Also known as evaporative coolers, swamp coolers blow air through water-soaked pads, where it cools and gains humidity. It then travels through ductwork into your home.
Swamp coolers circulate more fresh air than air conditioners. To encourage airflow, open a few windows when running the unit.
Get a professional inspection every year. In between, inspect the pads every few months for wear and mineral deposits. Watch out for stagnant water in your unit, which can lead to insect breeding, mold, and bacteria.