practice questions Flashcards
The evaporator in a refrigeration system:
Is the component where refrigerant boils and absorbs heat.
The purpose of the compressor is to change ___________.
Low-pressure, low-temperature vapor to a high-pressure, hightemperature vapor
A common refrigerant leak detection device is the:
Halide torch
Copper-plating of compressor parts is:
Caused by contaminants in the system
If not properly installed, a hot-gas muffler might trap:
Oil.
Unit ventilators are usually equipped with outside air dampers to
A. Partial Correct: Provide ventilation air during building occupancy
B. Partial Correct: Comply with most local or state codes
Face and bypass dampers should be adjusted to provide:
Tight shut off to reduce the possibility of overcooling or overheating
With belt driven equipment, alignment of the motor and driven equipment pulleys
Is accomplished using a string or straight edge.
To assist consumers in making an informed choice when purchasing unitary air conditioning equipment, the efficiency of such units is expressed as Energy Efficiency Ratio (EER or SEER) the units of which are:
Btuh/watt
Firestats located in the air stream of air handling units:
A. Partially Correct: Are required in both the supply and return air streams
B. Partially Correct: Should be the manual reset type
C. Partially Correct: Should be nonadjustable
A sleeve bearing would typically be used in a motor that:
Operates with a light load and where noise is a factor
A bearing used on the bottom of a motor where the shaft is positioned vertically is called a ____________ bearing.
Thrust
To produce electromagnetism, relative motion is required between a magnetic field and a/an:
Conductor
Materials which do not allow their electrons to spin out of orbit easily are called:
Insulators
A battery is an example of a/an ____________ source
Direct current
. “Current flowing through a conductor in one direction for a split second, then in the opposite direction for a split second” would be a good definition of:
Alternating current
If a pressure gauge reads five psig at sea level elevation, the corresponding absolute pressure is ___________ psia.
- 7
5. 0 psig + 14.7 = 19.7 psia.
Solar ________ is the amount of solar thermal energy produced divided by the water heating energy demand of the building
Fractional
The portion of the electromagnetic spectrum to which solar collectors respond is _____ and near-infrared radiation.
Visible light
During winter, ________.
Daylight is shorter and the Northern Hemisphere is angled away from the sun
Unless equipped with OSHA or Canadian Standards Association (CSA) approved ground-fault circuit interrupters, portable electric lighting used in wet and-or other conductive locations as, for example, drums, tanks and vessels, shall be operated at ______ volts or less.
12
Receivers are usually required in systems having:
Evaporative condensers
An important feature of a refrigerant receiver, in the case where the liquid line to the evaporator comes out of the top of the receiver, is a
Dip tube
A pressure regulator is constructed so that a rise in ____________ steam pressure reduces off the inlet flow of supply steam.
Downstream
A vacuum breaker is used to avoid which of the following:
Negative gauge pressure
Lock-out relays are used in air conditioning systems to:
Prevent compressor short-cycling
When measuring the winding resistance of a split-phase compressor motor, the smallest value will be measured between the:
The run terminal and the common terminal
Cavitation in a pump pumping hot water:
A. Partial Correct: Makes a pump noisy
B. Partial Correct: Is the result of water boiling into the steam
C. Partial Correct: Is the result of insufficient NPSH
D. Correct: All of the above
The amount of heat removed to lower the temperature of 15 lbs. of water from 48 degrees F to 39 degrees F is:
Correct: 135 Btu. Heat = Weight (lbs.) x Specific Heat (Btu/lb. per degree) F x Temperature (degrees F) = 15 x1 (48-39) degrees F = 15 x 1 x 9 = 135 Btu
Atmospheric pressure at sea level is:
14.7 psi
A dual-element fuse has:
A thermal cutout and a normal fuse link
A single-phase motor in which the run capacitor remains connected when the motor runs is called a:
Permanent-split capacitor motor
Refrigerant leaves the compressor through the ___________ line
Discharge
The symbol below would be used to indicate a ______ switch.
Temperature-actuated
A refrigeration system has a hand-operated needle valve for the refrigerant expansion device. If refrigeration load and suction pressure remain constant, a decrease in condensing temperature will:
Result in reduced refrigerant flow unless the valve is opened.
A full voltage starter has:
One contactor
The voltage rating of motor controller holding coils is:
Not necessarily the same as the motor supply voltage
A lock-out relay should drop out when:
An overload relay opens
In starting up a chilled water system, the first piece of equipment to start should be the:
Chilled water pump
In a gas-fired warm air furnace, the furnace fan should
Be controlled by furnace bonnet temperature
A damper that must throttle air flow should have:
Opposed blade operation
. A pressure regulator is constructed so that a rise in ____________ steam pressure reduces off the inlet flow of supply steam.
Downstream
A vacuum breaker is used to avoid which of the following:
Negative gauge pressure
If the R value on a section of insulation is 8, what would the value be when saturated with water?
0
In a RTD (resistance type device), as temperature increases, resistance will:
Increase linearly
Why is a surge suppressor used on a contactor coil?
To prevent damage to the control circuit
A minimum evacuation level for an air conditioning system is:
500 microns
One horsepower is the same as
746 watts
One watt is equivalent to
3.413 Btu
One kilowatt is equivalent to
1,000 watts
The purpose of the external equalizer line used with a thermostatic expansion valve is to compensate for:
Refrigerant friction through the evaporator
Cleaning refrigerants to ARI 700 standards is called:
Reclaiming
The unit of measure for the specific volume of air is:
FT 3/LB
The amount of heat removed by evaporating one pound of water in an evaporative cooling tower is approximately:
1000 btu
Which of the four lifting sling configurations shown below creates the greatest amount of load strain on the sling?
C- 45 degree strain
The components marked “B” would be called the
Motor contacts
__
__
Which of the following plans are typically NOT supplied in a complete set of Building Plans?
As built
Common Relay configurations are
A. (SPST) Single Pole Single Throw
B. (DPDT) Double Pole Double Throw
The __________ is a device that allows the use of a low voltage power source to operate a high Current load powered device
Contactor
When troubleshooting a contactor in a system. One should check the contact surfaces for
B. Pitting
C. Wear due to Arcing
Terminals “A” would be labeled
O O O
L1, L2, L3
The terminals marked “D” would be labeled
O O O
T1, T2, T3
. Pushing P1 down energizes
M1 first
Pushing P1 down energizes R1 relay coil, closing R1 normally open contacts, energizing TDR relay coil and R1 normally open contacts energizing M1 coil first. After TDR (Time Delay Relay) times out M2 coil energizes second
A (VFD) Variable Frequency Drive controls all but?
Motor life
Three general categories of motor starter problems include all except:
Sizing
VFD’s can be tested when ___________ by means of __________ Measurements for various sections.
Energized, Voltage
If the value of R1 is lowered, the current
Increases
lower resistance current increases
If resistor R2 burns open, the current
Goes to zero
If the value of R3 is raised, the current
Decreases
resistance increases current decreases
All Screw compressors consist of 2 Rotors:
One male and one female rotor
Capacity control for a helical screw compressor is done by?
A. The slide valve
B. Motor speed
If resistor R3 is shorted out the current
Increases
short to ground blows up
If the voltage goes up, the current
Increases
If you find yourself at odds with a confrontational customer, you should
Keep your cool, learn as much as possible, but call your supervisor to report the incident
For applications where quiet operation and light axial load characteristics are found, the type of bearing normally used is the:
Sleeve bearing
Sleeve bearings with the oil port lubrication system must be lubricated with the proper oil because
A. Oil that is too thin will allow the shaft to run against
the bearing surface.
B. Oil that is too thick will not run into the clearance
between the shaft and the bearing surface.
C. The correct oil allows the motor shaft to float on a film
of oil between the shaft and bearing surface.
D. Correct: All of the above.
Too much grease in grease lubricated ball bearing
Causes overheating.
A ladder must extend above the edge of a roof by at least ______ ______.
Three feet.
The proper angle for a ladder is achieved when the distance of the ladder from the building at the base is about __________ the working length (height) of the ladder.
One fourth
Air handling systems that employ economizers which permit outside air “free cooling”
Are most economical when controlled by an enthalpy controller
When face and bypass dampers are used on systems with direct expansion cooling coils:
Compressor capacity control is required
The rate of flow of electrons in a circuit is termed:
Amperage
“Pressure” differential in an electrical resistance is the:
Voltage
The unit used to measure electrical resistance is the:
Ohm
The four essential parts of the vapor compression cycle compressor, condenser, evaporator and
Expansion device
How is an anticipator connected to a single contact cooling thermostat?
In parallel with contacts
The process of removing moisture from air is called:
Dehumidification
Basic types of air supply outlets are
Grilles
With reference to copper tube, what is meant by the letters ACR?
Air conditioning and refrigeration tube
How is the heat anticipator wired in with heating contacts on a 24 volt space thermostat?
Series
A piece of ice weighs 20 LBS and its specific heat is 0.49. It will require __________ Btu to heat the piece of ice from 27 degrees to 31 degrees F
39.2 Solution: Use for Formula: Heat (Btu) = Weight (pounds) x Specific Heat (Btu per LB per degree F) x Temperature Difference (degrees F) = 20 x 0.49 x (31-27) degrees F = 20 x 0.49 x 4 = 39.2 Btu
Given a rate of air flow of 2250 cfm in a duct having a cross-section 18 inches by 18 inches, the duct velocity should be ___________ fpm.
1000
V = 144 x cfm divided by a
= 144 x 2250 (324,000) divided by 18 x18 (324) = 1000 fpm
If a refrigerant sight glass shows bubbles, you know
There is gas in the liquid
A liquid refrigerant receiver has two liquid level test cocks, one near the top of the receiver and one near the bottom. If the system contains enough refrigerant, when the lower cock is opened:
The test cock should discharge liquid refrigerant
Desiccants are used in
Driers
Only __________% of the direct radiation at the edge of Earth’s atmosphere reaches the Earth’s surface
51
Collectors should face as close as possible to ___________?
true South
_________ occurs in a Solar Thermal System when the heated transfer fluid within the absorber piping rises within the collector and is replaced by cooler fluid
downstream
Convection
A (n) ___________ system uses a Heat Transfer Fluid and heat exchanger to transfer heat to the Domestic Hot Water without the use of mechanical means to
circulate the HTF
Passive indirect
Self-pumping Systems are _________ systems.
Passive direct
The vacuum pump used in vacuum steam heating systems that creates a vacuum using high velocity water is the
Jet type pump
Vacuum pumps used in vacuum steam heating systems can be destroyed if they are made to pump
Air and Steam
If a vacuum pump in a vacuum steam heating system burns out, a very common cause is
A failed steam trap
Effective recovery of condensate reduces the following cost of making steam
Fuel/energy costs associated with producing steam.
Boiler water make-up and sewage treatment.
Boiler water chemical treatment
A symptom of a failed steam trap is
A trap that is warmer than condensate temperature
When entering a customer residential premises you should always
Place a clean pair of disposable covers over your shoes
If the technician is on a service call and notices another potential problem not related to the current work order, what should the technician do?
Discuss what you have with the customer and your supervisor so that the customer can decide whether to authorize the additional repair
Which of the following is required part of the work order?
B. Form completed in legible hand writing
C. Complete list of materials used and amount of time spent on the job
Getting the customer to sign the work order should be
The last thing that you should do before leaving the job
Which of the following is a part of your responsibility relative to your work crew?
Working safely on the worksite
The maximum desirable operating temperature of a ball bearing is
180 degrees F.
Shaft runout can be measured with
A. A dial indicator.
B. A runout gage.
The seal in a compressor is necessary to prevent
Refrigerant from leaking out the rotating shaft.
Oil from leaking out at the rotating shaft
The mating seal surfaces on a sleeve type rotary bellows seal are
Polished steel surfaces and a carbon ring
With belt driven equipment, alignment of the motor and driven equipment pulleys
Is accomplished using a string or straight edge
A lock and tag may only be removed by the employee that applied it, unless the employee is absent from the workplace, then the lock or tag may be removed
by a qualified person designated by the employer to perform this task provided that the employer ensures that ___________________________________
The employee who applied the lock or tag is not
available at the workplace
The employee who applied the lock or tag is aware that it has been removed before he or she resumes work at that workplace
Section 608 of the Act prohibits you from knowingly venting ozone-depleting compounds used as refrigerants into the atmosphere while maintaining,
servicing, repairing, or disposing of air-conditioning or refrigeration equipment (appliances). The prohibition went into effect on ____________.
July 1, 1992
When working on a HCFC-22 appliance, or isolated component of such appliance, normally containing 200 pounds or more of refrigerant and using
recovery or recycling equipment manufactured or imported on or after November 15, 1993, you are required to evacuate to a level of
10 in. Hg
If a compressor burn has occurred, the refrigerant must be ____________.
Recovered.
Reclaimed
An advantage of the inverted bucket trap is that
It also vents air and carbon dioxide continuously at steam pressure.
Flash steam is caused by:
Pipe friction
Reduced pressure.
A vertical rise in a condensate line
The purpose of a drip leg in a steam line is to
Let condensate escape by gravity from the fast-moving steam
Store condensate until it can be discharged through the steam trap
Inadequate trapping of steam mains often leads to
Water hammer and damaging slugs of condensate
Pressure in a vertical position condensate pipe will drop 1 psi for every ______ feet in elevation. This is an important factor, since boiling temperature drops as pressure drops. When elevating condensate, this drop in pressure can cause flash steam
2.31
When using a listening device to test a steam trap, what would the technician listen for that could indicate a problem
High velocity sound
If an inverted bucket steam trap is blowing live steam, what might the trouble be?
The valve may have failed to seat because of wear or a piece of dirt or scale
The trap may have lost its prime
The bucket is stuck or has a hole in it
The ____________ drains the condensate from the steam header and returns it to the boiler below the water line while preventing the boiler water from flowing out of the boiler into the return line main
Equalizing line
The ____________ is designed to protect boilers against the loss of water due to leaks in the return line
Hartford Loop
The control valve in a sub-atmospheric steam heating system is limited to approximately ______ % change per minute
3
When the discharge of one compressor is piped into the suction of another compressor, it is called a
Two stage system
What is the most common cause of valve noise?
Valve piped incorrectly
If too much refrigerant is being fed to the evaporator ____________.
The superheat will be low
The low pressure cap tube of an oil failure switch should be connected to the
Compressor crankcase
When copper tubing is being brazed, nitrogen gas can be purged through the system to prevent
Oxidation inside the tubing
In an economizer, an enthalpy control regulates the use of outdoor air on the basis of the air’s
Humidity and temperature
When removing the gauge port plug from a compressor discharge service valve, the valve should be
Back seated
An acid test kit is used to test acidity of
Oil
The TXV sensing bulb is mounted
On the suction line as it leaves the evaporator
In an air cooled system with capacity control, compressor unloading will cause the
Suction pressure to rise and the discharge pressure to fall
A lamp has a source voltage of 110 volts and a current of 0.9 amperes. What is the resistance of the lamp?
122.2 Solution: Ohms Law
R=E divided by I
110 divided by 0.9 = 122.2 ohms
The amount of heat removed to lower the temperature of 15 lbs. of water from 48 degrees F to 39 degrees F is
135 Solution: Heat = Weight (lbs.) x Specific Heat (btu/lb. per degree) F x Temperature Change (degrees F) = 15 x 1 (48-39) degrees f = 15 x 1x 9 = 135 Btu
A belt-driven fan is to turn at 580 rpm. If the fan is driven by a 1740 rpm motor and the motor has a pulley with a three-inch pitch diameter, the fan pulley should have a pitch diameter of ___________ in.
9 Solution: RPM x D = rpm x d
580 x D = 1740 x 3 (5220)
D = 1740 x 3 (5220) divided by 580
= 9 in.
Using a rule-of-thumb figure, approximately how much heat, in Btu/hr., must be rejected by the condenser when the net refrigerating effect is 25 tons?
375,000 Solution:
“Rule-of-thumb” figure for condenser heat rejection is 15,000 Btu per ton of
net refrigeration effect.
25 tons x 15,000 Btu per ton = 375,000 Btu per hour
The heat transferred by calculating water can be expressed by the following equation:
Btuh = 500 x gpm x delta T
A particular heat exchanger is supplied with circulating chilled water flowing at a rate of 100 gpm. If heat is added to the water at a rate of 500,000 btuh when the
initial (entering) water temperature is 40 degrees F, at what temperature does the water leave the heat exchanger?
50 Solution: Btuh = 500 x gpm x delta T 500,000 = 500 x 100 x delta T Delta T = 500,000 500 x 100 Delta T = 10 Leaving temperature = 40 + delta t Leaving temperature = 40 + 10 Leaving temperature = 50 degree F
What is the maximum safe amperage draw of the secondary winding of a 60 VA transformer output of 12 volts?
5 Solution: Divide VA by volts
60 divided 12 = 5 amps
Theoretically, a pump can raise water by suction approximately ___________ feet vertically.
34 Solution:
Atmospheric press. (14.7 psi) = 33.95 (34) ft. Weight of column of water 1’ high
(.433 lb. per foot)
The seal in a compressor is necessary to prevent
Refrigerant from leaking out at the rotating shaft
Oil from leaking out at the rotating shaft
Some codes require a manual reset device on a safety limit
So that the cause of the safety shutdown can be investigated prior to re-start.
A flame sensing relay strategy that takes advantage of the fact that hot gasses in a flame become ionized and conduct electricity is called a
Flame rod
When charging a system, the refrigerant cylinder pressure may drop too low for further charging. Which of the following methods should not be used to increase the pressure?
Heat the cylinder with a torch
In a thermostatic expansion valve, three forces act on the diaphragm in the power head, which is connected to the valve. Evaporator pressure acts to ______
the valve, spring pressure acts to ______ the valve and bulb pressure from the bulb attached to the evaporator outlet acts to ______ the valve
Close; close; open
A stuffing box type of shaft seal on a centrifugal pump needs periodic maintenance. If the seal is found to be leaking excessively, the technician should
Tighten the packing gland and/or replace the packing
Cavitation can destroy a centrifugal pump, is noisy and is caused by
Inlet pressure that is too low
Cavitation can destroy a centrifugal pump, is noisy and is caused by
Outlet pressure that is too high
A vacuum breaker is installed between equipment and a steam trap to
Allow condensate to drain after the steam has been shut off
Two types of thermal overload relays in common use today are
The bimetal relay and the melting alloy relay
When soldering, solder is drawn into the joint by
Capillary action
The efficiency of an electric furnace is usually ______ percent
100
Defective rigging components and hardware should be
Destroyed
In order to reduce pressure to an acetylene pressure regulator, the adjusting screw is turned
Counter-clockwise until the tension is off
Suction gas temperature leaving evaporator minus saturated suction temperature equals
Superheat
Which of the following gases must never be used to pressurize or leak test a refrigeration system?
Oxygen
For electric heat furnace what size should the flue pipe be?
No flue
Defrost systems can be terminated by
Time
Pressure
Temperature
A refrigerant heat exchanger might cause
The compressor to be overheated
The purpose of a suction line accumulator is to
Trap liquid refrigerant
The proper location for an oil separator is near the
Compressor
The two planes of alignment that must be considered when aligning a flexible coupling are
Parallel and angular
How can you identify reverse operation with a scroll compressor?
The compressor will not compress.
The compressor will stop on motor overload.
When in doubt, what should be installed at the bottom of a suction line riser?
A p-trap
Condenser saturation temperature on air cooled condenser should be higher than the ambient temperature by
30 degrees F to 35 degrees F
The compression ratio in a system can be determined by
Dividing discharge pressure absolute by suction pressure absolute
What is the “rule of thumb” in BTU’s per hour of heat rejection of a condenser?
15,000
Typical suction superheat at the evaporator outlet of an air conditioning system is expected to be
12 degrees F to 15 degrees F
The three pressures that operate the thermostatic expansion are bulb, spring and evaporator
Bulb opens, spring closes, evaporator closes the valve
To add refrigerant to the system through the suction service valve, the valve stem must be
Mid seated
How many Btu are there in 8 kW of electrical power?
27,304
An enthalpy controlled economizer system uses _______ for change from mechanical cooling to economizer operation
Outside temperature and humidity sensor
For a voltage measurement the meter is connected
In parallel to with load
To measure motor current
Apply clamp-on amp meter around wire
Before you work on an electrical circuit (touching components)?
Check voltage with a good meter
When measuring voltage, the meter test leads are connected in _________ with
the component being tested.
Parallel
If the voltage is kept constant at 240 volts, and the resistance measures 40 ohms, the current flowing through the conductor is
6 amps
“VA” is the common term for
Watts
The device which operates similar to a fuse, but which can be reused, is a
Circuit breaker
Fuses are sized by the __________ they can carry
Amperage
Current
The 120V side of the transformer found on most heating system is referred to as the
Primary winding
Relays are made up of a __________ and one or more __________.
Load, switches
Terminal reheat systems
Permit any zone to have year round heating or cooling
Variable volume systems
Control space temperature by regulating the flow of air to each zone
Volume limiting controls, also known as velocity controllers, used with variable air volume boxes
Maintain a stable discharge volume regardless of supply duct pressure
Air handling units of the multizone type
Are able to supply each zone with heated or cooled air in all seasons
Are less economical to operate than VAV systems
Can have their hot deck temperature reset on coldest
zone demand
To improve their operating economy, multizone air handlers should
Have their hot deck temperature reset by outside air
temperature or on coldest zone demand
To improve their operating economy, multizone air handlers should
Be used with a variable capacity squirrel cage fan
As compared to across-the-line starters, reduced voltage starters
Reduce starting current inrush
Closed transition starting means
The motor is never disconnected from the line during starting
For maximum safety of equipment, overload relays should be
Manual reset type
Outdoor reset of hot water temperature for heating gives
Hottest water during the coldest weather
The heating capacity of an air-to-air heat pump
Decreases as outdoor air gets colder
The instrument used for finding humidity levels in the atmosphere is the
Sling Psychrometer
Suction line filter-driers are usually equipped with gage connections so that pressure drops can be determined. Why?
So that you can determine when to change the filter-drier
The average house line pressure for Natural Gas is
7” W.C
What air distribution system includes both a warm air duct and a cool air duct, and utilizes mixing boxes near the zone to mix the cool air and warm air streams and achieve the desired temperature while delivering air at a near constant volume?
Dual duct
Capacity control on a helical-rotary (screw) compressor is obtained using
A sliding valve
Which of the following reduced voltage starters uses a switching arrangement to connect the windings of three-phase motors in different configurations during startup and normal operation?
Wye-delta starters
One type of pressure sensing device uses a flattened metal tube, which is bent into a part circle with one end fixed in place and connected to a system to be
measured. The other end of the tube is closed and free to move. An increase in pressure tends to straighten the tube. The movement of the free end of the tube is
connected to a dial that reads pressure. This type of gage is called a
Bourdon tube
With a change in temperature, a thermistor will change
Resistance
Electricity results from the movement of tiny negatively charged particles called
Electrons
___________ is the capacity of a material to store thermal energy for extended periods
Thermal Mass
The expansion tank in a steamback system is _________ a normally sized expansion tank for a Solar Heating Water System
Significantly larger than
Energy Efficient Ratio is a measure of the _____________.
Relative efficiency of a heating or cooling appliance
The ratio of the cooling output in Btu for the season, divided by the power consumption in watts per hour for the season
Seasonal energy efficiency ratio (SEER)
The heating Seasonal Performance Factor (HSPF)
Uses the total output of a system and the total electrical power used by a system over an entire heating season
You are called to a job site to perform some maintenance work on a system and after you are finished the customer approaches you and offers to pay you cash directly to perform some additional work. In this situation it would be ok to?
Refuse the offer politely and if it happens again notify your
supervisor of the situation
What should the technician do in a situation where he is working on a refrigeration system that operates a case that holds perishable food items, the
compressor has failed, it is 5:00 on a Monday evening, and will take a few additional hours to repair the rack?
Request authorization from the customer to stay on the job until it is finished that evening
The most important element(s) of non-verbal communication is (are)
Body language
The quality of customer service can be enhanced if the technician takes the time to
Actively listen
An HVAC technician should always attempt to convey a professional image by
Clean and neat personal appearance
Clean and neat service vehicle (inside and outside)
Maintaining a clean and organized work site
If a technician determines he cannot keep a scheduled customer appointment he should
Call the customer to keep them informed of your delay
Background checks are necessary to disclose employee history associated with
Criminal records
Credit reports
Drug testing
Which of the following would be a display of professionalism?
Work uniform with company logo
Being punctual
Use of good people skills
When completing a service call the last action taken is presenting the invoice to the customer and obtaining a signature. Why it is important that all work
performed is accurately described on the invoice?
To reference details at a later date
To identify warranty parts or service
To provide service details in written communication
form
Service technicians must be thorough in order to prevent a breakdown in communication that results in lost time (money). Which of the following is not part of the required invoice information?
Original supplier of equipment
What measures can service technicians take to ensure that work orders are complete?
Write legibly
Do not rush
Explain the work order to the customer and ask if they
have any questions
To correct for soft foot
Shim under the high foot with shim stock equal to a reading on the indicator
The two planes of alignment that must be considered when aligning a flexible coupling are
Parallel and angular
The first thing a service mechanic should do before performing service work on refrigeration equipment is to
Locate the disconnect switch
EER labels are used on window units, unitary equipment and __________.
Heat pumps
EER labels are used on window units, unitary equipment and __________.
Garbage disposals
The Seasonal Energy Efficiency Ratio is used to measure the efficiency of
Central air conditioning
AFUE stands for Annual Fuel _______ Efficiency
Utilization
Which Government agency requires the display of the AFUE rating on equipment?
Federal Trade Commission
It is not uncommon for condensing residential furnaces to approach AFUE levels of _______%.
96
___________ are used to control ventilation by monitoring the outdoor temperature and humidity.
Economizers
An air filter with a MERV-6 rating or higher will reduce levels of small particulates and improve indoor air quality. MERV stands for __________ value
Minimum efficiency reporting
A solar Chimney used natural rising of warm air through a structure to remove heat, this is true ________.
Passive cooling
There are two kinds of desiccant Solar Systems, they are ________ and ________.
Solid, liquid
To freeze one pound of water, ________Btu of latent heat must be removed
144
The type of refrigerant that must be used now must be ______________.
HFC
All fittings and connections where refrigerants may be present should be __________.
Brazed
The thermal storage system that uses small plastic balls for storage is called a ________.
Cell
The refrigerant line that connects the condenser to the metering device is ___________ line.
Liquid
The four main components of a refrigeration system are
Compressor, condenser, evaporator, & metering device
When an object is refrigerated
Heat is removed from it.
A hand placed near a hot stove or fireplace is quickly heated by
Radiation
If you want to replace a defective capacitor but the only replacements you can find do not have enough capacitance, you can increase their capacitance by
Connecting two or more capacitors in parallel
The rotation of a three-phase motor can be reversed by interchanging
Any two leads
A lamp source has a voltage of 110 volts and a current of 0.9 amperes. What is the resistance of the lamp?
122.2
The difference between a contactor and a motor starter is:
Overload protection
When a three-phase motor single-phases, it:
Draws power from only one phase
The approach temperature for the evaporator is
The difference in the refrigerant boiling temperature and the leaving-water temperature
In a chiller, the refrigerant boils by ___________
Absorbing heat from the water passing through it
If refrigerant condenses at a temperature of 105 degrees F and the water leaves the condenser at a temperature of 95 degrees F, the ___________.
Condenser approach temperature will be 10 degrees
When water is introduced into the end of a chiller it is contained in
Water boxes
When using a thermostatic expansion valve with a __________ charged element, hunting can be considerably reduced
Cross
A vacuum breaker is installed between equipment and a steam trap to
Allow condensate to drain after the steam has been shut off
The device which forms a water seal that prevents raw steam from entering and damaging pressure gauges, vaporstats, pressuretrols, etc. is a (n)
Pigtail
The boiler return line is connected to the steam main by a (n)
Equalizing line
The device which prevents a vacuum from forming in a low-pressure gravity
return steam heating system where automatic control is not used is a (n)
Air vent
The length of the pipe (drip connection) that is needed to overcome the pressure drop in a one-pipe gravity return steam heating system and return condensate to the boiler is
28 inches
In a one-pipe gravity return steam heating system, the main vent should be installed
In a tee at the end of the last steam carrying main
A thermostatic steam trap that fails in the closed position would cause a heating unit to become
Waterlogged
If the float in a F&T trap failed and filled with water, the trap would
Discharge steam continually
If used to drip the end of a steam main, the type of steam trap that would require a cooling leg is a (n)
Thermostatic
In a two-pipe gravity return steam system, the device that prevents raw steam from entering the piping is a
Steam trap
The pump motor on a condensate receiver is usually started by
High condition in the receiver
The device that could be used to regulate the discharge pressure of a condensate pump is a
Plug cock
The device used to actuate the vacuum pump in a vacuum steam heating system when there is a loss of vacuum in the system return piping is the
Vacuum switch
The device which can be used to elevate condensate in a vacuum steam heating system is a
Lift fitting
The device that is incorporated into a vacuum steam heating system to protect the vacuum pump from creating too low (deep) a vacuum is a
Vacuum breaker
In a vapor steam heating system, condensate is returned to the boiler by means of a
Boiler return trap (gravity)
Air is eliminated from a vapor system by a (n)
Air eliminator
The device that is used to maintain a pressure differential between the supply and return piping in a sub-atmospheric steam heating system is a
Differential controller
If the water flow to a water-cooled condenser is reduced, the temperature difference across the condenser will
Decrease
Basic types of heat pump, classified as to their heat source and the medium being heated are
Air-to-air
Water-to-air
Water-to-water
The external equalizer line on an expansion valve performs the following function
Compensates for any pressure drop in the evaporator coil
When the suction pipe from a direct expansion coil must rise to a level above the coil outlet, what purpose is served by a trap placed in the line directly at the coil outlet?
It assists the return of the oil to the compressor
If not properly installed, a hot-gas muffler might trap
Oil
Double suction riser are used in refrigeration system when
Large fluctuations in system capacity will occur
Suction risers are typically reduced by one size over that of the main suction run
To increase refrigerant velocity to aid in proper oil return
The liquid receiver is located between the?
Condenser and the expansion device
Which device is used in a refrigeration system to protect the compressor from liquid slugs?
Suction accumulator
Which device is used to stop the flow of liquid or vapor in a refrigeration system?
Solenoid valve
When soldering a copper pipe connection which of the following processes allow for alloy to be drawn into the space between copper pipe and the fitting connection?
Capillary action
Before proceeding to make any braze connection in a refrigeration system all of the internal piping should be purged of atmosphere with
CO2
Nitrogen
The purpose of the crankcase pressure regulator is to
Prevent a compressor overload condition
The function of the evaporator pressure regulator is to
Prevent a minimum pressure in the regulator
Oxygen hoses are generally what color?
Green
A type of copper tube joint is
Soldered
Flared
Compression
If you were on a job and ran out of 5/8” O.D. fittings while installing 5/8” ACR tube which of the following sizes of copper water tube fittings could be used?
“1/2”
When soldering copper tube, after the tube and fitting are cleaned and fluxed, they should be soldered
As soon as possible
Condensate drain traps must be used on draw through evaporator coils in order to prevent
Water overflow
An excess of acetylene in an oxy-acetylene flame will give a/an
Carburizing flame
In order to reduce pressure to an acetylene pressure regulator, the adjusting screw is turned
Counter-clockwise until the tension is off
The wall thickness of Type K copper tube is
Greater than that of Type L or Type M
Overheating a joint when brazing a wrought copper fitting causes
Oxidation and distortion of the joint
Which action is incorrect when working with an oxy-acetylene?
Use grease on the hose and regulator threading connections
When in doubt, what should be installed at the bottom of a suction line riser?
A p-trap
With reference to copper tube, what is meant by the letters ACR?
Air conditioning and refrigeration tube
Superheater tubes are protected from warping or burning out by
Circulating steam through them
To increase the life of furnace refractory, water-tube boilers are equipped with
Waterwalls
When steam is superheated its
Temperature is increased with no increase in pressure
Air is eliminated from a sub-atmospheric system by a (n)
Vacuum pump
The device that controls the steam pressure on the supply side of a subatmospheric steam heating system is a
Control valve
In order to return condensate to a boiler, the height of the water column needed to overcome the pressure drop in a two-pipe gravity return system is
28 inches for each pound of pressure the boiler is producing
The pump motor on a boiler feed pump is started when there is
A low water condition in the boiler
Soot should be
Removed from boiler tubes for better heat transfer
Soot deposits reduce heat transfer rates on the heating surfaces and consequently reduce boiler efficiency, and increase metal surface deterioration
Thermostatic traps are opened and closed by a (n)
Flexible bellows
In a float and thermostatic trap the float rises to discharge
Condensate
Condensate in steam lines could result in
Water hammer
The type of traps normally used on steam radiators are
Hermostatic traps
Which of the following is the common cause of back pressure in a condensate return line?
Faulty steam trap
A vacuum breaker is used to avoid which of the following
Negative gauge pressure
System powered variable air volume systems
Operate by the system duct air pressure
The secondary water temperature of primary-secondary hydronic cooling system, supplied to induction coils or chilled beams is regulated to
Achieve maximum sensible cooling without latent cooling
When used as terminal units, induction units with chilled water coils require
A source of dehumidified primary air
Fan coil units used with a two-pipe dual temperature system
Require a changeover control to reverse the action of the fan coil thermostat
As a rule, the best general type of air diffuser to use in a variable air volume system is the
Slot diffuser
What is the maximum safe amperage draw of the secondary winding of a 40 VA transformer output of 24 volts?
1.67 amps
The purpose of a hot-gas bypass valve is too
Maintain evaporator load
If a refrigerant sight glass shows bubbles, you know
There is gas in the liquid
A hermetic motor should never be energized or tested with a megohmeter when in a deep vacuum because
The dielectric strength of the motor’s insulation would be greatly reduced
In order to protect a load, safety limit devices are most often wired
In series.
In a balanced three-phase system, the phase the voltage waveforms differ in phase by
120 degrees
Electrical pressure is measured in
Volts
A bellows is used
In both pressure and temperature controllers
Roller bearings are normally used with
Large motors operating with a heavy load
The width of a drive belt is classified as
Large or small.
Narrow or wide.
An instrument often used to check the alignment of two shafts is the
Dial indicator
A loose-fitting belt on a belt-driven device will cause
Worn pulley grooves
A flexible coupling between the drive and driven device
Corrects minor misalignment
If refrigerant is to be added to a system, the refrigerant cylinder is usually connected to the
Center port of gauge manifold
On centrifugal pumps, if it is ever necessary to reduce pump flow, do so by
Throttling the discharge
Which of the following would happen if the vent port on a gas regulator is plugged?
Outlet pressure will be reduced
Which of the following is NOT used to size gas regulators?
Type of ignition system
Which of the following is the common cause of back pressure in a condensate return line?
Faulty steam trap
An evaporative cooling tower’s bleed rate is adjusted to maintain
The desired concentration of total dissolved solids
The run windings of a motor have ___________turns as compared to the start windings
Fewer
On a typical split-phase electric motor the start winding circuit is de-energized as it reaches approximately ____________ of its operating speed?
75%
What component wired in series with the start windings on a single-phase motor will create greater starting torque
A capacitor
A three-phase motor does not have
Start windings
A start capacitor
A start relay
A start component that is rated in microfarad would be a
Capacitor
What effect will a higher than rated supply voltage have on the current draw of an electric motor?
It will be lower than it should be
With an electric motor running normally at full load the amperage reading would be called?
Run-load amperage
What device would be discharged using a 20,000-ohm, 5 watt resistor?
Capacitor
The run-load amperage on an electric motor is typically
1/5 that of a full-load amperage
What device is used to energize another load such as a contactor or motor starter which in turn would start or stop a motor?
A pilot duty relay
A magnetic coil and electrical contacts are the primary components of this electrical device?
A contactor
A magnetic coil, overload protector and electrical contactors are the primary components of this electrical device
A motor starter
An electric motor that has an internal overload would have a?
A thermal device buried in the motor windings
What device could be used as external protection for a motor?
A line fuse
A circuit breaker
Magnetic overload
If a technician uses an ohm meter to check the windings of an electric motor
and records an infinite reading on the start windings this would indicate?
The start winding has an open somewhere
What type of motor would a technician switch any two legs on to reverse the rotation of the motor?
Three Phase
Induction motors obtain good starting and running torque from
Start windings
Shaded-pole motors can most easily be identified by
A small pole of thick copper wire
The primary application for shaded-pole motors would be
When low start torque is required
When low run torque is required
One of the most popular motors used in the HVAC industry with low starting torque but improved running is the ___________ motor.
Capacitor-run
