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Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the
question.
1)
1)
How can the centrifugal compressor speed be higher than the motor speed?
A)
By using a drive belt with a larger pulley on the motor than on the compressor
B)
By using speed-increasing gears
C)
By using a drive belt with a smaller pulley on the motor than on the compressor
D)
Because of the inertia of the impeller
Answer:
B
Explanation:
A)
B)
C)
D)
2)
2)
What happens to the flash gas formed in a chiller economizer?
A)
It is piped to the chiller bundle.
B)
It is piped to a later stage in the compressor.
C)
It is condensed.
D)
It is absorbed into the economizer adsorbent solution.
Answer:
B
Explanation:
A)
B)
C)
D)
3)
3)
Compared to reciprocating compressors, centrifugal compressors:
A)
Can operate against higher head pressures.
B)
Can operate at higher compression ratios.
C)
Can work effectively on smaller systems.
D)
Can move a larger volume of refrigerant.
Answer:
D
Explanation:
A)
B)
C)
D)
1
4)
4)
The economizer decreases the amount of gas that flashes when the liquid enters the:
A)
Control valve.
B)
Cooler.
C)
Compressor.
D)
Condenser.
Answer:
B
Explanation:
A)
B)
C)
D)
5)
5)
During the vapor recovery phase, what is pumped from the condenser to the storage tank?
A)
High-pressure vapor
B)
Cooling water
C)
Low-pressure vapor
D)
Liquid refrigerant
Answer:
D
Explanation:
A)
B)
C)
D)
6)
6)
Which of the following statements is TRUE about the economizer?
A)
The economizer cools the liquid refrigerant but does not affect the volume of available
liquid refrigerant.
B)
The economizer is directly connected to the compressor, so liquid refrigerant that flashes is
returned directly to the compressor.
C)
The economizer acts as a control valve and separates the liquid cooled and warmed
refrigerant.
D)
The economizer provides more cooled liquid refrigerant to the cooler than do systems
without an economizer.
Answer:
D
Explanation:
A)
B)
C)
D)
7)
7)
Purged air is released from the:
A)
Top of the condenser.
B)
Bottom of the chiller.
C)
Bottom of the condenser.
D)
Top of the chiller.
Answer:
A
Explanation:
A)
B)
C)
D)
2
8)
8)
When air enters a low-pressure system, it collects in the condenser because:
A)
The air will not condense.
B)
It is routed to the air collection accumulator.
C)
A small amount of air helps the system operate more efficiently.
D)
The air falls to the bottom of the condenser shell.
Answer:
A
Explanation:
A)
B)
C)
D)
9)
9)
What type of compressor is most often used in large chillers?
A)
Scroll
B)
Rotary
C)
Centrifugal
D)
Reciprocating
Answer:
C
Explanation:
A)
B)
C)
D)
10)
10)
What types of prime movers can be used for centrifugal chillers?
A)
Gas turbines, AC motors, and steam turbines
B)
AC motors, calibrated springs, and wind
C)
Steam turbines, natural convection, and radiation
D)
Radiation, natural convection, and wind
Answer:
A
Explanation:
A)
B)
C)
D)
11)
11)
Compared to centrifugal chillers, screw chillers generally:
A)
Are physically larger for comparable capacity.
B)
Are arranged in multiple stages to improve compression ratio.
C)
Operate at lower compression ratios.
D)
Are physically smaller for comparable capacity.
Answer:
D
Explanation:
A)
B)
C)
D)
3
12)
12)
In a flooded chiller, the chilled water is circulated:
A)
Through the compressor water cooling jacket.
B)
Over the outside of the chiller tubes.
C)
Over the outside of the chiller shell.
D)
Through the inside of the chiller tubes.
Answer:
D
Explanation:
A)
B)
C)
D)
13)
13)
Which of the following statements regarding chillers is TRUE?
A)
Dry (direct expansion) chillers require less refrigerant than do flooded chillers.
B)
Flooded chillers have less potential for freeze-ups than other chillers.
C)
Regional zone chillers are more cost-effective than centralized units.
D)
Top-loaded chillers do not use shell-and-tube arrangements.
Answer:
A
Explanation:
A)
B)
C)
D)
14)
14)
The evaporator in a low-pressure chiller:
A)
Operates in a vacuum.
B)
Operates between 5 and 10 psig.
C)
Is generally higher than the condenser pressure.
D)
Operates between 10 and 50 psig.
Answer:
A
Explanation:
A)
B)
C)
D)
15)
15)
Why must some valves be left open between the storage tank and the compressor, and the
compressor and the cooler?
A)
To allow the liquid in the storage tank to flash
B)
To empty the condenser
C)
To draw suction through the storage tank
D)
To push vapor from the cooler to the storage tank
Answer:
C
Explanation:
A)
B)
C)
D)
4
16)
16)
Absorption chillers move refrigerant using:
A)
Steam-driven turbines.
B)
Heat from steam, hot water, or gas.
C)
Reciprocating compressors.
D)
Large centrifugal compressors.
Answer:
B
Explanation:
A)
B)
C)
D)
17)
17)
How should refrigerant be recovered from a chiller?
A)
Always begin the refrigerant recovery using vapor recovery methods.
B)
The chiller should be operated to build pressure before starting recovery.
C)
Refrigerant should be pushed out by pressurizing the chiller with 50 psig of nitrogen.
D)
Always begin the refrigerant recovery using liquid recovery methods.
Answer:
D
Explanation:
A)
B)
C)
D)
18)
18)
Refrigerant vapor removed from the oil travels directly to the:
A)
Cooler suction.
B)
Cooler outlet.
C)
Compressor suction.
D)
Compressor outlet.
Answer:
A
Explanation:
A)
B)
C)
D)
19)
19)
In a water-cooled condenser, the higher the number of passes of water through the shell, the
greater the:
A)
Water temperature.
B)
Pressure drop.
C)
Refrigerant flow.
D)
Discharge rate.
Answer:
B
Explanation:
A)
B)
C)
D)
5
20)
20)
The pressure of a low-pressure chiller is raised for leak testing by:
A)
Adding nitrogen to the chiller bundle.
B)
Circulating warm water through the chiller bundle.
C)
Adding refrigerant to the chiller bundle.
D)
Operating the chiller.
Answer:
B
Explanation:
A)
B)
C)
D)
21)
21)
For what applications are low-pressure refrigerants well suited?
A)
Cryogenic equipment with reciprocating compressors
B)
Commercial refrigeration rack systems
C)
Residential air conditioning
D)
Centrifugal chillers operating with 40°F evaporators
Answer:
D
Explanation:
A)
B)
C)
D)
22)
22)
When leak testing a low-pressure chiller, the pressure should not be allowed to exceed 10 psig to
avoid:
A)
Opening the high-pressure cutout and shutting the system down.
B)
Breaking the rupture disk and losing the refrigerant charge.
C)
Freezing the chiller bundle.
D)
High compressor current draw.
Answer:
B
Explanation:
A)
B)
C)
D)
23)
23)
What is the function of a purge unit?
A)
A purge unit is used to purge the air out of the chilled water loop.
B)
A purge unit is used to purge the refrigeration oil out of the refrigerant.
C)
A purge unit is used to purge the superheat from the condenser.
D)
A purge unit will purge the air from the top of the condenser.
Answer:
D
Explanation:
A)
B)
C)
D)
6
24)
24)
What is the purpose of a chiller economizer?
A)
To use outdoor air for cooling
B)
To limit the compressor current draw
C)
To subcool the liquid refrigerant before it enters the chiller
D)
To superheat the liquid refrigerant before it enters the chiller
Answer:
C
Explanation:
A)
B)
C)
D)
25)
25)
What could happen if you charge liquid refrigerant into a chiller that is under a deep vacuum?
A)
The refrigerant will flash at a low temperature, freeze the water, and crack the chiller tubes.
B)
The vacuum will draw in an excessive amount of refrigerant, causing an overcharge.
C)
The compressor motor amp draw will cause the motor overload to trip.
D)
The refrigerant will fractionate when it flashes off in the chiller.
Answer:
A
Explanation:
A)
B)
C)
D)
26)
26)
Which type of chiller is more likely to freeze the tubes if charged or recovered improperly?
A)
Direct expansion chillers
B)
Flooded chillers
C)
Absorption chillers
D)
Screw chillers
Answer:
B
Explanation:
A)
B)
C)
D)
27)
27)
In a direct expansion chiller, the chilled water is circulated:
A)
Over the outside of the chiller shell.
B)
Through the inside of the chiller tubes.
C)
Through the compressor water cooling jacket.
D)
Over the outside of the chiller tubes.
Answer:
D
Explanation:
A)
B)
C)
D)
7
28)
28)
What type of chiller is capable of continuous (stepless) capacity control?
A)
Screw chillers
B)
Rotary chillers
C)
Centrifugal chillers
D)
Reciprocating chillers
Answer:
A
Explanation:
A)
B)
C)
D)
29)
29)
Traditional methods of capacity control for centrifugal compressors include:
A)
Cylinder unloading.
B)
Adjustable pitch impellers.
C)
Discharge outlet vanes.
D)
Variable inlet vanes and motor speed control.
Answer:
D
Explanation:
A)
B)
C)
D)
30)
30)
In a flooded chiller, the refrigerant:
A)
Circulates in tubes inside the chiller.
B)
Surrounds tubes filled with refrigerant.
C)
Circulates throughout the building.
D)
Surrounds tubes filled with chilled water.
Answer:
D
Explanation:
A)
B)
C)
D)
31)
31)
The largest-capacity chillers use:
A)
Rotary compressors.
B)
Reciprocating compressors.
C)
Centrifugal compressors.
D)
Scroll compressors.
Answer:
C
Explanation:
A)
B)
C)
D)
8
32)
32)
Packaged chillers with air-cooled condensers usually use:
A)
Hydrostatic chillers.
B)
Flooded chillers.
C)
Hydroponic chillers.
D)
Direct expansion (DX) chillers.
Answer:
D
Explanation:
A)
B)
C)
D)
33)
33)
When a purge-recovery unit runs to purge the air from the condenser of a low-pressure chiller,
most of the refrigerant that is purged with the air is:
A)
Released with the water.
B)
Recovered and returned to the system.
C)
Reused as chiller fuel.
D)
Released into the air.
Answer:
B
Explanation:
A)
B)
C)
D)
34)
34)
Typically, the zone control valve not only opens to allow water to flow to the zone, but also turns
on:
A)
Circulator pump.
B)
The boiler.
C)
The blower.
D)
The fan coil unit.
Answer:
A
Explanation:
A)
B)
C)
D)
35)
35)
In a series loop system:
A)
Only part of the water flows through each convector in the loop.
B)
All the water flows through each convector in the loop.
C)
Each convector is supplied with the same temperature hot water.
D)
The amount of water flowing through each individual convector is controlled by a
thermostat.
Answer:
B
Explanation:
A)
B)
C)
D)
9
36)
36)
In the zoned system, how many motorized valves does each circuit contain?
A)
1
B)
2
C)
3
D)
4
Answer:
A
Explanation:
A)
B)
C)
D)
37)
37)
The mixing valve controls the temperature of water supplied to the:
A)
Radiant loop.
B)
Cooler.
C)
Supply pump.
D)
Boiler.
Answer:
A
Explanation:
A)
B)
C)
D)
38)
38)
Most hydronic heating systems are:
A)
Open systems in cooling and closed systems in heating.
B)
Closed systems in cooling and open in heating.
C)
Closed piping systems.
D)
Open piping systems.
Answer:
C
Explanation:
A)
B)
C)
D)
39)
39)
What is a hydronic terminal unit?
A)
A unit that is specifically designed for use in airports and train stations
B)
A reverse return loop that is installed on the end of a hydronic run
C)
The last convector in a hydronic loop
D)
The coils and devices that heat the building
Answer:
D
Explanation:
A)
B)
C)
D)
10
40)
40)
What is the purpose of the venturi on a one-pipe venturi system?
A)
The venturi creates a negative pressure at the main connection, drawing the necessary flow
through the branch.
B)
The venturi increases the pressure in the pipe to offset piping losses.
C)
The venturi separates air bubbles from the circulating water.
D)
The venturi mixes the supply and return water for more even temperatures.
Answer:
A
Explanation:
A)
B)
C)
D)
41)
41)
A piping system that has the main supply pipe from the boiler enter the first baseboard unit, all
baseboard sections connected in series, and the outlet from the last baseboard section connected to
the circulator pump, which connects to the boiler, is called a:
A)
One-pipe, venturi piping system.
B)
Two-pipe, reverse return hot water piping system.
C)
Series loop, single circuit hot water piping system.
D)
Series loop, double circuit.
Answer:
C
Explanation:
A)
B)
C)
D)
42)
42)
Which of the following statements about zoned systems is correct?
A)
Individual zone temperature control is not available in zoned systems.
B)
Water flow in zoned systems is controlled by a motorized valve.
C)
One thermostat controls all the motorized valves in the system.
D)
Zoned systems are only used for commercial buildings.
Answer:
B
Explanation:
A)
B)
C)
D)
11
43)
43)
A building requires a pump with a head pressure of 15 feet and a flow rate of 12 gallons per
minute. Which of the following pumps should be used, based on the supplied performance data?
A)
Total head pressure range: 16 to 2 feet; flow rate: 0 to 14 gallons per minute
B)
Total head pressure range: 32 to 8 feet; flow rate: 0 to 8 gallons per minute
C)
Total head pressure range: 12 to 3 feet; flow rate: 0 to 32 gallons per minute
D)
Total head pressure range: 8 to 0 feet; flow rate: 0 to 10 gallons per minute
Answer:
A
Explanation:
A)
B)
C)
D)
44)
44)
In a two-pipe system:
A)
The convector can be used for both heating and cooling.
B)
The main supply water temperature drops a little through each convector.
C)
Each convector is supplied with the same temperature hot water.
D)
All the water flows through each convector in the loop.
Answer:
C
Explanation:
A)
B)
C)
D)
45)
45)
What component is used to compensate for different pressure drops and load requirements?
A)
Check valve
B)
Return pump
C)
Balancing valves
D)
Venturi units
Answer:
C
Explanation:
A)
B)
C)
D)
46)
46)
You will never see a pump with a profile of:
A)
High pressure and high flow.
B)
Low pressure and high flow.
C)
High pressure and low flow.
D)
Low pressure and low flow.
Answer:
A
Explanation:
A)
B)
C)
D)
12
47)
47)
Pumps for hydronic heating systems are usually:
A)
Diaphragm pumps.
B)
Piston pumps.
C)
Centrifugal pumps.
D)
Gear pumps.
Answer:
C
Explanation:
A)
B)
C)
D)
48)
48)
Which piping arrangement allows every unit to receive the same temperature water?
A)
One-pipe venturi system, single circuit
B)
Two-pipe system, direct return
C)
Series loop, single circuit
D)
One-pipe venturi unit, double circuit
Answer:
B
Explanation:
A)
B)
C)
D)
49)
49)
Balancing valves are required:
A)
On single circuit loops.
B)
To allow adjustable flow.
C)
On venturi pipe systems.
D)
To create negative pressure.
Answer:
B
Explanation:
A)
B)
C)
D)
50)
50)
What do modern hydronic systems use to circulate the hot water?
A)
Convection
B)
Pumps
C)
Fans
D)
Gravity
Answer:
B
Explanation:
A)
B)
C)
D)
51)
51)
What happens when the electrical contacts close in the motorized valve?
A)
The bypass pump starts.
B)
The circulator pump stops.
C)
The circulator pump starts.
D)
The bypass pump stops.
Answer:
C
Explanation:
A)
B)
C)
D)
13
52)
52)
Which system heats a room more evenly, leading to fewer cold spots?
A)
Fan coil heating system
B)
Baseboard radiator systems
C)
Forced-hot-air system
D)
Radiant floor heating system
Answer:
D
Explanation:
A)
B)
C)
D)
53)
53)
What materials are most commonly used for hydronic piping?
A)
CPVC and polybutylene
B)
Copper and cross-linked polyethylene
C)
PVC and CPVC
D)
Copper and galvanized iron
Answer:
B
Explanation:
A)
B)
C)
D)
54)
54)
What is the primary way a convector heats a room?
A)
By releasing microbursts of steam into the room
B)
By radiating heat into the space
C)
Through natural convection along the outer walls
D)
By absorbing the cold in the room
Answer:
C
Explanation:
A)
B)
C)
D)
55)
55)
Mixing valves control the final temperature of radiant loops:
A)
By mixing the hot boiler water with fresh makeup water.
B)
By mixing the hot water from the boiler with the cold water from the chiller.
C)
By bleeding off some of the hot water before it enters the loop.
D)
By mixing the hot boiler water with cooler return water.
Answer:
D
Explanation:
A)
B)
C)
D)
14
56)
56)
What is the purpose of the expansion tank?
A)
To provide pressure for the water system
B)
To allow for water volume changes due to temperature change
C)
To allow room for extra water
D)
To reduce the water temperature by expansion
Answer:
B
Explanation:
A)
B)
C)
D)
57)
57)
The different types of terminal units used for hot water heating systems include:
A)
Series loop, parallel loop, and reverse return loop.
B)
One-pipe and two-pipe terminal units.
C)
Baseboard heaters, convectors, fan coil units, and radiators.
D)
Heating only, cooling only, and combination heating-cooling units.
Answer:
C
Explanation:
A)
B)
C)
D)
58)
58)
A modern hydronic heating system typically:
A)
Heats by circulating hot water through a closed system of piping.
B)
Uses water to cool the condenser of a water-to-air heat pump.
C)
Heats using low-pressure steam.
D)
Heats both the house and the domestic hot water.
Answer:
A
Explanation:
A)
B)
C)
D)
59)
59)
Compared to air heating systems, hydronic heating systems:
A)
Are normally less expensive to install.
B)
Automatically add humidity as well as heat.
C)
Can be more easily used for air conditioning.
D)
Are normally more expensive to install.
Answer:
D
Explanation:
A)
B)
C)
D)
15
60)
60)
Zone control is accomplished in hydronic systems using thermostats that activate:
A)
A zone control valve for each zone.
B)
A zone boiler for each zone.
C)
A zone compressor for each zone.
D)
A zone damper for each zone.
Answer:
A
Explanation:
A)
B)
C)
D)
61)
61)
Water circulating pumps are rated by:
A)
Flow.
B)
Head pressure.
C)
Flow and head pressure.
D)
Wet and dry capacity.
Answer:
C
Explanation:
A)
B)
C)
D)
62)
62)
How do mixing valves save energy?
A)
By maintaining a hot loop regardless of outdoor temperature
B)
By mixing costly boiler water with inexpensive domestic hot water
C)
By delivering only enough heat to the loop to meet the load
D)
By reusing loop water for domestic hot water
Answer:
C
Explanation:
A)
B)
C)
D)
63)
63)
What is the purpose of a reverse return piping system?
A)
To reduce the amount of piping required
B)
To allow the flow direction to be reversed for cooling
C)
To keep the length of piping the same for each convector unit
D)
To operate a two-pipe system like a one-pipe system
Answer:
C
Explanation:
A)
B)
C)
D)
16
64)
64)
Sensors for the mixing valve control are located:
A)
On the supply line and on the boiler.
B)
Outside the building, on the supply line, and on the boiler.
C)
Outside the building and on the supply line.
D)
Outside the building and on the boiler.
Answer:
B
Explanation:
A)
B)
C)
D)
65)
65)
What materials are boilers commonly made from?
A)
Most boilers are either aluminum or copper.
B)
Most boilers are either cast iron or steel.
C)
Most boilers are either cast iron or brass.
D)
Most boilers are either steel or aluminum.
Answer:
B
Explanation:
A)
B)
C)
D)
66)
66)
What is a low water cutout?
A)
It is an operating control that energizes the water fill solenoid at the end of an automatic
blow-down cycle.
B)
It is a safety device that shuts off the boiler if the water level is low.
C)
It is an operating control that shuts off the boiler at the end of every operating cycle when it
senses that the boiler has used up its supply of water.
D)
It is a hand valve installed near the bottom of the boiler, which is used for filling and
servicing the boiler.
Answer:
B
Explanation:
A)
B)
C)
D)
17
67)
67)
What is the difference between a steam boiler and a hot water boiler?
A)
Steam boilers are used to superheat the steam produced by a hot water boiler.
B)
A hot water boiler does not actually boil the water.
C)
Hot water boilers do not heat the water over 212°F.
D)
The steam created by a hot water boiler is vented to the air.
Answer:
B
Explanation:
A)
B)
C)
D)
68)
68)
Medium and large commercial buildings typically use:
A)
Low-pressure steam boilers.
B)
Medium- or high-pressure steam boilers.
C)
Medium- or high-pressure hot-water boilers.
D)
Low-pressure hot-water boilers.
Answer:
B
Explanation:
A)
B)
C)
D)
69)
69)
Radiant floor heating systems typically operate at temperatures of:
A)
85°F to 140°F.
B)
280°F to 300°F.
C)
180°F to 200°F.
D)
200°F to 250°F.
Answer:
A
Explanation:
A)
B)
C)
D)
70)
70)
What is the purpose of the zinc rod used in steel boilers?
A)
It cycles the burner by sensing the water temperature.
B)
It acts as an electrical ground for safety purposes.
C)
It prevents corrosion by reacting with corrosive elements before they attack the boiler.
D)
It acts as a flame safety device.
Answer:
C
Explanation:
A)
B)
C)
D)
18
71)
71)
What controls the firing of a water boiler?
A)
An aquastat that senses the temperature of the water in the boiler
B)
A wall thermostat that senses the temperature of the house
C)
The boiler water temperature is normally maintained by the high limit and the low water
cutout.
D)
The auxiliary switch on the zone valve
Answer:
A
Explanation:
A)
B)
C)
D)
72)
72)
How does a closed expansion tank work?
A)
It uses a flexible diaphragm with an air charge above the diaphragm.
B)
Air is trapped at the top of the tank.
C)
The walls of the tank are made of a flexible material.
D)
The top of the tank is open to the atmosphere.
Answer:
B
Explanation:
A)
B)
C)
D)
73)
73)
The highest available output for a water boiler is:
A)
500,000 BTU.
B)
50,000,000 BTU.
C)
300,000 BTU.
D)
30,000,000 BTU.
Answer:
B
Explanation:
A)
B)
C)
D)
74)
74)
An expansion tank problem may be indicated by:
A)
A clogged air separator.
B)
A weeping relief valve.
C)
A low pressure problem.
D)
A defective mixing valve.
Answer:
B
Explanation:
A)
B)
C)
D)
19
75)
75)
What is the minimum desired return water temperature for a gas-fired boiler?
A)
At least 180°F returning to the boiler
B)
At least 100°F returning to the boiler
C)
At least 140°F returning to the boiler
D)
At least 80°F returning to the boiler
Answer:
C
Explanation:
A)
B)
C)
D)
76)
76)
Most hot water boilers heat the water up to temperatures of:
A)
280°F to 300°F.
B)
180°F to 200°F.
C)
100°F to 150°F.
D)
200°F to 250°F.
Answer:
B
Explanation:
A)
B)
C)
D)
77)
77)
What kind of boiler is used for residential installations?
A)
Hot-water
B)
High-pressure
C)
Steam
D)
Low-pressure
Answer:
A
Explanation:
A)
B)
C)
D)
78)
78)
What is a pickling solution?
A)
A water additive that is used to improve heat transfer
B)
A corrosion inhibitor used on steel pipes
C)
A thread sealant that stands up to boiler duty
D)
The circulating water in a hydronic heating system
Answer:
B
Explanation:
A)
B)
C)
D)
79)
79)
What is the maximum working pressure for a low-pressure hot water boiler?
A)
100 psi
B)
160 psi
C)
10 psi
D)
15 psi
Answer:
B
Explanation:
A)
B)
C)
D)
20
