Troubleshooting an Electronic Ignition Furnace

Induced Draft Furnace Components
With this type of furnace you'll see the following components "under the hood":

Draft Inducer Motor

Pressure Switch (limit control)

Pressure Switch Tube

Electronic Control Center or Pilot Control Module

How It Works

The thermostat calls for heat,

Draft inducer motor starts up,

Pressure switch attached to the draft motor by a small tube will sense the negative pressure created by the draft inducer,

The draft inducer motor runs for 30 to 60 seconds,

Flame sensor senses heat from the pilot or HSI and allows gas to flow to burners,

Gas burner is ignited by the hot surface igniter or the intermittent pilot,

These processes are controlled by the electronic control center module.