NATE Heat Pump Exam Questions with Correct Solutions, A+

A technician places a heat pump into the auxiliary electric heating mode with the compressor de-energized. He measures a temperature rise between the return and supply air of 40 degrees. The measured voltage at the electric elements is exactly 222 volts and the measured amperage of the heaters is 60 amps. Using the equation CFM = BTU divided by 1.08 x TD, what is the CFM of the system? A: 825 CFM B: 950 CFM C: 1055 CFM D: 1500 CFM - Correct Solution C: 1055 CFM 222 x 60 = 13,320watts 13,320 / 1000 = 13.32 Kw btuh = 13.32 x 3415 = 45,488 cfm =((45,488 / (1.08 x 40)) cfm = 45,488 / 43.2 = 1052.95 Solid state defrost control boards can be adjusted to: A: Program the thermostat from outside the house B: Change the frequency of defrosts C: Control the speed of the outdoor fan during defrost D: Control the speed of the indoor fan during defrost - Correct Solution B: Change the frequency of defrosts A thermistor is an: A: Electronic temperature sensor that changes its resistance with changes in temperature B: Electronic pressure sensor that changes its resistance with changes in pressure C: Electromechanical thermostat used to terminate the defrost cycle when outdoor coil is clear of ice and frost D: None of these is correct - Correct Solution A: Electronic temperature sensor that changes its resistance with changes in temperature The correct way to size a heat pump is to perform both heating and cooling load calculations and select the heat pump size by: A: Adding the heating load and cooling loads B: Subtracting the smaller load from the larger load C: Using the heating load to size the system D: Using the cooling load to size the system - Correct Solution D: Using the cooling load to size the system Auxiliary electric heat is necessary because: A: It provides heat for the home during defrosts B: It provides heat for the home in the event of a heat pump failure C: It provides heat for the home if the heat pump is unable to meet the demand for heat D: All of the above - Correct Solution D: All of the above Reading a voltage across the contacts of the outdoor thermostat means: A: The thermostat contacts are closed B: The thermostat contacts are open C: The thermostat contacts are stuck D: The thermostat contacts are working correctly - Correct Solution B: The thermostat contacts are open Which of the following is not a type of heat pump? A: Ground to air B: Air to air C: Water to air D: Direct coupled - Correct Solution D: Direct coupled The coefficient of performance is determined by: A: Dividing the output btuh by the input btuh B: Dividing the input btuh by the output btuh C: Multiplying the input by the output D: Subtracting the output from the input - Correct Solution B: Dividing the input btuh by the output btuh The coefficient of performance or COP of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work required. Higher COPs equate to higher efficiency. The "balance point" of a heat pump is: A: The lowest temperature at which the heat pump can meet the heating requirement for the structure B: The lowest temperature at which the heat pump can operate C: The temperature at which the heat pump has the highest efficiency D: The point at which the heating and cooling loads meet - Correct Solution A: The lowest temperature at which the heat pump can meet the heating requirement for the structure Which of the following is an incorrect term for the solenoid valve that switches the heat pump between the heating and cooling modes? A: Changeover valve B: Reversing valve C: Four-way valve D: Discharge operator valve - Correct Solution D: Discharge operator valve The best location for the outdoor section of an air to air heat pump is: A: Where it gets the winter sun B: Where it is sheltered from the sun's radiation C: Where it never snows D: Under the shelter of a porch - Correct Solution A: Where it gets the winter sun What may happen if the body of a reversing valve is slightly dented? A: Nothing, as they are made to be very durable B: The internal slide may stick C: The valve may make noises from the gas trying to pass through partially open ports D: Both b and c are correct - Correct Solution D: Both b and c are correct