Schneider Electric (Barber Colman) TK-1301 Reverse Acting Day/Night Pneumatic Thermostat 55°F-85°F W/Manual Override

The Schneider Electric Barber Colman TK-1301 Day-Nite Stat 55/85F Da W/Mano is a direct-acting pneumatic thermostat that provides proportional control of heating, ventilation, and air conditioning systems. You may schedule pleasant temperatures for different times of the day and possibly save electricity by using its distinct heating and cooling setpoints for day and night. This is the manner in which it operates: A tiny metal bellows used by the thermostat expands and contracts in response to temperature variations. The HVAC machinery, such as a boiler, furnace, or air handler, receives this movement's translation as a pneumatic signal, or pressurized air. The amount of warmth or cooling that is provided depends on the signal pressure.