HVAC NATE Heat Pump Exam Questions With Correct Answers Updated 2024/2025 (Graded A+)

HVAC NATE Heat Pump Exam Questions With Correct Answers Updated 2024/2025 (Graded A+) What is the primary purpose of using flux when soldering copper or brass parts? -Ans Prevent Oxidation The water that results from a defrost cycle of an air to air heat pump(runoff) must? -Ans Drain off and away from the outdoor coil. Why must the runoff be drained off and away from the outdoor coil? -AnsExcessive ice can build up on the bottom of the coil and can reduce capacity. What is the component that reduces sound transmission and prevents water leaks of a package heat pump installed on a roof? -Ans Curb Gasket Why do you need to add a control for a heat pump indoor coil that is installed on a fossil fuel furnace? -AnsSo the heat pump and furnace do not operate at the same time in normal heating. What happens when you energize a hermetic refrigeration compressor and the system is in a deep vacuum? -AnsMotor windings could become damaged. What needs to happen in order to consider an evacuation to be complete? -AnsSystem should be evacuated to a vacuum of 500 Microns or below. A system is supplied from the factory with charge for a 15 foot line set. The data plate shows the required system charge to be 5 pounds 10 ounces. The line set uses a 3/8 inch liquid line and is 25 feet long. The manufacturer's instruction sheet specifies 0.6 ounces of refrigerant to be HVAC NATE Heat Pump Exam Questions With Correct Answers Updated 2024/2025 (Graded A+) added for each added foot of refrigerant line length. How much refrigerant is needed to completely charge the system? -Ans6lbs Where are drive slips typically installed? -AnsOn the shorter sides of rectangular duct. What is a necessary check to properly set a heat anticipator? -Ans Heating control circuit amperage draw. A heat pump operating in normal ice free conditions maintains a certain temperature difference between the outdoor coil temperature and the surrounding outdoor ambient. What is this temperature referred to as? -AnsCoil TD. What is the smallest refrigerant leak that an electronic leak detector should be capable of sensing? -Ans .o5oz per year. When checking the pressures in an operating system with a manifold gauge set, will refrigerant oil in a hose will have an effect on the gauge? -AnsNo What is the absolute pressure at sea level if a gauge pressure is 35 psig? -Ans49.7psia 100,000 BTUH output furnace. Return air temp is 65F. Supply air is 135F. What is the CFM? -Ans 1323CFM What is the best method of repair when a residential supply diffuser is noisy because of a loose vane? -Ans Replace the diffuser. When performing preventive maintenance on a heat pump what should the technician check and why? -AnsOutdoor fan. To be certain it runs freely with no binding. What is the effect of 170 volts supplied to a 208/230 volt compressor? -Ans Would cause the current to increase and the motor may trip on overload. On a service call for a cooling problem with a heat pump, your inspections find a liquid line that has condensation on it. What is most likely to cause this? -Ans Restriction in the liquid line. What is a reason for cool air complaints when a heat pump is operating in the heating cycle? - AnsExcessive supply air velocities. The following measurements are recorded on an operating heat pump system. The heat pump is operating with the compressor only with no auxiliary heat: • Heat pump only supply air temperature 92°F • Heat pump only return air temperature 70°F • Outdoor temperature 54°F • Supply air temp. /auxiliary heat ON 115°F • Return air temp. /auxiliary heat ON 70°F • CFM 1228 What is the heating capacity in BTUH? -Ans29,177 BTU/H Inadequate heating can be caused by what? -AnsDirty or clogged air filter. To minimize noise problems in residential duct systems, what is the range (recommended to maximum) of design air velocity in the rectangular main supply trunk? -Ans 700 to 900 fpm conditions while checking a packaged heat pump in cooling. • The unit has a piston type metering device on both the indoor and outdoor coils. • Outdoor temperature 75°F • Superheat 55°F What is wrong with the system? -AnsUndercharged. What will you get when a capillary tube is overcharged? -Anslow superheat and high sub cooling What is the effect of a low charge on the switchover operations of a reversing valve? -Ans Reversing valves are less likely to transfer if charge is low. A technician is working on a heat pump with a capacitor start-capacitor run compressor. On initial startup, the compressor hums momentarily and the shuts down on internal overload. What is the problem? -AnsToo great a pressure difference on the compressor. A step down transformer has a rating of 40 VA. Its primary voltage is 120V with a secondary voltage of 24V. What is the maximum current draw of a load connected to this transformer? - Ans1.7amps What does a bright red or orange glow from the resistance element in a duct heater indicate? - AnsFlow of air is insufficient. What does the outdoor fan do during defrost on a heat pump and why? -AnsThe fan stops to minimize defrost time. What do bent vanes on a direct drive blower wheel in an air handler cause? -AnsLoss in air flow, excessive motor wear, and increased noise. A split system heat pump is using thermostatic expansion valves. The system performs properly in heating but in cooling the compressor pumps down. What could this mean? -AnsThe power element of the indoor expansion valve has lost its charge. What condition can cause a reduction from design capacity in a heat pump? -Ans Undersized vapor line. What is the result of excessive liquid line length or lift? -AnsFlash gas. What symptom could a technician expect on a heat pump system in the cooling mode if the check valve is leaking internally? -AnsFlooding of the indoor coil. Voltage across a closed contact in a 24V control circuit could indicate what? -AnsPitted or dirty contacts. What two checks typically made first on an electronic control? -Ans Proper input voltage and proper output voltage. In a low voltage circuit, what does a corroded wire-to-terminal connection acts like? -AnsAn additional resistor. How should you test the continuity of a fuse? -Ans Power off, fuse removed What is the first check made for most electrical troubleshooting? -Ans Voltage check of the supply line. EMAIL ME: EMAIL ME: The following conditions exist in a circuit that supplies power to three parallel loads. One load is resistive One load is capacitive One load is inductive How do you find the total current? -AnsThe sum of the currents through each load. The technician is using an analog multimeter to check a run capacitor. With the meter set to ohms the needle swings toward zero and then slowly rises toward infinity. What does this tell the technician? -AnsThe capacitor charges and discharges. When should a technician test a hermetic compressor for a permanently open internal overload protector? -AnsWhile its cool. What is defined as two or more switch contacts connected in a circuit, or set of circuits, to control a load? -Ans Control String In order to troubleshoot a load controlled by a control string, what should the technician check first? -AnsProper voltage applied across the load. The technician suspects that an outdoor thermostat used to bring on auxiliary heat may be out of calibration. The thermostat is a close-on-fall type that is adjustable. What is one method for checking the thermostat calibration? -AnsManually rotate the shaft until the thermostat closes and compare the dial setting to an accurate outdoor temperature reading plus 10°F When must the installer must be certain to plumb the cabinet so its sides are vertical? -Ans When changing out an evaporator coil.