18 In. X 4 In. X 11 In. Moisture Mold Reducing UnderAire Crawlspace Ventilator Fan

The Tjernlund UnderAire Series Crawl Space Ventilators are designed to circulate fresh outdoor air underneath homes and porches. Excessive humidity levels in Crawl Spaces is the leading cause of premature rotting of support columns, joists, floors and beam supports. Humidity can promote fungus growth and increased termite activity. Humidity may also cause plumbing failures due to rust and corrosion. Constant operation helps vent radon gases, treated wood off-gassing and other odors that might migrate into living areas. The (V4D) is controlled by a dehumidistat which actuates the fan if the relative humidity rises above the selected set-point.