Thread: Studor vents, no vent of roof

Old Florida cottage, 1 bath: Found three studor vents in the attic; one on main stack and two on branch stacks (no outside venting). Also the main and one branch is mounted out sideways (not vertical). I know all this is incorrect but not sure what to tell customer & seller why its wrong. My main questions are: What bad effects will there be by not having a vent to the exterior and why its wrong for two of them to not be installed vertical. Thanks

Mark,

"At least one" vent must (is required to) go to open outdoor air - it can go through the roof or through the side wall (with special requirements).

AAV (Air Admittance Valves) are not designed for pressure, having AAVs on all vent could lead to buildup of pressure (such as when toilets are flushed, plungers are used, and other causes). The vent system with AAV must operate at atmosphere pressure (be open to outdoor air).

AAVs work by pressure differentials and a diaphragm opens when there is negative pressure in the vent system, that admits air (air admittance valve ), when the AAV is installed more than 15% from vertical the diaphragm may not properly open, may not properly close, may not open at all, or once open may not close at all.

What bad effects? Sewer gas in the house from AAV not opening (properly or at all) or from not closing (properly or at all) ... and sewer gas in the house is a "bad thing" .

Originally Posted by Jerry Peck

Mark,

"At least one" vent must (is required to) go to open outdoor air - it can go through the roof or through the side wall (with special requirements).

AAV (Air Admittance Valves) are not designed for pressure, having AAVs on all vent could lead to buildup of pressure (such as when toilets are flushed, plungers are used, and other causes). The vent system with AAV must operate at atmosphere pressure (be open to outdoor air).

AAVs work by pressure differentials and a diaphragm opens when there is negative pressure in the vent system, that admits air (air admittance valve ), when the AAV is installed more than 15% from vertical the diaphragm may not properly open, may not properly close, may not open at all, or once open may not close at all.

What bad effects? Sewer gas in the house from AAV not opening (properly or at all) or from not closing (properly or at all) ... and sewer gas in the house is a "bad thing" .

Jerry, thanks. Any chance the house will blow up or damage pipes until its corrected. The buyer is asking if it needs to be addressed right away or could it wait for a month or so. Got to go out for a while but will be back in a few hours. Thanks

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Originally Posted by mark petty

Jerry, thanks. Any chance the house will blow up or damage pipes until its corrected. The buyer is asking if it needs to be addressed right away or could it wait for a month or so. Got to go out for a while but will be back in a few hours. Thanks

BTW, his plans are to move into one room and then gut the place to do a complete interior rebuild including all mechanicals. He just wants to know if he'll be alright for a while. Just him and his wife.

How urgent it needs to be addressed depends on how much or how likely the buyer is upset that there is or may be sewer gas in their house.

Also, a contributing factor to how urgent this needs to be done is that, if not done now, it will likely not get done until they become the seller and their buyer's inspector reports the same thing, and they go "OH, CRAP! I never fixed that did I!"

Originally Posted by mark petty

Jerry, thanks. Any chance the house will blow up or damage pipes until its corrected. The buyer is asking if it needs to be addressed right away or could it wait for a month or so. Got to go out for a while but will be back in a few hours. Thanks.

The pipes won't blow up or be damaged. Even if all the vent pipes were closed the pressure will find a way out via the fixture traps. The homeowners could potentially have a cold backside if the City is jetting the sewer line in the street, as this does create pressure in the sewer lines.

But, yeah, like Jerry said, sewer gas could be an issue, since there is methane gas in it, among others, which is no good, except for igniting...