An AHU schedule packs the selection data a contractor needs; reading it correctly prevents mismatched coils, fans, and connections on site.
What the Schedule Contains
The schedule lists the duty: supply airflow in m³/h, external static pressure in Pa, and the cooling and heating capacities in kW. These three numbers define the unit and should match the load calculation, not just the previous unit that happened to be installed.
An AHU schedule is the single document that tells the manufacturer exactly what to build, and reading it well prevents the most expensive mistake in HVAC: a unit that arrives correct on paper but wrong for the room. The schedule lists airflow, external static pressure, cooling and heating coils, filter grades, and the fan duty, each as a design value the supplier must meet.
Airflow and static pressure head the list because they set the fan. The schedule states the supply volume in m³/h and the total external resistance in Pa the unit must overcome including coils, filters, duct, and terminals; these two numbers alone determine the wheel size and motor power, and any ambiguity here propagates into under- or over-performance on site.
Coil entries name the fluid, the entering and leaving conditions, and the capacity in kW. A chilled-water coil is described by water flow and temperature difference, while a heating coil adds the control valve type; reading these against the plant's available hydraulics confirms the coil will actually deliver the load with the water the building can supply.
Filter grades are given by efficiency class such as ISO coarse or fine ePM ratings, and the schedule also notes the final resistance at which the filter is replaced. This final value sets the fan's reserve because the unit must still move design air when the media is loaded, so the fan curve point is taken at the dirty-filter condition, not the clean one.
The company's AHU range is built under ISO 9001:2015 with CCC certification at its 80,000 m² production site, and because it supplies more than 50 countries its schedules are returned with a documented test point from the in-house laboratory, so the specifier can confirm the quoted unit meets every line of the schedule before order release.
Coil rows and fin density describe the heat-exchange surface. More rows or finer fins raise capacity but also pressure drop, so the schedule balances heat transfer against the fan energy needed to push air through, and against the fouling behaviour in the local air.
The fan section gives the type, duty point, and efficiency, plus the motor rating. The curve, when supplied, shows whether the operating point sits on a stable part of the performance map where small resistance changes cause only small flow changes.
Filter grades and dimensions, casing panel type, and the overall footprint complete the picture. Dimensions matter for plant-room access, so the schedule should state both the unit size and the door or hatch it must pass through during delivery and installation.
Reading the Numbers
Airflow and static pressure together define the fan; a unit rated at 20,000 m³/h but only 300 Pa is a different machine from one at 20,000 m³/h and 800 Pa, and the motor sizes, frame, and noise follow directly from that difference.
Coil capacity must line up with the water flow and temperature difference available from the system; a 100 kW coil is useless if the chilled-water plant cannot deliver the corresponding flow, and the pump head must also be available.
Fin spacing, often 8-14 fins per inch, signals the coil's dirt-holding and pressure-drop behaviour; tighter fins clean better but clog faster in dusty air and may need more frequent washing or a coarser pre-filter upstream to protect them.
Cross-check the schedule against the drawn layout for connection sizes and handedness, because a mirrored unit can put the wrong service side against a wall, forcing rework of piping and ductwork that were already set out for the original orientation.
| Item | Specification | Note |
|---|---|---|
| Airflow | m³/h | Sets fan size |
| Static pressure | Pa | Sets motor size |
| Cooling capacity | kW | Match water system |
| Coil rows | 4-8 | Capacity vs ΔP |
| Fin density | 8-14 fins/in | Cleaning trade-off |
| Footprint | mm | Plant-room access |
Selection Checklist
- Confirm airflow, static pressure, and capacity match the load calc.
- Check the coil rows and fins suit the water side and dust level.
- Read the fan curve to confirm a stable operating point.
- Verify motor rating covers the stated static pressure with margin.
- Compare dimensions with the actual plant-room opening.
- Reconcile connection sizes and unit handedness with the drawing.
About the Manufacturer
Keruite Air Conditioning Group, headquartered in Dezhou, Shandong, has more than 30 years of HVAC manufacturing experience and operates an 80,000 m² production site with its own performance testing laboratory. Products are built under ISO 9001:2015 quality management and carry CCC certification, and are supplied to customers in over 50 countries.
Our engineers respond to selection enquiries within 24 hours and can provide project-specific sizing, performance curves, and documentation to support specification and procurement.