NATE Heat Pumps 2 — Questions and Answers
Question 1: Which type of heat pump extracts heat from the ground rather than outdoor air?
- Air-source heat pump
- Geothermal (ground-source) heat pump (Correct answer)
- Mini-split heat pump
- Absorption heat pump
Correct answer: Geothermal (ground-source) heat pump
Geothermal heat pumps use underground loops to exchange heat with the earth, which stays at a relatively constant temperature year-round.
Question 2: When a heat pump is in heating mode and the emergency heat is energized, what happens?
- Both the compressor and electric strips run simultaneously
- Only electric resistance strips provide heat; the compressor is locked out (Correct answer)
- The reversing valve switches to cooling mode
- The outdoor fan runs at high speed
Correct answer: Only electric resistance strips provide heat; the compressor is locked out
Emergency heat bypasses the heat pump compressor and relies solely on electric resistance heat strips, typically used when the heat pump has failed.
Question 3: What is a common symptom of a stuck reversing valve in the heating position?
- System heats normally but will not cool
- Compressor short cycles
- Outdoor coil ices over in summer
- Both A and C (Correct answer)
Correct answer: Both A and C
A reversing valve stuck in heating mode causes the system to heat when cooling is called for, and the outdoor coil may ice in summer because it acts as an evaporator.
Question 4: What is the purpose of the check valves used in a heat pump refrigerant circuit?
- Prevent compressor oil from leaving the crankcase
- Redirect refrigerant flow so both the indoor and outdoor coils can act as either evaporator or condenser (Correct answer)
- Limit high-side pressure during summer operation
- Remove moisture from the refrigerant
Correct answer: Redirect refrigerant flow so both the indoor and outdoor coils can act as either evaporator or condenser
Check valves route refrigerant around the metering devices depending on the direction of flow, allowing a single bidirectional circuit.
Question 5: What outdoor temperature indicates a heat pump may need a 'cold climate' or variable-speed model to remain effective?
- Below 50°F
- Below 32°F
- Below 0°F (Correct answer)
- Below 20°F
Correct answer: Below 0°F
Standard heat pumps lose significant capacity below 32°F, while cold-climate models maintain heating capacity down to -13°F or lower.
Question 6: What does HSPF2 measure for a heat pump?
- Cooling efficiency over a season
- Heating efficiency measured as total heat output divided by total electrical energy over the heating season (Correct answer)
- Defrost cycle frequency
- Compressor efficiency ratio
Correct answer: Heating efficiency measured as total heat output divided by total electrical energy over the heating season
HSPF2 (Heating Seasonal Performance Factor 2) rates heating efficiency; higher values indicate more efficient heating performance.
NATE Heat Pumps 2
Which type of heat pump extracts heat from the ground rather than outdoor air?