Anatomy of an Air Handling Unit
An AHU conditions outdoor air before it enters a building. The core components are: the supply fan, the exhaust fan, filters, coils (heating/cooling), and – increasingly – a heat recovery core. How these are arranged decides both air quality and energy use.
Fans
Supply and exhaust fans move the air. Their efficiency and the pressure drop across every component set the fan power. A recovery device that adds 100 Pa can quietly raise energy use by 10-20%.
Filters
Filters protect occupants and coils. Rating runs from coarse (ISO Coarse / MERV 8) to fine (ePM1 / MERV 13+). Cleaner air costs more pressure drop, so filter choice and recovery placement must be balanced together.
The recovery core
The recovery core – plate, rotary, heat pipe, or run-around coil – sits between the two airstreams. In a new build it is designed in; in a retrofit it is added to the exhaust riser (see retrofit guide).
Sizing the whole unit
Recovery must be sized with the AHU, not bolted on. Use our AHU selection calculation to balance effectiveness, pressure drop, and fan energy before ordering.