Hvac Nate Heat Pump Certification Exams Answers

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 {Ans: 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}Which of the following airflow rates is the most reasonable for a heat pump system operating in the heating cycle? A: 200 cfm per ton B: 300 cfm per ton C: 400 cfm per ton D: 450 cfm per ton {Ans: D: 450 cfm per ton}Which of the following can prevent the reversing valve from changing positions? A: Low refrigerant charge B: Overcharge of refrigerant C: Air in the system D: Low indoor airflow due to a dirty air filter {Ans: A: