Ua star

Absolute zero is: o degrees F 32 degrees F 460 degrees F -460 degrees F

-460

Condensers are sized in a system to be ______ % larger than in the system evaporator. 25 20 15 10

25

How many Btu are there in 8 kW of electrical power? 26,286 5,968 27,304 68,260

27,304

Condenser saturation temperature on a air cooled condenser should be higher than the ambient temperature by: 100 degrees F to 105 degrees F 90 degrees F to 100 degrees F 10 degrees F to 15 degrees F 30 degrees F to 35 degrees F

30 degrees F to 35 degrees F

When in doubt, what should be installed at the bottom of a suction line riser? a check valve a p-trap a service port a balancing valve

P-trap

Lithium-Bromide is used in absorption systems as: a salt solution an absorbent (attractant) a solution that creates a pressure difference all of the above

all of the above

The rotation of a three-phase motor can be reversed by interchanging: the collector ring any two leads the starting winding the running winding

any two leads

What is the maximum safe amperage draw of the secondary winding of a 60 VA transformer output of 12 volts? a.7.2 amps b.5 amps. c.720 amps. d.0.2 amps.

b. 5 amps.

If a vacuum pump in a vacuum steam heating system burns out, a very common cause is a.backward rotation. b.a failed steam trap. c.incorrect voltage to the pump d.a failed vacuum breaker

b. a failed steam trap

A vacuum breaker is installed between equipment and a steam trap to a.prevent condensate from draining after the steam has been shut off. b.allow condensate to drain after the steam has been shut off. c.trip on low pressure cutoff. d.allow a vacuum to be pulled on the system.

b. allow condensate to drain after the steam has been shut off.

The heating capacity of an air-to-air heat pump: a.decreases as outside air gets warmer b.decreases as outdoor air gets colder c.increases as outdoor air gets colder d.is not affected by outside temperature

b. decreases as outdoor air gets colder

Defective rigging components and hardware should be a.washed b.destroyed c.repaired d.recycled

b. destroyed

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 a.thermocouple. b.flame rod. c.ion sensor. d.cad cell.

b. flame rod.

Outdoor reset of hot water temperature for heating gives: a.hottest water during milder weather b.hottest water during the coldest weather c.night setback d.hottest water only in the morning

b. hottest water during the coldest weather

Fuses in motor branch-circuits primarily provide: a.motor running overcurrent protection b.motor short-circuit protection c.protection against single-phasing d.protection against motor overheating

b. motor short-circuit protection.

For a electric heat furnace what size should the flue pipe be? a.6" b.no flue c.10" d.8"

b. no flue

Which of the following would happen if the vent port on a gas regulator is plugged? a.nothing, this is normal operation b.outlet pressure will be reduced c.outlet pressure will increase d.inlet pressure will be reduced

b. outlet pressure will be reduced

An in-line ammeter must be connected to the circuit: in series in parallel around the conductor with the jaws closed.

in series

With belt driven equipment, alignment of the motor and driven equipment pulleys is not critical, since the belts are flexible. is accomplished using a string or straight edge. is accomplished when the belts are parallel to one another. is accomplished using a dial indicator.

is accomplished using a string or straight edge.

The evaporator in a refrigeration system: meters the refrigerant. condenses the refrigerant. is the component where refrigerant boils and absorbs heat. compresses the vaporized refrigerant.

is the component where refrigerant boils and absorbs heat.

Heat flows downhill. This means: -it falls off hot surface to the floor. -it naturally flows from a colder to a warmer substance. -heating ducts should flow downhill. -it naturally flows from warmer to colder substance.

it naturally flows from warmer to colder substance.

Refrigerant and / or oil out of place or composition in the refrigerant system is known as: loss of oil lack of lubrication loss of refrigerant pure motor failure

lack of lubrication

The refrigerant line that connects the condenser to the metering device is ___________ line. -discharge -expansion -liquid -suction

liquid

The purpose of the compressor is to change ___________. -low-pressure, low-temperature liquid to a high-pressure, high temperature liquid -high-pressure, high-temperature vapor to a low-pressure, low-temperature vapor -low-pressure, low-temperature vapor to a high-pressure, high-temperature vapor -high-pressure, high-temperature liquid to a low-pressure, low-temperature liquid

low-pressure, low-temperature vapor to a high-pressure, high-temperature vapor

To add refrigerant to the system through the suction service valve, the valve stem must be: back seated. front seated. mid seated none of the above.

mid seated

If not properly installed, a hot-gas muffler might trap: hot gas. superheated vapor. suction gas. oil.

oil

The difference between a contactor and a motor starter is: -physical size -overload protection -wire size -timing

overload protection

The two planes of alignment that must be considered when aligning a flexible coupling are axial and parallel. parallel and perpendicular. horizontal and vertical. parallel and angular.

parallel and angular.

A single-phase motor in which the starting capacitor remains connected when the motor runs is called a: -capacitor-start induction-run motor -permanent-split capacitor motor -split-phase motor -capacitor-start capacitor-run motor

permanent-split capacitor motor

A hand placed near a hot stove or fireplace is quickly heated by: -radiation -convection -conduction -refrigeration

radiation

The approach temperature for the evaporator is: -the difference in the suction and head pressure converted to temperature -the difference in the refrigerant boiling temperature and the suction-line temperature -the difference in the refrigerant boiling temperature and the inlet water temperature -the difference in the refrigerant boiling temperature and the leaving-water temperature

the difference in the refrigerant boiling temperature and the leaving-water temperature

What is the maximum allowable current imbalance rating in a three-phase supply? None 2% 5% 10%

10%

Typical suction superheat at the evaporator of an air conditioning system is expected to be: 10 degrees F to 20 degrees F 12 degrees F to 15 degrees F 20 degrees F to 25 degrees F 60 degrees F to 80 degrees F

12 degrees F to 15 degrees F

A lamp source has a voltage of 110 volts and a current of 0.9 amperes. What is the resistance of the lamp? 12.22 122.2 0.008 0.08 ohms

122.2

The amount of heat removed to lower the temperature of 15 lbs of water from 48 degrees F to 39 degrees F is: 0.0113 135 Btu. 970 Btu/lb 135 Btu/lb

135 BTU

Atmospheric pressure at sea level is: -0 psi -14.7 psi -32 psi -212 psi

14.7 PSI

What is the "rule of thumb" in BTU's per hour of heat rejection of a condenser? 10,000 12,000 15,000 18,000

15000

Evaporators should never exceed a pressure drop of: 0 psig 1 psig 2 psig 4 psig

2 psig

In a three-phase system, the voltage imbalance between any two legs may not vary by more than: -10% -5% -2% -1%

2%

The economizer might be described as: a controllable damper. a compressor cylinder bypass. a return air system. an indoor air recirculating system.

a controllable damper.

A dual-element fuse has: -two normal one-time fuse links -a thermal cutout only -a thermal cutout and a normal fuse link -the ability to carry locked-rotor current of a motor but not to protect against short circuits.

a thermal cutout and a normal fuse link

The efficiency of an electric furnace is usually ______ percent. a.100 b.10 c.80 d.50

a.100

In a chiller, the refrigerant boils by ___________. -absorbing heat from the air passing through it -absorbing heat from the water passing through it -rejecting heat to the air passing through it -rejecting heat to the water passing through it

absorbing heat from the water passing through it

In a balanced three-phase system, the phase emf's differ in phase by: a.120 degrees b.square root of 3 c.90 degrees d.zero degrees

a. 120 degrees

The average house line pressure for Natural Gas is a.7" W.C. b.3.5" W.C. c.3.5 psi. d.7 psi.

a. 7" W.C.

When soldering, solder is drawn into the joint by a.capillary action b.the heat of the torch. c.flux. d.gravity.

a. capillary action

If refrigerant is to be added to a system, the refrigerant cylinder is usually connected to the a.center port of gauge manifold b.right-handed port of the manifold gauge c.left-handed port of the manifold gauge d.discharge service valve of the compressor

a. center port of gauge manifold

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. a.close; close; open. b.close; open; open. c.open; open; close d.open; close; close.

a. close; close; open

In order to reduce pressure to an acetylene pressure regulator, the adjusting screw is turned a.counter-clockwise until the tension is off b.clockwise to its limit c.clockwise one full turn d.clockwise one half turn

a. counter-clockwise until the tension is off

For maximum safety of equipment, overload relays should be: a.manual reset type b.included in contactors c.not affected by motor current d.automatic reset type

a. manual reset type

Which of the following gases must never be used to pressurize or leak test a refrigeration system? a.oxygen b.nitrogen c.helium d.CO2

a. oxygen

Lock-out relays are used in air conditioning systems to: a.prevent compressor short-cycling b.lock-out the thermostat c.provide automatic restart d.lock-out the overloads

a. prevent compressor short-cycling

The instrument used for finding humidity levels in the atmosphere is the: a.sling psychrometer b.manometer c.infrared thermometer d.micron gage

a. sling psychrometer

Some codes require a manual reset device on a safety limit a.so that the cause of the safety shutdown can be investigated prior to re-start. b.so that the equipment will not short-cycle. c.because automatic reset is more costly. d.so that more technicians are needed, which helps the economy.

a. so that the cause of the safety shutdown can be investigated prior to re-start.

Two types of thermal overload relays in common use today are a.the bimetal relay and the melting alloy relay. b.the melting alloy relay and the Mercury bulb. c.the bimetal relay and the magnetic relay. d.the bimetal relay and the trimetal relay.

a. the bimetal relay and the melting alloy relay.

On centrifugal pumps, if it is ever necessary to reduce pump flow temporarily, do so by a.throttling the discharge b.throttling the suction line c.both A and B d.none of the above

a. throttling the discharge

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 a.tighten the packing gland and/or replace the packing. b.replace the carbon washer and/or tension the spring. c.replace the entire seal as this is cheaper than repairing a leaking seal. d.replace the pump, as the seal is an integral part of the pump and not easily replaced or repaired.

a. tighten the packing gland and/or replace the packing.

Cavitation can destroy a centrifugal pump, is noisy and is caused by a.inlet pressure that is too low. b.outlet pressure that is too low c.inlet pressure that is too high. d.outlet pressure that is too high.

a. inlet pressure that is too low.

Electrical pressure is measured in a. volts b. ohms c. watts d. amps

a. volts

Suction line filter-driers are usually equipped with gage connections so that pressure drops can be determined. Why? a. so that accurate superheat calculations can be made. b. so that you can determine when to change the filter-drier. c. to ensure that flash gas does not occur in the filter-drier. d. to ensure that excessive load is not imposed on the compressor.

b. so that you can determine when to change the filter-drier.

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? a.autotransformer starters. b.star-delta starters. c.star-wye starters. d.start-run starters.

b. star-delta starters.

Suction gas temperature minus saturated suction temperature equals a.condensing temperature b.superheat c.evaporator operating temperature d.subcooling

b. superheat

In the hot-gas bypass control method, the system component which is bypassed is: a.an expansion valve. b.the condenser. c.the compressor. d.the evaporator.

b. the condenser.

How can you identify reverse operation with a scroll compressor? the compressor will not compress. the compressor will stop on motor overload. you can see it running backwards. both A and B from above.

both A and B from above.

The three pressures that operate the thermostatic expansion are bulb, spring and evaporator -bulb closes, spring closes, evaporator opens the valve -bulb closes, spring opens, evaporator opens the valve -bulb opens, spring closes, evaporator opens the valve -bulb opens, spring closes, evaporator closes the valve

bulb opens, spring closes, evaporator closes the valve OCO

Capacity control on a helical-rotary (screw) compressor is obtained using a.variable speed motors. b.inlet vanes. c.a sliding valve. d.hot gas bypass.

c. a sliding valve.

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? a.dual temperature system. b.multizone. c.dual duct. d.mixing box system.

c. dual duct.

Electricity results from the movement of tiny negatively charged particles called a.neutrons. b.ions c.electrons. d.protons.

c. electrons.

Which of the following is the common cause of back pressure in a condensate return line? a.excessive steam pressure b.vacuum c.faulty steam trap d.inadequate steam pressure

c. faulty steam trap

A bellows is used: a.only in pressure controllers b.only with remote-bulb thermostats c.in both pressure and temperature controllers d.only in temperature controllers

c. in both pressure and temperature controllers

In order to protect a load, safety limit devices are most often wired a. downstream. b. upstream c.in series. d.in parallel.

c. in series.

What test method or instrument could be used to leak test a piping system containing ammonia? a.ultrasonic leak detector b.electronic leak detector c.soap bubbles d.halide torch

c. soap bubbles

If a refrigerant sight glass shows bubbles, you know: a.a restriction must be causing flash gas. b.there is air in the system c.there is gas in the liquid. d.the system has too much refrigerant.

c. there is gas in the liquid.

Closed transition starting means: a. the machine is started with the inlet vanes closed b. the starter has timed-closed contacts c. the motor is never disconnected from the line during starting d. the motor is only temporarily disconnected during start-up

c. the motor is never disconnected from the line during starting

Copper-plating of compressor parts is: done at the factory to prevent rusting. caused by contaminants in the system. unlikely to happen unless the motor has a ground. prevented by adding methanol to the system.

caused by contaminants in the system.

What should always be done just before you work on an electrical circuit (touching components): check amperage with a good meter check voltage with a good meter look to make sure switch is down turn power on

check voltage with a good meter

The four main components of a refrigeration system are -compandium tube, cooler, hot coil, & compressor -compressor, condenser, evaporator, & metering device -eliminator, pressure-enthalpy device, refrigerant, & oil separator -receiver, sight glass, accumulator, and compressor

compressor, condenser, evaporator, & metering device

For a voltage measurement the meter is connected to a circuit: in series in parallel that is open that is closed.

in parallel

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 -condenser approach temperature will be 95 degrees -evaporator (chiller) approach temperature will be 10 degrees -evaporator (chiller) approach temperature will be 105 degrees

condenser approach temperature will be 10 degrees

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 series -connecting two or more capacitors in parallel -increasing the voltage with a potential relay -reducing the motor current with a current relay

connecting two or more capacitors in parallel

When using a thermostatic expansion valve with a __________ charged element, hunting can be considerably reduced. -gas -liquid -cross -parallel

cross

In a CSR motor with 10 microfarad run capacitor and a 110 microfarad start capacitor, the total capacitance will be ___________. a.100 microfarads. b.60 microfarads. c.9.17 microfarads. d.120 microfarads.

d. 120 microfarads.

The seal in a compressor is necessary to prevent a.refrigerant from leaking out at the rotating shaft b.air from leaking out at the rotating shaft. c.oil from leaking out at the rotating shaft. d.Both A and C from above.

d. Both A and C from above.

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? a.Heat the cylinder with a heat lamp. b.Heat the cylinder by wrapping it in a specially built electric heater. c.Heat the cylinder by immersing it in a tub of warm water. d.Heat the cylinder with a torch.

d. Heat the cylinder with a torch.

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 a.bimetal tube. b.flat-tube gage. c.whiskey tube. d.bourdon tube.

d. bourdon tube.

As compared to across-the-line starters, reduced voltage starters: a.reduce starting torque required b.reduce inertia loads c.reduce accelerating time d.reduce starting current inrush

d. reduce starting current inrush

With a change in temperature, a thermistor will change a.impedance. b.voltage. c.current. d.resistance.

d. resistance.

An evaporative cooling tower's bleed rate is adjusted to maintain a.return water temperature b.a water seal in the drain line trap c.the desired leaving water temperature d.the desired concentration of total dissolved solids

d. the desired concentration of total dissolved solids

Defrost systems can be terminated by a.time b.pressure c.temperature d.any of the above

d. any of the above

QUESTION 19 A hermetic motor should never be energized or tested with a megger when in a deep vacuum because a.the vacuum pump could be damaged. b.the motor could draw too much amperage c.electric arcs can contaminate refrigerant in the system. d.the dielectric strength of the motor's insulation would be greatly reduced.

d. the dielectric strength of the motor's insulation would be greatly reduced.

Which of the following is NOT used to size gas regulators? a.inlet pressure b.pipe size c.volume d.type of ignition system

d. type of ignition system

The compression ratio in a system can be determined by: -multiplying discharge gage pressure by suction gage pressure -dividing discharge pressure absolute by suction pressure absolute -dividing suction pressure absolute by discharge pressure absolute -subtract suction pressure absolute from discharge pressure absolute and divide by 12,000 btu/hr

dividing discharge pressure absolute by suction pressure absolute

When a three-phase motor single-phases, it: draws power from the two remaining phases draws power from only one phase always short-cycles runs cooler

draws power from only one phase

Refrigerant leaves the compressor through the ___________ line. suction expansion discharge liquid

dsicharge

A pressure switch that contains a high and a low switch is called a: thermostat humidistat time clock dual-pressure switch

dual-pressure switch

The most accurate thermometer is the: glass stem thermometer. electronic thermometer. dial-type thermometer. pocket dial-type thermometer.

glass stem thermometer.

A common refrigerant leak detection device is the: micron gage. halide torch. U-tube manometer. all of the above.

halide torch.

When an object is refrigerated: -some of its heat energy is destroyed. -heat is removed from it. -more cooling is added. -its molecules move faster.

heat is removed from it.

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: relief valve control line vacuum switch vacuum breaker

vacuum breaker

When water is introduced into the end of a chiller it is contained in: -water boxes -a combination filter receiver -a receiver -none of the above

water boxes