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Proper Attachment for Plumbing Vent Covers

D107D107 Member Posts: 1,715
edited September 13 in Plumbing
When the previous homeowner's added a bathroom on first floor 30 years ago, they ran 2" copper drain lines, some of which partly did double-duty as vents. See vent cover on the right. I would hope that the 2" pipe went right up to the inside edge of the vent cover.


When we added blown-in-cellulose insulation and insulated vinyl siding in 2006, the vent cover was removed and holes were drilled in the vinyl siding to serve as a vent cover. (Number of holes is obviously less than with the old vent cover.)


In trying to troubleshoot sporadic sewer smells, one theory has emerged that since the vinyl and 3/4" styrofoam insulation probably extended the house envelope by about 1.5 inches, if the 2" copper vent pipe was not likewise extended or sleeved to cover the gap, there could be some sewer or fixture leakage from winds at certain times blowing back into the house; or alternately, some of that cellulose insulation could be partially blocking that vent. Our sinks are draining OK so perhaps that's not an issue. (Note despite photo annotation, probably doubtful 2nd floor was vented with that.)

I've seen some vents piped with a 90El pointing downward to deal with wind issues. Is there some better way to do this than what was done?

Comments

  • JUGHNEJUGHNE Member Posts: 7,098
    Do you have any vent stacks going thru the roof?
    It seems that the 2nd floor bath was original to the house and would have VTR.

    You could hole saw that siding open, maybe get a rubber coupling onto the 2" pipe. Then attach a PVC street 90 ell pointing down. Maybe some deep PVC escutcheon to cover the rubber coupling. I would put 1/4' SS screen pushed up into the outlet of the 90. A very short (3/8") length of pipe holds the screen in place.

    Also a vinyl "block out could be installed there. That mounts tight to the old sheathing of the house. Keeping any gas from getting behind the siding.
    D107
  • D107D107 Member Posts: 1,715
    @Jughne thanks. Great suggestions. Yes; plumber said ordinarily shower, sink and bath would be stack vented. Main 6inch cast iron stack comes up into attic, does a 90EL for 5-6 feet on the attic floor, then another 90EL through the roof. (Someone drilled a 1-inch hole in the horizontal part of the main for the AC overflow--not to code I know--but it makes me wonder if that originally served as the sink-shower vent?)

    It seems that if the 2FL sink, shower and toilet are stack-vented, the sink and shower drain through the new 2" copper line that drops down and ends in a T where one direction goes to basement--eventually to Main––and the other to the vent. Not sure how the water going into that T knows to drain only to the right.
    Here's a link to another thread on this that shows photos of the piping from the ceiling below and in the basement.

    https://forum.heatinghelp.com/discussion/180677/waste-piping-mystery#latest
  • JUGHNEJUGHNE Member Posts: 7,098
    Your 6" pipe is probably a 4" cast iron pipe.

    I see you have inside access to the horizontal pipe going to the wall vent. You could cut that inside the house and then extend it farther out side with rubber coupling. There is a good no hub coupling specifically for CU DWV to Pvc DWV .
    Then you could have a clean hole outside in the vinyl for the pipe and add the 90 ell outside.
    D107
  • D107D107 Member Posts: 1,715
    @JUGHNE Well that access was temporary while we installed the shower mini-vent, replaced that short galvanized piece, and replaced the dropped ceiling with sheetrock years ago. But your prior post's advice points the way. I'll try to get a strong flashlight to look into the existing vent from outside and see what I can see.
  • hot_rodhot_rod Member Posts: 13,737
    I think I think plumbing vents are supposed to terminate above the roof?
    Remember that is moist air coming out, certainly do not want that in the building envelop either.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
    D107mattmia2rick in Alaska
  • hot_rodhot_rod Member Posts: 13,737
    Above the roof plumbing ventheight: vent pipesshould extend to outdoors above the building roof and should terminate vertically not less than 6" above the roof surface (nor more than 24") and must be at least 12" from any vertical surface (such as a nearby sidewall). (UPC (i) 906.1 and 
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
    D107mattmia2rick in Alaska
  • D107D107 Member Posts: 1,715
    edited September 14
    @hot_rod great point HR. I do see that in this 1924 house they have another vent (just on the house side of the main house trap) that is a few feet off the ground in the brick foundation wall; they used to have another one since cemented over on another foundation wall corner.

    Not sure how well something will vent sideways; is the stack effect operative here or is that just for the much hotter combustion air? Perhaps the vent termination should face up rather than down?
  • D107D107 Member Posts: 1,715
    @hot_rod just saw your second post. Yes, the main stack does exit the roof properly but I'm only assuming that the 2nd floor fixtures are stack-vented. Pretty sure the toilet is. When they added the first floor bathroom, they should have vented everything via the main stack. But it might have been tough to stick to code--which I think requires all fixtures to be within four feet of the main stack?
  • mattmia2mattmia2 Member Posts: 1,728
    the distance from the main stack if only if they are wet vented, they use the stack directly as drain and vent with one pipe. if there is a separate vent that ties in up higher they can be virtually any length.

    Plumbing vents are supposed to be above the roof so that the sewer gasses don't get pulled back in to the house. Those should go up and out the roof or above the roof on the sidewall, they shouldn't just end like that. Given the vent just dumping out the sidewall and the tees where there should be wyes I don't think a plumber did the copper modifications.
    D107
  • D107D107 Member Posts: 1,715
    @mattmia2 Understood; however if all the fixtures' traps and main house trap are working, there should be no sewer gas sporadically escaping, yes?
  • mattmia2mattmia2 Member Posts: 1,728
    It is probably coming in through the walls. exterior walls aren't perfectly sealed, enough for you to smell it can leak in. It also contains methane. that is why plumbing code requires it to be extended above the roof.
    D107
  • ZmanZman Member Posts: 5,948
    Could you convert the vent to an automatic air vent with an vented access plate on the inside of the house?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    D107STEVEusaPA
  • D107D107 Member Posts: 1,715
    @Zman I guess someone more advanced than me would have to respond to help me understand how that would work. You're talking about an HVAC auto-vent, sort of functioning like a mini-vent so it shuts when not venting?
  • ZmanZman Member Posts: 5,948
    edited September 15
    It actually stands for air admittance valve (AAV). Air goes in but wont come out.
    https://www.plumbingsupply.com/autovent.html#minirecessedbox
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    D107
  • ratioratio Member Posts: 2,545
    I think @Zman meant one of these: https://www.supplyhouse.com/Sure-Vent-Air-Admittance-Valve-14971000. They're a real plumbing fitting. I hear that the Code goes back & forth regarding their permissability every few years, but I can't imagine a pipe pointing through a few holes drilled in the siding is super compliant either.
    D107mattmia2
  • D107D107 Member Posts: 1,715
    edited September 15
    @Zman @ratio Yes, those are what I was calling minivents. We have them installed on 2nd floor shower, 1st floor kitchen and bathroom sinks, and basement slop sink. So aside from the first floor toilet, not sure what is actually venting through that side wall.

    The question would be how many fixtures could one auto-vent cover?

    Photo below shows basement piping--large 1st floor toilet waste line. "F" 2" hard-to-see copper angled line is waste from 2fl shower and sink and plumber thinks they also vent those fixtures plus the kitchen sink and 1st floor toilet. But can that toilet, or other fixtures be vented from below like that?

  • hot_rodhot_rod Member Posts: 13,737
    Yes toilets, tubs, showers are vented below the floor, how else?🤔
    the toilet vent looks correct it needs to take off the horizontal run above the centerline of the pipe.
    wonder how the kitchen vents?

    Auto vents need to be accessible, the disc inside does fail after time and they can leak sewer gas into the space, use the larger more expensive brand if you go that route
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
    D107
  • Intplm.Intplm. Member Posts: 1,173
    @D107
    What you have installed is terribly against plumbing code, and you will continue to have the smell issues you have written about earlier.
    Take a good look at what @Zman posted above. Those items are what you should install if you cannot extend a vent through the roof.



    You can install one of these at each fixture or you can install a larger single one for a group of fixtures. All will give you more proper venting.

    When you install these, you will be abandoning old current vent pipes in the wall. This should get rid of the problems that you have with the smell and the holes in the side of the house.
    D107
  • dopey27177dopey27177 Member Posts: 378
    The vent shown in this picture is supposed to above the flood rim of the fixture.

    In many loosely written codes they allow this vent to be installed as shown.

    Think about a stoppage in the drain line, When water will be entrapped in the sink water and waste products from shaving, tooth cleaning can collect in the vent fitting. At that point the vent can leak onto the floor. Additionally, the vent will need to be disassembled and the diaphram cleaned or the vent replaced.

    Cheap plumbing gets un-expected results.

    Jake
    mattmia2
  • Danny ScullyDanny Scully Member Posts: 1,253
    edited September 24
    You are incorrect @dopey27177. AAVs can be installed 4” above the weir of the trap (unless if used for a washing machine, in which case in needs fo be above the standpipe). The reason this is acceptable is because AAVs let air IN, and do not allow water to leak out in the event of a backup. 
    D107
  • JUGHNEJUGHNE Member Posts: 7,098
    Having done a lot of remodels of old houses with the only vent being the 4" vent stack, which was used for drains for everything along the way up, it is always a compromise of what is code and what is practical or possible without tearing the walls up for 2 or more floors......IMO.
    D107
  • D107D107 Member Posts: 1,715
    edited September 24
    Just to be clear, the first photo below--kitchen sink--looks like minivent is high enough;

    but 2nd photo, 1st floor bathroom looks very low. What extra effort would it have been to add another foot of pvc? But it does look like it might be 4 inches above the weir.

    Third photo --2nd floor sink--I was told the piece after the trap is too short before it hits the wall to T-off for a vent. Yet it looks to me like it has as much room --about 5"--to do the same as photo #2. Though the vertical piece from the stopper might get in the way. If I can vent this sink here, and lengthen the other sink vent I will have all fixtures bypassing that side-wall vent except the downstairs toilet. Then I can check that sidewall vent, see where it ends and extend it outwards.




  • hot_rodhot_rod Member Posts: 13,737
    Looks like they are both installed per the manufacturers requirement, they inspector could, would go by that if they are uncertain. It is an ASSE listed product. I like to run them up to the4 underside of the counter for additional piece of mind.

    I plumbed quite a few log homes over my career and these were often the only option, when lavs and kitchens were on outside log walls. Unless the builder would build a chase on the log wall.
    Same with many timber frame homes.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
    D107
  • D107D107 Member Posts: 1,715
    @hot_rod Thanks for the diagram. Don't know the code here in NYS for that horizontal distance, but seems like if #2 is ok, adding vent for photo #3 would work too if I get that metal piece out of the way.
  • mattmia2mattmia2 Member Posts: 1,728
    #2 looked like #3 before the offset. Might need to offset the pipe to the air admittance valve with a 45 and by turning the tee 45 degrees as well to clear the popup linkage.
    D107
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