Air handling unit. Central station AHUs are built from sections: mixing box, filters, preheat, cooling coil, heating coil, supply fan, sometimes return fan and humidifier, served by chilled and hot water or direct expansion refrigerant. Unlike a rooftop unit, an AHU usually holds no compressor of its own. In homes, the indoor unit with blower and coil is also called an air handler.
AHU-3 cooling coil valve is 100 percent open and the discharge is still 62, check the chilled water supply temperature.
Also heard as
- air handler
- air handling unit
Related terms
RTU
Rooftop unit: a packaged air conditioner, often with gas heat, that sits on a roof curb and ducts straight down into the building.
VAV
Variable air volume: a system that holds supply air temperature steady and varies the amount of air to each zone.
Chiller
A refrigeration machine that cools water or glycol, which is then pumped to coils to cool a building or process.
Fan coil
A small terminal unit with a fan, a filter and a water coil that heats or cools one room or zone.
Economizer
Dampers and controls that bring in cool outdoor air for free cooling instead of running compressors.