The Properties of Fluids are not Strained

November 28, 2008 10:47 PM

Why does my dryer have to be vented to work?

I live in an apartment. My dryer vent duct to the outside allows the smell of my neighbor's drying clothing to come into my apartment, since for some damnsilly reason the two vents are connected. I wanted to block off the vent and just let my dryer vent out into the room.

But if I do not have the dryer hooked up to the dryer vent, it does not ever get hot. It gets warmish, but not hot. This seems exactly opposed to what I imagine should happen, which that the dryer air flowing out into the room with no obstruction would allow for much faster drying. I hooked it back up to the vent, incidentally.

I have an extremely tiny compact Maytag High Efficiency MDE2400AYW, if it matters. When I can get it to work it makes a pleasing song after my clothes are done. I delight in the carol of my machine, but it does me no good if I open the box to find the clothes are almost as damp as when they entered it.

Is there some mechanical feature of the dryer which causes this, or is it the long column of air inside the duct is acting as a chimney to suck the air out of the dryer?

posted by winna to home & garden (13 comments total)

My dryer is attached to a hose that vents directly into the living room. It dries clothes just fine (and also keeps the apartment toasty). If, for some reason, a hose is required for your setup to work, you can get one at a hardware store for less than 10 bucks, and you can make it vent wherever you want. But I don't know about dryer mechanics; there might be something else going on here.
posted by phunniemee at 10:58 PM on November 28, 2008

Dryers need venting to operate efficiently and safely. Is there a problem with having the vent connected other than smelling your neighbor's laundry? If that's a real problem, can you hassle your landlord to put in a proper, separate vent for you?
posted by anarchivist at 11:03 PM on November 28, 2008

Does the dryer really vent unobstructed into the room, or is it venting into a small gap between the back of the unit and the wall? Even if the gap is as wide as the diameter of the hose, you might be impeding the flow of air by removing it. The hose acts as a guide to duct the air up and out of the space, while if it's coming straight out the back and hitting a wall it'll turn into a turbulent mess back there. It's also worth mentioning that forcing all that hot, damp air against the wall is an invitation for mold/mildew.
posted by contraption at 11:37 PM on November 28, 2008

An improperly vented dryer will not get hot enough, in my experience. I've had numerous instances of plugged vents, and each time the clothes would never dry, and the dryer never felt hot enough. I don't think the issue is as much that you are venting it indoors, as that it's not venting properly at all.
posted by Fuzzy Skinner at 11:46 PM on November 28, 2008

You can put a one way valve on your line before it exits that will cut down on your neighbors laundry intrusions.
posted by lee at 12:08 AM on November 29, 2008 [1 favorite has favorites]

If you're venting your dryer into your living space you are, basically, dumping a couple gallons of water on your floor. Depending on how well sealed (or not) your living space is, you're just begging for mold issues.
posted by Kid Charlemagne at 1:40 AM on November 29, 2008 [2 favorites has favorites]

Recirculating the air makes the machine work harder by taking the water out of the clothes and into the room's air but then sending the room's air, along with some of the same water, right back into the machine for another cycle. Every molecule of water you send through more than once is a waste of electricity and money.

To be efficient, you want to use relatively dry air to pick up moisture from clothes and then exit your home through a vent with all of the unwanted water and lint.

If you can't get a separate vent, you need to buy or make a vent with a flap such that air pressure from your side forces the flap open, but air pressure from the other side (from the neighbor's machine or blowing in from outside) forces the flap closed. I'm not talking about the usual flap on the outside of the building, but a flap inside your home (between your machine and your wall) or in your wall, so that the flap separates your home from the neighbors by opening only when you are drying clothes.
posted by pracowity at 3:23 AM on November 29, 2008

what I imagine should happen, which that the dryer air flowing out into the room with no obstruction would allow for much faster drying

What you imagine should happen is not what will in fact happen.

All that water that's in your clothes has to go somewhere. If it doesn't go out the vent, it goes into the air in your laundry and gets sucked back into the dryer. Super-humid air is not much good at drying clothes; essentially, by getting rid of the venting, you've turned your dryer into a steamer.

Now, if you were to run a duct from the back of your dryer to somewhere near your air conditioner and run that at the same time, it would suck the water right back out of the air again and your clothes would dry much better (the water from your clothes would end up dribbling out of your aircon's drip tray drain). But that's an unbelievable waste of electricity.

What you actually want is a butterfly backflow damper. For under $10 you can stop your neighbour's dryer venting into your space while allowing yours unobstructed access to the shared vent. Buy one for your neighbour as well.
posted by flabdablet at 3:58 AM on November 29, 2008 [1 favorite has favorites]

We use one of these indoor vents on our dryer. The way it works is you fill it with water and as the air runs over the surface of the water, the water should catch some of the dust from the warm dryer air.

Yes, water vapor is being released into the air, but not gallons and very slowly over time. We heat with wood which makes the house pretty dry. The moist air here is almost instantly diffused so no problems mold and such. The bigger annoyance is dust. The filter won't catch it all. The room with the dryer will get dustier faster than the rest of your place. We only do this in the winter, as we really don't want the additional heat in the house in the summer. It helps to reuse the energy used to dry the clothes in the winter so we think there are green reasons for doing it, too.

I have no experience with the kind of dryer you cited and am puzzled by why it cools when not vented. I don't think that's a feature.
posted by Toekneesan at 4:59 AM on November 29, 2008

...if I do not have the dryer hooked up to the dryer vent, it does not ever get hot. It gets warmish, but not hot.

My guess is that the dryer is engineered with the assumption that the airflow through it will be restricted by friction/static pressure in the exhaust hose. Without that resistance, the blower is able to push more air through the dryer than the heating element is capable of making hot.
posted by jon1270 at 5:07 AM on November 29, 2008 [2 favorites has favorites]

I have a device on the dryer vent that allows me to choose between venting outside or venting into the house. I can vent inside when the clothes are nearly dry to save some heat. A good hardware store should be able to help.
posted by theora55 at 7:55 AM on November 29, 2008

These are fantastic answers! I will go to the hardware store and buy one of those flutter valves tomorrow. I am also getting the apartment complex to clean the vent on Monday.

Thank you for your help, everyone. For some reason searching for information on dryers on the internet is difficult. It took me four hours of searching online to find out precisely what the hose on the dryer is called and how to install it. And now I can stop their air from backing up into my house, too!

I will buy them a valve as well, and I will report back on how this all works out for me.
posted by winna at 1:01 PM on November 29, 2008

Getting the valve and having them come blow out the vent worked great!

They used a gas-powered backpack leaf blower, which I found an odd choice, but if it worked I don't suppose I can quibble.
posted by winna at 9:31 PM on December 15, 2008