Venting Down Sewer Question

M

Moonlight

Member
Ok i need help from anyone with plumbing experience. I want to vent down the sewer.


The soil pipe in our house runs down an outside wall, i can't connect a vent to the bottom of this pipe but i can cut into it in the attic (plastic pipe so no sparks). The pipe sticks out the roof i suppose to vent any methane that builds up. If i connect a vent to this pipe and blow air down into it, will i be risking anything? Are there any special precautions i need to take or do i just hook it up and turn on the fan, making sure to seal the system of course.

Any advice would be great.
 
ScrogThis

ScrogThis

Active Member
It's do-able. I'll pop back in w/ some pics a bit later, sorry for the "tease" but the wife is ready to go...
 
ScrogThis

ScrogThis

Active Member
Ok I'm back. These pics are from an old thread (circa 2001) and are not mine, all credit to OP.

Venting.pngVenting6.jpgVenting1.jpgVenting5.jpg

Hope that helps, I know it's not exactly what you are talking about but hopefully will give you some ideas.
 
M

Moonlight

Member
That is helpful thanks but that setup appears to be venting the air upwards instead of downwards. Venting upward won't do as i'm trying to get rid of the heat output. My concern is about the methane from the sewer no longer getting to vent out the roof and instead being blown back into the sewers.

I'm simply concerned about the safety of pumping a large volume of air down into the sewer, don't want to damage our plumbing or cause the neighbors trouble. Or worst of all have the council poking around in the sewer because it's broken lol.

Could you post the link to that thread you got the pictures from please, i did search but found nothing.
 
ScrogThis

ScrogThis

Active Member
Sorry, that particular site no longer exists, those pics are from my archives. You do not want to produce a back pressure in your sewer vents, your sinks and toilets won't drain well, not to mention the potential for odor and/or accumulation of flammable methane. This concept as you say is just using the plumbing vent stack to exhaust the air, it won't work the other way 'round. Are you looking to exhaust air/heat or trying to get a fresh air intake? The vent stacks serve two purposes; vent sewer gases out and as a vent to prevent a vacuum in the plumbing so the water will drain.
 
M

Moonlight

Member
Yeah looking to disguise the heat, nothing else. Sadly despite marijuana being the best medicine for a condition both my friend and i suffer from it's also still illegal where i am. So disguising the heat is really important.
 
ScrogThis

ScrogThis

Active Member
Understand. I have seen a number of threads that use the furnace or water heater vent to mask the heat signature (here and elsewhere) but I have no experience with that. Assuming you use a "Y" to introduce the exhaust I don't see why it wouldn't work just be careful not to create a back pressure that could extinguish the pilot or force carbon monoxide into the room. Maybe a flapper to prevent a back flow? Good luck!
 
motownklown

motownklown

Active Member
i was just recently informed by my attorney that the heat print arials are no longer admissable in court. they cannot use that as evidence to raid suspect grows.
 
DrFever

DrFever

New Member
i think it could work if you used a why Y if you went straight into the pipe it would block the lower gasses from leaving and it would be stopped by your heat entering pipe you need a Y pvc pipe and place it upside down that might work depending on amount of force entering pipe from your exhaust fan what im saying is the entrance of your heat must be vertical to the pipe not straight in you will dead end the gases
 
M

Moonlight

Member
The fan blows 183 cubic meters per hour so i don't think the Y piece will work. I'll have to figure something else out.

motownklown, that might be correct in your country but not in mine.
 
Pullin' weeds

Pullin' weeds

Well-Known Member
I've been venting out my house's soil stack for about a year now with 100% success. I've got a 3 in flex hose running from a small bathroom fan in my grow cab blowing into the sewer without any problem. Though my need is primarily for odor control - what better place to hide odor than in a shit pipe...
I guess it really depends on the size of your grow and the amount of air you need to get rid of.

vent-01.jpg
 
ItsJohny

ItsJohny

Member
only worry i could see if the smell when ur not running your system. Could smell like sewer, just when your not running it cap it or plastic wrap to seal it.
 
Pullin' weeds

Pullin' weeds

Well-Known Member
My vent fan blows 24/7 so it's not much of a problem. But if it were a concern, you could install a flapper valve - they sell 'em with dryer vents at home inmprovement places. Moving air keeps it open, but it snaps shut on any backflow.
 
woodsmaneh!

woodsmaneh!

Well-Known Member
Couple of things:

Forcing air into the vent pipe at the top could cause your pluming to not work right. Sinks will drain very slow if at all, toilet won't flush right. You need the vent so air can escape up the pipe for your pluming to work right.

Heat rises so some will come out the top of the waste pipe.

To much pressure will push the water out of the P traps and allow the gas into your house. Very bad.
Way to much pressure will toss all the water in the drains onto the floor. Very bad and Mom will be pissed.

If you use anything use a y not a tee. Position the y so it will allow the air to ride up the pipe and out the top.

The set up above looks OK as it it very close to where the waste pipe enters the ground and he has a constant air flow, your talking about at the top of the vent stack.

Low pressure is the key.
 
M

Moonlight

Member
The replies to this thread have really been great, thanks guys. I will have to sort something out, i'll do some more reading and see what i can hook up :) It seems the worst i have to worry about is sewer smell leaking into the house when i test things out.

woodsmaneh! - I don't have to worry about my Mom lol i dont' live at home. So i guess if things go wrong i''ll just have to clean it up and hope the landlord doesn't notice :P But thanks for the tips, it makes sense that pushing air into it higher up could screw the drainage.
 
Pullin' weeds

Pullin' weeds

Well-Known Member
My vent tapped into an existing screw-capped PVC fitting - a "clean-out". It's very easy to detach and recap and it looks as if it never happened. If you don't have a clean-out available, if you have any clue what you're doing, you can cut and splice one in pretty easily. I've done it for a different project - PVC is easy to cut and glue.
You'd have to be blastin a pretty good amount of air through your typical stack pipe before it would impact your plumbing. As long as your vent hose is not bigger than the sewer pipe, you're pretty golden.
 
solosmoke

solosmoke

Active Member
just to let ya know how that vent works ,its sucks air every time you flush your tolet and when just not in use the smell from sewer comes up threw pipe ,thats why its on top of house ,
 
M

Moonlight

Member
Looking at these last two replies, does that mean if i use a reducer for my outtake and feed it into the soil pipe that it will still function correctly? What i mean is that it would be a small pipe feeding into the large soil pipe and so the soil pipe would still be able to suck air from the roof vent when toilets are flushed, sinks are drained etc.
 
Pullin' weeds

Pullin' weeds

Well-Known Member
The reducer would be a possible problem point - When I said "As long as your vent hose is not bigger than the sewer pipe, you're pretty golden", I was assuming the same size vent hose from grow to sewer connection. Putting reducers in can create higher air velocities and pressure problems etc...
 
M

Moonlight

Member
I understand it would increase the velocity of the air but when toilets flush the suction of air must be pretty strong so i'm not sure why that would be a problem. If the soil pipe could still suck from the roof air while i also exhaust downwards into it then wouldn't the problem be solved?
 
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