# Venting



## Nestor_Kelebay (Jun 17, 2008)

The toilet doesn't get vented. It discharges directly into the vent stack, which is the main pipe that all the other vents connect to. In the event that you add a toilet in your basement rec room, then the plumbing code won't require that you provide venting for it because that would require cutting big holes in the walls of your house up to the roof to put in an auxilliary vent stack. In a case like that, the code only requires that you connect the toilet's floor flange to the main drain line from the building.

The drain pipe diameters needed and the distance vent connections can be from the drains is best gotten directly from your local plumbing inspector's office. Normally they'll have a kiosk there with brochures with drawings outlining do's and don't of drain pipe and vent connections. Phone ahead to make sure they have such brochures to ensure you don't make the trip for nothing. Typically, the code will require a 1 1/4 inch drain for the sink, a 1 1/2 inch drain for the bathtub and a 3 inch drain pipe for the toilet. But, if it wuz me, I'd use 1 1/2 for both sink and tub.

Also, if you have the option, run 3/4 inch lines from your cold and hot water supplies to the bathroom, and tap off of each 3/4 inch pipe with 1/2 inch diameter pipes to each fixture. Since a 3/4 inch supply pipe can supply full water flow to two 1/2 inch pipes simultaneously, there won't be any change in temperature in the shower if someone flushed the toilet in the other part of the bathroom.

The purpose of venting is apparant to anyone who's ever been in a subway station. When the subway train leaves the station, you get a strong wind into the tunnel behind it. Similarily, water draining down a drain pipe can create a partial vaccuum behind it. This partial vaccuum can be strong enough to suck the water out of the p-traps below your sinks and bathtub. If that happens, then sewer gas can come into your house through those empty traps making your bathroom smell like an outhouse.

The purpose of a vent is to allow air to rush into the drain pipe whenever there's a partial vaccuum at the vent pipe connection. That quenches the vaccuum and prevents the water from being sucked out of the p-trap. Thus, the vent connection has to be at the upstream end of the drain pipe, but still downstream of the p-trap.

Sometimes you really can't connect a vent to a drain pipe. For example, if you have a sink on a kitchen counter top island, you don't want to see a vent pipe coming out of that counter top surface and going up into a hole roughly cut in the ceiling. In a case like that, you'd use an AIR ADMITTANCE VALVE instead of a vent pipe. An air admittance valve is nothing more than a big plastic check valve with a weak spring holding it closed. Any time there's a sufficiently strong partial vaccuum in the drain pipe, the air admittance valve on the drain pipe opens against spring pressure to allow air into the drain pipe so that the partial vaccuum doesn't suck the water out of the p-trap. Thus, the air admittance valve would connect to the drain piping roughly where the vent would, but would be out of sight so as not to mess up the appearance of the kitchen.


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## Chemist1961 (Dec 13, 2008)

Nestor, I have 3 toilets which are low flush all the same brand, valve, etc.
The best performing of the 3 vents directly into the 3" stack behind it in my ensuite. Seldom if ever an issue.
The other two are vented main floor via a sink vent branch up to the 3" main in the attic and upstairs via a 1 1/2" stack in an outside wall tied intro the 3" main stack in the attic.
Could these narrow vents be the likely cause of continuous plunging requirements on the other 2 toilets ? Is the venting more significant since I have upgraded to low flush?


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## II Weeks (Jan 6, 2009)

can help you a lot better if show us the plans and be careful what you read here, I just read a good one. Meant well but omg


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## ponch37300 (Nov 27, 2007)

Thanks guys. So would i just run the drain from the sink and other fixtures into a trap and then into the wall and drain goes down and vent straight up and then tie everything together in the attic? Lets say i have a wet bar in the basement, can i vent into the main stack or is this considered wet venting? And would i have to run this vent up to the attic to tie into the main stack? 


And lets say a kitchen sink with a window above it, do i just run the drain into the wall and then drain down and vent over then up to the ceiling and then tie into the main stack? Sorry for all the questions but just trying to make sure that i understand everything. Thanks again


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## II Weeks (Jan 6, 2009)

without seeing any plans I'll just through this out there for you. The last three bathroom house we worked on had three vents through the roof around the home. You do what you have to. Under the sink you could install a pro-vent after the trap or run a vent from there just following the drain and so on and so on. Hard to help in the blind here but I will add that wet venting is really discouraged.


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## Nestor_Kelebay (Jun 17, 2008)

Chemist1961 said:


> Nestor, I have 3 toilets which are low flush all the same brand, valve, etc.
> The best performing of the 3 vents directly into the 3" stack behind it in my ensuite. Seldom if ever an issue.
> The other two are vented main floor via a sink vent branch up to the 3" main in the attic and upstairs via a 1 1/2" stack in an outside wall tied intro the 3" main stack in the attic.
> Could these narrow vents be the likely cause of continuous plunging requirements on the other 2 toilets ? Is the venting more significant since I have upgraded to low flush?


Chemist:

I'm probably not a good person to talk to about "toilet venting". My understanding is that the plumbing code in Manitoba (where I live) may be different than other localities because we NEVER connect any other plumbing fixture to the same drain pipe that the toilet discharges into.

Here in Winnipeg, where I live, the plumbing code requires that the toilet be within 10 feet of the vent stack it discharges into, unless you're adding a toilet in the basement of an existing house. In that case, the toilet can be anywhere. You just connect it's floor flange to the main drain line from the house, and that's it. No venting requirement.

Also, up until about 20 years ago when PVC and ABS came along, toilets here in Winnipeg were installed using "lead bends", which is a 4 inch diameter lead elbow weighing about 50 pounds. You cut a 5 inch diameter hole in the floor, pushed one end of the lead bend up through that hole and used oakum and something called a "wiped" solder joint to connect the other end of the lead bend into a hub in the cast iron vent stack using a brass ferrule. The other end of the lead bend would be heated with a torch and pounded out with a hammer to flare out over a brass floor flange screwed to the floor.

I have a 21 unit apartment building, and approximately 19 lead bends (two of which have been replaced with plastic) and none of those toilets are "vented". In every case, there are 1 1/2 inch "bungalow" fixtures on the vent stack that provide both a 3 inch hub (for the toilet) and a 1 1/2 inch threaded hole (for the sink and tub drains). Thus, both the toilet drain pipe and the 1 1/2 inch drain to the sink and tub connect to the same "Bungalow" fixture on the vent stack.

Consequently, it has been my understanding until now that toilets aren't vented. But, I just tried Googling "toilet venting" and found lots of references to it, so there has to be a basic difference in the plumbing codes that requires it there, but not here in Manitoba.

Maybe it's because our toilet drain lines are always short, and no other plumbing fixtures that would normally need to be vented are ever connected to the same drain line as a toilet.

Sorry I couldn't have been more help.

In the following web page, a ceramic tiling contractor who was apparantly not familiar with lead bends cut it just like a cast iron or plastic pipe. That is, just above the tile height so that a plastic floor flange could be cemented into it. (He didn't realize that a brass floor flange would be dropped over that lead pipe sticking out of the floor, the lead pipe cut shorter and then flared out over the brass floor flange.)

http://www.askmehelpdesk.com/plumbing/lead-bend-toilet-flange-53065.html

Lead bends are common in Manitoba, and I can't imagine how you could even vent one.


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## Nestor_Kelebay (Jun 17, 2008)

ponch37300 said:


> Thanks guys. So would i just run the drain from the sink and other fixtures into a trap and then into the wall and drain goes down and vent straight up and then tie everything together in the attic? Lets say i have a wet bar in the basement, can i vent into the main stack or is this considered wet venting? And would i have to run this vent up to the attic to tie into the main stack?
> 
> 
> And lets say a kitchen sink with a window above it, do i just run the drain into the wall and then drain down and vent over then up to the ceiling and then tie into the main stack? Sorry for all the questions but just trying to make sure that i understand everything. Thanks again


The bar sink in the basement and the sink in front of a window are good places to use an air admittance valve instead of a vent pipe.


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## Chemist1961 (Dec 13, 2008)

Thanks Nestor, didn't mean to hijack the post

Given the history of heaving in River Heights / Osborne and the freeze etc, I can understand the difference in codes in Winterpeg. I have seen those lead bends...

My question was meant to be more general ...3" versus 11/2"flushing ability on a low flow toilet anywhere. I thought this might be a relevant question given the reno posted. Given how a gas can vents I assume the 3" stack would give a boost to any toilet, especially a low flow....


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## zosoplumber (Nov 21, 2008)

1 1/2" vent is sufficient for a 3" toilet line, I vent every fixture, wether it be with one wet vent for an entire fixture group( toilet, lav, tub) or seperate dry vents for toilet and tubs. you can't go wrong with having extra vents, better flow in the lines.


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## ponch37300 (Nov 27, 2007)

Thanks for all the help guys. I think i understand most of it now. I made a little drawing(I'm definitely not an artist!) of a two story house with a toilet on each level by the main stack. Then the kitchen sink on the other side. When i vent the kitchen sink can i tie into the main stack in between the 1st floor and 2nd floor or is this considered wet venting and not good? Should i just run the sink vent up to the attic and tie into the main stack above all the drains? Also if i have a sink in the 1st floor bathroom how would i vent that? Can i tie it into the main stack on the 1st floor or would this also be wet venting? Or do i have to run this all the way up to the attic and tie into the main stack above the drains for the 2nd floor fixtures? Thanks again for your knowledge


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## II Weeks (Jan 6, 2009)

I wouldnt vent the kitchen sink to the main vent line. Install one of these instead. Theyre legal in most places. Safe and easy to install.


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## II Weeks (Jan 6, 2009)

heres another option for venting an island sink. little harder


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## zosoplumber (Nov 21, 2008)

darn right, studer vents are great, never had a probrlem with drainage, and compare the cost and time it will take to run the vent and i bet you'll go with a mechanical vent


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## Nestor_Kelebay (Jun 17, 2008)

II Weeks said:


> I wouldnt vent the kitchen sink to the main vent line. Install one of these instead. Theyre legal in most places. Safe and easy to install.


Your drawing shows a 22 1/2 degree elbow on a 1 1/2 inch drain line.

I understand that you might need a 45 to get the vent vertical. My point is that I've never seen a 22 1/2 degree elbow in the smaller plastic pipe sizes like 1 1/2 inch. Do they exist?


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## WaldenL (Jan 9, 2009)

Dumb question here... Any reason the OP couldn't just vent the kitchen sink out the sidewall by the sink? (Might be aesthetic reasons, I'm looking for a plumbing one) Must the vent go vertically through the roof? I don't see why.


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## ponch37300 (Nov 27, 2007)

The vent is on the drain side of the trap so it would let out any/all sewer gases which i don't think anyone would want to walk by their house and smell sewer gases or open the window and have the house smell like a sewer.


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## Wildie (Jul 23, 2008)

Nestor_Kelebay said:


> Your drawing shows a 22 1/2 degree elbow on a 1 1/2 inch drain line.
> 
> I understand that you might need a 45 to get the vent vertical. My point is that I've never seen a 22 1/2 degree elbow in the smaller plastic pipe sizes like 1 1/2 inch. Do they exist?


 Look again Nestor, it takes a 180 degrees to reverse direction. There's one 90 at the the top, so the other two must be 45's!


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## Wildie (Jul 23, 2008)

ponch37300 said:


> Thanks for all the help guys. I think i understand most of it now. I made a little drawing(I'm definitely not an artist!) of a two story house with a toilet on each level by the main stack. Then the kitchen sink on the other side. When i vent the kitchen sink can i tie into the main stack in between the 1st floor and 2nd floor or is this considered wet venting and not good? Should i just run the sink vent up to the attic and tie into the main stack above all the drains? Also if i have a sink in the 1st floor bathroom how would i vent that? Can i tie it into the main stack on the 1st floor or would this also be wet venting? Or do i have to run this all the way up to the attic and tie into the main stack above the drains for the 2nd floor fixtures? Thanks again for your knowledge


 A vent should not connect to the main stack, where excrement passes by! Some will find its way into the vent and eventually the vent will plug!


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## ponch37300 (Nov 27, 2007)

Thanks wildie..Is that considered wet venting? So my best option would be to run the vent to the attic and then tie into the main stack or use a mechanical vent?


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## Wildie (Jul 23, 2008)

ponch37300 said:


> Thanks wildie..Is that considered wet venting? So my best option would be to run the vent to the attic and then tie into the main stack or use a mechanical vent?


 Yes! annnd Yes!  I have used mechanical venting, and they work well also!


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## ponch37300 (Nov 27, 2007)

:thumbsup:Thanks everyone. Think i have a good grasp on this venting stuff!


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## Mike_C (Mar 2, 2012)

I realize that this post is well beyond the time in which to help anyone who was involved with it previously....but felt the need to join the forum to post a few things that may help future readers. 

I was simply doing a search to re-familiarize myself with some plumbing codes and when I saw the answers here I could not just let well meaning but definitely somewhat misleading information be stated without at least making sure that more research would have to done before applying anything learned here. As one user pointed out the first thing to do is check out your local codes on plumbing!!! These vary so much from city to city and especially from state to state. I am from Wisconsin and most larger municipalities follow the UDC (Uniform Dwelling Code) which is pretty strict in its guidelines. Many other state's codes would not pass here....in fact most plumbers from other states cannot plumb here without getting recertified! 

What I have seen posted may be adequate for some places but virtually everything I have read here would NOT satisfy the UDC code!!

For one thing the mechanical vents are no longer allowed....at all! (recent code change...unsure of if this thread was before it happened).
And the diagrams/images shown with the mechanical vent below the sink's bottom would not pass inspection even when they were allowed (has to be above).

Everything must be vented! 

Vents must always be either level or be slanted upward....and be a minimum of 30 inches above the floor height before changing from vertical. 

Wet venting, although allowed, needs special consideration...limits on how many per size of drain and also the drain size from each fixture usually have to be increased (for instance a sink drain would have to be 2 inches instead of the standard 1.5 inch). A 3 inch drain can only accommodate just so many fixtures (fixture types are figured as well when determining this). 

Again....I just want to make sure that people are not taking what has been stated here in this thread as gospel....that it is a must to find out from your local codes what is required.


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## md2lgyk (Jan 6, 2009)

zosoplumber said:


> darn right, studer vents are great, never had a probrlem with drainage, and compare the cost and time it will take to run the vent and i bet you'll go with a mechanical vent


I agree. But I have lived in ten different states in the USA, and AAVs were illegal in most of them. The IRC allows them but the UPC does not.


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## jaydevries (Jan 29, 2012)

yes and so do 60's


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## peterbrooks (Feb 22, 2013)

*Venting Low Flow Toilets*

Can having an oversize vent effect the way a low flow toilet flushes? One story condo built in 1955 in North Carolina. If this is the case can I try closing off half or a third or the vent on the roof to see if it makes the toilets flush better.

I replaced two toilets that are back to back but they never flushed right. The association said it was problem with my toilets I bought but how can two toilets be bad at the same time,,,, I think it might be the venting.


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## Javiles (Dec 12, 2011)

No ,, vents are for pressure Equilibrium in the system.


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## peterbrooks (Feb 22, 2013)

*They only have one purpose?*

I thought they were for venting gasses.


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## Javiles (Dec 12, 2011)

peterbrooks said:


> I thought they were for venting gasses.


secondary purpose, third purpose access in to a line. etc,


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## peterbrooks (Feb 22, 2013)

Somewhere in the thread above there was a hint to an astm specification for venting but I could not fully understand what they wrote, sounded like 3" was too big.


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## Javiles (Dec 12, 2011)

There are multiple reasons for the size of a vent but weather a toilet is affected by a larger or smaller vent is not the case.


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## peterbrooks (Feb 22, 2013)

So you firmly disagree with that ASTM stuff up above. Thanks


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## Javiles (Dec 12, 2011)

peterbrooks said:


> Can having an oversize vent effect the way a low flow toilet flushes? One story condo built in 1955 in North Carolina. If this is the case can I try closing off half or a third or the vent on the roof to see if it makes the toilets flush better.
> 
> I replaced two toilets that are back to back but they never flushed right. The association said it was problem with my toilets I bought but how can two toilets be bad at the same time,,,, I think it might be the venting.



this is what you asked and venting may be an issue but not because the vents are too big.

why toilets flush bad ? there could be a bunch of reasons.


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## peterbrooks (Feb 22, 2013)

What other possible venting reasons could there be? This is the second time I am replacing the toilets in 4 years and they never work right.

The bucket of water trick is great! Never saw a plumber do that guess because they wouldn't make as much money if they didn't take everything apart run up on the roof and down to the basement to check for a clog when all they have to do is pour a bucket of water in the bowl.


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## Javiles (Dec 12, 2011)

1 brand of toilet
2 style, one piece or two piece,
3 place purchased at, plumbing supply house or Homedepot type store
4 water level in tank
5 toilets installed correctly/ level, flange. wax, 

without me personally looking and troubleshooting them it hard to say


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## TheEplumber (Jul 20, 2010)

peterbrooks said:


> Somewhere in the thread above there was a hint to an astm specification for venting but I could not fully understand what they wrote, sounded like 3" was too big.


This thread is all over the place....
Your plumbing stack is a typical application. I think you can rule out a vent issue


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## md2lgyk (Jan 6, 2009)

Chemist1961 said:


> Could these narrow vents be the likely cause of continuous plunging requirements on the other 2 toilets ? Is the venting more significant since I have upgraded to low flush?


I suspect the problem with the two toilets is because they ARE vented and should not be. As described above, venting prevents water from being sucked out of the p-traps. Well, a toilet is basically a large p-trap that's SUPPOSED to be sucked out. Venting it makes it suck less.

I have two low-flush toilets in my house. Both are about 15 feet from the main stack and neither is separately vented. Both work just fine.

I should point out that my house was plumbed per IRC 2003. The UPC, as I understand it, addresses venting very differently. So you may get some input that is contradictory to mine.


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## joes plumbing (Jan 27, 2013)

You can not tie in a vent to the stack if there is other fixture draining into the stack above where you want to connect vent so be safe and bring vents to highest point of stack above where the last drain connection is probably easier in attic. A wet vent is a drain that also serves as a vent on the same floor level hope you understand you also cannot wet vent thru a kitchen sink. Nestor what part of country do you live in where no vent required for toilet? In Ma everything has to be vented and an island sink can have a bow vent those automatic vents only if plumbing inspector allows it


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## joes plumbing (Jan 27, 2013)

What the f--k are you talking about venting a toilet makes it flush poorly are you insane it's the pipe after the toilet that you are venting your codes in wherever your from are a joke you should learn plumbing theory before you say stupid things


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## Javiles (Dec 12, 2011)

joes plumbing said:


> What the f--k are you talking about venting a toilet makes it flush poorly are you insane it's the pipe after the toilet that you are venting your codes in wherever your from are a joke you should learn plumbing theory before you say stupid things


Its OK Joe calm down calm down Joe,,,,, remember we need folf like that so we can go back and fix it right.. for a reasonable charge of course :laughing:


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## md2lgyk (Jan 6, 2009)

joes plumbing said:


> What the f--k are you talking about venting a toilet makes it flush poorly are you insane it's the pipe after the toilet that you are venting your codes in wherever your from are a joke you should learn plumbing theory before you say stupid things


Struck a nerve, did I? Far be it from me to argue with your Exalted Eminence of Plumbingdom, but I can't help what the code is where I live (Eastern WV). All I know is that my house is plumbed in accordance with it, passed inspection, and everything has worked fine for almost five years now. 

Have you ever even read the IRC section on plumbing? It is quite different from the UPC, especially regarding venting.


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## Javiles (Dec 12, 2011)

md2lgyk said:


> I suspect the problem with the two toilets is because they ARE vented and should not be. As described above, venting prevents water from being sucked out of the p-traps. Well, a toilet is basically a large p-trap that's SUPPOSED to be sucked out. Venting it makes it suck less.
> 
> I have two low-flush toilets in my house. Both are about 15 feet from the main stack and neither is separately vented. Both work just fine.
> 
> I should point out that my house was plumbed per IRC 2003. The UPC, as I understand it, addresses venting very differently. So you may get some input that is contradictory to mine.


*P3101.2.1 Venting required.* Every trap and trapped fixture shall be vented in accordance with one of the venting methods specified in this chapter.
*
This the IRC...what you read and how you interpret are two different things. a inexperienced person usually interprets incorrectly.*


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