appliances - dryer operation - moisture sensor dryer
The clothes dryer consists of a motor-driven rotating basket, an electric heating element or a gas flame, a thermostat, and a timer.
Some models also have selector switches.
The air is heated by an electrical element or a gas flame and forced by a fan to pass through the rolled clothes.
The fan is driven by the drive motor.
The temperature of the heated air entering and leaving the basket is controlled by the thermostat, which maintains a balance between wind speed, air volume and air temperature.
The temperature of the exhaust is the standard to measure the degree of drying of clothes.
After the dryer starts and loads wet items, the temperature inside the basket rises rapidly.
When the temperature reaches about 30f, the evaporation of moisture in the load will absorb heat as quickly as the heat generated by the heater.
Until the load is almost dry, the temperature does not rise significantly to more than 30f.
When the load is close to drying, there will not be enough moisture in the clothes to absorb the heat, and the temperature of the baskets and clothes will rise.
This heat rise will continue until about Fahrenheit is emitted.
At this point, the heater circuit is disconnected by the thermostat.
The dryer basket will continue to rotate in what is called an out-of-time period, and the cool, fresh air will enter the basket and cool the clothes for handling.
The overrun time may last for 3 to 10 minutes and is controlled by a timer or overrun thermostat that will stop the dryer.
Today's modern dryer, Maytag, Kenmore, GE, Whirlpool, Frigidaire has a moisture sensor that delivers moisture conditions inside the dryer to the control panel for control cycle time and coolingdown modes.
The moisture sensor consists of two conductive metal wires located inside the dryer and mounted on the plastic lint filter housing.
A very low wire.
The current AC voltage applied to it and another ground.
When moisture is present, there is a conduction path intermittently between the two wires.
When the clothes are dry, there is no conduction path.
When the dryer is in an automatic drying cycle, the control board will move forward to the cooling statedown mode.