How Many Ductable Air Coolers Do You Need? A Sizing and Installation Guide for Factories and Warehouses
September 11, 2026
Ductable evaporative air coolers are one of the most economical ways to cool large industrial spaces in India's dry summer months. But a cooler only performs as well as the system around it. Undersized units, poorly planned ducts or a building with no way for hot air to escape are the most common reasons buyers feel "the cooler is not cooling". This guide covers how to size and install ductable coolers correctly.
Step 1: Understand cooler capacity (CMH)
Ductable coolers are rated by airflow in cubic metres per hour (CMH). More airflow means more cooled fresh air delivered to the space. As a reference, here is how capacity, power and coverage relate across a typical range:
| Model | Airflow | Motor | Approx. coverage | Best for |
|---|---|---|---|---|
| AYZAIR-18 | 18,000 CMH | 1.5 kW | ~100 m² (~1,075 sq ft) | Mid-size workshops, showrooms |
| AYZAIR-22 | 22,000 CMH | 2.2 kW | ~139 m² (~1,500 sq ft) | Larger production bays |
| AYZAIR-30 | 30,000 CMH | 3.0 kW | ~150 m² (~1,615 sq ft) | Tall sheds, foundries, full warehouses |
Coverage figures assume typical Indian industrial buildings with 5–7 m roof heights and are nominal values; please refer to each model page for its full specifications.
Step 2: Estimate how many coolers you need
- Measure the area that actually needs cooling. In many factories only the working zones — assembly lines, packing areas, workstations — need cooling, not the whole floor.
- Adjust for roof height. Taller buildings hold more air volume, so they need more airflow per square metre.
- Adjust for heat load. Furnaces, ovens, moulding machines, compressors and metal roofs without insulation add heat; foundries and forging shops typically need the larger units.
- Divide by the coverage of the chosen model and round up.
Step 3: Plan the exhaust — the step most people skip
Evaporative coolers push fresh, cooled air into the building. If that air has nowhere to go, the building becomes humid and the cooling effect drops sharply. Every cooler installation needs an exhaust path: open doors and windows on the opposite side, roof ventilators, or heavy-duty exhaust fans. A good rule is to plan exhaust capacity roughly matching the cooled air supplied.
Step 4: Choose placement and discharge direction
- Top discharge — cooler on the ground, duct rising to the roof level and running across the space.
- Down discharge — cooler on the roof or a platform, duct dropping into the building; saves floor space.
- Side discharge — cooler mounted on an outside wall, blowing directly in through the wall.
Place coolers where they draw outside air that is not contaminated by exhaust, dust or hot air from other equipment.
Step 5: Design the ducting
- Run ducts above the working zones and drop diffusers or grilles close to where people work.
- Keep duct runs as short and straight as possible; long runs and many bends reduce the airflow that reaches the floor.
- Size ducts to the cooler's outlet (for example, a 620 mm duct on an 18,000 CMH unit).
Step 6: Water, power and maintenance
- Provide a reliable water supply and drain at each cooler; a typical unit uses around 20–25 kg of water per hour.
- Confirm single-phase or three-phase supply before ordering.
- Clean cooling pads, tanks and filters regularly and drain the tank periodically to control scaling and odour.
Combine with air circulation
In large, high-roofed buildings, HVLS ceiling fans help spread the cooled air evenly across the floor, so fewer coolers can cover the same area.
Ayzair, a Pune-based manufacturer, offers free cooling sizing for factories and warehouses based on your building drawings and heat load. Share your requirements at ayzair.com/contact.
