The TH 193 HC free energy band thermostats are proportional dual output, dual set point, 2-pipe (dual 1-pipe, low air capacity) or 3-pipe (dual 2-pipe, high air capacity) sensor controllers. Each thermostat includes a wall mounting plate for installation in a variety of rough-in terminal boxes. Sensitive bimetals respond to temperature changes to modulate control air through a flapper nozzle. As the heating load decreases due to internal heat gains, a Free Energy Band (FEB) of control minimizes energy consumption while the set point changes from 72?F (22?C) heating mode to 78?F (26?C) cooling mode. Two set point dials allow adjustment of the FEB 4?F (2?C) minimum. Air connections are made with 5/32? (4 mm) OD plastic tubing, directly to the thermostat chassis for retrofit applications or with plug-in adapters (provided with the TH 192 rough-in terminal box or optional accessories) which slide into the wall mounting plate.