your news or existing home based on your zip code and other basic information about your home.
zip code
_________ spaces include the areas of the residence that are heated or cooled.
Conditioned
Low emittance is also referred to as low _____ factor.
emissinity
Measuring the total air duct leakage is accomplished with _________ test.
blower door
_______ draft is the draft taken over the fire.
Over fire
How is air leakage through the house’s shell determined?
Infrade camera or blower door test
Most occupants will normally operate their system at about ______ 75F.
a. 68
b. 72
c. 75
d. 80
c
AHRI rates condensers with _______F air passing over them.
a. 70
b. 75
c. 85
d. 95
d
At what conditions are air conditioning system rated?
a. 95 F outdoor 70 F DB and 50% indoors
b. 95 F outdoor 75 F DB and 50% indoors
c. 95 F outdoor 80 F DB and 50% indoors
d. 100 F outdoors 80 F DB and 60% indoors
c
At typical operating conditions, the standard air conditioning system will operate with an evaporator boiling point of _____ F.
a. 40
b. 45
c. 50
d. 55
a
A normal evaporator superheat at the evaporator outlet in a standard efficiency air conditioning system operating under design conditions will be _____ F.
a. 10
b. 15
c. 20
d. 25
a
At typical operating conditions, the high efficiency air conditioning system will operate with an evaporator boiling point of _____ F.
a. 40
b. 45
c. 50
d. 55
b
The _____ rating is a steady state rating and does not account for the time the unit operates before reaching peak efficiency.
a. ARR
b. SAR
c. DER
d. EER
D
Ratings that are not completely accurate are know as ______.
a. load rating
b. maximal ratings
c. nominal ratings
d. floor ratings
c
T/F Since the evaporator absorbs both sensible and latent heat, humidity must be taken into account and considered part of the load on the evaporator.
T
T/F High efficiency condensers can actually be too efficient on cold days.
T
T/F The larger the EER rating, the less efficient the equipment.
F
Typically, the fan will run on high speed when the outdoor temperature is above _____ F.
85
The evaporator ______ heat.
absorbs
The condenser _____ heat.
rejects
A 4 ton air conditioning system that requires an input power of 5 kw would have an energy efficiency ratio of ______.
1 ton = 12000
1 kw = 1000
48000/5000 = 9.6
The electrical operating conditions are measured with a voltohmmeter and a _______.
ammeter
For residential air conditioning units, _______ V single phase is the typical voltage.
230
Air conditioning systems normally move about _______ cfm of air per ton.
400
A four pole motor runs at ______ rpm.
1800
A two pole motor runs at ______ rpm.
3600
As a rule of thumb, the air leaving the evaporator will be about ____ than the air entering the evaporator.
a. 10 - 15 warmer
b. 10 -15 cooler
c. 17 - 20 cooler
d. 17 - 20 warmer
c
A service valve can be used to
a. check the elctrical service to the compressor
b. isolate the refrigerant so the system can be serviced
c. check the air flow across the evaportor
d. check the ambient temperature at the condenser
b
