Replies

1. 
   G.LaLonde | Apr 20, 1999 09:35pm | #2

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   Glenn, Another way that I use quite often is to install the rectangular shaped units with the long slip joint and a 4" hole on the top and bottom of the unit for the inlet and outlet connection. It fits easily in the 3 1/2" space of a 2x4 wall and is adjustable for height. I like to run it through the bottom wall plate and connect the 4" round vent pipe to it below the floor joists and then run it parallel with the joists and through the outside band joist. It is especially handy if you have an exposed or accessible ceiling so you can take it apart periodically and make sure it is clean and free of lint.

2. 
   Gilly_Bear | Apr 20, 1999 09:39pm | #3

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   All that heat just flowing to the outside. Has anyone come up with a safe way to capture that heat and redistribute it. It seems like an awful waste of energy. Everytime I see that cloud of vapor coming out the side of the house, I try to invent a capturing device for all that expensive heat. Is there anything available now that can sefely do that job? Am I trying to reinvent the wheel? Any info will be welcomed. GB

3. 
   Guest_ | Apr 20, 1999 09:44pm | #4

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   Glenn:

   Just installed a laundry room in an interior space this summer.

   We built a chase out of dry 2x2's, ran 4" aluminum dryer vent up through the chase, made a couple 90's, and through a roof rafter to the eaves.

   Here are a couple tips:

   1. Length of run. If the run gets over about 16 feet, there will be a lot of static pressure in the tube. You may want to install a helper fan similar to a downdraft kitchen exhaust fan. Otherwise the dryer will back up, you will smell gas, and suffocate the family if it is a gas dryer. Graniner has those fans. Check it out.

   2. The aluminum flex is easy to install, but I would make all the straight runs in 4" PVC. It is straighter, more sturdy, and has less ridges and less resistance. If you you use aluminum, I'd cover it with plywood so nails won's puncture it.

   3. Consider 2x6 wall to hold the duct. I would put in a 2x6 or even a 2x8 wall. It could have held neat built ins, drop down ironing boards, and the plumbing (waste and supply) for the laudry facility.

   4. If the laundry facility is in a second floor, install floor tile and a 2" floor drain, for overflows.

   5. We didn't install an auxilary lint trap, but I like Brian's idea.

1. 
   Guest_ | Apr 21, 1999 12:07am | #5

   *Gilly: That same lost of energy has always bugged me too. IF you have an electric dryer and are in a cold climate, you could run the exhaust staight into your house in winter (when you want both heat and humidity) after running it through a good filter (like for a whole-shop vacuum system? - like the inside panel saw at Home Depot). If you have a gas dryer DO NOT try that. There's CO2 and CO that you've got to get out of the house. Any heat exchanger of any efficiency would present a lot of pressure drop to the outgoing air and those little fans are already taxed to get the air through 20 feet of straight pipe. In addition to beefing up the existing fan, you'd need a fan for incoming air (approximately equal flow). Or you could run the outgoing air through a large "radiator" of sheet metal to disipate heat back to the room. It ought to have a provision for draining condensed water out the bottom and would also require more ummph from a booster fan. But you could skip the incoming air stream. You'll also want easy access to clean out the lint that builds up inside. -David

1. 
   Guest_ | Apr 21, 1999 12:34am | #6

   *To add to Scooter:Most dryer manufacturers will detail their venting limitations in their instructions. Look for maximum runs and heights. I believe that bends also cost so many feet each. A fan that claims to be able to handle dryers is made by Fantech (at http://www.buildingshowcase.com/fantech/). The FX series has a kit with a pressure switching system for dryers. Though Grainger and local plumbing suppliers can provide the fan, I found the best price through Park Supply Company (http://www.parksupply.com/) for my own Fantech bath fan. These fans are also limited in how close they may be to the dryer, so as to not affect dryer performance and safety, so this is another factor to consider. The biggest problem with using four inch PVC drain pipe is that it doesn't transition to ducting very well -- incompatible inside and outside diameters, so locating adapters can be a challenge. Otherwise, it's very smooth, rigid, and easy to work with. I used the green variety (not sure what schedule that is), as it's thinner and lighter than the white.Sorry David, but I wouldn't consider venting any dryer into the house, even if it's filtered. What's it carrying, after all? In my case it's a ton of moisture and the smell of Downy fabric softener. Have you done this yourself? Too much humidity has replaced too little as a typical winter malady since we've been sealing up our homes over the years. A whole house humidifier is a rarity in my part of the country -- not even sold anymore in home improvement stores. I tend to believe that any system that effectively recaptured the heat from dryer exhaust also wouldn't be economically feasible.

1. 
   Guest_ | Apr 21, 1999 03:47am | #7

   *Don't under ANY circumstances consider using flexible plastic vent in any closed space (wall, chase, etc). Always use PVC or metal with an adequate way to clean out the lint.Within the last year here in the Milwaukee area -Dryer vented with flexible plastic in a closed space accumulated years of lint - wife started a load of clothes drying late in the evening and the family went to bed - fire started and by 2 AM a family of four was dead and cremated.

1. 
   Guest_ | Apr 21, 1999 03:56am | #8

   *Don't know about everywhere; but in cold country, like your Alaska David, and places like CO venting a dryer into the house is frowned on because of the moisture. My experience supports that. Took the vent off, put a really good filter on, and within a few days the house was really wet. If I had continued there is no doubt in my mind there would have been moisture damage to say nothing of the mold and mildew.Also, want to be sure the dryer and bath vents actually go to the exterior of the house. Had a job repairing a house where the builder vented into the roof cavity and relied on that ventilation to get the moisture the rest of the way. Maybe he thought he would get the repair contract, who knows?

2. 
   Guest_ | Apr 21, 1999 04:27am | #9

   *Scooter et. all:For longer dryer vent runs could 6" duct pipe be used to relieve some of the static pressure?TIA

4. 
   Tom_Laing | Apr 21, 1999 06:37am | #10

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   Glenn

   If you've got access to a copy of the '97 UMC, check out section 504.3, 3.1 & 3.2. It requires smooth, metal ducting (if over 6' in length); an installed backdraft damper without screening; no screws in duct connections. It specifically says that the duct should not extend into or through ducts or plenums. (Sounds like others do this, though.) Unless otherwise permitted by the manufacturer, total duct length may not exceed 14', including 2, 90 degree elbows. You have to deduct 2' for every elbow in excess of two.

   Absolutely, no flex or plastic ducting in walls!!! And it's better if none of it is in a wall. Do you have a crawl space? That's the route of choice.

   In response to the comments on venting indoors.....I tried it years ago and my windows just rained moisture. It's just too much without some kind of controls. I, too, would be worried about mildew and mold in hidden places. And a "second" to venting clear outside the building. I've inspected a couple houses that had dryer and bath too close to the soffit vents and was causing mildew and mold in the attic where the exhaust was being sucked right back into the roof cavity.

   Tom Laing

5. 
   Guest_ | Apr 21, 1999 06:44am | #11

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   If the utility room is to be over a crawl space back the dryer up to a 2x6 plumbing wall if possible. I usually use a standard 4" 90 to get below the floor, then pitch the pipe just like waste lines. This can be done between joists and go out through the rim, or drop down below the joists and be sure to leave a block out in the foundation.
   The piping should always be pitched like plumbing waste lines because of condensation. I once made the mistake of installing flex pipe in a crawl space and it produced enough water to make the pipe sag to the ground.

1. 
   Guest_ | Apr 21, 1999 12:57pm | #12

   *I agree that dryer exhaust will smell fruity and perfumey if you're into that kind of scented detergent and scented Downy fabric softener. We only get the unscented stuff. To each their own. And I also agree that in a very tight house, build up of moisture can be a problem. But when it's 10F, much less -40F outside, it gets wicked dry in the place we're currently in. Nasty static sparks when the dog runs between my legs and the towels dry as fast on a chair as they do in the electric dryer. Unlike a humidifier running all day long or a pot of water on the wood stove, the dryer-as-humidifier has the problem of often being 4 loads at once, once a week. For our place and it's 1,800 pounds of indoor air, you'd like about 18 pounds of water in the air (50%RH at 65F). One or two dryer loads would provide that. More would be too much. No, I haven't done it. I try to address the low humidity with hot showers without the bathroom fan, pasta pots left uncovered while cooking and towels and sheets line-dried inside.Economically feasible? You spend 60 cents of electricity on each of 4 loads a week. And could recover 50-80% of that in a HX or 90+% by direct venting. $100/year is worth the parts if you don't count your labor to design, source, and install it. Also the time to switch it back to the outside vent when the humidity is already high enough.Definitely not for everyone. Actually, only for those few who need the moisture, want to tinker, and keep an eye on it. -David

1. 
   Guest_ | Apr 21, 1999 01:08pm | #13

   *Yes, Matt. Going up one pipe size allow dramatic longer runs, and/or less back pressure. If 16 feet of 4 inch is allowed, 110 feet of 6 inch would give the same back pressure. I've used that trick to get the vent out from under a newly installed deck to avoid condensation under the deck. But the larger diameter is more prone to the lint settling out. Not as air velocity to keep it moving. Also the more it cools before the end of the pipe, the more water will condense and help form a pulpy mass of soggy dryer lint. As short, straight, smooth, and metallic as you can make it.

1. 
   Guest_ | Apr 21, 1999 08:49pm | #14

   *Thanks for all the responses. Venting into the house was never an option as we live near Houston and the humidity is more than "sufficient"(it down right sucks). Not sure what type of foundation the new house will have but would like a crawl space for accessibility. Never thought of going up with a duct because I didnt figure it would push the weight of all that lint and moisture. I like the idea of going through the slab or into a crawl space though. If using metal duct and going into a concrete slab would the concrete have an effect on the duct as far as rotting it out? Also what is a backdraft damper? Thanks again for all the comments.glenn

6. 
   Tom_Laing | Apr 21, 1999 09:12pm | #15

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   A backdraft damper, in the case of a dryer vent, is that, sometimes, useless flapper that comes as part of the vent hood that mounts on your outside wall. There area various models available. I'd suggest getting the best. There's one type that is activated by the dryer exhaust lifting up a lid-type apparatus that flops back down when the dryer shuts off, making a pretty positive seal against air coming back into your house. In Houston, this may not be such a big deal. Here in Alaska, it is.

   Tom Laing

7. 
   Guest_ | Apr 22, 1999 02:34am | #16

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   glenn,
   If you would rather use metal pipe and are worried about corrosion first I would be sure it was galvanized pipe. Where the pipe contacts concrete I would wrap it with visqueen or sleeve it with pvc pipe of a size that would fit over the 4". I live in Louisiana and assume construction methods in Houston are similar. Your slab on grade will probably be only 4" thick and the only places the concrete will contact the vent is where it penetrates the slab and/or crosses footings. If your pocket book is deep and you are worried about corrosion buy 4" stainless steel or copper pipe. Even though CABO may not allow it I have seen both dryers and Jenn air stoves vented through slabs using pvc pipe. Im skeptical about the stove though. You could also run the flexible 4" aluminum dryer vent through a 6" pvc pipe but this could get costly especially if the run is long. Oh well if it were mine I would go the pvc under the floor.

1. 
   Guest_ | Apr 22, 1999 03:08am | #18

   *I've seen a device just for this purpose in a catalog once. It has a filter in it to filter out the lint. It also had a flap in it so you could change back and forth from sending it all to the outside or keep it inside. Sorry I have no idea what catalog I saw it in........

8. 
   Guest_ | Apr 22, 1999 03:08am | #17

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   I have been looking at house plans to get ideas on designing a house. I have noticed that in some plans the clothes dryer is not adjacent to an outside wall. How would a vent be installed in a situation like this? Thanks for any info.

   glenn

1. 
   Guest_ | Apr 20, 1999 09:14pm | #1

   *we have built chases around dryer vents and vented them through utility rooms, closets, etc if that is the only obstacle. Have also seen dryers vented under the slab using pvc sch 40 pipe. you can also vent upward thru the wall but i beleive this could be a fire hazard if you dont keep the lint cleaned out that settles back to the bottom of the pipe.hope this helps