When a cold air producing air conditioning (AC) unit is running, it extracts heat from the indoor air and cools it down. The process of cooling the air involves several components, including an evaporator coil and a condenser coil. The hot air blowing out of the back of the AC unit is a byproduct of this cooling process, and it serves a specific purpose. Here's an explanation of why hot air is expelled from the back of a cold air producing AC unit:
Heat Exchange: The AC unit contains refrigerant, a substance that cycles through the system, alternately absorbing and releasing heat. When the AC is in cooling mode, the refrigerant absorbs heat from the indoor air and carries it outside to be released.
Evaporator Coil: Inside the AC unit, the refrigerant passes through an evaporator coil. The coil is kept at a low temperature, typically below the indoor air temperature. As the warm indoor air passes over the evaporator coil, the refrigerant absorbs the heat from the air, cooling it down in the process. This cools the air that is then circulated back into the room.
Condenser Coil: The refrigerant, now carrying the absorbed heat from the indoor air, is pumped outside the building to the condenser coil. The condenser coil is located in the outdoor unit of the AC system. Here, the heat is released into the outdoor air.
Fan and Exhaust: The AC unit has a fan that helps to circulate the indoor air over the evaporator coil for cooling. Simultaneously, another fan is used to blow air over the condenser coil in the outdoor unit. This helps to dissipate the heat absorbed from the indoor air. As a result, the hot air generated by the condenser coil is expelled out of the back or the sides of the AC unit.
The purpose of expelling the hot air is to ensure efficient heat exchange and maintain the cooling process. By removing the absorbed heat from the refrigerant and releasing it into the outdoor air, the AC unit can continue cooling the indoor air effectively.
It's worth noting that the hot air blowing out of the back of the AC unit should be directed away from the immediate vicinity of the outdoor unit to prevent recirculation and potential overheating. Proper clearance and airflow around the AC unit are important for optimal operation and efficiency.