Air flow from a fan will vary considerably with the blade pitch. The pitch is adjustable. To save engine horsepower, an operator may set the blade pitch at 15° during the winter. During the summer, he may attempt to maximize air flow by setting the blade pitch up to maximum—22.5°. Almost all fan cooler blades are adjustable over this range.
Watch for loss of air flow through the finned tube bundle by air by-passing the bundle. Especially in older units, the tube bundle may no longer “square-up” with the fan’s frame very well. Seal the leaking areas with strips of sheet metal.
In southern Texas, the most common cause of reduced air flow is attributed to moths. In their uncounted millions, these tiny kamikazes clog the tube bundle. Along with dust and other assorted bugs, moths must be hydro-blasted from the exterior of tube bundles several times a year.
