Lennox 63W57 SPST 2-Stage Pressure Switch 0.55/0.95 WC

The Lennox 63W57 2-Stage Pressure Switch, is an essential part of many Lennox HVAC systems, especially those that are gas and oil furnaces. In the switch, there is a diaphragm that is sensitive to changes in air pressure. When pressure drops to a preset low limit, the switch gives an “on” signal. This signal switches on the furnace or the oil burner to heat the house. This is because as the system produces heat the air pressure increases. When pressure rises to a second higher set value, the switch sends an “off” signal to the burner to eliminate pressure buildup.