Recently a new family of frost protection devices has become available. Heaters are now being made from petroleum wax or coke and molded in various forms, such as candles, bricks or flat trays. Because these devices have a much lower heat output per unit than conventional heaters, and information about their protection ability is limited, preliminary tests were initiated to learn more about this type of heating.

This study was conducted under project 400U. Richard B. Tyree, Norman Ferrari of the Department of Viticulture and Enology, and Richard Ramsdell of the Department of Agricultural Engineering assisted in the field tests. The petroleum coke bricks were made available by Mobil Oil Co. Inc.