How gas dryers work is a mystery to most folks. I can tell you from having trained hundreds of appliance service technicians all across the country that a lot of service technicians who are paid to repair gas dryers are not familiar with the basic operation of gas dryers. These folks often change parts starting with the most common failed gas dryer parts, until they get it right.
If you are a homeowner or do-it-yourselfer you should be very careful when repairing a gas dryer. Although the basic operation of a gas dryer is straightforward, any changes in the way the dryer burner assembly was designed by the manufacturer to operate, could be dangerous.
Before I give you the step-by-step breakdown on how gas dryers work, I want to remind you that all gas dryers should be vented to the outside of the house. And that is because in the unlikely event of a carbon monoxide issue, the carbon monoxide is more likely to be vented to the outside.
So let’s take a look at how a gas dryer works, and how a basic gas dryer burner was designed to function.
Here is the sequence that allows gas to flow and ignite in a typical gas dryer.
1. Power is applied to the ignitor (igniter) and it starts to glow hot
2. The heat from the ignitor heats the flame sensor to a point sufficient to allow gas to ignite
3. The heat from the ignitor flexes a bimetal in the sensor opening the circuit to the ignitor
4. Once the circuit is open to the ignitor power is applied to the secondary coil of the coil kit
5. Current starts to flow through the secondary coil
6. As the current flows it creates an electromagnetic field opening the valve
7. Gas flows through the burner and is ignited by the still glowing ignitor
8. Heat from the now burning gas keeps the bimetal flexed in the sensor allowing the coil to remain energized keeping the gas flowing
9. Under normal conditions the control thermostat cycles off interrupting the circuit to the gas burner assembly causing the coils to lose their electromagnetic fields shutting down the gas flow. Check this website for more info.