Description
The Johnson Controls T-4000-2140 is a beige plastic cover used for the horizontal installation of pneumatic thermostats. It is not a thermostat itself, but it is an accessory that has a protective function as well as a practical one. This cover fits most Johnson Controls T-4000 series pneumatic thermostats. Bimetallic thermostats are used to regulate temperature in structures by using compressed air pressure. Changes in the temperature of the room put pressure onto the thermostat and then it changes its size to regulate the heating, ventilation, and air conditioning system to the right temperature.
