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October 13, 2007 9:51 AM   Subscribe

I thought I was doing an environmentally smart thing by switching our dryer vent to an indoor water filtered vent in the winter, but a friend claims the fumes may be harmful. Crap or not crap?

A friend of ours was horrified to discover that during the winter I switched the vent for our dryer to vent indoors. All of the bedrooms are upstairs, as is the master bath, where the washer and dryer are located. I figured it was wasteful to let that warm moist air vent outdoors in the winter. Our friend claims it's only a matter of time before our children grow giant tumors due to all of the carcinogens we're exposing them to. I've found a few questionable sites claiming dryer sheets may be problematic, but haven't found anything confirm her assertions that the exhaust is dangerous. She claims her opinion was informed by her mother's belief in the same danger and her mother is a doctor. Her mother is a doctor but she's a psychiatrist.
Killer dryer exhaust: Crap or not crap?
posted by Toekneesan to Home & Garden (24 answers total)
I would think it would depend on if it was a gas dryer. If it is, then you have a problem. You want that vented to the outside. If it is electric, I don't see much of a problem with it. Not a doctor though. I have lived in a place where it was vented to the inside, by construction problems. It was electric and I don't seem to have too many problems!! lol.
posted by Climber at 9:57 AM on October 13, 2007

If it's electric, it's probably okay, since no combustion is taking place. I'd think that dumping all that warm, moist air into a living space might not be the best idea, though. The heat's obviously not a problem, but all that humidity could grow mold.

If it's a gas dryer, then yeah, I think it would almost certainly be quite dangerous. Burning usually results in at least some carbon monoxide, which is odorless, colorless, and quite lethal.

You say it's a 'water filtered vent', but I don't have the expertise to say whether it could remove CO from the air.
posted by Malor at 10:11 AM on October 13, 2007

Response by poster: Electric dryer. Vent like this.
posted by Toekneesan at 10:27 AM on October 13, 2007

When I was a kid, my parents vented our electric dryer into the basement in the winter to keep it warm. I don't think it gives off much more than warm moist air. With a gas dryer, you wouldn't want to do this.
posted by pombe at 10:27 AM on October 13, 2007

Response by poster: Oh, and we heat with wood, which makes the house very dry. Mold and mildew has never been an issue though the water doesn't catch all the lint and the area around the dryer does get a bit dusty.
posted by Toekneesan at 10:29 AM on October 13, 2007

We do this with our electric dryer. Nice and humidifying in the winter, and works perfectly well. I'm not that worried about the dryer sheets, but what do I know.
posted by walla at 10:32 AM on October 13, 2007

Venting a dryer indoors strikes me as a very bad idea, especially if you have a newer home that's well-sealed - you're pumping a fairly large amount of humidity into the home with every load of laundry you dry.

If you want to be environmentally friendly, use a drying rack. Even if the drying rack is indoors, the water that evaporates from the clothing will do so over a much longer time period (around 24hrs depending on the clothes), which allows the normal ventilation of the home to balance out the humidity.

It's not the fumes that are the problem here, it's the rapid release of a large amount of moisture into your living space. Heating with wood might make the house feel dry, but you should get a hygrometer (moisture meter) to find out exactly what the humidity level is.
posted by gwenzel at 10:37 AM on October 13, 2007

One element of home design is to eliminate or mitigate high levels of moisture in the house because it leads to mold and rot.

Unlike a humidifier, which is controlled, a dryer will dump all of the moisture into a small area in a short amount of time.

If you have asthma or are allergic to mold, I'd recommend against it.
posted by zippy at 10:39 AM on October 13, 2007

Regardless of whether or not you dryer is electric, it is still venting in lots and lots of lint from the clothing into your house. This might not sound that dangerous but cotton lint (cellulose) in large quantities is not a good thing to inhale (ignore the carcinogen tag in there I just used it to find the study. The study concludes it probably is not carcinogenic but details why it's bad anyway). Even if you are running it through some sort of water filter it is not reducing the very small, highly mobile fibers as water filtration is inferior to HEPA filtration in this regard.

This is a bad idea across every standard I can think of and gets even worse if your dryer is natural gas based as has been mentioned above.

One more thought, fine cellulose dust in the right concentrations is explosive but I doubt you'd have to worry about this.
posted by 517 at 10:47 AM on October 13, 2007

If you're heating the house with wood, you're probably not using an electrostatic particulate accumulator on the furnace's return duct, which would take out most of the fine cotton dust 517 talks about. So yeah, possibly some effects from that.

You could run a whole fleet of standalone electrostatic air cleaners, (like the Sharper Image stand-up model but there are others) but I think by that point you might as well just vent outside.

For what it's worth, we vent ours to the inside a few weeks out of the year when it's really dry, and we're not dead yet. But we do have serious filtration on the furnace, and we only vent inside when the hygrometer says we need to.
posted by Myself at 10:57 AM on October 13, 2007

Well, I think it's true that you aren't suppoed to vent gas dryers inside due to fumes. But for electric dryers they sell these heat saver devices that allow you to switch between indoor and outdoor at will. It has a built in lint screen. We use one in the unheated basement of our 80 year old home.
posted by cabingirl at 12:01 PM on October 13, 2007

As a couple of others have pointed out, builders go to great pains to help your house vent moisture outdoors. Paint is in fact designed to allow moisture to evaporate out, or else it would pop right off your exterior walls. The winter air that feels so dry to you? Your house LOVES it.

Venting your dryer indoors is a terrible idea.
posted by Camofrog at 12:02 PM on October 13, 2007

See also this previous MeFi thread with similar question.

And this LaundryForum thread.

Option for apartment dwellers who can't vent outdoors: Ventless clothes dryers.
posted by beagle at 12:13 PM on October 13, 2007

You're in good shape (and if I may say so, in good company). No dire harm will befall you, even if you do fog the windows in that room. We vented quite happily over multiple years into the basement laundry/utility room, and it was one room in the house that wasn't dreadfully dry because of the lack of humidity.

As memory serves, that room didn't have a door, just a door-sized opening, which no doubt would at least move *some* of the heat and humidity around, but not a whole lot.

You'll want to keep the filter extra-clean so that you don't impair the airflow out of the dryer, which will slow the entire drying process.

Otherwise, talk to me in 20 years and maybe then we'll compare tumors...
posted by LoraxGuy at 2:45 PM on October 13, 2007

I had a dryer with a water filter in an apartment years ago and it drove my allergies (I'm allergic to "dust") completely crazy. I ended up hanging all of my clothes to dry and not using the dryer at all.
posted by jeffmik at 3:33 PM on October 13, 2007

I was at Home Depot today looking at dryer vents. They had several different set-ups for venting the dryer indoors. All of these carried the warning that they were for electric dryers only.
posted by winston at 3:37 PM on October 13, 2007

Can you add a second lint filter somewhere in the line, to avoid the extra particulate in the air? As far as a wood heated house goes, I don't think the moisture would be a problem unless you have zero air circulation in the dryer room.
posted by oneirodynia at 5:55 PM on October 13, 2007

Another vote for venting it indoors. You won't do any harm unless you let your home get really wet for a long period of time. Just don't run it with the door closed for any length of time.

Many people in my area (especially those who heat with wood) have humidifiers running during the winter to keep themselves and their houses reasonably moist. Keeping the air very dry in your house during the winter can cause cracking in wood floors and other bits of wood as the wood expands over the summer and then contracts and dries out in the winter.
posted by ssg at 7:07 PM on October 13, 2007

I have vent mine down to the basement for the last two years. I actually built a filteration system out of some HVAC filters and directed the dryer's venting pipe into it. The dryer is located directly above one floor up.

I have sat in the room where the filter system sits. I was breathing at the time and continued to do so thereafter.

If you break it down to the elements you have clothing, heat and moisture blended to together for a short time, constantly filtered by HEPA type filters- unless your clothes are made out of abestos I don't see the problem. I would worry more about driving behind a diesel truck more than I would worry about venting the filtered exhaust, containing the by products from clothe, moisture and heat, from my dryer into my basement.
posted by bkeene12 at 7:13 PM on October 13, 2007

i think what she's thinking of is radon.
posted by buka at 7:54 PM on October 13, 2007

I know it *sounds* bad to have your gas dryer venting into the house, but has it actually been proven so? Consider that my oven and cooktop burn natrual gas, and they vent into the house. Also, that "indoor forklifts" run on natural gas.

But my real comment in to mention an air heat exchanger that I read about that fits in the vent. So the "stank/moist" air goes outside, but the heat exchanger captures heat. I couldn't find it on Google easily (lazy first page).
posted by markhu at 8:08 PM on October 13, 2007

Any chance you could ditch the dryer sheets? They seem to be the real carcinogen. There are lots of new, environmentally-friendly products that do the same thing (here, for example), but whiffle balls work just as well. Tennis balls are often recommended, but they're full of nasties, too.

Otherwise, especially with wood heat, I think you're better off with the extra moisture and heat in the air. Just make sure your circulation is good (set up a fan in the laundry room, perhaps), and keep your filter clean.
posted by tempest in a teapot at 5:54 AM on October 14, 2007

Second the reference to radon. Easily fixed if it's an issue, but the point is not to push the radon up into the living areas. Nevertheless, I'm in the "heats with wood, overly dry air, vent it in the basement" club. I'll take any additional heat and moisture I can get in February. In newer houses this is probably not such a good idea.
posted by Area Control at 9:36 AM on October 14, 2007

Nearly everybody in Australia vents electric dryers indoors (no gas dryers here). It is harmless and doesn't do more humidity than a shower does to a bathroom.
That said, I would not run it all the time in an enclosed little laundry, just open the door when you are drying.
posted by bystander at 9:30 PM on October 14, 2007

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