The causes of a dryer not heating are numerous. As dryers get more sophisticated with each passing model year, the causes of no heat remain the same. We'll examine common causes and solutions and finish with recommendations for better performance.
- 1 DRYER NOT HEATING - WHAT CAUSES IT?
- 2 TROUBLESHOOTING TIPS
- 3 TOP FIVE TIPS FOR BEST DRYER PERFORMANCE
- 4 CONCLUSION
DRYER NOT HEATING - WHAT CAUSES IT?
A dryer depends on three specific functions for normal operation. Note that an overloaded dryer or dripping wet clothes prevent normal operation and must be corrected. To understand how a dryer works, you need to know the three things a dryer has:
The heat source within a dryer can be from gas (natural or propane) or electricity. A gas dryer uses a glow plug or spark to ignite the gas at the appropriate time. Gas is fed into the dryer via a gas regulator and gas lines. When the start button is pushed, the main drive motor turns, allowing the igniter to operate. The igniter must reach a certain temperature before gas flows to the burner.
Gas dryers use two solenoids - primary and secondary - that energize when the flame sensor detects the correct temperature of the igniter or glow plug. The solenoids work together to deliver gas to the burner. When gas reaches the burner, and the igniter is hot enough, ignition occurs producing heat for the dryer. This is a simplified description because other critical components required for ignition sit in line before current flows to the igniter.
In line with the electrical connection to the igniter is a thermal fuse. It prevents operation of the dryer when internal temperatures exceed a preset limit. A high-limit thermostat protects against high temperatures by checking for a runaway heating event and then cuts off ignition immediately. An electric dryer operates on 220V AC and uses a heating element for its heat source. Similar steps are required for heating, except electrical current instead of gas is used to produce heat.
Dryers depend on unrestricted airflow to vent warm, moist air produced during the drying process to the outside. If the dryer vent becomes clogged or restricted, the result is long dry times or the dryer not heating due to a blown thermal fuse. Sometimes, a high-limit thermostat may open due to high heat.
A blocked or restricted dryer vent causes a heated condition but clothes take long to dry or remain damp after a drying cycle. If moist, heated air doesn't vent to the outside, it becomes trapped inside the dryer, causing the dryer to turn its heat off assuming the temperature is at the correct level. Similar symptoms occur if the lint screen isn't cleaned before each load. Since air passes through the screen, a blockage here mimics a blocked vent scenario.
Movement or Tumbling Action
Some may remember hanging wet clothes on a clothesline on a warm breezy day. The warm breeze and movement is what dries the clothes. A dryer works in much the same way. The drum tumbles the clothes in the presence of fresh air and exhausts the air through the vent to the outside. As you can see, proper drying requires heat, good airflow, and movement of the clothes for best results. If one or more of the functions fail, drying will not occur.
A dryer not heating sometimes gets misunderstood to mean that clothes are taking too long to dry. The natural assumption is that the dryer is not heating at all. In some cases it's true. Many times it isn't, and the cause is the poor airflow discussed earlier.
We've discussed the operation of a typical dryer and what makes it produce heat. If you find your dryer is not producing any heat regardless of settings and airflow considerations, the cause may be internal. If you're not versed in dryer repair, we suggest hiring a professional technician todiagnose, troubleshoot, and repair your dryer. We understand you want to know other causes of a dryer not heating. Aside from internal sensing devices tripping due to high temperature and airflow issues, other, less common failures also occur and are discussed here.
An electric dryer requires 220V AC for operation. Two legs of 120V AC add together to equal 220V AC. One leg powers the dryer functions other than heat, while the heater itself requires both legs, or 220V AC.
Failed Heater Relay
If the dryer uses a circuit board to control its operation, a possible cause of a dryer not heating is a failed heater relay mounted to the board. The relay cannot be replaced separately. The entire board must be replaced.
Defective Dryer Timer
Contacts inside the timer control heating and if they become pitted or lose connection, the result is no heat until the timer is replaced.
Failed Heating Element
Occasionally, the dryer heater fails due to age and wear. Only a person skilled in its replacement should attempt this.
Defective Centrifugal Switch
The dryer motor contains a centrifugal switch closing with a motor rotation which provides the neutral return for current flow to and from the heating element. If the switch fails, there's no heat and the motor should be replaced.
Burnt Terminal Block
Electric dryers use a terminal block which connects to the 220V AC source. If the connections become loose, they can burn and cause a loss of power, causing the dryer to shut down or stop heating.
The possible causes of a dryer not heating listed above will require a person with knowledge of electricity and a mechanical aptitude. An experienced appliance technician is the best solution, but if one is not available, consult other sources of repair information.
TOP FIVE TIPS FOR BEST DRYER PERFORMANCE
We've mentioned several causes for a dryer not heating, but there are preventative measures to consider, too. We talked about good airflow for best dryer performance. What we have not talked about yet is how to achieve good airflow to help prevent long dry times.
TIP #1 - MAKE SURE YOUR DRYER VENT STAYS CLEAN
A clean vent makes a big difference with drying clothes. It saves money, wear and tear on the dryer, and your clothes look better when properly dried. Correct venting for a dryer is overlooked most times and is treated as unimportant as long as the vented air ends up outside. How the air gets outside matters greatly. A straight, rigid vent 12 inches long vented directly outdoors works best. As the vent gets longer, each foot means less efficiency and slightly longer dry times.
A vent longer than 8 feet creates back pressure that the dryer isn't designed to overcome. The result is less airflow and longer dry times. A rigid vent has smooth walls and less chance for lint to stick and build up. Remember, a clogged vent is a major cause of a dryer not heating. Vertical vents work, but after 8 feet, they lose efficiency quickly due to gravity. Measure vents with straight sections where possible. For reference, a 30-foot long, straight, rigid vent from the dryer represents minimal efficiency for venting. The goal is as short as possible.
Each bend in venting subtracts four feet due to added back pressure. One turn in the vent gives you 26 feet of linear feet which provides minimal efficiency. Each subsequent turn shortens the length of vent required for minimal efficiency by 4 feet. Always use 4-inch diameter, rigid aluminum vents.
Foil vents are common but aren't as effective or safe as rigid aluminum. Rigid vents require more installation steps but pay for themselves over time with their increased efficiency. Professional vent cleaning services understand the advantage of clean vents, and they can advise you on the best course of action to improve your situation.
TIP #2 - AIRFLOW IS AN IMPORTANT ELEMENT IN DRYER PERFORMANCE
It can't be stressed enough. The lint screen in the dryer contributes to airflow, either positively or negatively. If it's neglected, it's like having a blocked dryer vent! Always clean the lint screen before every load.
TIP #3 - YOUR WASHER MIGHT CAUSE LONG DRY TIMES
Yes, you read that right. If your washer isn't spinning out your clothes properly, the dryer must work harder to dry. Check your washer performance if you notice a sudden change in dry times.
TIP #4 - HAVE YOUR DRYER PROFESSIONALLY CLEANED AND CHECKED
A good cleaning isn't cheap but still costs less than a new dryer. Often, neglected dryers end up in the landfill before their time because their owner didn't see the need for preventative maintenance.
TIP #5 - DON'T OVERLOAD YOUR DRYER
The same reason you're told not to overload your washer applies for the dryer, too. An overloaded dryer cannot efficiently perform the work it's designed to do.
A dryer not heating is frustrating, but the suggestions and causes discussed here should provide insight into what you can do proactively to minimize downtime for your dryer. Heating elements and other parts in the dryer wear out over time. To minimize problems, the main point to remember is that regular, preventative maintenance helps keep your dryer running longer and most efficiently.