NATE Heat Pump Exam Revised Questions and Answers / Sure A + A customer is concerned that during the heating season heavy ice builds up on one side of the concrete equipment pad and coil. The rest of the coil is clear of ice and the heat pump is meeting the heating needs of the house. What is most likely the cause o f the problem? A: High winds on that side of the outdoor unit B: The outdoor unit is not level C: There is more refrigerant on that side of the coil D: A defrost problem exists - ✔✔B: The outdoor unit is not level A heat pump defrosts even when there is no ice on the outside coil. Which of the following is most likely the problem? A: The defrost time clock is set for too short a cycle B: The outdoor coil is dirty and the system uses a pressure differential type of defrost initiation C: The sensing bulb of the defrost control is mounted too close to the bottom of the outdoor coil D: Each of these could cause the problem - ✔✔D: Each of these could cause the problem A heat pump is operating in the heating mode. The lower the outside air temperature, the: A: More efficient the heat pump becomes B: Higher the SEER rating C: Higher the compression ratio D: Lower the balance point - ✔✔C: Higher the compression ratio A heat pump operating in the cooling mode would be expected to have a return -to-supply air temperature differential in the range of: A: 5 to 6 degrees B: 5 to 8 degrees C: 8 to 12 degrees D: 18 to 22 degrees - ✔✔D: 18 to 22 degrees A heat pump operating normally in the heating mode would be expected to have a supply air temperature in the range of: A: 70 to 80 degrees B: 80 to 90 degrees C: 85 to 105 degrees D: 100 to 130 degrees - ✔✔C: 85 to 105 degrees 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 an d 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 - ✔✔C: 1055 CFM 222 x 60 = 13,320watts 13, = 13.32 Kw btuh = 13.32 x 3415 = 45,488 cfm =((45,488 / (1.08 x 40)) cfm = 45,.2 = 1052.95 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 - ✔✔A: Electronic temperature sensor that changes its resistance with changes in temperature A typical 3 ton split system residential heat pump would have auxiliary electric heating elements of about how many watts total? A: 4 kw B: 5 kw C: 15 to 20 kw D: 40 to 60 kw - ✔✔C: 15 to 20 kw One ton of heat is 12,000 BTU's
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 an d 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 - ✔✔C: 1055 CFM 222 x 60 = 13,320watts 13, = 13.32 Kw btuh = 13.32 x 3415 = 45,488 cfm =((45,488 / (1.08 x 40)) cfm = 45,.2 = 1052.95 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 - ✔✔A: Electronic temperature sensor that changes its resistance with changes in temperature A typical 3 ton split system residential heat pump would have auxiliary electric heating elements of about how many watts total? A: 4 kw B: 5 kw C: 15 to 20 kw D: 40 to 60 kw - ✔✔C: 15 to 20 kw One ton of heat is 12,000 BTU's
