How can i blow water out of a 3" pvc pipe?

[tireshark]

A friend has a dryer vent that exits too close to the ground, and got water in it. When you turn the dryer on, you can hear gurgling in the pipe. It's a 3" pvc line.

What's the best way to do this? I'm assuming i need a 3" cap, and then somehow drill a hole in the middle, or something, and attach a fitting so that an air compressor will blow the water out?

Thanks!

 

[Matt30]

I would be surprised if you were able to build enough pressure to blow out water. Chances are you would blow a seam out of the pipe before that happens.

How long of a run? Could you reach it with a wet vac? It's just ventilation pipe, take it apart to get the water out if you need to.

 

[Chris]

How about shop vac a string through it the tie a rag on one end and pull it through? I shop vac strings hundreds of feet through five inch line all the time, I usually tie a little piece of a plastic bag to it to help suck it through.

 

[frodo]

send a mouse down the pipe with a wet vac and some paper towels.

then put a snake in there to get the mouse out.

if the snake will not come out, stick a hose in the pipe,,,he will come out then

or,,, do as chris suggested..tie a string on a towel,,,pull it thru to dry it out.

maybe the mouse will take the string to the other end for you

 

[tireshark]

lol frodo.

Thanks for all the input guys, here is what happened.

First of all, here is a pic of how the dryer vent was when i saw it:

I dug it out, and discovered that the actual vent pipe was about 4 inches below ground level, and that someone had placed a couple of 3" PVC bends to bring it up above ground level.

The problem was that the vent pipe was actually smaller than 3 inches, so the PVC fittings couldn't make a proper seal (they had tried to use canned foam to seal it), and mud, water, and lint had completely plugged up the vent pipe.

here's the vent pipe clogged:

and after i cleared it:

all of the backed up water immediately flowed out, so at least it has some slope to it.

After the initial water flowed out, i was still left with a mess inside the pipe as it still had a lot of mud in it. I tried 3 different snakes and finally got it all the way through (it had 2 90 degree bends to get up through the floor) with this big metal tape that thankfully my dad had acquired some time ago:

Anyway, i ended up tying some rags to it and running them through the pipe to clean it out. I pulled a rag through the 90 degree bends twice, but then stopped because i was afraid the rag was going to come off and get stuck in there. After that i just ran them up the straight section and back out to clean it out. Sprayed a garden hose through it both ways, and after a few hours of doing all this i finally got the water to run clear.

Both the homeowner, and myself, are scratching our heads as to why anyone would route a dryer vent below ground surface. Also scratching our heads as to why the home inspector okay'd it when she bought the place.

Anyway, i'm trying to think of a way to seal this pipe somehow... but like i said it isn't a normal 2" or 3" pipe... it's sort of halfway in between, and the 2/3" PVC fittings dont fit properly. All i can think to do is to put the 3" fittings back on it, stabilize it somehow, and then just smear silicon all over it to fill in the gaps between the vent pipe and PVC fittings.

I told the homeowner that long term it is a pretty lousy solution, and will probably fail again (unless anyone knows a way to seal it really well), but it will at least let her use her dryer again. My thoughts were that if she wanted it fixed long term, they would probably have to install a new exhaust out the top of the roof or something.

Thanks again!

 

[Matt30]

Glad you got it, I didn't notice it was pvc, I've never saw that on a dryer vent before.

Ideally that pipe wouldn't come thru the foundation, but the side of the house thru the siding. That way you get it out of the cold ground where come thin like that could freeze, and eliminate an elbow

 

[Matt30]

I think maybe you can't find fittings for that pipe because you are using the wrong ones. That's not regular schedule 40 pvc, that's sewer pipe. You have to use fittings for that application.

 

[frodo]

they use 4'' pvc around here all the time Matt,

we run them under the slab.

but..we only use 1, 90

we butt a coupling against the form board ..just under the concrete, 90 up just outside the wall. in the corner, behind the dryer

when we trim the house..install a vent cover over the coupling

 

[Matt30]

How do you adapt to the dryer though? They have a sheet metal connection

 

[tireshark]

Interesting Frodo... so if you guys install it, maybe it is an approved method here as well.

I think maybe you can't find fittings for that pipe because you are using the wrong ones. That's not regular schedule 40 pvc, that's sewer pipe. You have to use fittings for that application.

Any special name for sewer pipe fittings or anything? Maybe i will cut off a small section and take it to a plumbing store to see if they have anything that fits it. I tried to measure it, but it's cut off really uneven and it was hard to get a good measurement. Seemed to be between 3" and 3 1/4" inside diameter.

 

[Matt30]

It's pretty well just referred to as sewer pipe here. When I order it at the wholesaler its branded as SDR29 or SDR35....the numbers just indicate a higher pressure ratings. The fittings for sewer pipe are different. There's a sleeve to transition to sch40 pvc, but sewer pipe will use the same solvent

 

[Matt30]

Also from the picture that pipe looks a bit ovaled. Be sure to check that out while you have it exposed.

 

[Chris]

The thickness looks like sdr35 but I have never seen 3" SDR. Sdr26 will have a thicker wall and is intended for deeper 15' + situations. SDR 35 and 26 fittings fit either pipe as the OD is the same.

 

[frodo]

How do you adapt to the dryer though? They have a sheet metal connection

drop the flex into the pipe and silver tape


on the outside...use a dryer vent rough in..cut off the metal part that goes thru the wall...except for a inch...stick it in the pipe...tap con to wall


4'' sdr 35 fitting will fit into sch 40 pipe

 

[Matt30]

Right fancy! All residential dryer venting is 4" ridgid vent pipe here.

 

[frodo]

it works out pretty slick..IF your foundation walls are above the finish grade

the end of the pipe gets a coupling,,duct tape..and strapped to the form board.

after form is stripped. you can see the duct tape.. add what ever you need

like for brick, or stocco, or just a skim coat

we always used sch 40..because that is what we carried on our trucks.

same thing is done for the AC line set and condensate drain..

4'' pipe to the ac closet stub up using a 45..

we also..install closet rods...because its pipe..

3/4 galvinised if closet is 5' or under..1'' if over 5'

 

[tireshark]

I think maybe you can't find fittings for that pipe because you are using the wrong ones. That's not regular schedule 40 pvc, that's sewer pipe. You have to use fittings for that application.

Just for an update, you were right. Cut off a section and took it to a plumbing supply store and they had sewer pipe fittings that fit it perfectly. Apparently the 3" sewer and drain pipe is smaller than the regular 3" pipes you find in the retail stores.

Thanks again.

 

[Matt30]

Just for an update, you were right.

Oh my....air is gettin thin up here!

Glad it all worked out.