View Full Version : Moving some vents in my attic

Chris Padilla
01-15-2008, 1:44 PM
So I'm FINALLY (!!!) getting my new roof. Roofers come tomorrow to tear off; weather is finally cooperating.

Once the cathedral ceiling roof sections are gone, the insulation remover guys will suck/pull out any insulation in the rafter bays.

During all this, the expanding insulation spray foam guys will be in my house filling up stud bays in my living room and the crawl space under my house.

When the roof rafters are clear, they will fill those up as well.

During all this, the solar pool heater guys will be on the uppermost roof roughing in some plumbing and brackets for their install after the roof is done.

Some day down the road, I want to put up PV (photovoltaic) solar panels for electricity generation and this brings me to my question (FINALLY!!!).

I have a 1.5" and 2" vent that I wish to move in order to get them out of the way so that PV panels can be installed more easily and cleanly.

My roof pitch is 3:12 or 15 degrees (as the industry claims but do the math and it is 14 degrees) and I want to move the vents higher up on the roof as close to the crest of the roof as possible.

Basically, I'm looking for some plumbing fittings that give me a 75 ( or more correctly a 76) degree bend but, of course, no such puppy exists.

What we do have are 45, 22.5, and 60 degree bends out there. Or as the industry likes to call them: 1/8, 1/16, and 1/6 bends, respectively. Of course, there are 90 degree ones, too, or 1/4 bends.

So I need to combine these to get me close to 76 degrees so that I can take my vent and run it up along/near the top of my attic before it exits.

22.5 and 60 get me 82.5 (6.5 degrees too low)
45 and 22.5 get me 67.5 (8.5 degrees too high)

Now I realize there might be some code issues with this but I don't care; I'm moving the vents; no one needs to know about it 'cept you fine folks here at SMC. Besides, I honestly don't see how adjusting the vents will hurt anything in the least. They are being moved higher up the roof.


David G Baker
01-15-2008, 2:00 PM
I am assuming that you are talking about drain vents. If you aren't worried about code I am sure that there is some flexible material out there in the size you need that could work for you. Check with an industrial plumbing supplier.

Chris Padilla
01-15-2008, 2:19 PM
Yeah, but I gotta get it done TONIGHT!! haha The borg is it for my supplier. I've seen bendy/adjustable angle PVC fittings but only online so I'm gonna have to go with the fixed ones for my little project. I'm not totally worried about code but perhaps just a wee bit enough to not do something really dumb. ;)

Yes, DWV: ABS schedule 40 fittings.

Matt Meiser
01-15-2008, 2:28 PM
I could swear I've seen 15 and 30 degree bends in PVC. Not sure if you can transition between the two. I've also found there to be a lot of play in PVC where you could get at least a few degrees either way. Finally, there's flexible rubber connectors with hose clamps usually intended for repairs.

Chris Padilla
01-15-2008, 2:34 PM
Yeah!! That is true...the flex rubber fittings! Shoot, I even used that on my last big plumbing project and plumb forgot about it! A 90 degree fitting could probably be bent up or a 45 bent down...something.

However, I'm with you, Matt. I thought for sure I'd seen 15 and 30 degree bends before but a search online didn't yield what I thought I thought. :(

You are also further right in that you can bend the fittings/pipe a wee bit one way or the other. I'm just trying to decide if I should bend it up a wee bit or force it down a wee bit (assuming I stay with hard fittings).

Rob Russell
01-15-2008, 2:49 PM

It seems to me that I've heard about plumbers heating the PVC so it's soft enough to bend. Use a heat gun, not a blowtorch.


Tom Godley
01-15-2008, 3:15 PM
I have what is called a "heating blanket"

I use it for the gray electric plastic conduit (for THHN) -- you wrap it around the pipe and it heats the pipe to a point that it bends. It allows you to make offsets and turns without any thought of the angle.

They do make them for larger pipe -- mine is only good for max of 1.5 or 2 inch.

Before I bought it I used to use my propane grill :O'

I have never tried this on dwv pipe -- I would think that is what you are using. But I know you can bend it because I have seen it listed in the charts for the different size blankets.

If I was going to try to do this I would use a section of pipe wider than the grill that way you can control it with the solid ends. You do not want to over heat the pipe -- mid rare is best -- otherwise it will flex all over the place.
Also you want to turn the pipe as you heat it -- It will heat up faster than you think.

Chris Padilla
01-15-2008, 3:37 PM
Hmmm, I have a nice Milwaukee heat gun that could be fun to play with.

I would need two bends...one from the original vent pipe and one to pop back through the roof.

I just don't think I have the time for that kind of fun...I've got to get this thing done and get the living room cleared of crap. I'll be bailing from work a bit early, too.... :)

Matt Meiser
01-15-2008, 4:11 PM
I just don't think I have the time for that kind of fun...I've got to get this thing done and get the living room cleared of crap. I'll be bailing from work a bit early, too.... :)

No, but getting a 10 degree bend in the middle to straigten things out shoudn't be to difficult, if you need. I've done it in 6" pipe, but I used a propane torch to get enough heat into it quick enough.

Randy Cohen
01-15-2008, 4:26 PM
you can cut a fitting and i think you could end up with the angle you need.

Reed Wells
01-15-2008, 4:46 PM
Chris, Try this site, this guy really knows what hes talking about.

Chris Padilla
01-15-2008, 5:13 PM
Yes, I recall Bill's pages on bending/forming PVC but that page isn't coming up for me. I still think I'll just go with some fittings and call it good. :)

Greg Funk
01-15-2008, 6:28 PM

I assume you are using the black ABS pipe. I think you are overthinking this exercise. Using a 22.5 and a 45 you will have 4 hub and socket junctions. There is a fair amount of slop in the fittings and you shouldn't have any problem at all adding a couple of degrees extra at each junction. Alternatively you could use a 22.5 and a 60 and twist them a little. I may not be explaining this properly but it is a similar principle to adjustable vent fittings.


Ben Grunow
01-15-2008, 8:59 PM
Chris, put a 90 on the stack so it faces horizontally (so a pipe placed in the outlet would be parallel with ridge ) and another 90 in that and swivel it up to the 15 deg (or 14) angle.

You could/should combine those vents into one 3" pipe so there are fewer roof penetrations.


Chris Padilla
01-16-2008, 10:41 AM
I overthink everything...just my nature! ;)

I went with a 22.5 and a 60 degree fitting to create an 82.5 degree fitting...worked fine and there was enough slop in the fitting to adjust things decently.

I meant to take some pics but I had a lot to do yesterday evening and forgot to take them...will do tonight.

Your idea, Ben, also would have worked out quite nicely and I didn't think about it! Lottsa ways to skin this cat and I thank everyone for their thoughts.

I'll post a few pics later on since I know y'all are itchy to see how it turned out. ;)