Reznor® series 100, model F gas-fired, gravity-vented unit heaters are designed for 80% thermal efficiency and are designed for use with natural or propane gas, as specified, in sizes from 25,000 to 400,000 BTUH gas input. Model F unit heaters are designed for ceiling suspension with a propeller fan for air delivery. Standard features include a manual match-lit pilot with 100% shutoff and a single-stage, 24-volt gas valve. A terminal strip connector facilitates field connection to a remote 24-volt thermostat for automatic operation. Each unit is provided with a fan control and all required limit safety controls, including an energy cutoff (ECO) device and a blocked vent switch. These units are approved for installation in the United States and Canada by the Canadian Standards Association(CSA).