Integrations
What is an air handling unit?
An air handling unit (AHU) is the central HVAC plant that conditions and moves supply, return and exhaust air in a commercial building. Filters, coils, dampers, heat recovery and sensors sit in one cabinet the BMS sequences.
An air handling unit (AHU) is the packaged plant that filters, heats or cools, and distributes air through a commercial building's ductwork. Supply, return and exhaust streams meet inside the unit. A simple exhaust fan or a residential FTX box is not the same thing: a commercial AHU is multi-component plant the BMS sequences every day.
AHU components
Inside a typical commercial unit you find filters, heating and cooling coils, supply and return fans, mixing and outdoor-air dampers, and often a heat-recovery wheel or plate exchanger. Sensors for temperature, humidity, differential pressure and airflow, plus valve and damper actuators, close the loops. Variable-air-volume boxes are zone terminals fed by the AHU; they are not the unit itself.
How a BMS runs an air handling unit
A DDC loop on the BMS (or BAS) owns occupied and unoccupied modes, economiser and free-cooling logic, frost protection, and pressure or airflow setpoints. The controller writes damper and valve commands from those sequences. For what sits inside the field controller and panel, see our BMS controller guide. Analytics sits above that control stack: it reads the same points and ranks what is drifting.
| Equipment | What it is | How it relates |
|---|---|---|
| Air handling unit (AHU) | Packaged plant with filters, coils, fans, dampers and often heat recovery | The central air plant a commercial BMS sequences |
| Exhaust / supply fan | A single fan moving air without full conditioning trains | Simpler device; not a full AHU |
| Residential FTX | Heat-recovery ventilation sized for dwellings | Different market and control model; not this page |
| VAV box | Zone terminal that meters air from a central AHU | Downstream of the AHU, not a substitute for it |
Typical AHU faults
Operators see the same signatures again and again: filter loading that starves airflow, stuck dampers, sensor drift, hunting between heat and cool, simultaneous heating and cooling, a seized or slipping heat-recovery wheel, and fan or VFD degradation. Each leaves a pattern in the points the BMS already trends. Catching them early is the job of predictive maintenance for buildings, not another CMMS screen.
Points worth trending
Make AHU faults visible by trending supply and return air temperatures, mixed-air and outdoor-air temperatures, heating and cooling valve positions, fan VFD speed or %, differential pressure across filters, and outdoor-air damper %. Add frost-protection and economiser status where the sequence exposes them. Those points are usually already on the BMS; the gap is ranking the evidence.
How FrostLogic Explore fits. Explore is Sensor Intelligence: it reads existing BMS and meter points on the AHU and returns a ranked queue of findings. It is not a CMMS and not a dashboard replacement. Writes start off; predictive maintenance in Explore is the commercial path for AHU degradation ranked by cost and urgency.
Before you ask
Air handling units, the common questions.
An air handling unit (AHU) is the central HVAC plant that filters, heats or cools, and distributes supply, return and exhaust air in a commercial building. It is multi-component plant under BMS control, not a simple fan.
Outdoor and return air are mixed and filtered, then heated or cooled on coils before the supply fan pushes conditioned air into the ductwork. Exhaust and heat recovery close the energy loop. A BMS DDC sequence sets modes, economiser behaviour, frost protection and airflow or pressure setpoints.
A commercial AHU is sized and sequenced for buildings: larger fans, heating and cooling coils, dampers and BMS points. Residential FTX is heat-recovery ventilation for dwellings. Same air-movement idea, different plant and control stack.
Filter loading, stuck dampers, sensor drift, hunting, simultaneous heat and cool, a broken heat-recovery wheel, and fan or VFD degradation. Each leaves a signature in temperatures, valve positions, DP and fan speed.
Supply and return temperatures, mixed and outdoor air, valve positions, fan VFD %, filter differential pressure, and outdoor-air damper %. Those points make the common faults visible without new hardware.
Explore reads the BMS and meter points already on the AHU and returns a ranked queue of findings. It is Sensor Intelligence for predictive maintenance, not a CMMS and not a dashboard replacement. See predictive maintenance for buildings.
Related terms
Keep reading
From glossary to product
Rank AHU faults before they become complaints
FrostLogic Explore is Sensor Intelligence: ranked findings from the BMS and meter points already on your air handling units. Filter loading, stuck dampers and coil fights surface as a prioritised queue, not another alarm wall. Explore is not a CMMS.
See predictive maintenance in Explore