We use a product called the Breeze for our basement. It has a gentle exhaust fan (115 cfm) that is rated for continuous operation, controlled by a humidistat. Instead of replacing the exhausted air with outdoor air, it draws on the "conditioned" air from the home's first floor, avoiding the humidity problems and allergens that outdoor air present, especially on a rainy or humid day. The air quality in the basement has improved dramatically and we've been able to unplug the energy drawing dehumidifier. No filters or drains are needed. The company sells one and two-fan models that cost from $349 to $449 and carry a 5-year warranty. I strongly recommend the appliance. It's available on the company website or on Amazon and Ebay. Much cheaper than the $1,500 to $1,800 units sold by Wave Ventilation, Humidex or EZ Breathe.