AHU | Preventative Maintenance Checklist covering Weekly to 3 Years + Download

December 6, 2022 |

To ensure that any air handling unit [AHU] installed is maintained, operates efficiently, and is in line with the current design requirement years after installation, they should be inspected, tested, and maintained at the following intervals:

  • Weekly
  • Monthly
  • 6-Months
  • 12-Months
  • 24-Months &
  • 36-Months

There are 8 good reasons for maintaining them, and not having a straightforward, detailed, regular maintenance programme can significantly affect their operation, failures/wear/tear, and energy usage:

  • Higher failure rates of the equipment and its components, increasing overall costs and maintenance/repair requirements.
  • Higher running costs due to the blower motor having to work harder to blow the air through unmaintained filters and coils.
  • Coils cannot operate to their peak efficiency, operating conditions, and performance characteristics.
  • Additional complaints from occupants because comfort levels are affected due to the filters, coils, controls, and valves not working as designed.
  • Smells and general internal air quality problems, from dirty filters, coils, and drain pans/drip trays.
  • Damage to existing installations, for example, ceilings and walls becoming contaminated from airborne dirt particles and dirty air, is usually seen by dirty streaks.
  • Fire risk due to the building up of potentially combustible materials within the ducting.
  • The early operation and troubleshooting of issues will help maintain an efficient system.

In the below article, we will go through a typical preventative maintenance regime for the air handling unit and some of its peripheral equipment.

🟩 Who will complete the checks and maintenance?

If the building construction process is still ongoing or it is still within the defect’s liability period, then the responsibility for the maintenance will be the general/main contractor.

Where the building/systems are outside of the defects liability period, the maintenance of the unit will be completed by the building facilities manager/operator.

🟩 Parts and components to be inspected

The following parts and components will be inspected under this work:

  • Air Intake and Plenum
  • General Ducting
  • Attenuators
  • Air Handling Unit Frame and Casing
  • Dampers
  • Mixing Box
  • Filters
  • Frost Coil
  • Blower Fan and Direct Drive Motor
  • Vibration Mounts
  • Electrical Isolators
  • Emergency Stop
  • Dx System Compressor
  • Dx System Evaporator
  • Dx Condenser
  • CHW Cooling Coil
  • Condensate Tray and Pipework
  • LTHW Heating Coil
  • Electric Heater
  • Steam Generator
  • Humidifier
  • Heat Exchanger/Thermal Wheel
  • Pumps
  • Control Valves
  • Actuators
  • Pressure Sensors
  • Temperature Sensors
  • Thermostats
  • CO2 Sensor
  • Smoke Detector
  • Variable Speed Drive
  • Air Handling Unit Control Panel
  • Air Terminal Devices
  • External Dx Unit
🔗 If you would like to understand more about air handling units check out our article 'AIR HANDLING UNITS | All we need to know', for more information.

🟩 Standard routine maintenance schedule

The routine and timings for the checks will be broken into the following time frames/schedule:

  • Weekly inspections
  • 1-month inspections
  • 3-month inspections
  • 6-month inspections
  • 12-month inspections
  • 24-month inspections
  • 36-month inspections

⚠️ Note: Before any work takes place on the equipment, the following should be in place:

  • Full Risk Assessments
  • Electrical isolations, including ‘lock out tag out’ of Equipment and Panels, including documentation

🟩 Weekly inspection checklist

TypeTask
W-1InspectUnit - Observe and review the unit for any changes in operating conditions.

If any are noted, they should be investigated further.
W-2InspectUnit - Listen for any unusual noises.

If any are noted, they should be investigated further.
W-3InspectSet Point - Visually Inspect temperature setting to ensure as per design/operational needs.

If it is not, investigate as to why and reset if no reason provided.

Note: changes could impact the buildings energy usage.
W-4InspectSteam Generator - Inspect for damage and leakage.
W-5InspectSteam Humidifier - Check for damage and leakage
W-6InspectSteam Humidifier - Visually inspect water levels.
W-7InspectSteam Humidifier - Visually inspect the overall steam installation and supply pipework for any damage or leakage.
W-8InspectSteam Humidifier - Visually inspect drainage pipework for any blockages and obstructions.
W-9InspectSteam Humidifier Control Panel - Visually inspect electrical connections, components, and cables for damage/issues.

🟩 Monthly inspection checklist

TypeTask
1M-1InspectFilters - Visually inspect filter for dust, debris, foreign objects, moisture, and smells taking note of any issues.

Replace filter if smells or contains moisture.
1M-2InspectFilters - Visually inspect filter frames and rails for contamination, foreign objects, corrosion, and damage.

If anything noted, then clean or inspect/conduct remedial action.
1M-3InspectFilters - Take readings from the differential pressure devices/bms across the filters.

Replace or clean if max differential pressure is exceeded.
1M-4InspectStrainer - Remove strainer mesh inspect for contamination, foreign objects, corrosion, and damage.

If anything noted then clean or inspect/conduct remedial action.
1M-5MeasureSteam Humidifier - Take samples and analyse the water quality and conductivity serving the steam equipment to ensure it is in line with the manufacturer’s requirements.

Any noted issues should be investigated, and remedial action taken.

🟩 3-month inspection checklist

TypeTask
3M-1InspectUnit - Visually inspect the internal and external cleanliness of the unit.

If anything noted, then conduct remedial action.
3M-2InspectFan Motor - Inspect belts and pulley tensions, in line with the manufacturer’s requirements, and for wear and tear.

Any noted issues should be investigated, and remedial action taken.
3M-3InspectFan Motor - Inspect motor bearings for vibrations, noise, overheating and lubrication.

If anything noted, then conduct remedial action/lubricate.
3M-4MeasureChilled Water - Take samples and analyse the water quality serving all wet coils to ensure it is in line with the original design requirements.

Any noted issues should be investigated, and remedial action taken.
3M-5MeasureHeating Water - Take samples and analyse the water quality serving all wet coils to ensure it is in line with the original design requirements.

Any noted issues should be investigated, and remedial action taken.
3M-6InspectFrost Coil - Visually inspect for contamination, foreign objects, corrosion, leakage, and damage.

If anything noted, then clean or inspect/conduct remedial action.
3M-7InspectCooling Coil - Visually inspect for contamination, foreign objects, corrosion, leakage, and damage.

If anything noted, then clean or inspect/conduct remedial action.
3M-8InspectEvaporator - Visually inspect for contamination, foreign objects, corrosion, leakage, and damage.

If anything noted, then clean or inspect/conduct remedial action.
3M-9InspectEvaporator - Visually inspect for any ice build-up.

If anything noted, then conduct remedial action.
3M-10InspectCondenser - Visually inspect for contamination, foreign objects, corrosion, leakage, and damage.

If anything noted, then clean or inspect/conduct remedial action.
3M-11InspectCompressor - Inspect the oil levels to ensure they are in line with the manufacturer’s requirements.

If anything noted, then conduct remedial action.
3M-12InspectCondensate Drain - Visually inspect pan for contamination, foreign objects, corrosion, and damage.

If anything noted, then clean or inspect/conduct remedial action.
3M-13TestCondensate Drain Pan - Conduct flow test on drain pan, trap and pipework system.

If anything noted, then conduct remedial action.
3M-14InspectHeating Coil - Visually inspect for contamination, foreign objects, corrosion, leakage, and damage.

If anything noted, then clean or inspect/conduct remedial action.
3M-15InspectThermal Wheel - Visually inspect for contamination, foreign objects, corrosion, and damage.

If anything noted, then clean or inspect/conduct remedial action.
3M-16InspectThermal Wheel - Visually inspect all seals for contamination, foreign objects, corrosion, damage and wear and tear.

If anything noted, then clean or replace.
3M-17InspectThermal Wheel - Inspect bearing play, lateral movement or if out of balance.

If anything noted, then conduct remedial action.
3M-18InspectThermal Wheel - Inspect motor bearings for vibrations, noise, overheating and lubrication.

If anything noted, then conduct remedial action/lubricate.
3M-19InspectThermal Wheel - Inspect belts and pulley tensions, in line with the manufacturer’s requirements, and for wear and tear.

Any noted issues should be investigated, and remedial action taken.
3M-20InspectThermal Wheel - Visually inspect motor mountings for wear and tear/issues.

If anything noted, then conduct remedial action.
3M-21InspectThermal Wheel - Inspect the drive elements of the unit.

If anything noted, then conduct remedial action.
3M-22InspectThermal Wheel Condensate Drain - Visually inspect pan for contamination, foreign objects, corrosion, and damage.

If anything noted, then clean or inspect/conduct remedial action.
3M-23TestThermal Wheel Condensate Drain Pan - Conduct flow test on drain pan, trap and pipework system.

If anything noted, then conduct remedial action.
3M-24TestThermal Wheel - Conduct test on the operation and function of the exchanger ensuring it rotates and operates in line with manufacturers requirements.

If anything noted, then conduct remedial action.
3M-25InspectSteam Humidifier - Visually inspect the overall operation of the equipment including spray nozzle, pumps, control panel, drainage.

If anything noted, then conduct remedial action.

🟩 6-month inspection checklist

TypeTask
6M-1TestFilters - Measure the differential pressure across all filters within the unit with calibrated instrument, cross reference with the BMS.

Adjust setting if difference noted.

Replace or clean if max differential pressure is exceeded.
6M-2InspectAttenuator - Visually inspect externally and internally for contamination, foreign objects, corrosion, damage and wear and tear.

If anything noted, then conduct remedial action.
6M-3InspectAir Mixing Box - Visually inspect for contamination, foreign objects, corrosion, damage and wear and tear.

If anything noted, then conduct remedial action.
6M-4TestAir Mixing Box - Move damper blades to ensure they are not damaged, obstructed and move smoothly.

If anything noted, then conduct remedial action.
6M-5InspectAir Mixing Box - Inspect damper bearings and linkage for any issues.

If anything noted, then conduct remedial action.
6M-6InspectFan Impeller - manually rotate the fan to check for any obstructions or issues.

If anything noted, then conduct remedial action.
6M-7InspectFan Motor - Visually inspect motor mountings and brackets for torque and wear/tear in line with manufacturers requirements.

If anything noted, then conduct remedial action.
6M-8InspectFan Motor - Inspect alignment of motor and shafts.

If anything noted, then conduct remedial action.
6M-9InspectFan Impeller - Inspect for misalignment, imbalance, vibrations, contamination, foreign objects, corrosion, and damage.

If anything noted, then conduct remedial action.
6M-10InspectEquipotential Bonding - Inspect the bonding of the unit, parts, and components.

If anything noted, then conduct remedial action.
6M-11InspectCompressor - Visually inspect mountings and vibration elements.

If anything noted, then conduct remedial action.
6M-12InspectElectrical Heater - Visually inspect for contamination, foreign objects, corrosion, and damage.

If anything noted, then clean or inspect/conduct remedial action.
6M-13TestElectrical Heater - Conduct test on the operation and function of the heater ensuring it operates in line with the design and manufacturers requirements.

If anything noted, then conduct remedial action.
6M-14InspectSteam Humidifier - Drain off steam cylinder and clean scale collection tank.
6M-15InspectControl valves - Visually inspect to ensure that they are not damaged, contaminated or corroded.

If anything noted, then conduct remedial action.
6M-16InspectActuators - Visually inspect to ensure that they are connected and not damaged, contaminated or corroded including wiring and connections.

If anything noted, then conduct remedial action.
6M-17InspectTemperature Sensors - Visually inspect to ensure that they are clean, not damaged, corroded, or contaminated, including wiring.

If anything noted, then conduct remedial action.
6M-18InspectHumidity Sensors - Visually inspect to ensure that they are clean, not damaged, corroded, or contaminated, including wiring.

If anything noted, then conduct remedial action.
6M-19InspectPressure Sensors - Visually inspect to ensure that they are clean, not damaged, corroded, or contaminated, including wiring.

If anything noted, then conduct remedial action.
6M-20InspectThyristors - Visually inspect to ensure that they are clean, not damaged, corroded, or contaminated, including wiring.

If anything noted, then conduct remedial action.
6M-21InspectSmoke Detector - Visually inspect to ensure that they are clean, not damaged, corroded, or contaminated, including wiring.

If anything noted, then conduct remedial action.
6M-22InspectTime Clock - Visually inspect the time clock settings for the unit and ensure they are set in line with the design intent.

If anything noted, then conduct remedial action.
6M-23InspectControl Panel - Visually inspect externally and internally to ensure that it is clean, not damaged, corroded, or contaminated, including wiring connections.

If anything noted, then conduct remedial action.
6M-24TestControl Panel - Conduct lamp test on panel to ensure they illuminate.

If anything noted, then conduct remedial action.
6M-25InspectFresh Air Ducting- Visually inspect to ensure free and clear and the flexible connection to the plenum/louvre is in good condition.

If anything noted, then conduct remedial action.
6M-26InspectInsulation to Fresh Air Ducting - Visually inspect to ensure has no damage, torn and that the vapor barrier is unaffected.

If anything noted, then conduct remedial action.
6M-27InspectRecirculating Air Ducting - Visually inspect to ensure free and clear and the flexible connection to the unit is in good condition.

If anything noted, then conduct remedial action.
6M-28InspectInsulation to Recirculating Air Ducting - Visually inspect to ensure has no damage, torn and that the vapor barrier is unaffected.

If anything noted, then conduct remedial action.
6M-29InspectSupply Air Ducting - Visually inspect to ensure free and clear and the flexible connection to the unit is in good condition.

If anything noted, then conduct remedial action.
6M-30InspectInsulation to Supply Air Ducting - Visually inspect to ensure has no damage, torn and that the vapor barrier is unaffected.

If anything noted, then conduct remedial action.
AHU Preventative Maintenance Checklist [MS Word]

Air Handling Unit Inspection and Preventative Maintenance Checklist Template covering WEEKLY, MONTHLY, 3-Mths, 6-Mths, 12-Mths, 24-Mths & 36-mths, in [Microsoft Word] format allowing editing and clean exporting for you full use.


#CC: 117
Buy Here | $1.99

🟩 12-month inspection checklist

TypeTask
12M-1InspectIntake Louvre - Visually inspect for contamination, foreign objects, corrosion, and damage.

If anything noted, then conduct remedial action.
12M-2InspectExhaust Louvre - Visually inspect for contamination, foreign objects, corrosion, and damage.

If anything noted, then conduct remedial action.
12M-3InspectUnit - Visually inspect all screws and bolts on the unit are tight and secure
12M-4InspectUnit Door Seals - Visually inspect for contamination, foreign objects, corrosion, damage and leakage.

If anything noted, then conduct remedial action.
12M-5InspectUnit Section Seals - Visually inspect for contamination, foreign objects, corrosion, damage and leakage.

If anything noted, then conduct remedial action.
12M-6InspectUnit Casing - Visually inspect for moisture or condensation build up.

If anything noted, then conduct remedial action.
12M-7ChangeFan Motor - Change all belts.

If anything noted, then conduct remedial action.
12M-8InspectFan Motor - Visually inspect for electrical connections and torque settings.

If anything noted, then conduct remedial action.
12M-9TestFan Motor - Take current readings from the motor whilst in operation and compare with manufacturers data sheet for the equipment.

If anything noted, then conduct remedial action.
12M-10TestEmergency Stop - Test emergency stop button and its operation.

If anything noted, then conduct remedial action.
12M-11TestSafety Switches - Test all safety switches and cut out devices.

If anything noted, then conduct remedial action.
12M-13InspectFan Impeller - Clean the fan, blades, and impeller, remove any rust from the shaft and recoat where necessary
12M-14InspectFan Impeller - Adjust the fan if rubbing
12M-15ChangeFilters - If not previously completed, change 1st Level set
12M-16TestFilters - Measure the differential pressure across all filters within the unit with calibrated instrument, cross reference with the BMS.

Adjust setting if difference noted.

Replace or clean if max differential pressure is exceeded.
12M-17InspectFrost Coil - Test coil flow rate with a calibrated instrument to ensure it is in line with the system design requirements, cross reference with the BMS where applicable.

If anything noted, then investigate and conduct remedial action.
12M-18InspectCooling Coil - Test coil flow rate with a calibrated instrument to ensure it is in line with the system design requirements, cross reference with the BMS where applicable.

If anything noted, then investigate and conduct remedial action.
12M-19InspectHeating Coil - Test coil flow rate with a calibrated instrument to ensure it is in line with the system design requirements, cross reference with the BMS where applicable.

If anything noted, then investigate and conduct remedial action.
12M-20InspectCompressor - Inspect the rota lock valves ensuring they are free to move.

If anything noted, then investigate and conduct remedial action.
12M-21InspectCompressor - Visually inspect the oil sump heater condition.

If anything noted, then investigate and conduct remedial action.
12M-22InspectCompressor - Inspect the collector pipework and connections.

If anything noted, then investigate and conduct remedial action.
12M-23TestCompressor - Test the operation of the high-pressure sensor.

If anything noted, then investigate and conduct remedial action.
12M-24TestCompressor - Test the operation of the low-pressure sensor.

If anything noted, then investigate and conduct remedial action.
12M-25TestCompressor - Take current readings and power consumption whilst in operation and compare with manufacturers data sheet for the equipment.

If anything noted, then conduct remedial action.
12M-26InspectCompressor - Inspect refrigerant charge and oil levels.

If anything noted, then conduct remedial action.
12M-27TestEvaporator - Test function of the expansion valve.

If anything noted, then conduct remedial action.
12M-28TestCondenser - Test function of the expansion valve.

If anything noted, then conduct remedial action.
12M-29InspectRefrigerant System - Check safety valve is in good condition.

If anything noted, then conduct remedial action.
12M-30InspectRefrigerant System - Check for any leakage of refrigerant from pipework and joints.

If anything noted, then conduct remedial action.
12M-31InspectSteam Humidifier - Inspect and clean the steam cylinder.

If anything noted, then conduct remedial action.
12M-32InspectSteam Humidifier - Inspect and clean the humidifier.

If anything noted, then conduct remedial action.
12M-33TestActuators - Inspect and test function, measuring input signals and checking operating and adjustment ranges.

If anything noted, then conduct remedial action.
12M-34TestTemperature Sensors - Check the calibration of each sensor cross referencing with a calibrated instrument and the BMS/controls.

If anything noted, then conduct remedial action.
12M-35TestHumidity Sensors - Check the calibration of each sensor cross referencing with a calibrated instrument and the BMS/controls.

If anything noted, then conduct remedial action.
12M-36TestPressure Sensors - Check the calibration of each sensor cross referencing with a calibrated instrument and the BMS/controls.

If anything noted, then conduct remedial action.
12M-37TestAnti-Frost Thermostat - Check the calibration and operation of sensor cross referencing with a calibrated instrument and the BMS/controls.

If anything noted, then conduct remedial action.
12M-38TestCO2 - Check the calibration and operation of sensor cross referencing with a calibrated instrument and the BMS/controls.

If anything noted, then conduct remedial action.
12M-39TestSmoke Detector - Test operates inline with the design.

If anything noted, then conduct remedial action.
12M-40InspectVariable Speed Drive - Check operation and settings are in line with design cross reference with the BMS /controls.

If anything noted, then conduct remedial action.
12M-41InspectElectrical Isolators - Check operation of all isolators [On/Off].

If anything noted, then conduct remedial action.
12M-42InspectControl Panel - Visually inspect cable glands and terminals ensuring they are secure.

If anything noted, then conduct remedial action.
12M-43InspectControl Panel - Inspect to ensure wiring diagram is available near to or inside the panel.

If anything noted, then conduct remedial action.
12M-44InspectControl Panel - Visually inspect to ensure all protective covers are installed.

If anything noted, then conduct remedial action.
12M-45InspectControl Panel - Test that all switches operate as required.

If anything noted, then conduct remedial action.
12M-46TestControl Panel - Test control functions of the unit in line with the design intent.

If anything noted, then conduct remedial action.
12M-47InspectFresh Air Ducting - Visually inspect the internal surfaces of the ducting in 2 locations for contamination, moisture, condensation foreign objects, corrosion, and damage.

If anything noted, then add other areas, investigate and conduct remedial action where required.
12M-48InspectSupply Air Ducting - Visually inspect the internal surfaces of the ducting in 2 locations for contamination, moisture, condensation foreign objects, corrosion, and damage.

If anything noted, then add other areas, investigate and conduct remedial action where required.
12M-49InspectReturn Air Ducting - Visually inspect the internal surfaces of the ducting in 2 locations for contamination, moisture, condensation foreign objects, corrosion, and damage.

If anything noted, then add other areas, investigate and conduct remedial action where required.
12M-50InspectGrilles and Diffusers - Clean terminal devices

🟩 24-month inspection checklist

TypeTask
24M-1ChangeFilters - If not previously completed, change 2nd Level set
24M-2TestFire Dampers - Fresh air, recirculating air & supply air, test the fire dampers to ensure operates as per design.
24M-3InspectHygiene - Check Air Handling Unit for hygienic cleanliness.

[if has humidifier installed]
🔗 To see our other 'Maintenance Checklists', click here.

🟩 36-month inspection checklist

TypeTask
36M-1InspectHygiene - Check Air Handling Unit for hygienic cleanliness.

[if not have humidifier installed]

⬜ AHU Inspection and Preventative Maintenance Checklist [MS Word] & [PDF]

To help us expand the site and create more resources, we created the documentation below in [Microsoft Word] for download.

Click the ‘Buy It Here’ button to purchase the fully editable copy of the document below, which can be used immediately.

You will direct to our shop page.

117-AHU-Maintenance-Inspection-Schedule

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