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

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

Comments

[Randy Lahey]

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

[DrChill]

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

[iPodGuy]

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

[DrChill]

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.

[lemonie]

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

[DrChill]

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]

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]

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]

Clapping? L

[Beest921]

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

[Broom]

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]

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]

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.

[Gilo]

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

[Jeremy B]

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!

[benkline]

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]

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.

[headone]

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

[scottfromscott]

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!

[ScottSEA]

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

[lemonie]

It's good if you can. L

[arutkow]

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

[ronmaggi]

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

[DrChill]

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.

[divolb]

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

[Woodenbikes]

Great Energy saving project!  I want to make one.

[joneser005]

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]

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.

[mcgary911]

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]

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]

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]

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]

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]

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]

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]

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.

[photogirlmim]

Couldn't just add a lint filter to the intake and use the exhaust for your source also?

[DrChill]

In the closed loop you describe, water will increasingly saturate the small volume of circulating air, until it can no longer hold any additional water, and the clothes will not get any dryer. So, no, that will not work.

[millenniumtree]

Not only that, but if you have a gas dryer, the oxygen in the exhaust will be less than the intake.  Less oxygen means more carbon monoxide production.

Whatever you do, do not EXHAUST the dryer into the attic or into the house - that's a recipe for disaster.  The excess moisture in the air will rot your walls out, and with a gas dryer, the combustion gases could kill you.
It's also a good idea to replace your plastic exhaust hose (illegal in most places) with a smooth metal pipe.  Less chance for the dryer to ignite the lint in the plastic and burn your house down.  o_O

As the instructable describes, sucking INTAKE air from a hot area seems like a very effective way to reduce your energy consumption.

Cool idea.

[DrChill]

 I exhaust my Electric dryer into our semi-heated basement or our living space with no condensation problem at all.

You can use a filter 'sock' at the end of the hose to avoid lint dust.

Lint can be a fire hazard if you do not clean your filters regularly.
More so, if your dryer has a GAS flame!