Venting dryer directly downwards


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Old 08-30-13, 06:02 PM
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Venting dryer directly downwards

I need to vent my dryer through the floor. The floor is 3x6 T&G fir. Beneath that are joists, logs, and the river is 2 feet below the floor. So it really doesn't matter if I am venting moist air beneath the house. The wind will blow it away.

What I really want to know is: does anyone know of a termination which will allow the dryer to vent, but which will keep pests out? I can easily poke a hole in the floor and stick a duct down, but what do I put on the bottom of it? Standard dryer vent fittings are made to go through a wall and have a flapper that closes when the dryer is not running. That will obviously not work for me. Is there a nice fitting or should I just bend some hardware screen over the end and put a couple of screws in it?

Thank you.
 
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Old 08-30-13, 06:19 PM
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It would be nice to have some kind of fitting to not only keep out the pests.....but the cold air in the winter too.

Let me think.
 
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Old 08-30-13, 06:43 PM
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Drop the rigid duct through the floor, attach a 90 degree elbow so it is horizontal and then use a conventional dryer vent hood.

Do NOT use hardware cloth over the end or use sheet-metal screws as either will catch the lint and soon plug the duct.
 
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Old 08-30-13, 06:44 PM
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A dryer is not as bad as...for instance a bath fan with no flapper. The dryer will be closed when not in use and prevent air leakage into the house.

They make spring loaded terminations...but I'm not sure they would overcome gravity in that situation.

Why not bring it through and then turn it 90 degrees to horizontal? Plenty of flappers with hoods that will still direct the air down.
 
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Old 08-30-13, 06:55 PM
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It was my understanding that the more bends, the less efficient the dryer. I'm not so worried about cold air getting in. This is the bottom floor of a three story house and has just the utility room and a shop. And there is no insulation in the floor other than 3" of solid fir with tar paper and 1/4" plywood on top of it.

But yes, I guess I could bring it down and turn it 90 degrees. I'll need to find a really reliable flapper/hood whatever you call it, though because this is going to involve paying my skinny nephew to crawl under there and install it and I bet he won't do that twice!
 
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Old 08-30-13, 07:33 PM
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How about this: Eave and soffit vent. I learned some terms from your responses and did some searching and that looks like it might work. I can poke it through the floor from below, put stainless screws in the four corners and it should outlive me. If I need to clean it out, I can pull the hose off the top and stick my vacuum nozzle down there.
 
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Old 08-30-13, 10:31 PM
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That should do the job for you.
 
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Old 08-31-13, 02:38 AM
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I had this in my picture archives. Have installed them on a couple of houses, and they work pretty well. Just a variation of the soffit vent you proposed. I think I got them at big orange.

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Old 08-31-13, 04:02 AM
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Problem with that type cover is the same if you put wire mesh over it. It will build up lint and have to clean it.
 
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Old 08-31-13, 10:38 AM
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Yeah, that makes sense. And I won't have access to it except from the top. I think I'll stick with the safe and simple stainless one.
 
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Old 08-31-13, 11:51 AM
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It might be a bit of a hassle to construct but you could make a lint filter that was in-line with the duct and accessible from the laundry room. Use a wide open duct after the filter and let it rip. The filter would prevent any animals from using the duct as an entrance to the house.

Maybe get a lint filter from an old dryer at an appliance recycler and built a sheet-metal box to hold the filter. Have the duct from the dryer inter the box above the filter and the exhaust below the filter dropping through the floor with no obstructions. Clean this secondary filter every load or two through the dryer and once a year of so remove the filter and dryer duct and pass a duct-cleaning brush through the whole thing.
 
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Old 08-31-13, 12:31 PM
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I installed one of these for a client who wanted additional filtering prior to a fan boosted ejection system. He said the dryer filter worked OK, but this one caught everything else and was at waist/eye level for him to clean the filter, and see if it was dirty. Amazon.com: Lint Trap with TURN KEY LID FASTENING SYSTEM: Appliances
 
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Old 08-31-13, 12:59 PM
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I would have to see if I could find such a lint trap to buy because I don't have the tools to make one.

Edit: oh, I see that Chandler was writing at the same time as I was. That looks like just the ticket. So I could just put an elbow on the outlet side of it and poke a duct through the floor and not have to go under at all. That is a really great plan! Thanks.
 

Last edited by FatBear; 08-31-13 at 01:16 PM.
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Old 08-31-13, 01:16 PM
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OK, someone has to ask..... Why are you not looking to vent horizontally out a wall or even through a window with one pane replaced by wood with a hole in it? You have a utility room and shop, doesn't sound like you can do much to the aesthetics by adding a rigid vent pipe at ceiling height or even between the joists. Much less evasive than breaching a 3"+ floor over an active river. If it is block, you can rent tools to cut a hole and use a traditional wall vent with flappers.
 
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Old 08-31-13, 01:42 PM
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Nice product! Too bad it is discontinued.
 
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Old 08-31-13, 01:54 PM
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I have actually considered that, but it's not how I am going to do it. I live in a very rainy area. The siding is very heavy cedar, long boards, and I simply do not wish to breach them and I don't want the extreme hassle of flashing. There is no risk of water intrusion if I poke it through the floor, no siding to pull off and break and need to have re-manufactured because it is no longer made, no flashing to put on and still leak when I am done, etc.

Existing above the river is not nearly as scary as it might seem to a land lubber. :-) It just runs along down there, doing its own thing. The top of my floor is 24" above the water, so the bottom is still 21" above. The outer two logs of my float get a lot of overwash from wakes, but even out there no splashes reach the level of the decking. This vent will be more than 20' from the outer edge and so will never see a splash. If water ever goes up this pipe I have much bigger things to worry about!
 
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Old 08-31-13, 01:59 PM
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What a bummer!! OK, here's one in stock, but only 5 left Amazon.com: American Aldes Dryer Lint Trap: Home Improvement

Actually this one resembles the one we installed more, since it has vertical pipes, but I guess it doesn't really matter. Just turn it on its side.
 
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Old 08-31-13, 02:09 PM
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Discontinued is OK. I didn't know they existed at all. It got me searching and I can see that there are actual metal ones available, too. I will select one of those and everything will be fine.
 
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Old 08-31-13, 02:12 PM
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Hi Chandler. Postings crossed again. :-)
That looks perfect. I won't even need to turn it on its side and I don't think the door would work, anyway. I'll just put the dryer hose in the top and put a duct on the bottom and poke it through the floor. This seems like a very clean installation and very easy to do.
Thank you all very much for your help. I think we've got 'er nailed.
 
 

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