Programmable Timer Thermostat and Your Safety - Dryer Mainte

Have you ever thought about how hot your dryer gets? Thermostats and thermal fuses are put in dryers for your safety and if you don't maintain them, you could be putting yourself, your house, and your family at risk.

Your dryer uses of a combination of heat and airflow to dry your clothes. The heat generated in your dryer is produced by a heating element controlled by a series of thermostats. If any of your dryer's thermostats are defective, the results can be disastrous.

Safety Warning: Before performing any tests or repairs on your dryer disconnect the power source to eliminate the risk of electric shock. You can do this by unplugging the dryer, removing the related fuse from the fuse box, or flipping the appropriate switch on the breaker panel.

Programmable Timer Thermostat is usually oval shaped and about an inch and a half in length. The thermostat contains a bimetal that opens and closes a pair of contacts depending on the temperature inside the dryer.

The bimetal inside the thermostat is designed to bend at specific temperatures. When the bimetal bends, it pushes an actuator. The actuator then pushes on a contact, opening the electrical circuit and breaking the electrical connection to the related component. When the thermostat cools, the bimetal returns to its original shape and the contacts close, allowing the current to flow through the circuit.

Here's how it works: The dryer is turned on and heat begins to radiate from the heating element into the dryer's drum. The air in the drum passes by a thermostat. As the thermostat reaches its maximum temperature, the bimetal bends, cutting the power to the heating element. The circuit stays open until the bimetal cools. Because the heating element isn't providing additional heat, the dryer's temperature gradually falls. The bimetal returns to its original shape and the electric current flows to start the heating element again. This process happens many times throughout your dryer's cycle.

There are at least two thermostats in your dryer: cycling (operating) thermostat and hi-limit safety)thermostat. The difference between these two thermostats is their opening and closing temperatures.

The cycling thermostat is typically found in the path of the air leaving the drum. A cycling thermostat is usually found on the fan housing or just under the lint filter area, on the blower wheel housing or inside the venting/exhaust system.

Some dryers may have as many as five thermostats - one for each of the different heat cycles. The temperature setting or cycle selected determines which thermostat is used to control the heat. If your dryer is malfunctioning on the low heat setting, the thermostat for that particular setting is probably defective.