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Author Topic: Dryer Vent Airflow Restrictions  (Read 4521 times)

Offline TechnicianBrian

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Dryer Vent Airflow Restrictions
« on: July 05, 2008, 06:19:30 AM »

Vent restrictions are possibly the number one cause for poor or under performing dryers and unless you are able to see the problem with your own eyes, it is often difficult to assure the customer it is the venting and not the dryer that is at fault. Fortunately, Whirlpool has added an airflow test to the diagnostics of the new Duet electric dryers that can show whether the airflow out of the dryer is good, bad, or somewhere in the middle.

How Dryers dry Clothes
In order to function properly, dryers need to be able to not only heat the clothes, but they must then be able to vent the warm moist air out of the dryer drum. The heat produced by dryers doesn't really dry the clothes, but instead, will force the moisture trapped within the fabric to evaporate into the surrounding air within the drum. That air will become saturated with moisture and once it reaches 100% humidity will not be able to hold any more water. By constantly moving air through the drum and to the outside, our machines are able to remove the remaining moisture and dry our clothes.

Only on the New Models
This new style Duet (the one with the teardrop trim that breaks when you remove it) utilizes two thermistors to determine air inlet and blower outlet temperatures. By taking both readings the electronic control is able to interpret the approximate airflow through the home dryer vent to the outside, and show this CFM (Cubic Feet per Minute) on the display. The test will also illuminate one of three indicator lights to show if the airflow is good (no restriction), OK (little restriction or long vent run), or just plain bad (big restrictions, collapsed vent, bush in front of outside vent, etc.,). The test is available as part of the diagnostics program, and can be a quick and easy way to verify a possible vent restriction.

Airflow Diagnostics
I have included an excerpt from the WED9200SQ tech sheet that shows how to enter diagnostics and use the airflow test. For further details, consult the tech sheet for the specific model you are working on.

As you can see, the process is a quick and painless way to verify the airflow from the dryer, and reassure the customer as to the operation of their appliance, or demonstrate visually that there is a problem within the venting. Try using this feature next time you are servicing one of these new Duet dryers and possibly save yourself from trying to fix a dryer that isn't broken.