Do you heat your greenhouses with large (possibly old) steam boiler units? Ohio State law requires that these boilers be run by a licensed operator! An Ohio Grower was visited recently by an inspector. The inspector gave the grower some choices -- change the heating system from steam to hot water or hire 6 people to run two boilers 24 hours a day in the winter.
According to the State of Ohio Stationary Steam Engineers and Boiler Operators License Laws:
Section 4739.04 (1045) Horsepower Defined.
"No person shall operate a stationary steam boiler or engine of more than thirty horsepower without obtaining a license. A horsepower means twelve square feet of boiler heating surface. No owner or user or agent of an owner or user of any such steam boiler or engine shall permit it to be operated unless it is in the charge of a licensed engineer".