Introduction: Easy Savings - Run Your Dryer on Free Energy

Picture of Easy Savings - Run Your Dryer on Free Energy

Modify your electric dryer to use free hot air and save energy.

Dryers only have one hose fitting. - To blow hot air out.
But this Instructable shows how to create a dryer hood with a fitting for a hot air intake hose.

Once the hood is attached, you connect the dryer to your hot air source with a dryer hose, and use free energy - hot air- to dry your clothes.

On hot summerdays , I use it to take hot attic air right into the dryer in my cool basement.
On warm days I use the air dry or the low temperature "Permanent-Press" setting.
In winter I use my dryer normally.

You can use your attic, a warm room, a solar heater, or you can use outdoor air as a source of warm or hot air. (The source of warm or hot air should be drafty, or open to a source of replacement air, like the outdoors.)

This Instructable helps you avoid consuming your indoor air, it makes your dryer more efficient, it saves energy on drying, and It can save on air conditioning cost too.

This Instructable is intended for electric dryers only, and is NOT recommended for gas models.
Modifying a gas model would present special challenges and hazards, which I have not addressed.

Material : Use a 4 foot roll of Aluminized Bubblepack plastic (Astro-foil) or similar material, a scissors, duct tape, plus scrap metal or cardboard and a dryer vent hose. Thats all thats needed. A screwdriver is optional.

Step 1: Unplug and Inspect

Picture of Unplug and Inspect

Unplug your drier , remove the exhaust vent hose, and inspect your Electric drier.
Look for the slotted vents in the back.

Step 2: Remove the Back Cover - Optional

Picture of Remove the Back Cover - Optional

Step 2: * Optional *
Loosen or remove the back of the dryer to inspect your dryer.
I studied it for a while so I felt comfortable making this modest modification.
I confirmed that the one main source of air was through the slotted vents.

Replace the back panel loosely. Tighten it later.

I suppose this modification could work on a gas model, but I'd worry about a mistake that would interfere with the proper combustion and exhaust. I'd worry about a potential fire hazard too.

I was careful with my electric dryer and happy not to mess with a gas model.

The photo shows the air intake on the bottom right, and the exhaust on the left.

Step 3: Sizing & Shaping the Hood

Picture of Sizing & Shaping the Hood

Begin planning and sizing the shape of the hood. Cut a large piece of material. Trim and shape it as the project processes.
I used aluminized bubble pack from a hardware store.

The photo shows the first rough cut.

Step 4: Begin Taping the Material to the Dryer

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Start applying the material to the dryer to surround but not cover the intake air vent slots.
Start to trim the material and tape the edges to the dryer.

Step 5: More Duct Tape !

Picture of More Duct Tape !

Apply the material to the back of the dryer up to the vent slots. 'Do not cover the vents!'
Tape both the inside and outside edges to the dryer.

Continue to Shape and trim the Material to fit around the shape of the air intake vents.

Step 6: Create a New Vent Hole

Picture of Create a New Vent Hole

Use cardboard or other stiff material to form a vent hole. Make it big enough to accommodate your duct hose. Fix it to the top of the dryer.

I used a 6 inch diameter scrap sheet metal vent duct, and tucked its thin edge between the dryer and the back panel, and tightened the screws on it.

I was lucky to have a machine made part. If you do not have one, carefully construct one of the right size and shape.

Step 7: Slit the Hood Up the Middle

Picture of Slit the Hood Up the Middle

Create a slit up the middle of the hood, to create an overlap. This tapers the shape of the hood from large at the top to smaller at the bottom.

Use scrap cardboard to create a rigid form to help the bottom of the hood keep its shape. I used a piece of 1/2 inch thick rigid foam insulation instead of card board.

Tape the rigid form to the hood and dryer.

Step 8: Finish Shaping and Taping the Hood

Picture of Finish Shaping and Taping the Hood

Tape the inside and outside of each edge and seam, and where the hood joins the dryer..

Continue trimming and taping the hood to the Dryer.

When Possible, fold the edges of the hood between the back panel and the dryer, and screw the back panel in place tightly. You may need to reach inside the hood to reach the screws in order to tighten them. I was Glad to have a 6" vent hole to reach into the hood, and the sheer size of the hood made it easier to work in.
And I made it plenty big enough for air to flow in easily.

Finish by wrapping the material around the duct hole.
I made several "Daisy Petal" cuts to help wrap the material around the vent hole.

Make sure the vent hose fits snugly inside the duct hole.
Finish for looks and functionality.

If you are going to use tape on visible parts of the dryer you might want to pick up some White Duct Tape for a nicer look.

I spent time being neat and careful, and I think it paid off.

Step 9: Test It Out

Picture of Test It Out

Re-attach the original exhaust hose.

Plug in the dryer and turn it on to test the air flow to make sure its working properly.
Making sure the hood allowed air to easily enter the dryer was a major concern I had.

I used an incense stick to create a visible stream of smoke.
This is looking good.

Step 10: Almost Done - Hook It Up

Picture of Almost Done - Hook It Up

Run one end of the hose to your attic or other source of hot air.

I strung it up in our drafty attic, near the peak of the roof, where it gets very hot on summer days.
Its not dusty up there so I did not install a filter at the end of the hose.

Insert the other end into the dryer hood.

Put the dryer back in place.

Step 11: Results and Performance

Picture of Results and Performance

On a hot day I can dry my clothes on the "Air" dry setting. This means the dryer is not consuming electricity to make heat.

On warm days I use the high heat cotton setting or the lower heat permanent press setting. Either way, I know my dryer is getting a boost, because its heating up warm air, not cool air, and its not taking nice cool indoor air and blowing it to the outside.

In winter, I flip a lever on the exhaust valve ( top of the last picture) and it blows the nice warm moist exhaust air inside where it should be.
Remember this is an electric dryer, not a gas model, so I do NOTconcern myself with combustion products, ( CO and CO2)

In winterI also disconnect the new intake duct hose.- No need to use cold attic air!

This project might work with sturdy corregated paper-cardboard, foamboard, or corregated plastic board, instead of aluminized bubblepack plastic.
If you only need a vent hose it might cost only $10. to complete the project

I needed 2 lengths of 6 inch diameter hose, to fit the sheet metal vent I already had, and to reach the attic. A 4 inch diameter hose might have been too narrow considering the long run to my attic. I went with the bigger hose.

I also opted to avoid visibly taping the dryer. This gave it a neat clean look.
I went "High end" and used about $30 worth of materials.

Of course I'm not counting the duct tape. Everyone already has duct tape, right?


lemonie (author)2009-06-21

I like the idea of piping (otherwise useless) hot air from your loft / attic. But I can't help wondering whether hanging clothes outside on a line is something you just don't do where you live? L

ScottSEA (author)lemonie2009-08-06

My wife and I have started hanging our clothes on a line again. Works great, uses zero energy.

blodefood (author)ScottSEA2016-10-24

In some places clothes lines are actually banned believe it or not. I know, it is really stupid but, it's true. This 'ible should help mitigate it for some people who live in places where the clothes lines are banned.

lemonie (author)ScottSEA2009-08-06

It's good if you can. L

DrChill (author)lemonie2009-06-21

To be direct, no, most of us here in this residential urban area, do not use clothes lines. I'd need a bigger yard, a pole and co-operation of - nature- the weather, the squirrels birds and trees. Its raining now, and has been for the last 10 days! Dryers are quicker more reliable and require less manual labor. We'd have to carry wet clothes to a place near the line. On our 2nd floor residence, someone would have to hang out a window. It's not a popular option.

lemonie (author)DrChill2009-06-21

I see, it wasn't clear where you lived. I make the best efforts to use the free energy available from the sun, but sometimes things stay out for a day 'cos they got rained-on... Thanks for filling us in on that! L

DrChill (author)lemonie2009-06-21

Yep. New York. And we got attitude! ha ha. Press a button get it done. Hmm now if there was a way so I didn't have to press the button ... hmmmm

lemonie (author)DrChill2009-06-21

Clapping? L

mcgary911 (author)2009-06-27

Great Idea. I live in Florida, and my atticspace turns into a 140 degree dry heat desert environment in the summer. In the winter, it's probably only 85. Putting the intake high in the attic makes sense to get the warmest air, but also because it'll probably be the cleanest air. My home like many, has loose, blown cellulose insulation. Too low, and I'd be pulling this stuff into my clean laundry. I wonder if building the vent shroud out of corrugated plastic sheet would work well. It's sturdy, easy to work with, and should insulate pretty well because of the air space. I'm eyeing up my laundry room right now, trying to determine if i have a straight run to the attic. :) Oh, and vent hose to intake hose (attempt at perpetual motion machine?) wouldn't work, unless you had an inline condenser of some sort. The vent isn't there to exhaust heat, it's there to exhaust the moisture the warm air is evaporating out of your clothes. IF you vented back into the dryer, all the moisture would go there too, and your clothes would never dry. Neat thought though. Once again, great idea.

DrChill (author)mcgary9112009-06-27

I love it! I think you're onto something. I had considered using foam board, but this might be better. Let me know how it works for you. ( I used the flexible plastic because its flexible, sturdy easy to cut, thin enough to sandwich between the dryer and back panel, waterproof, and most importantly, I already had some. ) The plastic corrugated sheet is sturdy and waterproof easy to cut. (2 Sheets of plastic with corrugated plastic in between.) I think you may be able to create sharp edges by cutting it up to the opposite sheet, and bending it. I'll bet if you measure, plan, sketch on paper, and maybe make a paper scale model, you can plan to make it all in one piece. BUT Is one piece construction necessary? You can gut 5 pieces, Top bottom left & right & back. Tape the seams - ( Both sides ) With Whit duct tape. Tape or attach to dryer. Check to see if your attic has vents. If so run your dryer in the heat of the day, and you'll remove some of the hot air there. Cooler attic, cooler house... You might want to consider a thermostatically controlled attic fan to vent your attic. 140 is HOT ! And as long as the attic temp in winter is greater than in your house, you'll still benefit.

Marc Jensen (author)DrChill2012-03-21

I teach classes in sustainable business, and I always use this example as a creative way to approach alternative energy. I live in Oklahoma, and I'm sure my well vented attic hits 140 in the summer too (the outside temperatures were hitting 110 a lot last summer...). So this spring, I'm doing this conversion to my own dryer and I have a question regarding materials. Would there be any kind of fire risk to build the hood out of cardboard rather than plastic sheeting? The air from the attic isn't hot enough to ignite the cardboard, but I don't know about the body of the dryer. Your thoughts?

DrChill (author)Marc Jensen2012-03-21

Another thought. Do remember to avoid gas dryers.
On your electric dryer, check the temperature at the exhaust and at the locations where your material may come in contact your dryer.
Run a load and just locate the dryer's hot spots, then consider that in your design ..
Good luck.

Marc Jensen (author)DrChill2012-03-22

Felt for hot spots last night. The back of the unit gets only slightly warm, but the lower left side gets extremely hot, which comes in contact with the edge of the hood. After this, I think I would recommend people to avoid cardboard for this project. It makes me nervous. I'm going to replace that section of my hood with corrugated plastic sheeting, or possibly sheet metal.

DrChill (author)Marc Jensen2012-03-22

Maybe the hot spot can be used as a source of incoming air.
Maybe create an off-set/space that allows air to flow over the hot spot.
That way the cardboard does not touch the hot-spot.

DrChill (author)Marc Jensen2012-03-21

I'm delighted that you're putting it to good use.
I don't think that 140 degrees, will be a fire hazard. And
The longer the run from the attic to the dryer, the cooler the air will get.
My dryer doesn't get hot to the touch.
I believe the main mechanism of drying is constant renewed supply and movement of -relatively dry air- over the tumbling clothes.

If heat from your attic gets to the dryer, thats great, but do not overlook the value of having the air supply and exhaust that is entirely outside the interior space.

If you dont exhause the dryer's waste air and humidity, and get the source air from outside the interior conditioned space, you risk bringing in outdoor air inside, or heating the interior space with humid dryer exhaust.
("Enthalpy" aka the latent heat in warm humid air.)

Cardboard. - Glad you asked.
I recommend going to a big box store to get it. Costco has great sheets - roughly 3x4 ft with 2 layers of corrigation. Its sturdy and a free building material. Sometimes they have lots of it. (Repurposing material !!! )

Design: The flexible hood lends itself to a curved manifold. But Cardboard is obviously flat, so you might want to consider a rectangular hood that fits around the back- top,sides, and bottom; a much boxier shape than the instructable I made.
Good luck and please keep me posted. I'd love to hear about real world experience with my invention.

Marc Jensen (author)DrChill2012-03-21

Thanks! I help run the cardboard recycling program at OU, so I have plenty of material to work with!

Yes, I'm going with a rectangular hood design that tapers from 8 inches deep at the top down to about 2 inches deep at the bottom. The dryer that you used in the instructable had a flat back, but mine is much more contoured, so using a more rigid material lets me cut it to fit more precisely and then tape that down.

I'm really interested in the problem of measurement with this experiment, and I can't just plug the dryer into my Kill-a-Watt. As a classroom example, I want specific numbers to put to this.

I'll send a photo when it's up and running.

joneser005 (author)2010-06-26

Living in Missouri, where the summers are hot, but also very humid, I wonder how much longer the dryer would have to run to compensate for using air high in humidity to dry the clothes. Vs. the dryer (!) air-conditioned air.... Would there still be a net energy savings or would the extended run time be a wash?

DrChill (author)joneser0052010-09-25

Lots of energy is used to heat air electrically.
Less energy is used to tumble the clothes.
Even less energy is used to blow air through the tumbler.

Unless the air is quite humid, running the dryer without heat will save energy.
How humid is that? I can't say.

Maybe your dryer has a listing for energy consumption.

Lets say the maximum is 1000 watts, and air only uses 400 watts.
then I'd say if your air only cycle takes twice as long as with heat, then 2*400 watts per cycle is still less than 1000 watts per cycle.

In practice, my hot attic air on hot humid NYC days, drys clothes in approximately the same time as cool air from my basement when I don't use the air dry cycle.

Woodenbikes (author)2010-03-07

Great Energy saving project!  I want to make one.

divolb (author)2009-12-20

Whats wrong with a good ol' close line?  Maybe it rains a lot?  Winters are too cold?

ronmaggi (author)2009-09-29

How about pulling air from your A/C's condenser? It seem's to be a good source of heat.

DrChill (author)ronmaggi2009-09-29

Sounds good to me. On hot days, the dryer gets either hot air from the outdoors, or the hotter air from the condenser, when the AC is on... Nice idea.

arutkow (author)2009-08-22

I love this idea! Just imagine if you could trap all of the heat that results as a by-product of our daily living (the lcd tv, the computers, the refridgerator, the bath exhaust, the stove and over heat) and trap it all in 1 room, them just draw from it as you needed heat for drying or other needs. I know its not practical because of the smells, grease, moisture, and ductwork, but your plan shows how much extra energy there is already in out house. Very cool plan. -Abram

scottfromscott (author)2009-07-15

Great idea using hot attic air. Here in south Louisiana attic temperatures can exceed 135 degrees. Find a way to use solar panels to run the dryer motor and you could dry your clothes for free!

headone (author)2009-07-06

Love this, anyway I can save a buck I will. Thanks well thought out.

benkline (author)2009-06-23

my friend blew his dryer exhaust into his garage to heat it as a extra hang out space - mold grew everywhere. it was disgusting. is there anyway to de-humidify the moist air before blowing it into your basement?

DrChill (author)benkline2009-06-23

This instructable is about where you intake the air for the dryer, not how to vent the exhaust. Normally you vent the exhaust into a warm/dry room, or vent it outdoors. Winter air here tends to be very dry when its near room temperature, so our basement in winter is about 60-65 degrees, and the air is dry, therefore venting dryer air in it is not a problem. Blowing exhaust into a cold unheated room will cause condensation, on.. well just about anything.

DrChill (author)2009-06-22

With all this talk about safety and incoming air and exhaust air, It reminded me that I did this project to save energy and INCREASE the SAFETY in my home. The contractor that installed my dryer exhaust vent to the outside, cautioned me to be careful about sealing and weatherizing my house too much. TOO Much !?? Our basement has a furnace and chimney. When it fires up, hot air goes up the chimney, and fresh (cold) air seeps in from all the crack and holes and spaces in the house. Air just seeps in to replace the air going up the chimney. He warned me that having the dryer on, blowing air from the basement to the great outdoors, would work against the air going up and out the chimney. The more I weatherized and sealed the basement the more likely this would become a problem. I have a very drafty attic, so I know that if I pull air out of the attic, its coming in from hundreds of holes vents and cracks there. So, in my case, this project INCREASED the safety of my home. I don't worry about the dryer pulling fumes down the chimney into the basement. Anyone doing any project involving fans and vents, should be mindful of where the air is coming from and where its going to. A dryer cant blow air out of a sealed room, and it can't blow air into a sealed room. So keep that in mind as you seal up and weatherize your home. Furnaces, and some other appliances need fresh air to breathe, and vents or chimneys to safely dispose of the exhaust.

Jeremy B (author)2009-06-22

This is a great idea! And it just so happens that my dryer is in my garage, that is connected to the side of the house with easy attic access. Its like this was written for me!

Randy Lahey (author)2009-06-21

Thats one hell of a good idea. you could also use a solar hot air heater.

Gilo (author)Randy Lahey2009-06-21

Back in the old country, we use hot air heated by a solar heat trap to dry grain.

DrChill (author)Randy Lahey2009-06-21

Wow, yes. People with solar heaters probably don't use them in the summer. This would put their solar heater to good use.

Beest921 (author)2009-06-21

This is one of those "Well why didn't I think of that?!" ideas! BRILLIANT!

Broom (author)Beest9212009-06-21

Seconded: brilliant. And, kudos for emphasizing the safety aspects of a gas dryer. One quibble: instead of venting dryer air directly into the house in the winter, it should be filtered for fine particles. The exhaust from a dryer has a lot of super-fine lint in it, and this can build up and cause a fire hazard if the dryer is located near a hot water heater or furnace (as is true for many people). I overcame this by building a 2'-long "sock" of muslin, which I duct-taped to the output of my dryer. A couple times a year I would detach it and clean it out. The sock (just a bag) is big enough to not clog up easily, filtering the dust.

DrChill (author)Broom2009-06-21

My exhaust vent diverter has a filter screen built in. (White box - top of frame - last picture) Its one of those $10 items that is worth every penny. Glad you like my project. I'd like to hear back from you if you try it.

Broom (author)DrChill2009-06-21

Ah, missed that! Much more attractive than my solution, although I just tucked my "exhaust sock" behind the dryer, where it was unseen throughout the winter. By summer, of course, I wanted the hot air vented out.

iPodGuy (author)2009-06-21

You should win some sort of award for this. Fantastic idea!

DrChill (author)iPodGuy2009-06-21

Award ! ? awe shucks, no. Just send cash.. ha ha ha. Seriously though, I'd like to know if people are trying it out for themselves, and how its working for them. I've gotten good feedback, and some good creative ideas too. I love that. Thanks.

creektilghmank45 (author)2017-07-04

If you want to make it too just use InpliX handbooks.

chronistergama (author)2017-07-04

Great to see that... I made it too. Using inplix handbooks :)

Alden Tortem (author)2017-02-17

THIS is better way to great savings. Thank you Gregory ! :

Daniel434 (author)2017-02-04

This is better way to Free Energy :)

LeslieF10 (author)2016-02-27

I just found this post and would love to try this. I've noticed this post was made years ago. I am wondering how is it going now? Still currently using the idea? Have you seen a change in your energy bills?

DrChill (author)LeslieF102017-01-13

Sorry to take so long to reply.
I still use it. The duct tape has held together on all the critical seams.
I have insulated my attic and now have much less hot air to tap into.
I havent heard much from people who have tried it.
Let me know if you have...

Kuffar (author)DrChill2017-01-28

Hey Dr. Chill,

Just ran across this ible. One thing I wanted to mention to some of your readers. Even if you live in very humid area, when the air is heated, it expands, lowering the relative humidity of that air. That's one problem with dry air, in the winter. It goes through the furnace, is heated, and that lowers the humidity of the air in your home, causing dry air, static, and dry skin.

By utilizing the heated air, trapped in your attic, it already has a much lower humidity, that the air outside. So, your little device should be very efficient, even in humid climates.

Before I painted our barn roof white, it was a dark gray. In the summer, it would probably surpass the 140 degree mark. It was miserable. But, it was great to put hay in, or green wood. Dried that stuff out, in no time. I don't do hay anymore, so it has lowered the temperature in the barn by quite a bit. Makes a nice shady, cool place to work on the car, when it's 90+ out.

And, yes we use the clothesline. It's free, and smells great. The only drawback, is the sandpaper bath towels. Ouch!

steve.schmor (author)2015-12-08

We usually hang our clothes in the summer and save 100% on drier usage. And if you're going to blow the hot air out from the laundry room why not (depending on availability) hook it up to and existing forced air vent and blow it throughout your house (usually laundry rooms are close to the furnace). Just make sure that you blow it away from the furnace down the pipe and not into the furnace. Just another mod thought.

oper8or (author)2015-11-23

and when the dryer overheats, you blow a VERY expensive overheat fuse

oper8or (author)2015-11-23

and when the dryer overheats, you blow a VERY expensive overheat fuse

Nyxius (author)2015-11-23

Running the exhaust vent through the intake to create a form of heat exchanger would increase your efficiency further.

Smarti1957 (author)2015-02-21

Just a thought, but "who uses a dryer in the heat of summer"? The minute clothes won't freeze outside (April to November), I hang stuff on the clothesline. And in the winter, I could never vent the dryer inside because of all the moisture. I have tried this and there was way too much humidity.

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