Common Terms and Phrases used Regarding Air Conditioners

It’s hard to understand the jargon of an industry you aren’t actively involved in, and HVAC (heating, ventilation, and air conditioning) is no different. This page is dedicated to filling you in on a few of the terms you might hear a HVAC professional using when they are talking about your air conditioning unit.

Air Changes per Hour – This is the hourly ventilation rate divided by the volume of a space. In layman’s terms this basically refers to the rate at which your air enters and leaves a given space. It is also referred to as air change rate or air exchange rate.

Air Handling Unit – This is what the central unit of the HVAC system is referred to as, it is composed of the blower, heating/cooling element, filter racks, humidifier, and dampers. Air Handling Unit or AHU is something of an umbrella term that includes anything that come into contact with the airflow, excluding ductwork.

Coil– These are the devices that are responsible for the transfer of heat from the machine to the air. The coils are generally in the air handling unit or ductwork and can be heated and cooled to affect the temperature of the air around them.

Condenser – The condenser acts as the main transfer point for heat moving out of the house and into the air conditioner. Heat is drawn towards the condenser, extracted from the air through the refrigerant, and then moves it to the heat sink. This is the hot side of the air conditioning unit.

Evaporator – This is the part of the air conditioner which adds heat to the air conditioner system. It absorbs heat from the air through liquid transfer method. This is the hot side of the air conditioner.

Fluid Regulation Value – This is the component of the air conditioner which is responsible for regulating the flow of liquid through the coils in the air conditioner.

Glycol – A liquid found in many air conditioners used as the heat removal medium. It is used because of its low freezing point and resistance to icing.

Super Heat – Super heat refers to the temperature of a liquid being above its regular saturation point.

Sub cooling – The condition where the liquid refrigerant has reached a lower temperature than its normal saturation level.