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

The reversing valve redirects refrigerant flow so the indoor coil acts as a condenser in heating mode and an evaporator in cooling mode.

Question 2

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

Accepted Answer

35–40°F

Answer

The balance point is typically 35–40°F, where the heat pump output equals the building heat loss and auxiliary heat is not yet needed.

Question 3

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

Accepted Answer

Prevent liquid refrigerant from entering the compressor

Answer

The accumulator is located on the suction line and traps liquid refrigerant, allowing only vapor to reach the compressor.

Question 4

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

Accepted Answer

Outdoor coil

Answer

In heating mode, the outdoor coil absorbs heat from the outside air (acting as evaporator) and the indoor coil releases heat (acting as condenser).

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

Defrost controls typically use a combination of time and outdoor coil temperature (or pressure differential) to trigger defrost when frost accumulates.

NATE - North American Technician Excellence Practice Test

NATE - North American Technician Excellence Practice Test

NATE Heat Pumps