Cooling - Tower Handbook

From the Cooling Tower Handbook, 4th Edition

Ice formation begins not at the bottom basin, but at the air inlets—specifically on the louvers and fill. As falling water droplets drift into the sub-freezing air stream, they flash into ice crystals that adhere to the leading edges of the fill. This is called accretion . If left unchecked, an ice bridge will form across the air intake, strangling airflow, collapsing the fill, and ultimately toppling the fan deck. cooling tower handbook

Respect the cold. Your tower will thank you in July. From the Cooling Tower Handbook, 4th Edition Ice