UA Service, Training, and Recognition (STAR) Practice Test

These questions are part of the practice quiz. Start practicing

• Which term correctly classifies belt width?
• What is a common cause of back pressure in a condensate return line?
• A common refrigerant leak detection device is the:
• Which motor is described as having greater starting torque in the comparison with a shaded pole motor?
• What happens to total capacitance when two capacitors are connected in parallel?
• The two planes of alignment that must be considered when aligning a flexible coupling are?
• The start capacitor in the CSR motor is larger than the run capacitor
• Which three items operate the thermostatic expansion valve in a refrigeration system?
• What device protects a vacuum steam heating system's vacuum pump from creating too deep a vacuum?
• In Ohm's law, if current doubles while resistance stays the same, voltage will
• Which of the following is NOT used to size gas regulators?
• Sleeve bearings are commonly made of ____________.
• In a starting-torque comparison, which motor is stated to have more starting torque than a shaded pole motor?
• Copper-plating of compressor parts is:
• Which device controls the flow rate of refrigerant into the evaporator?
• Which device is used to measure velocity pressure inside a duct?
• Which bearing type is typically used in the bottom position of a vertical shaft motor?
• When using a thermostatic expansion valve with a __________ charged element, hunting can be considerably reduced.
• Which seating position is used to add refrigerant through the suction service valve?
• Lock-out relays in air conditioning systems are used primarily to prevent what?
• The unit of measure for the specific volume of air is:
• A potentiometer is a / an?
• To reduce pressure to an acetylene regulator, the adjusting screw is turned:
• A full voltage starter has:
• When soldering copper tube, after the tube and fitting are cleaned and fluxed, they should be soldered:
• In a chiller, the refrigerant boils by which process?
• What is the watt equivalent of one kilowatt?
• Power in an electrical system is measured with which instrument?
• When checking voltage in a circuit, the meter should be connected:
• Which pressure-sensing instrument uses a curved metal tube that straightens as pressure increases and drives a dial?
• Evaporators should never exceed a pressure drop of:
• The boiling point of refrigerant is the same as which temperature?
• Refrigerant leaves the compressor through the ___________ line.
• To reverse the rotation of a split-phase motor, which action is used?
• The approach temperature for the evaporator is the difference between the refrigerant boiling temperature and which temperature?
• A knife switch should not be used to stop a motor because:
• A dual-element fuse is defined by which components?
• The voltage rating of motor controller holding coils is typically:
• The refrigerant line that connects the condenser to the metering device is the __________ line.
• In a dual-duct system, after mixing, air is delivered at a near constant which parameter?
• Which air distribution system includes both a warm air duct and a cool air duct and uses mixing boxes near the zone to mix the streams and achieve the desired temperature while delivering air at a near constant volume?
• Which of the following would be an acceptable means of controlling the capacity of air cooled condensers?
• Absolute zero is:
• If refrigerant is to be added to a system, the refrigerant cylinder is usually connected to the
• Heat flows downhill. Which statement best describes this concept?
• Which statement correctly identifies the three components that operate the thermostatic expansion valve?
• How many BTU per hour are equivalent to 8 kW of electrical power?
• At the bottom of a suction line riser, the recommended device is a:
• In an air source heat pump, supplemental strip heaters are typically energized during which condition besides extremely low outdoor temperatures?
• What is the rule of thumb for BTU per hour of heat rejection for a condenser?
• A belt drive on a motor driven fan has a drive sheave of 3 inch pitch diameter on the motor. The sheave of the fan shaft has a pitch diameter of 5 inch. When the motor speed is 1720 rpm, what is the fan speed?
• In an economizer control, three automatic dampers regulate exhaust air, outdoor air, and which other stream?
• Which flame classification corresponds to excess acetylene in an oxy-acetylene flame?
• The most accurate thermometer is the:
• A hand placed near a hot stove or fireplace is quickly heated by which mode of heat transfer?
• While servicing a packaged rooftop unit with a direct drive blower motor, you remove the access panel to the blower compartment to enable electrical checks on the blower to be made. The blower load increases, resulting in:
• Which line carries liquid refrigerant from the condenser to the metering device?
• Which flame type is produced when acetylene is in excess in an oxy-acetylene flame?
• Two types of thermal overload relays in common use today are
• Which of the following bearing assemblies must be greased?
• A flexible coupling between the drive and driven device:
• For dampers that throttle air flow, which blade arrangement provides the required control?
• For leak testing piping that carries ammonia, which test method is mentioned?
• Using Ohm's law, if the current is 2 amps and the resistance is 55 ohms, what is the voltage?
• In a dual-duct air distribution system, mixing boxes near the zone are used to
• How is an economizer best described in a cooling system?
• In the relationship between horsepower and watts, which option is correct?
• Which reduced-voltage starter uses a switching arrangement to connect windings in different configurations during startup and normal operation?
• A bellows is used
• Which statement best describes manual reset overload relays?
• What is the primary function of the compressor in a vapor compression refrigerant system?
• Which observations would indicate reverse operation in a scroll compressor?
• Suction-line filter-driers are fitted with gauge connections to determine what maintenance action?
• When in doubt, what should be installed at the bottom of a suction line riser?
• In the comparison statement, which motor is the baseline to which the PSC motor is compared?
• What happens to the heating capacity of an air-to-air heat pump as outdoor air gets colder?
• Which forces work to close the TEV valve?
• Condenser capacity is typically sized larger than the evaporator capacity by what phrase commonly used in system design?
• Which statement about a dual-element fuse is true?
• A failed steam trap most commonly causes back pressure in which part of the steam system?
• Which condition is addressed by condensate drain traps on draw-through evaporator coils?
• The amount of heat removed by evaporating one pound of water in an evaporative cooling tower is approximately:
• Suction line filter-driers are typically equipped with gauge connections to determine what?
• If condensing at 105°F and water leaves condenser at 95°F, the condenser approach temperature is:
• Condensate drain traps must be used on draw through evaporator coils in order to prevent:
• Which leaks does the compressor shaft seal prevent?
• 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?
• If an oxy-acetylene flame becomes carburizing, what is the likely cause?
• If the R value on a section of insulation is 8, what would the value be when saturated with water?
• Which component connects rotating parts in a direct-drive pump arrangement?
• Fuses in motor branch-circuits primarily provide
• The external equalizer line used with a thermostatic expansion valve is to compensate for which phenomenon?
• A fuse is intended to carry its rated amperes for how long?
• What is the atmospheric pressure at sea level expressed in psi?
• From the given comparison, which motor type is identified as having greater starting torque than a shaded pole motor?
• If not properly installed, a hot-gas muffler might trap:
• Excess acetylene in an oxy-acetylene flame most directly leads to which flame?
• Which motor type is described as having more starting torque when compared to a shaded pole motor?
• In a basic vapor-compression cycle, which component comes immediately after the condenser?
• In a gas-fired warm air furnace, the furnace fan should be controlled by:
• The difference between the suction gas temperature and the saturated suction temperature is called
• A hot-gas muffler that is not properly installed may trap which substance?
• What is the typical suction superheat at the evaporator for many air conditioning systems?
• A sleeve bearing would typically be used in a motor that:
• Which of the following is a type of copper tube joint?
• To lessen short cycling, what would you do to the pressure control?
• Out-of-place refrigerant oil or oil of improper composition in a refrigeration system is best described as which condition?
• Lockout relays in air conditioning systems are used to prevent what?
• In a three-phase system, the voltage imbalance between any two legs may not vary by more than which percent?
• In absorption systems, lithium-bromide solution primarily functions as which component?
• In oxy-acetylene welding, what flame type results from an acetylene-rich mixture?
• The width of a drive belt is classified as:
• Which statement correctly identifies lithium-bromide's role in absorption systems?
• Cavitation can destroy a centrifugal pump, is noisy and is caused by
• The rotation of a three-phase motor can be reversed by interchanging which of the following?
• A flame sensing relay strategy that takes advantage of the ionization of flame is called
• A lamp has 110 volts and 0.9 amperes. What is the resistance?
• Which gas must never be used to pressurize or leak test a refrigeration system?
• An economizer control contains three automatic dampers, one for exhaust air, one for outdoor air, and one for:
• The bleed rate of an evaporative cooling tower is adjusted to maintain which parameter?
• An instrument to be inserted into a duct for measuring velocity pressure is the?
• Which flame type would you observe when acetylene content is higher than needed in an oxy-acetylene flame?
• Electric heating elements are most commonly made from which component?
• In the CSR motor example, which capacitor has the higher capacitance?
• Which component is commonly observed through a sight glass to verify liquid refrigerant level?
• In a fluid at rest, the pressure at a point is primarily due to the weight of the fluid above that point. This describes which type of pressure?
• In evaporator design, the approach temperature is defined as the difference between the refrigerant boiling temperature and which water temperature?
• In a thermostatic expansion valve, three forces act on the diaphragm. Which sequence describes how these forces affect the valve?
• Which sequence correctly describes the operation of a thermostatic expansion valve with respect to the bulb, spring, and evaporator?
• Lock-out relays in air conditioning systems are used primarily to prevent which of the following?
• When an object is refrigerated:
• Lithium-Bromide is used in absorption systems as:
• If a three-phase motor is started on a single phase, it will:
• If a vacuum pump in a vacuum steam heating system burns out, a common cause is which of the following?
• In oxy-acetylene flame terminology, the carburizing flame results from which condition?
• For maximum safety of equipment, overload relays should be?
• The average house line pressure for Natural Gas is
• The efficiency of an electric furnace is usually:
• With belt driven equipment, alignment of the motor and driven equipment pulleys
• A lock-out relay should drop out when which condition occurs?
• The boiling point of refrigerant is the same as which temperature or pressure?
• Which arrangement is described as counter flow in a water coil?
• Cleaning refrigerants to ARI 700 standards is called:
• Which of the following lists represents the four main components of a refrigeration system?
• Electric heaters are usually composed of:
• The instrument used for finding humidity levels in the atmosphere is the
• The internal overload of a hermetic compressor senses which parameter?
• The star-delta operates by:
• What does TDS stand for in evaporative cooling tower maintenance?
• What is the function of a potential relay in a compressor start circuit?
• Roller bearings are normally used with:
• Condenser capacity is typically sized larger than evaporator capacity by which of the following statements?
• A vacuum breaker is used to avoid which condition?
• 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:
• In a three-phase system, the maximum voltage imbalance between any two legs should not exceed:
• A potentiometer is best described as which of the following?
• To reduce pressure to an acetylene regulator, the adjusting screw is turned:
• To order a transformer, we need to know primary voltage and secondary voltage. What is the third most important requirement?
• What test method could be used to leak test a piping system containing ammonia?
• If you want to replace a defective capacitor but the replacements you find do not have enough capacitance, you can increase their capacitance by:
• As compared to across-the-line starters, reduced voltage starters
• To protect a large compressor against excessive compressor discharge pressure we could use:
• Which statement correctly describes a full voltage starter?
• What is the proper handling of defective rigging components and hardware?
• In starting up a chilled water system, the first piece of equipment to start should be the:
• A vacuum breaker is installed between equipment and a steam trap to
• An excess of acetylene in an oxy-acetylene flame will give which type of flame?
• If the belt drive uses a 3 inch motor pulley and 5 inch driven pulley, and the motor runs at 3440 rpm, what is the fan speed?
• The difference between a contactor and a motor starter is:
• With a change in temperature, a thermistor will change which electrical property?
• During defrost cycles in heat pump operation, which component is energized to aid heating?
• Low superheat or a liquid floodback to the compressor could be caused by:
• Which instrument is used to measure electrical current in a circuit?
• In star-delta starting, which configuration is used during the starting phase?
• The design of the air supply duct will depend on the air velocity and
• The TXV maintains a constant:
• One horsepower is the same as
• What is the purpose of a receiver in a refrigeration system?
• A bearing used on the bottom of a motor where the shaft is positioned vertically is called a ____________ bearing.
• The evaporator in a refrigeration system:
• What precaution is necessary when installing ultrahigh efficiency filters?
• Sleeve bearings are commonly made of which material?
• A three-way valve having two inlets and one outlet is classified as a:
• When the motor of a two-wire spring return actuator is operating, the spring?
• A run capacitor that remains connected during operation defines which motor type?
• Some codes require a manual reset device on a safety limit. What is the purpose?
• Which of the following bearing assemblies can handle a larger load?
• The compression ratio in a system can be determined by:
• The voltage rating of motor controller holding coils is:
• Suction gas temperature minus saturated suction temperature equals
• Why is a surge suppressor used on a contactor coil?
• A three-phase motor to be used with a part-winding starter must have?
• What is the maximum safe amperage draw of the secondary winding for a 60 VA transformer with a 12 V output?
• One kilowatt is equivalent to how many watts?
• In a hot-gas bypass control, which component is deliberately bypassed to regulate system operation?
• What is the maximum allowable current imbalance rating in a three-phase supply?
• An air distribution system accomplishes heat transfer by:
• What simple method confirms proper pulley alignment on belt-driven equipment?
• Which statement describes the bottom, vertical-shaft bearing?
• Which component in the refrigeration cycle is responsible for rejecting heat to the surroundings?
• Widening the pressure control differential has what effect on the cycle?
• A pressure regulator is designed so that a rise in downstream steam pressure reduces off the inlet flow of supply steam. This action primarily reduces which flow?
• In HVAC control systems, a bellows is used in which controllers?
• A thermostat embedded in the winding of a motor provides?
• 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
• If a flow switch is used in a duct system that has a humidifier, the flow switch would be used to:
• Lockout relays in air conditioning systems primarily prevent which condition?
• Which component is primarily responsible for absorbing heat by boiling in the refrigeration cycle?
• To protect a load, safety limit devices are most often wired where?
• Safety controls should be wired?
• In a CSR motor with 10 microfarad run capacitor and a 110 microfarad start capacitor, the total capacitance will be
• Connecting two or more capacitors in parallel gives ____________ capacitance.
• For maximum safety of equipment, overload relays should be
• Defrost systems can be terminated by
• The amount of heat removed to lower the temperature of 15 lbs of water from 48°F to 39°F is:
• In pump applications, which two bearing types are commonly present?
• The mode of heat transfer responsible for heating a body without a physical medium is:
• Condenser capacity is typically sized to be what percent larger than the evaporator in a system?
• In the hot-gas bypass control method, which component is bypassed?
• Which force opens the TEV valve?
• Which instrument is often used to check the alignment of two shafts?
• Which of the following would happen if the vent port on a gas regulator is plugged?
• A standing pilot burns in which manner?
• Where must an inline ammeter be connected in an electrical circuit?
• On most 24 volt control systems the white stat wire is used for:
• A typical maximum evaporator pressure drop is:
• Which of the following flame types is associated with acetylene-rich conditions in oxy-acetylene welding?
• If a refrigerant sight glass shows bubbles, the most likely interpretation is that there is what in the liquid?
• The heating capacity of an air-to-air heat pump does what as outdoor air gets colder?
• To reverse the rotation of a split-phase motor, which action is effective?
• If a refrigerant sight glass shows bubbles, what does that indicate?
• In a chiller, water introduced at the end is contained in which component?
• Condenser saturation temperature on a air cooled condenser should be higher than the ambient temperature by:
• A lock-out relay should drop out when:
• A vacuum breaker is used to avoid which pressure condition?
• A type of copper tube joint is:
• For a damper that must throttle air flow, which blade arrangement is used?
• Capacity control on a helical-rotary (screw) compressor is obtained using which method?
• Electricity results from the movement of tiny negatively charged particles called
• A vacuum breaker is installed between equipment and a steam trap to
• Which of the following statements best describes electrons in electrical conduction?
• To add refrigerant to the system through the suction service valve, the valve stem must be:
• A minimum evacuation level for an air conditioning system is:
• Electrical pressure is measured in
• Which of the following could cause low superheat or liquid floodback to the compressor?
• The seal in a compressor is necessary to prevent which leaks?
• Which component is described as a controllable damper in the cooling system?
• Which device is commonly used to protect a compressor from excessive discharge pressure?
• On centrifugal pumps, if it is ever necessary to reduce pump flow temporarily, do so by
• Which motor would be expected to have higher starting torque than a shaded pole motor?
• Closed transition starting means:
• Outdoor reset of hot water temperature for heating gives hottest water during which weather?
• The pressure exerted by a liquid at rest, due to its own weight, is called ____________.
• In an electric heat furnace, what size should the flue pipe be?
• Name two types of bearings used in centrifugal pumps.
• For a voltage measurement, the meter is connected to a circuit:
• In a refrigeration system, which device is used to control defrost cycles?
• If 5/8 inch O.D. fittings are unavailable for 5/8 inch ACR tube, which copper water tube size could be used?
• A rise in downstream steam pressure in a regulator reduces off the inlet flow of supply steam. This action primarily reduces which flow?
• The refrigerant cylinder is usually connected to the center port of gauge manifold when adding refrigerant to a system. Which option below shows this correctly?
• The efficiency of an electric furnace is usually ______ percent.
• 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
• In an RTD (resistance type device), as temperature increases, resistance will:
• A four-pipe system for chilled water and hot water requires:
• In a balanced three-phase electrical system, the phase EMFs differ in phase by how many degrees?
• A pressure switch that contains a high and a low switch is called a:
• Which instrument is used to check shaft alignment?
• A water coil generally should be piped to provide:
• A single-phase motor in which the starting capacitor remains connected when the motor runs is called a:
• What should always be done just before you work on an electrical circuit (touching components):
• A loose-fitting belt on a belt-driven device will cause:
• Why should a hermetic motor be energized or tested with a megger while in deep vacuum?
• Give the equation for Ohm's Law.
• A single-phase motor in which the run capacitor remains connected when the motor runs is called a:
• If refrigerant condenses at a temperature of 105 degrees F and the water leaves the condenser at 95 degrees F, the condenser approach temperature will be:
• How can you identify reverse operation with a scroll compressor?
• In piping a water coil, why should the supply line be connected to the bottom rather than to the top of the coil?
• What is the device that removes the start capacitor from the electric circuit when the compressor is up to speed?
• One watt is equivalent to
• A direct drive pump often uses a ____________ that connects the shaft of the pump motor to the shaft of the circulator pump.
• Outdoor reset control adjusts hot water temperature based on outdoor temperature, resulting in the hottest water during which condition?
• During soldering, by what mechanism is solder drawn into the joint?