What is a defrost cycle in a heat pump and why is it necessary?

Prepare for the HVAC 403A Exam. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

Multiple Choice

What is a defrost cycle in a heat pump and why is it necessary?

Frost on the outdoor coil during heating reduces heat transfer and lowers efficiency. A defrost cycle is a brief reversal of refrigerant flow that uses heat from the indoor side to warm the outdoor coil, melting the frost. Once the ice is cleared, the system returns to normal heating. This keeps the heat pump operating at its rated capacity and prevents ongoing efficiency loss from ice buildup. It’s not about increasing refrigerant charge, reducing indoor humidity, or delaying defrost for better dehumidification.

Frost on the outdoor coil during heating reduces heat transfer and lowers efficiency. A defrost cycle is a brief reversal of refrigerant flow that uses heat from the indoor side to warm the outdoor coil, melting the frost. Once the ice is cleared, the system returns to normal heating. This keeps the heat pump operating at its rated capacity and prevents ongoing efficiency loss from ice buildup. It’s not about increasing refrigerant charge, reducing indoor humidity, or delaying defrost for better dehumidification.

More practice questions