AIR HANDLER HVAC GUIDE: ROLE, BENEFITS & USE CASES
In a modern HVAC system, the air handler is crucial to maintaining indoor air quality (IAQ). If the wrong or improperly installed or maintained air handler is used in an HVAC system, it can diminish the entire HVAC system’s efficiency.
What is an Air Handler?
An air handler is generally referred to as an air handling unit or AHU. It’s design or construction typically starts with a well-insulated metal box, which is tightly sealed to block air from passing through it–except through the installed ducting. An air handling unit’s components can be protected inside the box and may be supplemented with additional specialized parts.
How Air Handler Functions Within an HVAC System
The air handler conditions and circulates air through the HVAC system. A fan or blower moves air past or over coils, which help remove heat from the air and through filters that eliminate unwanted contaminants.
Use Cases for Air Handlers
A terminal air handler may be extremely simple, with a minimum number of components serving only a single zone. A more complex air handler may have additional components to control humidity and air pressure while serving multiple zones in a building or facility. Smaller AHUs can be located indoors, while larger ones are often relegated to the roof or hung from the side of a building above ground level.
Air Handler Components
The entire air handler is generally composed of three main components: a fan or blower, an air filter and a coil or set of coils.
The blower can be a single fan or a fan array. It is designed to move air with enough speed and force to flush cooled air through all ducting. In large HVAC systems, there can be additional fans located at key duct points to boost air circulation.
The fan speed can be constant, or a variable air volume (VAV) system used to accommodate different HVAC unit loads. VAV systems are typically used in buildings or facilities with significant cool air usage variances based on time of day or rooms in use.