Another Basement Bathroom Vent Question

[YankeeFaninPhilly]

Hello and Merry Christmas!

I have read a lot of posts in here - great site - thank you everyone. I have read dozens of venting posts to see if I can answer the question.

I am a DIY homeowner/engineer that has done a lot of plumbing and construction work over the years with new bathrooms, finishing basements, etc - I guess it means I move too much! However, I am stumped a bit here.

The basement has been stubbed out with (2) 4" lines that feed a poly pit for an sewage pit just 3 feet away. Unfortunately, the two stubs are less than 12" apart, and not enough room with the pit and pipes to do anything "as is"! The choice is to dig up concrete or build a floor. Since we have 9' 6" ceilings, we are building a 2 x 8 floor, and can then run the drain lines where we need to. There are 4 other toilets in the house that all work great, with 3 separate roof vent stacks from what I can see.

I am putting in a corner shower, toilet and sink (6 DFU's I believe). I plan to use a Zoeller M803 residential grinder for the pump with a check valve (any recommendation for a good, quiet one?).

Big challenge is that there is no way to vent these fixtures outside since we are not near any vent stacks on the first floor above - Everything nearby are horizontal drain lines heading to the main sewer pipe, which I don't believe qualifies as venting for new fixtures.

The local inspector said they would allow air admittance valve(s) as long as it/they were sized properly.

If I put an air admittance valve on the vent line for the pit, will that allow enough air to flow through the rest of the system? The Studor Redi-Vent 1 1/2 says it handles 6 DFU, but I feel like the Maxi-Vent would be"better". The pit is less than 10 feet away from the toilet and shower if that helps.

Every diagram I see for an ejector pump/pit shows its own vent line, and then the fixtures still have their own vent as well. I have pictures of the area, but not sure I am uploading properly

Any help would be most appreciated.

 

[Jadnashua]

An AAV only allows air in. To put waste into the pit, it must displace some air, so the pit itself must be atmospherically vented (as far as I understand). Then, each trap of things you add will need to be vented to prevent siphoning. In a single bathroom group, you can wet vent some parts, but essentially each of them needs to be vented, and it can't be at the pit. Those bits could be vented with an AAV.

I may be off on this, but conceptually, it's right. I know when I added a laundry basin/pump, the water wouldn't go into the basin with just an AAV on it...I would expect similar problems with a sewage ejector pit.

 

[Sponsor]

 

[Cacher_Chick]

Having to step up into a bathroom that has been raised to accommodate the plumbing spells out "hack job" to me. Needing to cut in some trenches for plumbing and running a new vent up through the existing structure should not be things that should prevent someone from doing the job right.

A basin must be properly vented to allow air flow in both directions. An AAV cannot do that.

The overall layout of the house determines where the best place to run a new vent will be, it does not have to be right at the fixtures or even near the bath.

If you want do something that you can be proud of which will work properly for the next 50 years, don't take shortcuts now that you will regret later.

 

[Master Plumber Mark]

What exactly is the 3 inch line doing by the 2x4 is that supposed to be a vent stubbed up ??
normally if the place was plumbed correctly their should be a 2 inch vent stubbed down
somewhere for everything in the bathroom to vent into...

if you are getting this inspected then its probably gonna be an issue ..... In the past , when it was totally
impossible to run a vent out the roof, I have had to run a 2 inch line up as high as possible in
the rafters the loop it back down and tie it into the main sewer line and it will work as a vent . It basically
is something akin to a "loop vent" and is much better and preferable to auto air vents...
It never has given me a problem because the whole system is vented

 

[YankeeFaninPhilly]

What exactly is the 3 inch line doing by the 2x4 is that supposed to be a vent stubbed up ??
normally if the place was plumbed correctly their should be a 2 inch vent stubbed down
somewhere for everything in the bathroom to vent into...

if you are getting this inspected then its probably gonna be an issue ..... In the past , when it was totally
impossible to run a vent out the roof, I have had to run a 2 inch line up as high as possible in
the rafters the loop it back down and tie it into the main sewer line and it will work as a vent . It basically
is something akin to a "loop vent" and is much better and preferable to auto air vents...
It never has given me a problem because the whole system is vented

Thanks everyone -

I understand now the need to have venting on both sides of the pit. Makes sense after I think through it. So the AAV won't work on the output side of the pump.

I understand the idea that a "step up" is not ideal - not sure I agree with the "hack" - will think about it, and see if we are up to attacking the concrete. Have seen it around here a lot.

Mark - I originally thought the same thing, that the 3" line could be the vent for the new bathroom. I just can't seem to find a pipe stub leading to the roof anywhere to which I would connect for venting. I was hoping that would be preplumbed. That is far more difficult to address than a sewage pit.

I keep thinking that the original plumber had an idea for how to vent the basement - I just can't figure it out.... Along the side wall in the picture there is a 3" drain line coming from the 1st floor powder room that leads to the sewer with a 2" Y that has been capped off. That's where I figured the sewage pump would get tied into. But I see nothing else for a vent. That powder room is 25-30 feet away on the first floor -

I was thinking about the loop vent idea - I just didn't know how large of a loop would be required.

Thanks everyone.

 

[Master Plumber Mark]

it looks to me that the wall was not installed in the proper place and the 3 inch stack is there to be both the arm for the lavatory in the same wall and then reduced down to 2 inch for the vent... you are gonna have to move the wall over to center on the stack....

A vent off the pit is easy to just tie
into the same lav line... You take the air vent up as far as possible in the rafters then back down so nothing can ever come back through the line and back into the pit.. Tie into the main 3 inch with a wye and it will work....Its only air


either do this or just break up the floor and put the toilet where you want it to be

 

[Cacher_Chick]

Whatever you decide, I would highly recommend drawing a proper plumbing diagram and getting it signed off on by the inspector before you get too far. What Mark is suggesting might fly where he is, but it would not where I am, and I doubt many other places either. Many places specify a pumped basin as such is to be individually vented. In some places the walls are layed out in such a way that it is easy to pipe, where at other times we run up through the back of a closet or a space where the piping can be hidden inside a chase.

 

[Master Plumber Mark]

Whatever you decide, I would highly recommend drawing a proper plumbing diagram and getting it signed off on by the inspector before you get too far. What Mark is suggesting might fly where he is, but it would not where I am, and I doubt many other places either. Many places specify a pumped basin as such is to be individually vented. In some places the walls are layed out in such a way that it is easy to pipe, where at other times we run up through the back of a closet or a space where the piping can be hidden inside a chase.

I totally agree with you on this , but sometimes you do what you have to do simply because their
is no other feasible way to accomplish the mission..... and it will work 100% of the time.
We are talking about vented , non pressurized
air here.... flowing back and forth through the plumbing system --- its not sewage ....
.
Running a loop vent up to the highest spot in the rafters and back down to the 3 inch line
or a wet vent , whatever you want to call it , ----is much much better than
throwing auto air vents on the sewage pit .... I have seen that before and it is a joke...

It is totally absurd to expect someone to run a full 2 inch vent up 3 flights of finished floors and
vent it out the roof just for a sewage pit..... Consider this the "ideal way" to do something
if the home is unfinished.....
In our area a 1 1/2 vent is all that is required and it can also catch
the lav vent and tie into the system anywhere above the flood rim of the highest fixture on the
floor above it.........
.