# clothes dryer air: Can I somehow reuse this warm air (heat recovery)?



## NewtownPA (Mar 5, 2007)

I've got an electric clothes dryer (house is all electric). Is there a way to somehow reuse this warm air?


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## keyman512us (Mar 5, 2007)

Hey it can be done (if you don't mind the moist air it will produce).
Biggest concern is the lint/dust it will produce. The home stores used to sell a little box gizzmo with a movable flapper to divert the air into the house...the opening was covered by a filter sock...which after it became hopelessly clogged, people would replace with a womans' "panty hose sock". Was popular for awhile...but requires constant attention. Also with liability/safety concerns being what they are these days...I doubt they still sell it.


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## Corey (Mar 5, 2007)

I built a 16"x20" box out of 1x4's, sealed one side with a 1/4" sheet of panneling.  Cut a hole (either in the back or one of the sides depending on how you want to set it) and installed and sealed a small section of 4" dia piping.  Then duct taped a medium efficiency furnace filter to the open side.  I get a couple years of use out of it before the filter needs to be cleaned.  I went ahead and replaced it (~$4.00) after 5 years of use.

A few warnings:

- I laid the filter box flat on the floor beside the dryer for several years and it worked great in the 'open' basement.  When we finally enclosed the laundry room into a true 'room' I needed a little 6" personal fan to blow the hot, humid air out the door.  Otherwise it built up a good amount of humidity in the room

- Not for use with gas dryers

- Probably not a good idea if you live in a 'super' tight or 'super' energy efficient house as you may already have trouble with stale, humid indoor air.

- I tend to only use this when I am home and awake.  There is a very, very slight possibility that a failure of a dryer heater element could set fire to any built-up lint in the rig which could set fire to the house.   Probably about the same possibility that the clothes in the dryer could catch fire and burn the house down anyway.

Anyway, that is the way I do it.  Not only do you recover all the heat, you recover the humidity, and you save the main house heat from having to heat up about 120 cubic feet of air per minute of dryer operation - about what the dryer would exhaust outside and cause cold, dry air to be pulled in the house.

Corey


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## mikeathens (Mar 5, 2007)

You need to be careful doing this.  You are going to boost particulates in your house and VOCs will also be emitted.  This compounds already-existing indoor air quality problems generated by carpet (VOC and formaldehyde), dust, pet dander, furniture finishes, polishes, etc. etc present in most houses.  I looked into it in the past and decided it wasn't worth the extra risk, especially now that I have a toddler in the house.  

Seriously, look into pollutants that you will get from this.  There might be something on the web.


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## NewtownPA (Mar 5, 2007)

Mike from Athens said:
			
		

> You need to be careful doing this.  You are going to boost particulates in your house and VOCs will also be emitted.  This compounds already-existing indoor air quality problems generated by carpet (VOC and formaldehyde), dust, pet dander, furniture finishes, polishes, etc. etc present in most houses.  I looked into it in the past and decided it wasn't worth the extra risk, especially now that I have a toddler in the house.
> 
> Seriously, look into pollutants that you will get from this.  There might be something on the web.




Hmmm... I have a toddler too... 

I just wish there was some way to easily and safely recapture that heat. It bothers me to see the vent spewing all this heat OUTSIDE the house... I may just have to live with it though - safety first!


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## Corey (Mar 5, 2007)

Mike from Athens said:
			
		

> You need to be careful doing this.  You are going to boost particulates in your house and VOCs will also be emitted.  This compounds already-existing indoor air quality problems generated by carpet (VOC and formaldehyde), dust, pet dander, furniture finishes, polishes, etc. etc present in most houses.  I looked into it in the past and decided it wasn't worth the extra risk, especially now that I have a toddler in the house.
> 
> Seriously, look into pollutants that you will get from this.  There might be something on the web.



Mike does bring up a couple of points.  As far as the particulate increase, I have never noticed any substantial increase in running the vent inside versus out.  My general unscientific observation would be that handling and folding clothes generates far more lint and dust than is discharged through the filter set-up.  Even the wood stove generates a notable amount of fine particulates when it is in use (mainly due to ash clean outs).  As far as VOC's - you do pick up some 'fabric softener' smell in the house due to the exhaust, although neither me or the wife have ever found it objectionable.  After all, any compound in the air is coming from clothes that are in contact with our skin and inches from our faces for nearly 24 hours a day when you consider clothes, bedding, pillows, etc.

Of course, we have no young 'uns and don't seem to be excessively sensitive to indoor air quality so it is certainly up to each person to evaluate their situation and decide if doing some modification like this is worth the risk.  Another option may be some type of air-to-air heat exchanger, although that would come with it's own set of maintenance requirements and may be especially sensitive to lint build up.

Corey


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## Sandor (Mar 5, 2007)

How about air drying your clothes?


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## NewtownPA (Mar 6, 2007)

Sandor said:
			
		

> How about air drying your clothes?



If I was a bachelor I would!


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## Jay H (Mar 6, 2007)

NewtownPA said:
			
		

> Sandor said:
> 
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> ...



I am a bachelor and I do!    I have one of those dryer racks I setup in front of the wood stove. I have a nylon accessory cord hanging above the stove for the wetter items from my winter hikes.. hat, gloves, etc.. or anything that I want to dry pronto..

Jay


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## jrosenboom (Mar 8, 2007)

I use a diverted box with a filter similiar to cozy in a open basement.  It steams up the windows pretty good when you run a few loads through it!


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## WarmGuy (Mar 8, 2007)

Warning: I tried this, and all of my tools rusted overnight.


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## NewtownPA (Mar 8, 2007)

Well it sounds like the problems oughtweigh any benefits; unfortunately. I think I won't be making a heat recapture device.


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## Sandor (Mar 9, 2007)

NewtownPA said:
			
		

> Sandor said:
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Lame excuse. Hey, you posted in the "Green" room and you need some green suggestions.

I live in a house with 3 Frickin' women! How much laundry to you think gets done around here?

Set up two folding racks by the woodstove and do a load a night. Everything is dry by the morning. Use the outside lines on sunny days. 

Its not really that difficult, and saves a substantial amount of money (and energy).

I did the math and figured it costs about 50 cents a load to dry. 

P.S. Hey, what the hell, let the coal powerplants fire it up to make up for our convenience.


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## mikeathens (Mar 12, 2007)

Sandor said:
			
		

> Lame excuse. Hey, you posted in the "Green" room and you need some green suggestions.
> 
> I live in a house with 3 Frickin' women! How much laundry to you think gets done around here?
> 
> ...



I know a bit off topic, but....3 WOMEN!  Woooohooooo!!  I don't know how you'd find the time to do ANY laundry.


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## Eric Johnson (Mar 12, 2007)

I live with two women, which means I have to pretend to like cats. Speaking of women, you think they'd have the common courtesy to lift the toilet seat back up after they're done.

How about venting through a long piece of that collapsible aluminum vent pipe--like 8 or 10 feet--before it gets to the outlet? All that surface area should dissipate heat into the room, though you might find that it clogs up more easily.


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## megan (Mar 12, 2007)

Here, here (or is that hear, hear?) to the clothesline.

We use one every day we can. When we can't, we use two wooden drying racks and an over the door hanger. 

We're a family of two adults and three cats, and my DH has to wash his workclothes after one wearing (municipal worker), so it's almost like having a third person on hand when it comes to laundry.

When our dryer quit working (i think it needs a new belt), we stopped using it. DH was the one who really wanted an electric dryer, i didn't care as long as i had a washer. He found that he preferred stuff hung on the line, so PECO hasn't gotten any money from us for our dryer usage for quite some time now. Works for me.

megan


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## Sandor (Mar 12, 2007)

Eric Johnson said:
			
		

> I live with two women, which means I have to pretend to like cats. Speaking of women, you think they'd have the common courtesy to lift the toilet seat back up after they're done.
> 
> How about venting through a long piece of that collapsible aluminum vent pipe--like 8 or 10 feet--before it gets to the outlet? All that surface area should dissipate heat into the room, though you might find that it clogs up more easily.



Eric, I go outside to take a leak.

Free fertilizer, cannot be acused of "missing", no lid issue.... and I'm free!

Girlz rolled their eyes at first, but now I gotem' trained! (or do they have me trained?)


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## Eric Johnson (Mar 12, 2007)

I use that technique for keeping the compost bins damp and full of nitrogen--when nobody's looking. Use the standard applicator.


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## megan (Mar 12, 2007)

Must be nice to have the "standard" applicator. My neighbor does this, too.

I want a composting toilet, but DH is not really on board with this. I told him it could go in "my" bathroom. (We have two--he chiefly uses one and i the other).

On the toilet seat issue, DH usually lowers the seat, and he also has very good aim, for which i'm thankful. I usually say nothing when he leaves the seat up, i'd rather have that than someone with bad aim who doesn't lift the seat (or clean up after himself).

But, one night it was in the middle of the night, and DH felt nature calling, so he walked half asleep into my bathroom, which is nearest our bedroom, and sat down, being too tired to stand up. He hadn't bothered turning on a light. He discovered upon sitting down that he had forgotten to lower the seat from the last time he had used "my" bathroom. I wouldn't have known except he let out a yell, causing me to wake up, as the cold porcelain and water greeted him like an impromptu bidet.

I stifled a laugh because i've had that happen, too, although i usually stand up in time to avoid the water. 

His experience wasn't for naught. He now nearly always puts the seat back down, especially if it's nearing bedtime.



			
				Eric Johnson said:
			
		

> I use that technique for keeping the compost bins damp and full of nitrogen--when nobody's looking. Use the standard applicator.


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## NewtownPA (Mar 13, 2007)

Eric Johnson said:
			
		

> Speaking of women, you think they'd have the common courtesy to lift the toilet seat back up after they're done.



NICE

Believe it or not, the "toilet seat" was my first marital argument after we got back from our honeymoon


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## cbrodsky (Mar 13, 2007)

Sandor said:
			
		

> Eric, I go outside to take a leak.
> 
> Free fertilizer, cannot be acused of "missing", no lid issue.... and I'm free!
> 
> Girlz rolled their eyes at first, but now I gotem' trained! (or do they have me trained?)



After our dog passed away, I found this was a highly effective method of filling in for his role of having kept the deer away for so many years.  They started to invade until I fought back in our greyhound's footsteps.

-Colin


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## begreen (Mar 14, 2007)

I wish this would work. Our deer have long gotten used to the smell of my pee. They poop right next to it now. This spring I am going to fight back and try some wolf poop from a local sanctuary for wolves.


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## youngstr (Mar 19, 2007)

What's the general consensus on venting into the garage via a "diverter valve"?  You night not heat the house directly but if you have an attached garage, the warmer garage might negate heat loss through that end of the house.


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## elkimmeg (Mar 19, 2007)

I aways thought there was a reason a garage required 1 hour fire protection to the adjoining living space. Putting a 4' vent in there Is not a good idea plus again not code compliant


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## Mo Heat (Mar 20, 2007)

In a 2 bdrm CA townhouse, I diverted my electric dryer vent hose into a return box/fan-housing/pedestal-for-the-HVAC and installed a 1 hour twist timer switch to the HVAC fan next to the dryer. On the end of the dryer vent hose I connected one of those wet filters that looks like an old ice cube bin with a grate-like top with a place to hook the hose. You fill it with an inch or two of water and it grabs a bunch of the lint as the air blows straight down onto the water. 

I liked it well enough, but it was always drying up and I had to unscrew a register to put more water in it. I could tell there was more dust in the house due to it settling on furniture tops and such, but I liked recycling the air and the added moisture in a dry California climate after moving from humid Tejas. 

I like cozy's filter box idea. My dryer is currently routed outside, but I've considered doing something like this again, but you need the filtration to keep the dust down. I think I'd combine the wet filter with the dry filter box ideas to keep dust down to a minimum. And if you can divert it into the HVAC, and dust is not a problem, then the humidity can get spread around the house well. Of course, then there is the loss of heat through the HVAC, so maybe that's not such a great idea. 

My old place was relatively small, so there was minimal HVAC duct losses, plus, they were all inside the insulation envelop. It's a tinkerer's thing. A real greeny will dry their clothes like Sandor, without a dryer. Not an option at my place. I can barely convince the ladies to let me use CF bulbs, "Mo, they look so haarrrrsh". Still, they let me do it and that's what counts.


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## youngstr (Mar 20, 2007)

elkimmeg said:
			
		

> I aways thought there was a reason a garage required 1 hour fire protection to the adjoining living space. Putting a 4' vent in there Is not a good idea plus again not code compliant



Is that true ?  I thought it was against code only if you didn't maintain the fire rating when you vented.  Are you code if you used a metal duct of appropriate thickness/fire resistance rating ?


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## elkimmeg (Mar 20, 2007)

Code requires the dryer exhaust to  exit the envelope of the building that means out side not in a garage.. That  dryer exhaust  flapper works ok the first week, then lint gets in there holds the flapper open,  bye bye  your one hour fire protection.  Yes I am a code official National certified

 Mo Dryer exhanust must exit the building retrofitting it into your HVAC system is a great way to  start mold amd mildew in your duct work.   Not a good idea  Add dryer exhaust should be hard piped  What you guys want to add to the satistics 15,600 Dryer fires in USA is not enough? you want more 15 deaths  400 injured? You want to join that list?


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## Mo Heat (Mar 20, 2007)

elkimmeg said:
			
		

> Mo Dryer exhanust must exit the building retrofitting it into your HVAC system is a great way to  start mold amd mildew in your duct work.



I wonder if I can get sued in Missouri for something I did in California?  :gulp:


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## begreen (Mar 20, 2007)

If that's true, perhaps the dryer is the least of your worries.


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## youngstr (Mar 20, 2007)

elkimmeg said:
			
		

> Code requires the dryer exhaust to  exit the envelope of the building that means out side not in a garage.. That  dryer exhaust  flapper works ok the first week, then lint gets in there holds the flapper open,  bye bye  your one hour fire protection.  Yes I am a code official National certified
> 
> Mo Dryer exhanust must exit the building retrofitting it into your HVAC system is a great way to  start mold amd mildew in your duct work.   Not a good idea  Add dryer exhaust should be hard piped  What you guys want to add to the satistics 15,600 Dryer fires in USA is not enough? you want more 15 deaths  400 injured? You want to join that list?



Whoa, hold on there tiger.  I don't want to die/become a statistic nor do I think anyone else here does.  

Thanks for your insight on code compliance.


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## elkimmeg (Mar 20, 2007)

There are more dryer fires than wood stoves incidents. I just wanted to point the magantude  of  a seemingly harmless appliance. 
 nothing personal but did get you attention.  When is the last time your dryer vent was cleaned out? Taking that thought a step further, removing the back and removing all the lint?

 Not will you be saving energy, but increasing the chances mishaps do not occure in your home. Lint is very combustiable.  thats why hard pipe is superior for the application nom corrugated ribbing for lint to attach to,  there for more of it exits the building... the down side is it requires more work and is more differcult to install.  I believe the energy saved and s saftey margine to be worth every extra penny


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