We just installed a full bathroom with sewage ejector in the basement. The sewage ejector is piped directly to the main drain line in the house, to vent the ejector we installed a 3' vertical pvc pipe in the lid's second hole and capped it with an AAV to avoid venting through the wall/roof. The problem now is that the toilet, when flushed will only go down the drain if we remove the AAV from the vent line. There seems to be a suction problem. Could the AAV be deficient? Undersized? Or not installed correctly?

Studor's install diagram shows a loop created with drain & vent pipe which we did not do. (we used a stupor knock off at the time and did not have this diagram)

Thoughts? Please help!

Hi Elisafri

Yup, 'fraid I know the issue here! If you read the ejector pump instructions it will clearly state that you CANNOT use an AAV for a sewage ejector.

You can't use an AAV because a sewage ejector pit system takes in air as much as it expels air. Since an AAV only lets air in one way, you are choking the system and the system can't pump properly.

Remove the AAV and install a proper 2" vent up and through the roof as required in all code books that I know of.

Good luck!

Mark

PS: Did you guys drill the 3/16" hole in the discharge pipe (inside pit) as required to prevent air lock?

Thank you Mark. Not sure about the 3/16" hole. Will double check that. Was trying to avoid the work & demo involved in venting through and through but guess not much choice if I want my toilet to flush.

I echo Mark's excellent response and advice... Milo