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What is an air handling unit, and why does maintenance matter?
An air handling unit is central ventilation equipment that filters outdoor and return air, heats or cools it, humidifies it when needed, and distributes it through ducts to the building. In hospitals, shopping malls, factories, sports halls and offices, all the air the building breathes passes through the AHU.
When AHU filters clog, the fan uses more energy to move the same air, airflow drops and spaces do not get enough fresh air. Dirt building up on coils and drain pans creates conditions for microbial growth. That is why AHU maintenance is about health and hygiene, not only efficiency.
What does air handling unit maintenance include?
- Differential pressure measurement and replacement of pre-filters and bag filters
- Filter frame and gasket seal check
- Fan wheel cleaning, balancing and vibration check
- Motor current and bearing check
- Belt tension, wear and pulley alignment
- Heating and cooling coil fin cleaning
- Drain pan cleaning, disinfection and trap check
- Damper and damper actuator operation test
- Humidifier and droplet eliminator check
- Heat recovery unit (exchanger/rotor) cleaning
- Frost thermostat and safety checks
- Automation, sensors and setpoints; written maintenance report
Maintenance intervals: which task, how often?
The table below shows the typical maintenance schedule we follow on site. Exact intervals are set in the maintenance plan based on manufacturer instructions, operating hours and how intensively the facility is used.
| Job | Monthly | Quarterly | Semi-annual | Annual |
|---|---|---|---|---|
| Filter differential pressure check | ✓ | ✓ | ✓ | ✓ |
| Pre-filter replacement | As needed | ✓ | ✓ | ✓ |
| Bag / fine filter replacement | — | As needed | As needed | ✓ |
| Belt tension and wear | — | ✓ | ✓ | Replacement |
| Fan, motor current and bearings | — | — | ✓ | ✓ |
| Coil fin cleaning | — | — | Control | ✓ |
| Drain pan and trap | — | ✓ | ✓ | Disinfection |
| Damper and actuator test | — | — | ✓ | ✓ |
| Heat recovery unit cleaning | — | — | Control | ✓ |
| Safety and freeze protection test | — | — | Before winter | ✓ |
✓: done on that visit. —: not required in that period.
Maintenance differences by AHU type
Hygienic air handling units (hospitals, operating rooms)
Filter stages, sealing and internal surface cleaning are critical for hygiene. Maintenance is planned in line with the institution's infection control procedures and documented.
Heat recovery AHUs
Fouling of a plate, rotary or heat pipe heat recovery unit reduces both efficiency and airflow. Heat recovery unit cleaning and the rotor belt are checked separately.
Belt-driven and EC fan AHUs
On belt-driven fans, belt tension and pulley alignment are the most common sources of faults. EC (direct-drive) fans have no belt; the motor drive, wiring and impeller cleaning are the focus.
100% fresh-air and mixed-air AHUs
In AHUs with a high fresh air ratio, filters clog faster and freeze risk is higher; filter intervals and frost protection are adjusted accordingly.
Maintenance form: values we measure on site
At every maintenance visit we measure the values below and record them on a per-unit maintenance form. Comparing the form at the next visit helps detect faults early.
| Measurement / check | Unit | Expected |
|---|---|---|
| Pre-filter differential pressure | Pa | Below the manufacturer's final pressure value |
| Bag filter differential pressure | Pa | Below the manufacturer's final pressure value |
| Fan motor current | A | Below the nameplate value |
| Belt tension | — | Per manufacturer value |
| Coil inlet / outlet air temperature | °C | Per design value |
| Drain flow | — | Draining, pan dry |
| Damper positions | — | Opens and closes on command |
| Frost thermostat test | — | Starts up |
What happens without maintenance?
- Filters clog, increasing fan energy consumption and noise
- Not enough fresh air reaches the rooms, and indoor air quality drops
- Microbial growth and odor in the drain pan
- A broken belt stops the AHU completely
- Risk of coil bursting from freezing in winter
Data: According to the U.S. Department of Energy, replacing a dirty, clogged filter with a clean one can lower an air conditioner's energy consumption by 5–15%. Dirt building up on the fins reduces airflow and lowers the coil's heat absorption capacity. Source
What factors determine the price of air handling unit maintenance?
Since maintenance pricing depends on equipment type and site conditions, we do not offer a fixed price list. During the site survey we clarify the items below and provide an itemized written quote:
- Number of AHUs, airflow and number of stages
- Filter class, sizes and quantity
- Belt, bearing or motor replacement
- Chemical coil cleaning and disinfection
- Heat recovery unit type
- Hygienic area requirements and working hours
- One-time maintenance or an annual contract?
The maintenance process in 5 steps
- Request: unit type, quantity and location are sent by phone, WhatsApp or form.
- Site survey and inventory: equipment is inspected on site, and the scope and schedule are defined.
- The written quote and maintenance plan are approved.
- Maintenance: measurements are taken, cleaning and checks are carried out, and approval is requested if parts need replacing.
- Report: unit-by-unit measurements and recommendations are delivered in writing.
Service areas
Our base is in Ankara Etimesgut. We provide air handling unit maintenance daily across all districts of Ankara (Çankaya, Yenimahalle, Etimesgut, Sincan, Keçiören, Gölbaşı, Mamak, Altındağ, Pursaklar, Polatlı, Kahramankazan, Elmadağ). We carry out project-based and annual-contract maintenance in all 81 provinces of Türkiye, including İstanbul, İzmir, Bursa, Antalya, Konya, Kayseri, Eskişehir, Kocaeli, Adana, Mersin, Gaziantep, Samsun, Trabzon, Erzurum and Diyarbakır, and we also take part in public institutions' maintenance tenders.
Regional pages: AHU maintenance Ankara · Ankara districts · İstanbul · All cities
Frequently asked questions
When should an air handling unit filter be replaced?
Filters are replaced based on differential pressure, not on a calendar: when the measured pressure approaches the manufacturer's final pressure value, the filter is replaced. In practice, pre-filters are replaced every 1–3 months and bag filters every 6–12 months.
How often should an air handling unit be serviced?
We recommend a monthly filter check, a belt and drainage check every 3 months, general maintenance every 6 months and comprehensive maintenance once a year. Hospitals and hygienic areas require shorter intervals.
Is ventilation shut off during AHU maintenance?
A short shutdown is required. We schedule maintenance around the building's operating hours and work outside working hours in critical areas.
Do you supply the filters?
Yes. We record the size and class of the existing filters during the site survey, then source and replace them with suitable filters.
How often should the belt be replaced?
Belt tension is checked at every maintenance visit; the belt is replaced if wear, cracks or stretching are found. Annual replacement is common practice on belt-driven AHUs.
Do you maintain hospital AHUs?
Yes. We carry out documented maintenance on hospital and hygienic-area AHUs in line with the institution's procedures.
What determines the price of air handling unit maintenance?
The price depends on the number and size of units, filter class and quantity, parts replaced and cleaning scope. We provide a written quote after the site survey.
Do you provide AHU maintenance outside Ankara?
Yes. We carry out AHU maintenance daily in Ankara and on a project or annual contract basis in other provinces.
Sources
- U.S. Department of Energy (DOE): Maintaining Your Air Conditioner
- Manufacturer maintenance manuals and YOİ Mühendislik field practice