Venting to the outdoors is important because it meets ALL dryer manufacturer recommendations.

Venting your dryer to the outside is IMPERATIVE! Indoor venting systems, such as lint trap kits are generally inadequate to handle lint accumulation. They MUST be cleaned constantly and if they are not, they pose a fire hazard. Venting into the attic or crawl space can cause indoor air deterioration and mold buildup.

A typical laundry load can contain up to a gallon or more of water. A few dryer loads would easily result in excessive moisture or humidity in the house leading to mold.
The additional humidity in the summer will make the space less comfortable, not to mention the extra AC load and the lint plugging the filters and AC coil.
Moist air and lint dust expelled into the laundry room will be drawn in by the dryer, causing long dryer times and possible overheating resulting in a fire condition.

If you do decide to try one of those indoor venting kits, I guarantee that who ever does the house cleaning will notice the excessive dust immediately.

do me a favor, wait until the temps are in the 40's or low 50's and start a load drying. after a few minutes, go outside and look at the water vapor coming from your dryer vent. do you really want all that dumping in the house? on top of that, it would ONLY heat when you are drying clothes, so 99% of the time it would be of no benefit.

there are 10,080 minutes in a week. if your dryer runs for 45 mins a load, 3 loads a week, then that still leaves 9,945 minutes that you are not supplementing your heat. not worth the risk to literally save a few pennies a month.

The cautionary notes above are valid, but I used to do this, and I know other people who vent electric dryers indoors with one of the lint trap kits, and I've never seen a problem with it. I've most often seen the ones that you fill with water - the dryer vent blows down toward the container of water and the water traps the lint. All you do is dump the water and refill with clean water.

You might find that there is more dust and too much heat/moisture, but you could try it for a few loads to see what you think. The vent kits are only about $10. One problem is you'll obviously have to maintain your current venting because you'll want to go back to that in the summer, so in winter you need to temporarily close off that vent pipe so cold air (and animals and other pests) don't get in. Those little plastic flaps on the outside part of the vent are inadequate for this.

All three answers bring up some pretty good points. It seems so inefficient to be letting that heat escape; even during the summer the room doesn't get very warm as it only gets a bit of early morning sunshine and it's downstairs.

I can't find a wattage rating in my manuals or on the machine. It's a Kenmore front loading machine, 220V. Let's assume it's using 3K Watts for 2 hours a week at $0.15/Kwh, that would only be $.90 a week. Maybe it's using 5K Watts for 3 hours a week and we are into the higher tier electric rate of $0.22/Kwh. That would be $3.30 a week. Either way it's not as much of a savings as I was hoping, considering the warnings of problems that you guys are giving me.

ky114, it's good to hear your counter opinion based on your personal experience. You write that you used to do this. Why did you stop?

My old house was much drier and draftier than my current one. In this house there is already adequate moisture, and generally I don't want more. But I still have that indoor vent kit, and on spells of very cold weather, like below 20 degrees for an extended time, sometimes I do vent it inside just to get the moisture and heat.

Try it! Just disconnect the vent line from the back of the dryer, attach a nylon stocking to the dryer vent with a hose clamp, and run a few loads.

When you have condensation dripping down the windows, when everything in the laundry room is damp, and you have dust-bunnies everywhere with a coating of gray grime on every flat surface -- you'll know why it was a rotten idea.

Just my two cents.

Who suggested running a dryer with a nylon stocking over the dryer vent?

you can try anything you want, my experience with venting the dryer into the water filled bucket didn't work out for me, the basement was damp to begin with, tools on my work bench started to get a coating of rust. Wasn't my house, only rented there but I stopped doing it. I guess is one of those things that combined with high energy costs, we try to make adjustments. We learn as we go, that doesn't make us dumb.

Okay, if you don't like the nylon stocking idea (it was a suggestion with little or no cost involved) go out and buy one of those dryer vent buckets that holds water in the bottom. Then try it! The end result will be just the same.

Do you have any information or experience to support that statement? I do to support what I said, because I did try it. It depends on your house, the weather conditions, how much laundry you do, etc. I have seen the indoor venting work quite well, and, as I said, I currently live in a house where it is less suitable.

Here is a link that might be useful: Indoor Dryer Venting Article

thanks ky114, nice article, not sure if I'll give it a whirl or not. I'm not overly concerned with the moisture, my dryer is in the bathroom which has a ceiling exhaust fan. I guess my biggest concern would be fiddling with the dryer hose, once in place don't touch it. Not sure how much benefit from my amount of drying it would give me, but don't it feel good on a cold night to keep some of that hot air inside rather then throw it away.

I don't think it's a great idea but you can experiment in your own house if you want to, but as a licensed contractor I wouldn't really touch it.

They do have inline dryer booster fans which Fantech sells which will come with a lint trap. You can direct the duct in the wintertime via a volume damper to allow the hot humid air into your return duct. Then I would assume you would have to change your filters way more often.

Think about what chemicals you are venting out from your dryer, the soap, chlorine, plus any clothing dye. Would you want that back into your breathing air?

I know in large facilities they will take their Boiler/Hot water flue gas and put it through a heat exchanger to warm or cool their system, which would greatly reduce the need of a compressor for a chiller or burner for a boiler. You can try something similar like that here, but that hot gas they are saving is a few hundred degrees, you wont have that with a dryer.

Here's another thing some people are doing which is similar. In cold climates, in places like supermarkets, they will allow the outside air to enter their freezers and refrigerators to save on electricity of running the compressors when it's below 20 deg or so. You can try that in your home in the wintertime, run a duct into your freezer with a outdoor temp sensor and to allow the damper to open up when it's in the teens.