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Every year there are an average of 14,500
dryer fires *.
Was
the problem the dryer? Rarely. After
investigating it's usually determined to have been the lint within the
homes venting system that caught on fire, and not the dryer.
The
drying process
When
clothes are being dried inside your family dryer there are two processes
happening. Firstly, heat is applied to the air inside the dryer drum as
it turns. This raises its internal temperature to approximately 155
degrees Fahrenheit, causing moisture to be driven out of the clothes
by evaporation. Secondly, a constant flow of air is passed through the
clothes. Surprisingly, the real trick to efficiently dry clothes is not
the heat, but rather this vast volume of air.
Most
people think the purpose of venting is to push the heat and lint
outside. Actually, its primary purpose is to dump the moisture outside
the home. This job is accomplished easily when the dryer is near an
outside wall.
The
venting pipe
In
many new houses the laundry room is located in the centre of the home to allow easier access.
But the distance from the dryer to an outside wall is substantially
longer. So, we have come to the crux of our problem, 'The venting is
too darned long'.
It
is more difficult to push air down a long venting pipe than a short one.
This results in the moisture and lint collecting in the venting until lint can block the venting closed. When this happens it can
cause the dryer to overheat. The normal drum temperature of 155 degrees
Fahrenheit can quickly shoot up to 300 degrees Fahrenheit or higher. It
may even get hot enough to allow lint in the venting to ignite.
For
this reason manufacturers now suggest a maximum venting length of 15
feet. Excluding the first two elbows.
The
true length of your venting
If
you want to know the true equivalent length of dryer venting, calculate
the following:
1.
Measure all the straight lengths and add them together
2.
Count the number of turns or elbows, and multiply this number by 4
3.
Add together the totals from steps 1 and 2
Example
20 feet of venting with 4 turns would actually be:
20 feet + 4X4 feet = 36 feet
Don’t
be surprised by the true equivalent length of your venting. In modern
homes it can be substantially longer than the manufacturers suggested
maximum.
Watch
for these signs
If
the blockage becomes critical the dryer will stop doing its job
properly. Signs that the venting
may be starting to block include:
- Clothes
coming out wet even though lots of heat
- Excess
lint on clothes
- Moisture inside dryer
- Too long to dry
- Clothes unusually hot at end of cycle
- Drastic increase in electrical
consumption.
Since
you can't move the laundry room the best thing you can do is be aware
that the problem exists. Consider taking down the venting and cleaning
out the lint buildup during your annual spring-cleaning. Also, regularly
check the vent cap where it exits your house. Remove
any lint buildup and make sure the flap moves freely.
If you
suspect a venting problem turn off the dryer, unplug it, and call your
appliance service company. Tell them your concerns, and ask for their
help. As the old saying states, "better safe than sorry".
* There are an average of 14,500
dryer fires every year.
(National Fire Prevention Association)
By Donald Grummett
Copyright © 2005 Donald
Grummett. All rights reserved
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