The International Comfort Products 1191249 SPST Pressure Switch is an essential part of HVAC systems, its main function is to measure and regulate the pressure in the system. Located at -0.27” WC, it monitors pressure changes and gives the signal to the system to start or stop the furnace safely. This pressure switch is applied to furnaces and heating systems to prevent dangerous oper... https://www.partshnc.com/42wc-spst-pressure-switch-3