Johnson Controls A19ABA-45 Remote Bulb Temperature Control -30/100°F 3'Spst Open Low Adjustable Diffuser

The Johnson Controls A19ABA-45 Remote Bulb Temperature Control is a mechanical tool which is used in the control of heating as well as cooling systems in a certain region. It employs a bulb containing liquid and a switch which is connected by a capillary tube. When the temperature around increases, the liquid also expands and this causes the switch to turn off the heating system. However, when the temperature is still low, the switch flips back to turn on the heating controller to on position. This basic but efficient design enables accurate regulation of temperature while at the same time not requiring electricity.