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Old 11-21-2009, 05:54 PM
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stonestacker stonestacker is offline
Join Date: Feb 2007
Location: Auburn, Calif
Posts: 100
Default Home made shop heater?

Has anyone ever built a shop heater out of the parts from a 230 volt
electric clothes dryer? yesterday the wife was doing laundry and i had gone into the garage to look for some bolts and it was really hot in there, the garage is not insulated and it was 38 deg out side. i looked behind the dryer
and the vent hose had fallen out of the wall. that got me thinking, why
cant you use the heating element, fan, ect to build one. at the moment
all i have is a propane heater, and the new shop is insulated and air tight,
so i no longer use it, not to mention the smell and moisture in the air to
rust up all your tools I am always seeing free dryers in the papers
and craigslist. Thanks Bill
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Old 11-21-2009, 06:24 PM
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greywynd greywynd is offline
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Join Date: Dec 2005
Location: Peterborough, Ontario
Posts: 3,561

For about $50-75 you can buy an electric construction heater, with all the parts in place already. Added bonus is that it is designed for the task, with no fear of fire if used properly. They will run quite readily from the same circuit as a dryer as well.
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Old 11-21-2009, 08:12 PM
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cutter cutter is offline
Join Date: Jun 2004
Location: Lubbock,Texas
Posts: 32,048

I'm inclined to add that older clothes dryers weren't really engineered for efficiency.
Another reason the heat felt good was probably the humidity from the laundry, not something you should cultivate.
So sure, you could rig it but there's probably a better way to po-boy around this situation.
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Old 11-21-2009, 08:52 PM
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OLD MAN OLD MAN is offline

2-3-1940 to 3-8-2011
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Join Date: Apr 2008
Location: TEXAS
Posts: 12,577

I built a travel trailer one time with a valve on the outlet hose on the dryer. If I was drying clothes it vented under the trailer. If I needed quick heat or a morning warmup, I flipped the valve and the warm air was exhausted into the trailer. It was fast effective and cheap.I never put it in the trailer when drying clothes. (rusts your shotgun)
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Old 12-17-2009, 01:55 AM
imagineer imagineer is offline
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Join Date: Jan 2007
Location: Wayne County, OH
Posts: 41
Default Coaxial heat exchanger

What about scavenging the heat from the outside of the dryer vent? I assume your dryer vent is a 4" duct. Wrap it with a section of 6" or 8" duct and cap the ends. Pump air into one end allow it to flow our the other and you should be able to recover some of the heat.

The way my house is set up, I had to run a 10' length of 4" metal duct through a wall and along the garage wall so to be able to vent it to the outside. Since I'm usually working in the garage on the weekends and our schedules are insane to the point where we can only get to the laundry on the weekends, it made sense to build a heat exchanger for the duct.

I slid a 6' long length of 6" duct over the 4" duct and, using some modified 6" to 4" reducers, capped each end. I took an old retired bathroon ceiling fan and using flexible 3" aluminum hose, ducted it to a homemade fitting on the 6" duct. At the other end, I cut a series of air exit slots, sized so the cumulative opening would be slightly less square inches than the 3" aluminum air inlet hose.

I tapped into one of the 110 leads inside the dryer, to power a 24v transformer that provides power for a low voltage contactor that will start the fan when the dryer is running. I have a remote switch so I can disable it in warm weather or when I know I won't be out there.

To increase the surface area for better heat transfer, I made some fin from sheetmetal and attached it to the 4" duct.

Recently, I also did something like this to get more heat from the wood burner out in my workshop. The attached pictures show the new 6" flue pipe wrapped in fin next to the 8" duct cover and the other picture is a closeup of the fin wrapped around the 6" flue pipe. (BTW, the fin material is salvaged from a power plant air cooled condenser).
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