Bathroom Exhaust Line Tear

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http://www.bing.com/images/search?q=4%27%27+snap+lock+duct&view=detailv2&&id=383DCFF026A55F0F64115E8062EE0B0F7EAB0200&selectedIndex=7&ccid=%2fkx4xnxH&simid=607986508808257767&thid=OIP.Mfe4c78c67c473e97cb564593852e5429o0

http://www.bing.com/images/search?q=metal+duct+tape&view=detailv2&&id=37CA3F0981E2A688BC7895A77729A973799C2928&selectedIndex=7&ccid=BJjEm5h2&simid=608018549255570892&thid=OIP.M0498c49b98768a417b22871a6446419ao0


http://www.bing.com/images/search?q=duct+crimper+tool&view=detailv2&&id=ABC4C8B272250ABC39311BBC6831A98ED41BE4A1&selectedIndex=10&ccid=4oygT29L&simid=608039994025512691&thid=OIP.Me28ca04f6f4b629b0ce62711e768dbc1o0


http://www.bing.com/images/search?q=duct+insulation+wrap&view=detailv2&&id=2DEA4C91B0DBB85957DBBE879B5781018B0531DE&selectedIndex=0&ccid=EL1X7Mtf&simid=608006871246505438&thid=OIP.M10bd57eccb5fc1c95e2dd9bcdedd0af8H0


the above items, snap lock duct
hvac metal tape
crimpers
insulation
use these items, to run that exhaust vent, what you curently have is not ment for what it is being used for

that is a dryer vent,,
 
It's been over a year and half since I posted on this thread. This project still isn't completely done. I know that's bad but hey, what can I say....life happens.

I thought I'd give some updates however. The flexible foil venting I installed was still intact when I revisited the subfloor but I decided I only wanted to do this once and do it the right way even if it was a little pricey. So I actually followed some of the possible "overkill" advice and the last post from frodo above. I already started installing rigid duct. And so far it has gone ok.

But there is a very important thing that I encountered when I started running this duct and this was just basic logic about the air flow. With rigid duct, the way you run the duct does make a difference. By this I mean, the crimped end of each pipe segment should be in the same direction as the air flow because otherwise, there is a higher chance of leakage at the joints. I figured this out a little under halfway through after I had already run the pipe ends in the wrong direction and so I had to cut off a crimped edge I made manually on the small piece of pipe that exits my house and basically start over.

Will add pictures later.
 
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thapranksta said:
It's been over a year and half since I posted on this thread. This project still isn't completely done. I know that's bad but hey, what can I say....life happens.

I thought I'd give some updates however. The flexible foil venting I installed was still intact when I revisited the subfloor but I decided I only wanted to do this once and do it the right way even if it was a little pricey. So I actually followed some of the possible "overkill" advice and the last post from frodo above. I already started installing rigid duct. And so far it has gone ok.

But there is a very important thing that I encountered when I started running this duct and this was just basic logic about the air flow. With rigid duct, the way you run the duct does make a different. By this I mean, the crimped end of each pipe segment should be in the same direction as the air flow because otherwise, there is a higher chance of leakage at the joints. I figured this out a little under halfway through after I had already run the pipe ends in the wrong direction and so I had to cut off a crimped edge I made manually on the small piece of pipe that exits my house and basically start over.

Will add pictures later.
Click to expand...

Oops, it not the kind of thing the pros will think of saying, good catch.
 
I am still deciding on whether or not I need to add insulation. Also it is a long run and there will be at least 8 elbows (which seems like a LOT) using the existing route the plastic flex followed through the i-joist webbing. I am using sheet metal screws and aluminum tape to secure each joint.
 
That's way too many elbows!
There's going to be almost no air flow.
Figure out how to run it a different way to make it a shorter run.
 
I had a feeling that might be the case. I will take some pictures tomorrow hopefully to show what I have so far before I go the route of ripping a lot of stuff out. If I do try to eliminate the elbows I will have to cut some more holes in the I joist and possibly seal some of the existing holes. I am aware that there are certain rules to follow as far as size and how far apart the holes can be from each other. Sigh...
 
If you can find the makers tag for the joists, they will supply instructions for hole but they are all similar.
[ame]https://www.youtube.com/watch?v=mndPt8qV5wg[/ame]
 
Pictures of current state of things as mentioned before:

Best shot I could get of run I already installed
IMAG0745.jpg


Where vent exits
IMAG0746.jpg


a mid point in the run
IMAG0747.jpg


current end
IMAG0748.jpg


As mentioned before, it would be 8 elbows with the current plan I have. The total estimated length of the completed run is ~25 feet. The longest run is 10'8'' and the shortest would be right where it connects to the bathroom fan box because it is a sharp angle - 2 90 degree elbows put together. Looks like I've got some more undoing and planning to do. Hopefully I can re-use a lot of my bad connections thus far instead of going to buy more new duct. I also hope I don't have to open up more subfloor.
 
Elbows are "adjustable" from 0 to 90, and using them as close to "0" as you can will reduce their limiting effect upon air flow.

You can accomplish this by the appropriate elongating of the holes in the joists, thereby eliminating elbows.
 
OK. I think I follow. I have two possible plans right now. One of them has 6 joints with angles of 45 degrees or less. The other plan has 5 angles but one would be a 90 degree.

Neither plan really eliminates 90 degree turns altogether because I basically have to turn 180 degrees to reach the fan box opening. I am just widening the curves. I am not sure if rotating the fan box is feasible but it doesn't seem like something to fiddle around with.

I am leaning toward the first plan with 6 joints of 45 degrees or less and leaving the fan box as is.
 
What about the possibility of changing the exit to daylight? Is there a straighter option? Just thinking out loud.....
 
Unfortunately, there isn't a straighter option without ripping up a good bit of subfloor and also cutting out rim board and siding. Also would have to pull up carpet and padding in a bedroom. This would change the exit to the rear of my house (vinyl siding) instead of the side (brick). Then there is no telling what I will encounter as I have learned so far.
 
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Your plan A will decrease the resistance, IE., back pressure, also, if you have the room, use 2, 45's instead of a 90, for the 90 degree change.
 
The bathroom is on the first floor which means I'd have to get it up through the 2nd floor and to the attic to run it vertically. There is a wall cavity near where the vent fan is housed but if I am thinking about this correctly, a 4'' pipe will not fit in a wall cavity because the max depth is only 3.5'' because of the 2x4 studs. Sounds like it is some questionable code stuff with that as well. :p Edit: I guess I could always just leave the pipe completely exposed instead of routing through the walls even though that isn't aesthetically pleasing.

I have been implementing Plan A and reduced 4 of the 90 degree joints into two 45 degree joints by taking a more direct path diagonally. I'm not done yet obviously but near the bath fan box, I plan to make the widest bend I can make within the joist bays to make a 180 degree angle. That will be four 45 degree joints (to make two wide 90 degree joints) and a couple of short straight lengths. This is how I came up with a total of six 45 degree angles Snoonyb. I wish I could make a graphic or something to give a better idea of what I mean because I can't take pictures of the entire length.
 
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I have the whole pipeline complete and just about finished adding insulation except I realize that I have not overlapped the insulation anywhere. I just have coverage on all the pipe except the elbow joints that go through holes in the joists.

Do I need to overlap the insulation? It seems like this would be more of an issue if I was venting through the attic instead of under the 2nd floor of my house but I have no idea how much temperature variance happens there. This room is not over the garage though which I know is a problematic area.

Please tell me I don't need to start this over again. *face palm*
 
Yep. I am taping the seams. Practically every seam has sheet metal screws as well as tape.

I am using two types of insulation - fiberglass and self adhesive.

IMAG0834.jpg


IMAG0827.jpg



Edit: Kinda hard to capture the whole run especially since some of it is hidden by subfloor but a couple more shots. I have to go back and make sure that seam in the first picture has tape.

A snake through joist
IMAG0839.jpg


At fan box
 
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