Air Handler Units and Coils Flashcards

What is the primary purpose of a drain pan in an air handler unit?

Answer: To collect condensate from the evaporator coil

The drain pan collects condensate water that forms on the evaporator coil during the cooling process and channels it to the drain line.

Which type of air handler configuration has the blower located downstream of the coil?

Answer: Draw-through

In a draw-through configuration, the blower pulls air through the coil rather than pushing it, which is the most common arrangement.

What causes a evaporator coil to freeze up during operation?

Answer: Restricted airflow or low refrigerant charge

Restricted airflow (dirty filter, closed registers) or low refrigerant charge causes suction pressure to drop below freezing, causing the coil to ice over.

What is the function of a TXV (thermostatic expansion valve) in relation to the evaporator coil?

Answer: It meters refrigerant flow into the coil based on superheat

The TXV meters refrigerant flow into the evaporator coil by sensing superheat, ensuring the coil operates efficiently without liquid refrigerant returning to the compressor.

When installing an air handler in a vertical upflow position, where should the evaporator coil be located?

Answer: At the top of the unit above the blower

In a vertical upflow air handler, the blower is at the bottom and the evaporator coil is at the top so air flows upward through the coil.

What is the typical fin spacing (fins per inch) for a residential evaporator coil?

Answer: 8-14 fins per inch

Residential evaporator coils typically have 8-14 fins per inch, balancing heat transfer efficiency with acceptable airflow resistance and ease of cleaning.

What material are most modern evaporator coil fins made from?

Answer: Aluminum

Most modern evaporator coil fins are made from aluminum because it is lightweight, cost-effective, and has good thermal conductivity.