Description
The Lennox 33W18 is a 2-stage pressure switch, an essential part of your HVAC system. The switch operates in two stages depending on the air pressure within the system is monitored. At the low pressure of 0.20 Inch water column ,the switch turns on the first stage, which can include only the furnace fan. The first stage is activated when the pressure increases to the high set point of 1.32 In. W.C., the switch then turns on the second stage which commonly is the furnace burner for heating. This two part procedure assists in keeping the temperature constant while using the least energy possible. This is incorporated in many Lennox HVAC equipment models.
