Another ejector / siphon problem

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Zpcaulca

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Had a plumber replace my basement sewage ejector pump after failure, he “upsized” to a bigger pump. Ever since then, when the pump runs, it causes siphoning (gurgling sound) from a ground level bathroom sink and sucks the trap dry so sweage smells permeate the house. The sewage ejector pump discharges into a pipe along the side of the house, which then runs right by the outlet for the ground level bathroom.

1. Is it possible the plumber “over-spec’d” the ejector pump, and its just too big for the system?
2. How can I test the adequacy of the air vent for the upstairs bathroom? Maybe it is blocked? I’m not even sure which stack on the roof belongs to it, but I think it is a 1.5” air vent.
3. If the u/s bathroom vent is clear, and the pump isn’t over sized, any other solutions to this? Someone suggested I try putting a bigger trap on the u/s sink drain.

I welcome any troubleshooting ideas or solutions. This is a smelly problem and the installing plumber is saying the issue is with ventilation and not their install or the pump. I’m not arguing with them, just want to get to the bottom of this one way or another.
 

Jeff H Young

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the ejector pit needs a 2 inch vent a 2 inch pumped waste tying into a 3 inch line using a wye thats rolled up . something was likely plumbed wrong (possibly existing befor this plumber came out ) a deeper seal trap may help but a properly built system wouldnt require that
 

Reach4

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I am not a plumber. I think the bigger ejector pump can certainly trigger the problem.

So is the ground level sink feeding the pit? I am thinking not.

Yes, you may be able to put on a trap with a bigger water seal. There are reversible 1.5 inch traps where you can have a 2 inch water seal or a 4 inch water seal. I don't know if they have those in 1.25 inch traps.

Maybe sketch or photograph were the ejector pump outflow joins the other pipes.

There is a way to measure the vacuum that the trap is seeing.
 

Zpcaulca

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the ejector pit needs a 2 inch vent a 2 inch pumped waste tying into a 3 inch line using a wye thats rolled up . something was likely plumbed wrong (possibly existing befor this plumber came out ) a deeper seal trap may help but a properly built system wouldnt require that
Can confirm there’s a 2” air vent and 2” outflow connected to the ejector basin. The problem appears to be when the sewage is flowing down the 3” pipe and running past the bathroom sewage outlet, it is creating suction and emptying the trap. Not sure why the air vent for that upstairs bathroom isn’t stopping this from happening - perhaps it is too small? I’m thinking of putting an AAV trap at the bathroom sink where the gurgling is coming from to see if that relieves the suction. I can also check the air vent for blockage, would have to invest in a camera I guess?
 

Jeff H Young

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If it is backing up in the drainage system and or plugged drain or vent it can cause traps to siphon toilets to gurgle suck water down in bowl . as can improperly plumbed . throw an AAV undersink if you want might take care of it its cheap and easy , better yet build it like you are going to put an AAV and leave it open if it works then buy the AAV if not just throw a cap on it
 

Zpcaulca

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I am not a plumber. I think the bigger ejector pump can certainly trigger the problem.

So is the ground level sink feeding the pit? I am thinking not.
NO. The ground level bathroom fixtures feed into the same sewer line, further "downstream" than where the ejector pumps into the line.
Yes, you may be able to put on a trap with a bigger water seal. There are reversible 1.5 inch traps where you can have a 2 inch water seal or a 4 inch water seal. I don't know if they have those in 1.25 inch traps.

Maybe sketch or photograph were the ejector pump outflow joins the other pipes.

There is a way to measure the vacuum that the trap is seeing.
I'll do a sketch. By way of update, I took the trap off and was going to install an AAV, thinking the problem is a vacuum on the bathroom sewer line. However, I cycled the ejector with the trap off, and what happened is it "burped" up a bunch of sewage - it shot out the sink drain, luckily I had a towel there. You can also see the water move in the toilet bowl when this happens, so for some reason that I don't understand, the ejector pump is surging UP the sewer into this bathroom. The trap was full of very dirty water and some debris.
 

Jeff H Young

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Didnt think it would be a vent so now you know its backing up for some reason.
 
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