NATE Heat Pumps

Question 1

What component allows a heat pump to reverse the refrigeration cycle between heating and cooling modes?

Accepted Answer

Reversing valve

Answer

Check valve

Answer

Thermostatic expansion valve

Answer

Accumulator

Question 2

At what outdoor temperature do most standard air-source heat pumps reach their balance point?

Accepted Answer

35–40°F

Answer

50°F

Answer

40°F

Answer

25°F

Question 3

What is the purpose of the accumulator in a heat pump system?

Accepted Answer

Prevent liquid refrigerant from entering the compressor

Answer

Store excess refrigerant charge

Answer

Remove non-condensables from the refrigerant

Answer

Regulate condenser airflow

Question 4

During a heating cycle, which coil in a heat pump acts as the evaporator?

Accepted Answer

Outdoor coil

Answer

Indoor coil

Answer

Auxiliary coil

Answer

Desuperheater coil

Question 5

What initiates a defrost cycle on an air-source heat pump?

Accepted Answer

Time/temperature or pressure differential control sensing frost buildup on outdoor coil

Answer

Indoor thermostat calling for auxiliary heat

Answer

Outdoor ambient thermostat dropping below 32°F

Answer

Compressor high-pressure lockout

Question 6

What does COP (Coefficient of Performance) measure for a heat pump?

Accepted Answer

Ratio of heat output to electrical energy input

Answer

Cooling capacity in BTUs

Answer

Seasonal energy efficiency ratio

Answer

Compressor displacement volume