Florida Home Inspector Practice Test

At what temperature does the defrost cycle on a heat pump normally activate?

1. 32 degrees F

2. 37 degrees F

3. 40 degrees F

4. 45 degrees F

The correct answer is: 37 degrees F

The defrost cycle on a heat pump typically activates at 37 degrees Fahrenheit. This temperature is strategically chosen because it's close to the freezing point of water, where frost accumulation on the outdoor unit can start to hinder the heat pump's efficiency. By initiating the defrost cycle at this temperature, the heat pump can effectively manage and remove frost buildup, ensuring optimal operation and preventing damage to the system. By activating the defrost cycle when the temperature is at or below this threshold, the heat pump can switch from heating mode to defrost mode, allowing it to blow warm air over the outdoor coils. This helps melt any accumulated frost or ice, thus allowing the heat pump to continue working efficiently when the temperature drops further or when the external conditions are more challenging.