How to properly test a pressure switch using the DDSM1 Draft Simulator

Using the DDSM1 Draft Simulator and the SDMN5 dual port manometer, you can easily test any pressure switch with complete accuracy. Pressure switches are one of the most misdiagnosed components in today's furnaces. Furnace manufacturers report that over 90% of the pressure switches returned under warranty are perfectly fine. That being said, more than 10% of the pressure switches in older furnaces are out of calibration and present an unsafe operating condition. You can use the DDSM1 with any manometer.