# Crown vented traps



## ILPlumber

This topic seems to be taking a life all it's own. I think it is fitting to give it it's own thread. Let the whipping begin.

To start. I will give you something to chew on. 

Reason number 1 why you need more than 2 pipe diameters from the trap weir to the tee in the wall.

Say you have hair,lint,or string in the trap (obviously very common). That foreign matter is laying in the outlet of the trap. If the outlet is within 2 pipe diameters of the drop pipe that foreign matter could be laying from the outlet of the weir and down the drop pipe. The water would be wicked/siphoned out of the trap by the foreign matter. 

It does happen. Think about toilet paper in a wcl drapped over the trap. Wicks it out doesn't it:yes:

This is one of the primary reasons for having more than 2 pipe diameters to the drop. What say you?


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## Ron

ILPlumber said:


> Say you have hair,lint,or string in the trap (obviously very common). That foreign matter is laying in the outlet of the trap. If the outlet is within 2 pipe diameters of the drop pipe that foreign matter could be laying from the outlet of the weir and down the drop pipe. The water would be wicked/siphoned out of the trap by the foreign matter.


I seen people out there that have long hairs, 2 pipe sizes don't help them out..


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## TheMaster

Dental floss will do it on toilets bigtime......Customer will come u the bathroom and the water in the bowl will be almost gone. Ive had that several times.


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## TheMaster

On a 1.5" lavatory drain dumping into a 3x1.5" sant. tee......the tee will get clogged in the 3". It cloggs in the sweep of the tee and just builds and builds untill the entire 3" potion of the vent is closed before the lavatory actually shows the problem by being clogged. If the clogg is "hard" enough somimes the cable will go up the vent and not unclogg the lavatory. Drophead cables work well but i prefer to unclogg from the roof if possible and its a one story. Ive seen that on pvc and cast iron/copper pipe dwv systems


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## Ron

Nothing in my code tell me distance to outlet, to be considered as a crown vent, they probably don't push crown venting here, even though it references it.


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## GREENPLUM

crown AAV vent ?


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## ILPlumber

That might be 2.5" from the weir. Hard to say without measuring.


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## Redwood

GREENPLUM said:


> crown AAV vent ?


No...
Just garbage plumbing....:whistling2:


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## ILPlumber

Unfortuately, it meets code in some areas.

Anyway... (awkward silence)


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## TheMaster

ILPlumber said:


> Unfortuately, it meets code in some areas.
> 
> Anyway... (awkward silence)


 Only in a manufactured home here in Al. manufactured homes fall under federal inspections here. Fed says they are fine. Go figure. They are ok for special purpose but no one should make a habit of installing them. You have a customer that wants to add a island wet bar off the patio....well yeah they are ok then. Want to plumb up an apartment building well hella no its not ok. Good judgement should be used.


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## Proud Plumber

GREENPLUM said:


> crown AAV vent ?


That puppy has mass production written all over it in my neck of the woods.

I can for see Ferguson trucks dropping those off on tract home sites everywhere.

But you guys would be proud, I found a place in my that they are forbidden. I was working in a large hospital about six months ago. They were doing a renovation in the children's ICU. The plumbers contracted for that particular renovation cut the CI vents away and slapped them in the hand wash sinks at the nurses station. The Plumbers employed by the hospital are all union and needless to say they all came out, by the new plumbers hired to finish the job.


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## Protech

:yes: Same here. I don't like it but hey, it's good job security for me. Just like all these homes with cpvc that they are slapping together since the turn of the century. I'm already reaping the rewards of there efforts:thumbup:.



Proud Plumber said:


> That puppy has mass production written all over it in my neck of the woods.
> 
> I can for see Ferguson trucks dropping those off on tract home sites everywhere.
> 
> But you guys would be proud, I found a place in my that they are forbidden. I was working in a large hospital about six months ago. They were doing a renovation in the children's ICU. The plumbers contracted for that particular renovation cut the CI vents away and slapped them in the hand wash sinks at the nurses station. The Plumbers employed by the hospital are all union and needless to say they all came out, by the new plumbers hired to finish the job.


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## ASUPERTECH

Protech said:


> :yes: Same here. I don't like it but hey, it's good job security for me. Just like all these homes with cpvc that they are slapping together since the turn of the century. I'm already reaping the rewards of there efforts:thumbup:.


 
Same hear, and as far as the AAV's what else can you do? HO, builder etc.. want everything cheap cheap cheap, you give it to them cheap. Thank the gods for the cpvc, pex, pb, AAV's, washerless faucets, 1.6gpf, tankless heaters and so on, it's for sure due to these great inovations in the plumbing industry that I will be working for years to come, and making more $ to make those repairs than if they had good old fashioned stuff in there.


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## 422 plumber

I think we can all agree that I am the recognized authority on crown vents


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## frostyplumber

GREENPLUM said:


> crown AAV vent ?


 no air admittance valve also called a cheater vent


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## nhmaster3015

It will never happen but if every plumber refused to sell and install crap then home owners and contractors would eventually get the point, so would the manufacturers and distributors.


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## Plumber Jim

nhmaster3015 said:


> It will never happen but if every plumber refused to sell and install crap then home owners and contractors would eventually get the point, so would the manufacturers and distributors.


 
Very true. If plumbers would refuse it install that junk the people making it would stop because of the lack of demand.


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## jnohs

what if is as pedistal sink?
than the distance is set by the manufacture.


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## jnohs

and a lot of euro sinks are very tight so once again if everything is to be centered and all doors and draws open than again the manufacture set the depth.


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## user7551

ILPlumber said:


> This topic seems to be taking a life all it's own. I think it is fitting to give it it's own thread. Let the whipping begin.
> 
> To start. I will give you something to chew on.
> 
> Reason number 1 why you need more than 2 pipe diameters from the trap weir to the tee in the wall.
> 
> Say you have hair,lint,or string in the trap (obviously very common). That foreign matter is laying in the outlet of the trap. If the outlet is within 2 pipe diameters of the drop pipe that foreign matter could be laying from the outlet of the weir and down the drop pipe. The water would be wicked/siphoned out of the trap by the foreign matter.
> 
> It does happen. Think about toilet paper in a wcl drapped over the trap. Wicks it out doesn't it:yes:
> 
> This is one of the primary reasons for having more than 2 pipe diameters to the drop. What say you?


Totally agree , its not that hard to bring your stack up to the left or right of the fixture being served to be able to put a long enough arm on it to keep it from being a crown vent.


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## walker426

422 plumber said:


> I think we can all agree that I am the recognized authority on crown vents


 Does that have to be 3 inch at the base of the stack for the laundry in cleveland where I am that would be code


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## Tommy plumber

I read somewhere that a crown-vented trap also inhibits the self-scouring action of the drain line which in turn allows build-up to collect in the vent opening. This could, theoretically, eventually block off the vent opening. I'll post something if I can locate.


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## billy_awesome

Tommy plumber said:


> I read somewhere that a crown-vented trap also inhibits the self-scouring action of the drain line which in turn allows build-up to collect in the vent opening. This could, theoretically, eventually block off the vent opening. I'll post something if I can locate.


I believe it has more to do with hydraulic gradient. Water will always find it's own level!


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## seanny deep

Lav crown vent? What? Dont you guys have vanity lights here their centered on the fixture so i dont understand.. im always in before electrions why would you run a vent right where a light fixture should be located. A washerbox sure.. i can see that happening kitchen sink is usually under a window? Atleast here so besides that how or why would a professional have ... Or run into this problem? As far as air admittance valves go, they are not a cheater vent for a cheater vent relies on a spring air admittance relies on atmospheri c pressure and differentials between it and the fixture its acting as a vent for hence in orxder for an air admittance valve to work their must be atleast one vent to outside air n the system for it to function correctly. A cheater vent will work, or not work regardless of outside air. Thanks seanny


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## Tommy plumber

Tommy plumber said:


> I read somewhere that a crown-vented trap also inhibits the self-scouring action of the drain line which in turn allows build-up to collect in the vent opening. This could, theoretically, eventually block off the vent opening. I'll post something if I can locate.


 






Something like this: It states: "vent opening would clog resulting in an un-vented trap."


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## NYC Plumber

seanny deep said:


> Lav crown vent? What? Dont you guys have vanity lights here their centered on the fixture so i dont understand.. im always in before electrions why would you run a vent right where a light fixture should be located. A washerbox sure.. i can see that happening kitchen sink is usually under a window? Atleast here so besides that how or why would a professional have ... Or run into this problem? As far as air admittance valves go, they are not a cheater vent for a cheater vent relies on a spring air admittance relies on atmospheri c pressure and differentials between it and the fixture its acting as a vent for hence in orxder for an air admittance valve to work their must be atleast one vent to outside air n the system for it to function correctly. A cheater vent will work, or not work regardless of outside air. Thanks seanny


Yeah your def not a plumber.


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## rjbphd

Hey fellow members... when did jnohs become a 'master plumber' on this site?


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## love2surf927

jnohs said:


> what if is as pedistal sink?
> than the distance is set by the manufacture.


You do know that your vent doesnt have to center on the fixture.... right, in most cases its better if it does not. Thats what trap arms are for... a plumber should probably know this, just sayin.


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## GREENPLUM

nhmaster3015 said:


> It will never happen but if every plumber refused to sell and install crap then home owners and contractors would eventually get the point, so would the manufacturers and distributors.


 
still just as right as you were in 2009 :thumbup:


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## 422 plumber

walker426 said:


> Does that have to be 3 inch at the base of the stack for the laundry in cleveland where I am that would be code


I am facetiously stating that, because I have been unknowingly crown venting for years.


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## billy_awesome

In your area, whats the minimum distance from trap to vent?

In Ontario (might be same all across Canada) minimum distance is two waste pipe diameters.


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## seanny deep

Same here max is 6' for 1.5" and 8' for 2" 10' for 3" except water closets are 12' emergency 3" floor drains do Not require à vent.. atleast here.


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## billy_awesome

seanny deep said:


> Same here max is 6' for 1.5" and 8' for 2" 10' for 3" except water closets are 12' emergency 3" floor drains do Not require à vent.. atleast here.


Yeah so there are some differences, pretty much a foot more in the Canadian National Code. And here floor drains require a vent unless within the 6 feet of the building drain or stack. Ontario still sees floor drains as a non-emergency fixture which is total BS. 

Ontario by law, must teach us Ontario code, but we get tested on the national red seal trade examination. No matter where you are in the world code is going to be different in small ways everywhere. By the time they fix problems with our testing I will already be licensed, seems a bit unfair but nothing we can really do about it.


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## Tommy plumber

billy_awesome said:


> In your area, whats the minimum distance from trap to vent?
> 
> In Ontario (might be same all across Canada) minimum distance is two waste pipe diameters.


 







Hack-tastically speaking, here in hack central, you can be a mile or two from the point of vent. Or in some cases, the vents are optional.

Now for licensed plumbers who follow the code, we are allowed:


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## U666A

Tommy plumber said:


> I think you meant maximum distance......
> Hack-tastically speaking, here in hack central, you can be a mile or two from the point of vent. Or in some cases, the vents are optional.
> 
> Now for licensed plumbers who follow the code, we are allowed:


No, i think he meant minimum, as per the thread title. Anything less than 2 WPØ's is considered to be crown vented.

The following user(s) wishes to thank U666A for this useful post: Mississippiplum, Plumber71, DesertOkie


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## Tommy plumber

My bad, I forgot what thread I was posting in......:laughing:

I jump around alot.


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## walker426

billy_awesome said:


> In your area, whats the minimum distance from trap to vent?
> 
> In Ontario (might be same all across Canada) minimum distance is two waste pipe diameters.


 We don't have a minimum from trap to vent the maximum is 5 foot


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## U666A

Tommy plumber said:


> My bad, I forgot what thread I was posting in......:laughing:
> 
> I get around alot.


T,IFIFY... :LAUGHING:

The following user(s) wishes to thank U666A for this useful post: Mississippiplum, Plumber71, DesertOkie


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## suzie

I have a bunch of brand new one of these darn things that were in a large auction bid I won. If anyone of yuse guys want these things let me know you can have em otherwise I will throw at the end of the month


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## Tommy plumber

billy_awesome said:


> I believe it has more to do with hydraulic gradient. Water will always find it's own level!


 















This is what I was referring to. The theory that a crown-vented trap could, in theory, allow debris and waste to settle up in the vent eventually closing the vent intake.


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## azmike

Tommy plumber said:


> This is what I was referring to. The theory that a crown-vented trap could, in theory, allow debris and waste to settle up in the vent eventually closing the vent intake.


That shows flat venting below the spill level of the fixure we are not allowed to do that here!


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## NYC Plumber

azmike said:


> That shows flat venting below the spill level of the fixure we are not allowed to do that here!


Ive never heard of that, can you send that code section?


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## azmike

NYC Plumber said:


> Ive never heard of that, can you send that code section?


sure! i.p.c. #905.4 Every dry vent shall rise vertically to a minimum of 6" above the flood level rim of the highest trap or trapped fixture being vented.


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## jeffreyplumber

NYC Plumber said:


> Ive never heard of that, can you send that code section?


 Upc code is similar. Although we allow a "flat venting" less than 6 inches above flood level when structural conditions dont allow the vent to rise as mentioned. 
Specificaly crown venting as shown in drawing I havent seen but dought it would ever fly in a new installation


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## Tommy plumber

jeffreyplumber said:


> Upc code is similar. Although we allow a "flat venting" less than 6 inches above flood level when structural conditions dont allow the vent to rise as mentioned.
> *Specificaly crown venting as shown in drawing I havent seen but dought it would ever fly in a new installation*


 






Agreed. The pic I posted would never pass code here for sure. I posted it to illustrate that crown venting is prohibited for several reasons; (1) reason is that debris washes up into the vent opening. This eventually can close off the vent, also it deposits bacteria in vent creating an unsanitary condition.


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## user8031

2 pipe diameters from the trap weir works for me. If I can't achieve that, it is time to rework something


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## jeffreyplumber

suzie said:


> I have a bunch of brand new one of these darn things that were in a large auction bid I won. If anyone of yuse guys want these things let me know you can have em otherwise I will throw at the end of the month


 I dont have a use for them but curios about them please describe size material etc is it an s trap as in pic? Ive never seen them cast iron, plastic, ?


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## ILPlumber

lead


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