Barber Colman Dead Band Reverse Acting Thermostat

The 2212-318 and 2212-319 Dual Setpoint/Deadband Pneumatic Room Thermostats are designed for the proportional control of pneumatic valves, damper actuators, or other final control devices in environmental control systems. These devices are used when it is desirable to set up, between selected heating and cooling setpoints, a temperature span within which the HVAC system uses no energy for heating or cooling. The high capacity, two-pipe, pilot-operated, relay-type design provides pneumatic feedback for accuracy and stability over the entire operating range. These thermostats are available in either direct- or reverse-acting models, each utilizing two bimetals, one heating and one cooling, to interrupt the deadband (branch) pressure. In the direct-acting model, the heating bimetal modulates the pressure between zero and the deadband pressure, and the cooling bimetal modulates the branch pressure between the deadband pressure and main air pressure. In the reverse-acting model, this action is reversed. The dea...