You can have both systems installed, but you should never run them simultaneously. Here's how to make a dual-system setup work:
Why you can't run them together:
Evaporative coolers add moisture to the air, while air conditioners remove moisture. Running both at once:
- Forces your AC to work overtime removing the humidity added by the evap cooler
- Wastes energy on both systems
- Results in poor comfort and efficiency
- Can cause mold and moisture issues
Dual-system strategy:
Many homeowners in the Southwest have both systems and switch based on conditions:
Use evaporative cooler when:
- Humidity is below 40-50%
- During spring and early summer
- On dry days during monsoon
- At night when it's cooler outside
Switch to AC when:
- Humidity exceeds 50%
- During monsoon season storms
- When you need precise temperature control
- If evap cooler isn't keeping up
Installation considerations:
1. Separate ductwork - Ideally, each system has its own ducts 2. Shared ductwork - Possible with dampers to close off one system 3. Hybrid units - Some manufacturers make combined units
Damper/changeover requirements:
When switching from evap to AC:
- Close all windows
- Shut the evap cooler damper to prevent hot air leaks
- Wait for indoor humidity to drop before running AC
When switching from AC to evap:
- Turn off AC
- Open windows for ventilation
- Open the evap cooler damper
- Allow AC ductwork to dry if shared
Cost-effectiveness:
A dual system makes sense if:
- Your climate has distinct dry and humid periods
- You want maximum savings during dry months
- You need reliable cooling during monsoons
- You're okay with the complexity of two systems
Alternatives to dual systems:
- Evap cooler + portable AC for humid days
- Evap cooler with "vent only" mode during humidity
- Whole-house fan as a third option