An air handling unit that receives systematic preventive maintenance — filter changes triggered by differential pressure, coils cleaned before fouling drives 20% efficiency loss, belts replaced on wear inspection rather than failure, and BAS sensors calibrated annually — costs significantly less to operate and lasts longer than one managed reactively. OxMaint's Preventive Maintenance module automates AHU PM scheduling across your entire air handler fleet, tracks component-level condition, and alerts on differential pressure, belt wear, and sensor drift before they become failures. Book a 15-minute demo to see AHU preventive maintenance in OxMaint.
Air Handling Unit Maintenance: Filters, Coils, Belts, and BAS Controls
Filter replacement, coil cleaning, belt tensioning, damper calibration, motor inspection, and BAS controls verification — CMMS-scheduled across every AHU in your building portfolio.
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AHU Component Maintenance — What to Do and When
Book a Demo — See AHU PM Scheduling Across Your Full Air Handler Fleet in OxMaint.
Filter ΔP alerts · Coil cleaning schedules · Belt inspection WOs · Damper calibration · BAS sensor records · Energy performance trending. Every AHU, every component, always on schedule.
AHU PM Tasks — Frequency and ASHRAE 180 Reference
| PM Task | Frequency | Standard | OxMaint Action |
|---|---|---|---|
| Filter differential pressure reading | Monthly | ASHRAE 180 §6.1 | Monthly PM WO — ΔP recorded, replacement WO triggered at threshold |
| Condensate pan and drain inspection | Monthly | ASHRAE 62.1 / ASHRAE 180 | Monthly PM WO — standing water triggers Legionella risk WO |
| Fan belt tension and alignment check | Monthly | ASHRAE 180 §6.5 | Monthly PM WO — tension value and wear rating recorded |
| AHU access door seals and gaskets inspection | Monthly | Manufacturer SOP | Monthly PM WO — bypass air deficiency triggers repair WO |
| Cooling coil approach temperature measurement | Quarterly | ASHRAE 180 §6.2 | Quarterly PM WO — approach temp vs design baseline stored per AHU |
| Damper full-stroke functional test | Quarterly | ASHRAE 180 §6.7 | Quarterly PM WO — stroke range and position feedback recorded |
| Fan motor amp draw measurement | Quarterly | ASHRAE 180 §6.5 | Quarterly PM WO — nameplate vs measured, overamp triggers investigation |
| Bearing lubrication — fan and motor | Every 3–6 months | Manufacturer schedule | Seasonal PM WO — grease type and quantity recorded per bearing ID |
| Coil full clean — cooling and heating coils | Annual | ASHRAE 180 §6.2 | Annual PM WO — approach temp before and after, method recorded |
| BAS sensor calibration — temperature, CO₂, pressure | Annual | ASHRAE Guideline 11 | Annual PM WO — as-found/as-left per sensor, linked to AHU asset |
| Economizer controls sequence verification | Annual (seasonal changeover) | ASHRAE 90.1 / IECC | Annual PM WO — OA damper position vs OAT logged for each mode |
| Smoke damper annual test and certification | Annual | NFPA 105 / UL 555 | Annual PM WO — fail-safe test and reset verified, certificate stored |
| Filter replacement — bag and HEPA filters (calendar fallback) | Annual or on ΔP trigger | ASHRAE 180 §6.1 | Annual WO or ΔP alert WO — filter type, MERV, and vendor recorded |
| Heat exchanger / heat wheel inspection and clean | Annual | Manufacturer SOP | Annual PM WO — heat recovery efficiency recorded before and after |
| Belt replacement — V-belts | Annual or on condition | ASHRAE 180 §6.5 | Annual PM WO or wear-triggered WO — belt size and brand recorded |
Sign in to OxMaint to configure your full AHU PM programme — all tasks auto-generated and tracked per AHU asset with component-level record storage.
What HVAC Engineering and Energy Management Leaders Say
The most common finding in commercial HVAC energy audits is not an undersized system or an inefficient chiller — it is a well-specified AHU running at 30% degraded performance because its filters have been replaced on calendar regardless of ΔP, its coils have never been cleaned since commissioning, and its economizer dampers are stuck because nobody tested them since the BAS upgrade two years ago. AHU preventive maintenance is the single highest-ROI activity in commercial building energy management. Every coil cleaning pays for itself within a cooling season. Every damper calibration recovers free cooling that was being wasted. The buildings that track this in a CMMS and trend the before-and-after data can prove it.
How OxMaint Manages Your Full AHU PM Programme
Book a Demo — See OxMaint Managing Your Full AHU Preventive Maintenance Programme.
ΔP-triggered filters · Coil approach temperature trending · Belt wear inspection · Damper calibration records · BAS sensor as-found/as-left · Fleet-wide AHU dashboard. Every component. Every AHU. Always on schedule.
AHU Maintenance — Common Questions
Should AHU filters be replaced on a calendar schedule or based on differential pressure?
Differential pressure is the correct trigger. Calendar replacement wastes budget in low-load periods when filters remain serviceable, and misses early saturation during high-load periods. ASHRAE 180 supports ΔP-based replacement — replace pre-filters at 150–200 Pa above clean baseline and bag/HEPA filters at the manufacturer's maximum ΔP. OxMaint triggers the replacement WO automatically when the BAS-integrated ΔP reading crosses the threshold. Sign in to configure ΔP filter alerts in OxMaint.
How often should AHU cooling coils be cleaned?
Annual cleaning is the minimum for most commercial AHUs — quarterly if the building is in a high-particulate environment or if the pre-filter is undersized relative to coil bypass. The performance indicator is coil approach temperature: if it rises more than 1–2°C above clean baseline, cleaning is needed regardless of calendar interval. OxMaint records approach temperature quarterly and generates a cleaning WO when the threshold is crossed. Book a demo to see coil performance tracking in OxMaint.
What are the signs that an AHU fan belt needs replacement?
Replace immediately on cracks, fraying, glazing, or visible cord exposure. Replace when belt deflection is more than 20% beyond the tensioned specification — excessive slack causes slipping and vibration. Monthly inspection by a trained technician is the minimum; acoustic emission sensors on high-criticality AHUs detect belt frequency anomalies 3–4 weeks before visible wear reaches failure. Sign in to configure belt inspection WOs in OxMaint.
How does OxMaint integrate with BAS systems for AHU monitoring?
OxMaint integrates via OPC-UA and MQTT with BAS/BMS platforms including Siemens Desigo, Johnson Controls Metasys, Honeywell EBI, and others. Filter ΔP, supply air temperature, return CO₂, and economizer damper position are all ingestible as alert triggers. When any parameter crosses its configured threshold, OxMaint generates a prioritised work order — linked to the specific AHU asset with the sensor reading attached. Book a demo to see BAS integration with OxMaint.
