Ejector Pump Venting Mystery

[amselm]

Setup: Basement bathroom (toilet, sink, shower stall) connected to "Little Giant" sewage ejector pump system (partially buried basin and pump). 2" waste rises vertically from basin 6' then horizontally for 1' then check valve installed then another 2' until it empties into stack. Shower and Sink vents are tied together rising 42" and then fitted with a studor vent. Basin is also fitted with a studor vent – I know this is not ideal and the only reason I went this route is that venting up through roof would have been impossible without major interior construction - I can go through the side of the house then up which is what I plan on doing if I can't solve this problem.
Problem: After 12 months of flawless performance the float on the pump became stuck in the on position which cycled the pump continuously for appox. 10-15 minutes. I removed the lid, disslodged the float and cleaned the interior (yuck) and tested the unit with the lid slightly ajar making sure it operated. All was well until I closed the lid and tested the system. I am now having a venting problem (toilet flushes when pump engages, problem flushing toilet in that water does not go down etc.)
Question: I am guessing this must be a vent problem because when I remove the studor vent all operates normally. What I can't understand is why did everything work perfectly for twelve months using this venting method and then all of a sudden it doesn't work anymore? Any help or advice would be greatly appreciated.

[Cass]

Your lid must not have been sealed during the first 12 months. When you fixed the problem and reinstalled the lid you secured it right and it is air tight like it should be. When you try to flush the pit pressureizes and doesn't allow it to flush. When the pump turns on it creates a vacume and alowes it to flush once or so. The studor only lets air in not out.

[amselm]

Thanks so much for the prompt reply - sounds like it makes sense, though it's odd I never smelt any sewer gas or foul smell in the basement all this time.

If I am going to have to vent out the side of the house do you have any idea on the max. distance a vent can travel at 45 degrees before exiting the house and going verical up the side to the roof? The basin is located about 7 feet from the side wall of the house and I have about 9 feet of overhead clearance.

Thanks again for everything.

[master plumber mark]

you cant use studor vents , they jsut dont work well
on this situation


If you jsut run a vent off the top of the sewage pit and maybe tie in
the other lines it will work fine.....
now how you get ittied into the main vent is another task..


How you accomplish this is your business........


But --I have seen people avoid going all the way out the roof by
just tieing this vent back into the main 3 inch drain line....somewhere behind wherer the sewage pit is tied in,
and then looping the vent
as high as possible into the basement rafters.to avoid the sewer from
backing up and going down that vent line........

air is air and does not know or care how many bends or crooks are
in that two inch line...

it basically will act like a vent too if their is literally no other way
to get an air line out of the house....

I see this all the time.....in lots of re-models

[amselm]

Thanks so much - I think I'll run the vent up on an angle and then out the side of the house to the roof. Any resource you could point me to (on the web) to see if this might pass code here in San Deigo, CA? I'm wondering how much of a horizontal run is allowed in a vent as the ideal situation is always to go straight up. Thanks again.