Johnson Controls A40HA-1 Pneumatic Temperature Control M/R Open on Rise 140°-220°F

The Johnson Controls A40HA-1 is a Pneumatic Temperature control device for precise temperature control in HVAC systems, however, some electrical thermostats, it uses air pressure to communicate changes. Thus, the copper bulb acts as a heat conduction and measures the change in temperature of the surrounding area. One of the essentialfeatures is the manual reset button. When the temperature rises, the control needs a button press to start working; this prevents rapid cycling and lets the user check before reactivating the system.