What Do You Do If Your Furnace Isn't Starting Right?

Your furnace is a complex piece of equipment. HVAC technicians train for years to know how to troubleshoot one. In this episode, though, we’re breaking it down for you. We’ll go over your furnace’s ignition system from start to finish. Then we’ll discuss how knowing the process can help you.

The first thing that happens when your system starts is that thermostat calls for heat. That signal reaches the furnace and tells it to turn on. The power kicks on and your inducer motor will start. It pulls air into the unit to make sure the pressures are right and the air-to-gas ratio is correct.

Once your inducer motor is running, your igniter will get ready to start. A glow surface igniter will start to warm up right now, and a spark igniter will be ready for the gas to arrive. After that, the gas valve opens up and the gas ignites. The flames light until they reach the flame sensor.