The Inspector's Journal Forums
Username:
Password:
Save Password


Join TIJ Forums
Lost Password?
Subscribe to TIJ's Newsletter

All Forums > Technical Forums > Plumbing Forum >

Dry vent vs. wet vent

Previous Topic: Stance on PB... again - Topic - Next Topic: Septic System Missing! New TopicReply to TopicShare Topic
Posted By  
View Profile
Active Member
Elizabethtown, PA
Posts: 621
Joined: May, 2007
Currently offline offline
  
Thread Start First Page
[#1] Posted: 09/02/2010 - 2:12:54 PM
Reply with Quote
I have long heard the terms 'dry vent' and 'wet vent' pertaining to venting systems for plumbing. It appears that a wet vent is simply a dry vent that also has drain water running in it (such as the typical PVC DWV system in the home above the highest drain connection (sink, tub, etc.) in the home). How does one tell the different b/w the two?

I run across this often with ejector/effluent pumps in basements with dual PVC vertical drain pipes both connecting into the main sewer line (one is a drain and one is a vent). Maybe I just need a good summary of these two terms.

Active Member
Posts: 908
Joined: Feb, 2004
Currently offline offline
  
Dry vent vs. wet vent
[#2] Posted: 09/03/2010 - 05:29:23 AM
Reply with Quote
Quote: Originally posted by msteger

I have long heard the terms 'dry vent' and 'wet vent' pertaining to venting systems for plumbing. It appears that a wet vent is simply a dry vent that also has drain water running in it (such as the typical PVC DWV system in the home above the highest drain connection (sink, tub, etc.) in the home). How does one tell the different b/w the two?

I run across this often with ejector/effluent pumps in basements with dual PVC vertical drain pipes both connecting into the main sewer line (one is a drain and one is a vent). Maybe I just need a good summary of these two terms.



Plumbing Vents: types of vents, wet vents, dry vents, vent ...

View Profile
Senior Member
Lafayette, Louisiana
Posts: 6372
Joined: Nov, 2009
Currently offline offline
  
Dry vent vs. wet vent
[#3] Posted: 09/03/2010 - 07:12:01 AM
Reply with Quote
Plumbing isn't my forte but this is from 'National Plumbing Codes Handbook' by Dodge Woodson:
Quote: Wet vents are pipes that serve as a vent for one fixture and a drain for another.


Marc

View Profile
Senior Member
Spring Hill (Nashville area), Tennessee
Posts: 3911
Joined: Nov, 2003
Currently offline offline
  
Dry vent vs. wet vent
[#4] Posted: 09/03/2010 - 07:39:35 AM
Reply with Quote
If you have (and you really should) a Code Check Complete or Code Check Plumbing, you will find some good diagrams of "wet vents" and proper uses.
View Profile
Senior Member
Rockville, VA
Posts: 2943
Joined: Jan, 2006
Currently offline offline
  
Dry vent vs. wet vent
[#5] Posted: 09/03/2010 - 08:21:04 AM
Reply with Quote
Quote: Originally posted by Marc

Plumbing isn't my forte but this is from 'National Plumbing Codes Handbook' by Dodge Woodson:
Quote: Wet vents are pipes that serve as a vent for one fixture and a drain for another.


Marc


That clears it up nicely. Thanks Marc!

View Profile
Senior Member
Lexington, KY
Posts: 2585
Joined: Nov, 2004
Currently offline offline
  
Dry vent vs. wet vent
[#6] Posted: 09/03/2010 - 09:16:06 AM
Reply with Quote
I typically find these when someone's added a bathroom after-the-fact on an upper level. They don't want to install a new drain line through closets or whatever, so they just tap into the vent stack. The reason it's not allowed, clearly, is to prevent the vent from becoming clogged and to prevent the whooshing water and solids from screwing with traps in the house.

Those injection pumps should have separate connections to a drain and a vent stack. No way should both be connected to just a waste line. If you have a photo of a set-up you're concerned about, it would be helpful.

View Profile
Active Member
Elizabethtown, PA
Posts: 621
Joined: May, 2007
Currently offline offline
  
Dry vent vs. wet vent
[#7] Posted: 09/03/2010 - 2:20:43 PM
Reply with Quote
Thanks guys.. I don't have a specific example or photo, but just something I run across from time to time. Marc's definition is essentially what I have understood the term to mean: "Wet vents are pipes that serve as a vent for one fixture and a drain for another." This makes sense for a single story home... but for most 2 or 3 story homes, aren't just about all of the vents considered wet vents? A vent for the 1st level is often the drain for the 2nd level...eh?

I do have the Code Check Complete book. I assume you are referring to Figs. 35 ~ 39.

View Profile
Senior Member
Lafayette, Louisiana
Posts: 6372
Joined: Nov, 2009
Currently offline offline
  
Dry vent vs. wet vent
[#8] Posted: 09/03/2010 - 3:03:54 PM
Reply with Quote
If I'm not mistaken, the plumbing codes in your part of the country (UPC?) make abundant use of wet venting techniques, more so than the South or West. They're not as common where I'm at. My own house has none.

Marc

Active Member
Posts: 908
Joined: Feb, 2004
Currently offline offline
  
Dry vent vs. wet vent
[#9] Posted: 09/04/2010 - 4:24:46 PM
Reply with Quote
Quote: Originally posted by msteger

I have long heard the terms 'dry vent' and 'wet vent' pertaining to venting systems for plumbing. It appears that a wet vent is simply a dry vent that also has drain water running in it (such as the typical PVC DWV system in the home above the highest drain connection (sink, tub, etc.) in the home). How does one tell the different b/w the two?

I run across this often with ejector/effluent pumps in basements with dual PVC vertical drain pipes both connecting into the main sewer line (one is a drain and one is a vent). Maybe I just need a good summary of these two terms.


Just google "plumbing wet vent" and you will have all the info you need.

Starting Member
Los Angeles, CA
Posts: 1
Joined: Feb, 2012
Currently offline offline
  
Dry vent vs. wet vent
[#10] Posted: 02/16/2012 - 09:07:02 AM
Reply with Quote
A more inclusive definition comes from the 2010 California Plumbing Code:

A wet vent is a vent that also serves as a drain.

View Profile
Senior Member
Georgetown, KY
Posts: 2878
Joined: Mar, 2002
Currently offline offline
  
Dry vent vs. wet vent
[#11] Posted: 02/16/2012 - 09:53:47 AM
Reply with Quote
The typical sewage ejector pump in the basement around here has the actual drains INTO the sump under the slab, then a vent pipe to the venting system and a drain pipe to the drain system, both coming out the lid of the sump. Neither of the pipes allows sewage to flow INTO the sump.
View Profile
Active Member
Sykesville, Maryland
Posts: 410
Joined: Nov, 2009
Currently offline offline
  
Dry vent vs. wet vent
[#12] Posted: 02/16/2012 - 10:28:13 AM
Reply with Quote
What Erby said, two lines out of the top, one is for the flow out (with a check-valve) and the other is a vent that should always be a dry vent I would think. Flow in is under the slab.
View Profile
Active Member
louisville, ne
Posts: 545
Joined: Feb, 2010
Currently offline offline
  
Dry vent vs. wet vent
[#13] Posted: 02/17/2012 - 8:55:22 PM
Reply with Quote
Id say you guys covered it pretty well
View Profile
Senior Member
Lafayette, Louisiana
Posts: 6372
Joined: Nov, 2009
Currently offline offline
  
Dry vent vs. wet vent
[#14] Posted: 02/18/2012 - 06:51:12 AM
Reply with Quote
Quote: Originally posted by plummen

Id say you guys covered it pretty well

'You guys'?

Marc

View Profile
Active Member
louisville, ne
Posts: 545
Joined: Feb, 2010
Currently offline offline
  
Dry vent vs. wet vent
[#15] Posted: 02/18/2012 - 07:57:41 AM
Reply with Quote
Im giving everybody credit today
Starting Member
new boston, nh
Posts: 9
Joined: Aug, 2010
Currently offline offline
  
Dry vent vs. wet vent
[#16] Posted: 02/20/2012 - 05:52:40 AM
Reply with Quote
Great timing guys!
I have been thinking about this for a few weeks now I am working on a basement refinishing project as I try to surrvive as I continue to aprentice with a local home inspector.

In the picture below you can see the 4" abs waste pipe, the home owners want to add a wet bar in the basement. To make this work I think I will need to add a sewer ejector pump. My question is can I tie in both the vent pipe and the waste pipe from the ejector pump into the 4" pipe shown in the picture? The cast Iron pipe thru the foundation is about 30" from the basement floor to the center of the pipe. If I put the vent pipe above the waste pipe will that work?



Click to View

71.18 KB

View Profile
Administrator
Chicago, IL
Posts: 12715
Joined: Dec, 2003
Currently offline offline
  
Dry vent vs. wet vent
[#17] Posted: 02/20/2012 - 1:34:04 PM
Reply with Quote
Nope. Ejector has to go to a drainage/waste pipe, vent to a vent pipe.

Wet vents came into being by being unable or uninterested to find and connect to a dry vent. More or less.




   
Previous Topic: Stance on PB... again - Topic - Next Topic: Septic System Missing! New TopicReply to TopicShare Topic
Jump To:
The Inspector's Journal Forums © 2002-2016 all topics or replies that are posted on The Inspector's Journal
are copyrighted material of the original author that posted the topic or reply.
Go To Top Of Page 
 
Pick an RSS Feed

The views expressed on this website are the views of the authors and
do not necessarily reflect the views or policies of the sponsors.
© 2002-2016 Copyright DevWave Software Inc.
Find a Home Inspector

Powered By: Snitz Forums 2000