HVAC NATE Heat Pump Practice Test

These questions are part of the practice quiz. Start practicing

• Why is superheat necessary in a system using hermetic compression?
• Why are electronic controls considered important in HVAC systems?
• What is a potential result of incorrect air filter maintenance in a heat pump system?
• Which type of blower motor is commonly used on air handling equipment with capacities of 4,000 cfm or greater?
• What can cause inadequate heating in a heat pump system?
• What is the function of a reversing valve in a heat pump system?
• What is the heating capacity in BTUH of a heat pump with a supply air temperature of 92°F and return air temperature of 70°F?
• A system should operate at least _____ before heat measurements are taken.
• How are disc type temperature limit controls reset?
• In a split system heat pump using thermostatic expansion valves, what might cause the compressor to pump down in cooling mode?
• What is the recommended maximum external static pressure for heating and cooling equipment with blowers for 5 tons of cooling or less?
• Voltage supplied to a motor may vary from the rated voltage by what percentage?
• What is the main purpose of a high pressure limit control?
• If a heat pump unit's first and second stage appear to be calling, but the compressor runs without the electric heater, what could be the problem?
• What happens to the suction pressure and discharge pressure when the load on a heat pump in cooling mode decreases?
• What is the purpose of a cross break in flat metal ductwork?
• Why do heat pump compressors often run hotter than those in cooling-only units?
• What are the first two checks typically made on an electronic control?
• A resistance reading of infinity across the "R" terminal and "S" terminal of a compressor motor indicates what?
• What is a common symptom of a refrigerant leak in a heat pump system?
• What is the coil of a potential relay connected to in a compressor system?
• Which condition could lead to high indoor humidity levels in a heat pump system?
• What is the role of the thermostat in a heat pump system?
• When should a suction line accumulator be used in a residential heat pump?
• What voltage is most commonly used to power the outdoor unit in a residential system?
• What does a high sensible heat ratio typically indicate about an HVAC system's performance?
• What might indicate an issue with the reversing valve in a heat pump?
• What is the primary function of a thermostat in an HVAC system?
• During maintenance, what is important to check in the duct systems?
• What do dashed or dotted lines in wiring diagrams typically represent?
• What condition can cause a reduction from design capacity in a heat pump?
• How are heat pumps typically sized?
• What is the primary function of a thermostatic expansion valve (TXV or TEV)?
• What is a common reason for the use of fire dampers in HVAC systems?
• What happens if there is significant pressure difference in a heat pump system?
• Which component protects compressor functionality by monitoring pressure levels in HVAC systems?
• At what maximum temperature can refrigerant be stored when a container is no more than 80% full?
• What should happen during a balancing check of a newly installed duct?
• A 24V transformer with a 40 VA rating can safely operate with a current of what value?
• Which component primarily benefits from the usage of hard-start kits?
• When is condensation on vapor lines a concern?
• What type of heat is primarily involved when heat is removed from the refrigerant in the evaporator?
• What is the specification for the sequencer code H1-24 C45-75?
• What happens to the system when the heat load on an evaporator is decreased?
• What problem may arise if a proper trap is not used on the condensate drain for a pull-through unit?
• What is one significant reason for using electronic controls in HVACR systems?
• What typical marking code is used for the timing specification of sequencers?
• How is work done on the refrigerant in the condenser transferred?
• What should be monitored to prevent system failures in HVAC systems?
• Which component is designed to reduce sound transmission and prevent water leaks on package heat pumps installed on roofs?
• Hard-start kits are often necessary for which type of compressor?
• Which tool is recommended to shorten a capillary tube?
• What does the term "SEER" stand for in relation to heat pumps?
• Why is it essential to monitor superheat in a heat pump system?
• Which factors affect a customer's level of comfort?
• What would likely happen if a compressor does not start up properly due to high pressure differences?
• What effect does raising the pressure in a sealed system have on refrigerant?
• What characteristic distinguishes a TXV from other valves in an HVAC system?
• What is the most commonly used type of fan in residential HVAC systems?
• What effect does a malfunctioning expansion valve have on system performance?
• What happens to the heater elements if airflow is too low?
• What is the purpose of a step-down transformer?
• Which reading would you expect from an intact, functional transformer?
• Which colors of leads indicate a 120-V AC primary on a step-down transformer?
• What is the measurable current that any individual load on a 24 V control circuit should draw?
• Which condition is indicative of an overcharged capillary tube in a heat pump system?
• What is the primary purpose of using a ground fault circuit interrupter (GFCI)?
• What should a technician do first when diagnosing a compressor failure?
• Where should the sensing bulb on a TXV be located for accurate refrigerant temperature?
• What happens to the capacity of a reciprocating compressor when the suction pressure is increased?
• What is the primary purpose of a heat pump's balance point?
• What is a likely cause of inadequate heating performance in a heat pump system?
• What is the purpose of a low pressure limit control?
• When checking pressures in an operating system, how does refrigerant oil in a hose affect the gauge reading?
• Where is a high pressure limit control typically installed?
• Which component is critical for protecting the compressor from overheating?
• An acceptable capacitance reading for a run capacitor is _____ the microfarad rating printed on the capacitor.
• What is the temperature difference maintained by a heat pump operating in normal conditions, between the outdoor coil or and outdoor ambient?
• Which method is commonly used to leak-test refrigerant tubing?
• What is the early reset capability of an electronic programmable room thermostat to achieve a desired temperature called?
• Which component of a heat pump is responsible for pumping refrigerant and raising vapor temperature?
• How is a heat pump's heating capacity commonly measured?
• Excessive noise from a heat pump is most likely due to which of the following?
• What is the typical water flow rate for water-source heat pumps operating in closed-loop systems?
• What is the function of a suction line accumulator in an HVAC system?
• Which brazing material is acceptable for use on refrigerant piping?
• What could indicate that the compressor is failing?
• Where are low pressure limit controls usually installed?
• What is typically the consequence of running a heat pump and a fossil fuel furnace at the same time?
• What type of valve is commonly affected by a low refrigerant charge?
• Do electric air cleaners effectively remove odors from the air?
• What issue do bent vanes on a direct drive blower wheel in an air handler cause?
• What is the output of a residential electric furnace when the voltage impressed is equal to 235 V and its current draw is 40 A?
• Which component is primarily responsible for generating heat in an electric furnace?
• In a low voltage circuit, how does a corroded wire-to-terminal connection behave?
• What is the maximum fuse size recommended when using a double element time-delay fuse with a 20 amp motor?
• If a system is supplied with a charge for a 15-foot line set, which is longer than the set's length, how much refrigerant will need to be added for a 25-foot line set?
• What does a short cycling compressor typically indicate in a heat pump?
• What gas should be purged through a refrigerant circuit to prevent the formation of oxides during brazing?
• What do the service site conditions suggest if a house feels "drafty" in cooling with a properly sized ductwork and high supply face velocities?
• What is the best method of repair for a noisy residential supply diffuser due to a loose vane?
• What is the typical result of improperly sized ductwork in a HVAC system?
• Why must caution be exercised when bending soft-drawn refrigerant tubing?
• In a heat pump system, which component primarily absorbs heat from the environment?
• What is defined as two or more switch contacts connected in a circuit, or set of circuits, to control a load?
• What is the balance point in a heat pump system?
• What distinguishes a register from a grille in HVAC systems?
• In a single zone system, what could be the cause of a customer feeling damp or sticky?
• What is the result of undersized duct work?
• Which of the following best describes "defrost mode" in a heat pump?
• When is the use of a ground fault circuit interrupter (GFCI) especially important?
• If a solenoid is vibrating or chattering, what is typically the cause?
• What happens to the suction and discharge pressure when heat load on an evaporator increases?
• What is the opening pressure in a TXV?
• When performing preventive maintenance on a heat pump, what should be checked to ensure proper function?
• What is the purpose of a sequencer in a heat pump with an auxiliary 20 kW electric heater?
• In a heat pump circuit, what is used to bypass refrigerant flow around the metering device?
• A small voltage reading across a closed set of contacts in an energized circuit suggests what?
• What is the primary purpose of using flux in the soldering process for copper or brass parts?
• What component in a heat pump system is responsible for compression of refrigerant?
• According to fire protection codes, when should fire dampers be used?
• Which of the following contributes to the effectiveness of electronic controls in HVAC systems?
• What is the common suction line on a heat pump connected to?
• What is a key benefit of using electronic air cleaners?
• Why is it crucial to clear the air filter on a heat pump regularly?
• Why is it important for the runoff from the defrost cycle to drain away from the outdoor coil?
• How do you find the total current in a circuit supplying three parallel loads, one resistive, one capacitive, and one inductive?
• According to Ohm's Law, what happens if voltage to a heater element is increased by 10%?
• What is the purpose of an auto change over switch on a t-stat?
• Which factor primarily affects the heating efficiency of a heat pump?
• What does a glowing red or orange light on a resistance element in a duct heater indicate?
• Which of the following is often critical when working with electrical circuits?
• What is an indicator that a heat pump may be malfunctioning?
• In a heat pump system, what often indicates the presence of moisture that could lead to compressor failure?
• What is an important factor in determining the efficiency of a heat pump system?
• What is the recommended design air velocity range to minimize noise problems in residential duct systems?
• What issue may arise if a heat pump capacitor start-capacitor run compressor hums momentarily and then shuts down?
• How is the typical staging of a two-stage heat pump system determined?
• What occurs if the CFM in a duct system is too low?
• What can a restricted drier cause in a heat pump system?
• What might be a sign of a refrigerant leak in a heat pump system?
• What certification is required before a technician is permitted to work on air conditioning and heat pump systems?
• What is heat transfer called when substances of different temperatures are in contact?
• What is a reason for cool air complaints when a heat pump is operating in the heating cycle?
• What is the standard additional refrigerant requirement for each extra foot of refrigerant line?
• What symptom might indicate a leaking check valve in cooling mode on a heat pump system?
• What internal voltage is typically measured in an electronic air cleaner?
• How does duct size relate to system efficiency?
• What is the primary role of the expansion valve in a heat pump system?
• How high can internal voltages reach in electronic air cleaners?
• Why is it necessary to add a control for a heat pump indoor coil installed on a fossil fuel furnace?
• What should be done with the water resulting from a defrost cycle of an air-to-air heat pump?
• Where does refrigerant boil in a heat pump system?
• What determines the efficiency of a heat pump system?
• What type of energy does the condenser remove from the refrigerant?
• What is the purpose of using dry nitrogen in refrigerant circuits during brazing?
• What is the formula for sensible heat ratio?
• How many BTUh correspond to one ton of cooling?
• What is the typical storage life of refrigerants used in residential and light commercial pumps?
• Why are more circuits required in outdoor coils of heat pumps compared to condenser coils of cooling-only units?
• What is the primary purpose of a heat pump in HVAC systems?
• What type of energy transfer occurs when work is done in the condenser?
• In wiring diagrams, what do solid lines usually indicate?
• Why is operating sound a consideration in the location of a condensing unit?
• What effect does supplying 170 volts to a 208/230 volt compressor have?
• What is the thermal balance point of a dual fuel heat pump?
• In the context of HVAC, what does TD stand for?
• What should a technician check first when diagnosing airflow issues in a duct system?
• Which component is typically inspected during routine maintenance for optimal performance?
• What is the maximum current draw of a load connected to a step down transformer rated at 40 VA with a primary voltage of 120V and secondary voltage of 24V?
• A good fuse will yield what reading on an ohmmeter?
• What issue arises when using a running trap on a condensate line at the evaporator coil?
• When is crankcase heat particularly needed in a heat pump system?
• What is the smallest refrigerant leak that an electronic leak detector should be capable of sensing?
• What is an example of a power-passing device?
• What can be concluded if a heat pump's superheat reading is significantly above normal?
• What is used to measure total resistance to airflow in a ductwork system?
• If you find condensation on a liquid line during a service call for a cooling problem, what is most likely causing this issue?
• What is the recommended face velocity for air leaving a supply register?
• What does a thermostat control in an HVAC heat pump system?
• What does the "HSPF" value indicate for heat pumps?
• Why are there more circuits in a heat pump outdoor coil compared to an air conditioning outdoor coil?
• What does the outdoor fan do during defrost on a heat pump and why?
• Which type of motor typically has the lowest starting torque in HVACR systems?
• Temperature readings taken 6 in. from the compressor discharge line should never exceed _____ F.
• To ensure accurate airflow readings, the fan system's airflow should be checked using which of the following?
• How can a technician check the calibration of an adjustable close-on-fall thermostat?
• What are the three actions that occur when a heat pump is cycled into defrost mode?
• Where is the sensor for an outdoor ambient thermostat typically installed?
• What is the general guideline for temperature rise in a heating system?
• On an R-22 system, line diameters and lengths should typically not exceed what vapor pressure drop?
• What type of duct system features a single trunk extending in one or two directions?
• At which point does a heat pump change its operation mode from heating to cooling?
• What could happen to a hermetic refrigeration compressor if it is energized while the system is in a deep vacuum?
• If a heat pump is undercharged, what condition might you observe during cooling operation?
• In a heat pump system, what is the role of auxiliary heat?
• What is the minimum circuit amp listed on a unit's data plate used to determine?
• If a technician has determined that a supply in a flexible duct system is leaking, what should be checked?
• The auxiliary drain line from an overflow pan must be terminated where?
• What could voltage across a closed contact in a 24V control circuit indicate?
• What is the purpose of the expansion valve in a heat pump system?
• What are the three processes that transfer heat energy?
• When wiring a 20 amp FLA motor, what is the minimum amp fuse or circuit breaker that should be used?
• During which season is the heating mode of a heat pump most commonly utilized?
• For a furnace output of 100,000 BTUH with a return air temperature of 65°F and supply air temperature of 135°F, what is the CFM?
• What size thermostat wire do most manufacturers recommend?
• What happens to air quality when humidity levels rise excessively in a conditioned space?
• What is the indoor air flow for an electric furnace given specific supply and return air temperatures, voltage, and current draw?
• What does it typically indicate if a fuse has a continuity reading?
• What is a potential effect of a low refrigerant charge on reversing valve operation?
• Disc type temperature limit controls are primarily used to protect what?
• What is a primary danger to people near an accidental refrigerant release?
• What is the primary impact of a low refrigerant charge on the operations of a reversing valve?
• When performing indoor air balancing tests, how should the thermostat be set?
• What is the absolute pressure at sea level if a gauge pressure is 35 psig?
• What is the first check made for most electrical troubleshooting?
• A resistance reading of 0 Ω across a coil indicates that the coil is what?
• Which combination of measurements indicates an open heater element?
• What is a necessary check to properly set a heat anticipator?
• What is an effective method of reducing sound when the air handling unit (AHU) is located in a closet?
• How are hermetic compressor motors primarily cooled?
• What does it indicate when an analog multimeter shows a needle that swings toward zero and then slowly rises toward infinity while checking a run capacitor?
• When using electronic controls, what is a critical factor in their effectiveness?
• Where are drive slips typically installed within a duct system?
• When the wet bulb reading is very close to the dry bulb reading, what does this indicate?
• What measurements are necessary to evaluate a complaint of "drafty" operation with a heating system?
• How do modern heat pumps achieve significant energy efficiency?
• How many CFM should be provided per ton of cooling?
• What is the effect on airflow when static pressure in the return is reduced?
• What does the Coefficient of Performance (COP) of a heat pump represent?
• What is the recommended method to test continuity of a fuse?
• Exposure to an electric current of how many milliamperes can be fatal if it lasts for one second or more?
• What is the formula to calculate CFM based on voltage and current?
• Which factor does NOT influence the efficiency of a heat pump?
• To ensure an evacuation is complete, what vacuum level should the system be evacuated to?
• What component is primarily responsible for switching the heat pump from heating to cooling mode?
• Which two methods are generally used for changing capacity on demand in a heat pump?
• What maintenance task is essential to ensure optimal heat pump performance?
• What voltage is measured between any two hot legs on a 3-phase 240V distribution panel?
• What occurs when refrigerant is in contact with a high-pressure environment?
• In troubleshooting a load controlled by a control string, what should the technician check first?
• What method do manufacturers recommend for attaching line sets to the air handling unit (AHU)?
• When must an installer ensure that the cabinet is plumb and its sides are vertical?
• What is the typical current rating of a standard 40 VA transformer?
• What impact does excessive supply air velocity have in a heating cycle of a heat pump?
• Where should you check voltage input to a compressor?
• What type of refrigerant is commonly used in modern heat pump systems?
• What is the impact on refrigerant density at low suction for heat pump compressors?
• What could an unusually high condensation on the outdoor coil suggest?
• What is the result of excessive liquid line length or lift?
• When should a technician check a hermetic compressor for a permanently open internal overload protector?