by Don Ames, www.detectenergy.com
Story appeared in my local newspaper the other day about an apartment laundry room that had dryer problems. It occurred to me, being the highly trained home energy auditor that I am, that any clothes dryer that had such a problem that it would catch fire, must have been a very inefficient clothes dryer for a long time.
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On one hand, this is about burning down an apartment complex and on the other, it is about energy conservation. It has occurred to me that every dryer that burst into flames has been using a lot more power, for a long time, than it should have been. I think there is a direct connection between an inefficient dryer and dryer problems that lead to a visit by the fire department.
"The Fireman responded to the Apartment Complex laundry room where the residents were huddled with a handy exhausted fire extinguisher in hand. The fireman pulled the blackened dryer outside and finished off any lingering hot spots. A second dryer in the laundry room was also damaged by the heat."
"Fireman speculated the appliance burst into flames when it overheated as a result of a broken dryer belt. A total of two fire engines, one ambulance, and 19 personnel responded to the scene."
First of all, let's discuss the news article and the fire. Sounds like the residents did a good job of locating a fire extinguisher and saving the laundry room from greater damage such as catching fire and burning down completely. The news article gives a good account of the number of fireman that were available to respond. 19 fireman responded to a dryer fire that was already under control. Of course, the fireman probably did not know the fire was under control when they jumped on the fire truck. Besides, what if the fire had spread to the apartment complex and an all out fire-fight was in the works. In that scenario, 19 fireman is the right number.
The article suggests that a broken dryer belt could have been the cause of the fire. Let's think about this a minute. The dryer belt breaks so the drum stops spinning and the clothes just sit in one place in the drum and heat starts to build up. Inside most dryers, since clothes have a problem with shedding lint, there is usually lint to be found throughout the dryer as a result of the drying cycle.
With what I know about dryers and lint and apartments, there is a real chance that the people living at the apartment complex were more interested in just turning the dryer on than actually cleaning the lint screen before hand. With the lint screen partially plugged and reducing the flow of air, the dryer runs warmer and longer during the drying cycle. In this warmer atmosphere, the dryer belt breaks down quicker and fails. Now that the belt is broken, the dryer builds up heat as the clothes are not tumbling and the electric motor that is suppose to be spinning the drum is running full speed without resistance.
It's hard to say which came first - the broken belt or the lint plugged screen and vent. One thing is for sure, if the dryer vent system is restricted and the heat produced by the dryer can not escape, the dryer is going to get hotter and hotter until a little piece of lint somewhere ignites.
I wonder if a dryer has a high temperature limit switch like a furnace does? I'm not sure.
That's brings us to the connection between a burning dryer and energy efficiency.
Let's talk about the lint screen first. The lint screen is designed to collect the lint and keep it from exhausting down the exhaust duct where it can cause problems. In most newer dryers, you have to remove and replace the lint screen before the dryer will turn on. This, at least, means you need to see the lint screen before starting the dryer. In older machines, the drying cycle can be started without checking the screen.
The one thing I like about lint and the lint screen is the neat way lint comes off the screen with the swipe of a damp finger. Sorry, but I think that's kind of cool.
The vent ducting is the secret to an efficient dryer. The easier the warm moist air from the dryer can get through the vent and be exhausted away the more efficient the dryer. It is back pressure within the dryer vent that increases drying time and therefore, increases the amount of power needed to dry the clothes.
The best dryer vent is a smooth round pipe connected together with very short metal screws. The vent is short in length and a straight run to the outside. Nothing to restrict the flow of air or to catch lint. If ever needed, this type of duct is easy to clean.
The worst dryer vent is some sort of plastic flex duct that is held together by long screws that runs fifty feet under the floor, twisting and turning until it finally reaches the outside. The accordion design of the flex duct traps lint, restricts the flow of air, and builds up lint deposits. If needed, this type of duct is impossible to clean and will need to be replaced.
There are just two advantages to the plastic flex duct. One is the cost - it is very cheap. And the other is knowing what probably caused the dryer fire, if and when it occurs.
Just after the dryer vent reaches it's termination, there is a vent cap or hood of some sort. The vent cap is designed with a flap or movable baffle of some sort. The cap is suppose to open up when the dryer is running and close down when not running. When closed, the flapper closes the opening to the vent and restricts air from blowing back through the duct. The flapper also keeps critters from using the vent as an entrance tunnel for access to your home.
In the same manner as the lint screen, the vent cap can become clogged with damp lint and restrict the flow of exhaust air. If the vent cap can not open completed, the dryer loses energy efficiency.
When a dryer catches fire, chances are there has been a build up of lint that has been restricting the exhaust vent over a long period of time. The build up of lint that occurs over a long period of time is not just a fire danger, it is also a dryer problem that gradually steels the energy efficiency of the dryer and increasingly cost you more and more money.
As the efficiency of the dryer decreases and dryer problems increase, the chance of a dryer fire also increases.
I have had clients complain to me that they must run their dryer through two drying cycles in order to get the clothes dry. Inspection of the vent system almost always identify's the problem as a serious reduction in dryer efficiency as a result of a restricted vent system.
So, if your single and living in an apartment complex and you don't really care how efficient the dryer is and you'd like the opportunity to meet 19 nice fireman, just let the lint build up on the lint screen.
I ran onto the following dryer lint screen on one of my home energy audits, for me, it was a new worlds record in lint build up. Enjoy.
For the screen cast please follow this link.
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