Under sink pump smell help

[accman]

I have a liberty 404 residential pump installed under my basement bar sink, by the builder, of a 2 year old home.

It is not vented to the roof, they installed an air admittance valve. I also have no idea how I'd get it vented at this point up 3 floors.

When running the sink I have a strong sewer smell from under the sink and from testing it seems to be radiating from the pvc pipes fitted into the pump itself, so the inlet and the vent holes. As in where they actually connect.

I've put a baggie on the air admittance valve to test for smell escaping, it's not failing so isn't the culprit.

There is a p-trap between the sink itself and the pump.

QUESTION: Can I seal where the pipes are connected into the pump, the inlet and vent? I think they are letting smell escape. Is there a best practice sealant that works but can be broken easily if repairs are needed and the pipes removed?

Lastly do these under sink sump pumps radiate smell typically, are they really air tight? There isn't a barrier between it and the sewer line so any backup smell into the sump could theoretically escape if not 100% sealed.

 

[Geofd]

Some of those pumps have strainers,to catch coffee grinds,or what ever else goes down the drain, the ones I have worked on have 3phillips
head screws on top, exposing the filter, its right in the waste stream before draining until the pump,the way we know a sink, has this set up is istarts to drain slowly, because of that strainer, if there is one it's very nasty,wash it with very hot water

 

[johnjh2o]

I have a liberty 404 residential pump installed under my basement bar sink, by the builder, of a 2 year old home.

It is not vented to the roof, they installed an air admittance valve. I also have no idea how I'd get it vented at this point up 3 floors.

When running the sink I have a strong sewer smell from under the sink and from testing it seems to be radiating from the pvc pipes fitted into the pump itself, so the inlet and the vent holes. As in where they actually connect.

I've put a baggie on the air admittance valve to test for smell escaping, it's not failing so isn't the culprit.

There is a p-trap between the sink itself and the pump.

QUESTION: Can I seal where the pipes are connected into the pump, the inlet and vent? I think they are letting smell escape. Is there a best practice sealant that works but can be broken easily if repairs are needed and the pipes removed?

Lastly do these under sink sump pumps radiate smell typically, are they really air tight? There isn't a barrier between it and the sewer line so any backup smell into the sump could theoretically escape if not 100% sealed.

Post a picture

 

[accman]

Just added a picture.

I'll add the p-trap is working as there's no smell from the sink itself nor the air admittance valve. The actual pump smells and seems to be coming from the inlet and vent connection points.

 

[Jeff Handy]

If the aav has failed, then the pump might be sucking the trap dry when it pumps.

 

[Jeff Handy]

Take everything apart and out, and clean it.
Then afterwards, only put water down that sink, no solids or organic waste.

Is that black coupling on the discharge pipe a check valve?

Maybe it has failed, and is letting sewage run back into the pump box.

 

[accman]

Thanks Jeff, to your first comment there isn't a smell from the sink itself so I think the p trap is good to go.

For your second one, I'll need to investigate if that's a check valve I'm not sure as I didn't install this setup.
I do think your cleaning remark and checking the lid seal may be needed too the more I rrsd about this thing.
It's only ever had water and leftover beer kinda thing, but it's also smelled since month one of living here so I just think somehow sewage gas is coming back through it and it's not sealed tight enough to keep it trapped.

 

[SHEPLMBR]

You are not supposed to use an AAV with these type of pumps.

 

[Geofd]

Just added a picture.

I'll add the p-trap is working as there's no smell from the sink itself nor the air admittance valve. The actual pump smells and seems to be coming from the inlet and vent connection points.

Have you removed that black cover and checked that may not be the cause but it does need maintenance

 

[JG plumbing]

If the threaded connections on top weren't tight I'd think you'd see water. The sewer gas should be less of a chore than the water.

You could try using tape and dope and re screwing the adapter into the top. Just use regular thread tape and use the roll of tape to work out into the male threads. Then use blue monster (as an example) pipe dope.

I think this may be a red haring.

 

[accman]

Understood, but this is how the builder plumbed it. I don't know how it got passed the code inspector and home inspection. It should have properly been vented but it's near impossible now without a $5,000 plumbing job and drywall fix through 2 floors.

 

[accman]

Thanks JG plumbing.

At this point I've:
1. Bagged and plastic wrapped all the pipes and air admittance valve just to rule them out. *Seemingly* the smell persisted even after airing it out and coming back 2 hours later.
2. Oatey seal/caulked all the threads connecting to the pump itself (inlet, discharge, vent). The smell still persisted.

I'm thinking all it can be at this point is taking the lid off, which is hard to do considering how tight the pipes are plumbed under there, break my new caulk seals , and check the actual lid seal. I suspect the actual pump is emitting the odor.

It really needs a proper vent. I'm guessing the sewer smell is backing into it and is making it's way out somehow.

I hate that I ever had a basement bar sink put in. Thanks everyone.

 

[Jeff Handy]

Not up to code, but it is fairly common to sneak a 1 1/2 inch pvc vent for a pumped basement fixture like that up and out through the rim joist, just above the foundation, as high as possible, almost touching the sub floor above.

Then extend it up a foot or two, and add an elbow, with a loose mesh screen for critters.

Similar to what you see for pvc vents for basement furnaces or power vent water heaters.

So not legal, but I have seen plenty like this.

For pumped laundry sinks and Saniflo macerating toilets, for example.

Just don’t put it right under a window, or near a door, or near another vent or intake for a gas appliance.

You might get caught when selling the house, maybe not.
It works in the meantime.

But not legal.

 

[GReynolds929]

Is the pump removing too much waste water leaving the bottom of the pump above the water level? Sewer gas can enter this way. There should be a couple of inches above the bottom of the pump. If not the float may need adjusted.

 

[accman]

Thanks, I haven't taken the lid off (yet) so will check this.

Are you saying pumps themselves can act as their own p-trap (similar gas backstop concept that is) if the float is configured correctly and the water left inside is enough to cover the ejection port?
Hadn't thought of that yet.

I have my general contractor coming this week to take a look. At this point, I think I'm getting over my head and beyond easy fixes to be honest.

Once this is resolved I'll reply back with the issue and resolution to help others. I appreciate all the feedback and will use your ideas to chat with my guy!

 

[Twowaxhack]

You are not supposed to use an AAV with these type of pumps.

Sheplmbr is correct, and using an AAV will cause short cycling.

Short cycling cause build up of crud in the pump and container.

This will produce a stink as it sits and cooks in the basin. You need a vent snd the basin and pump probably needs a good cleaning

 

[SHEPLMBR]

oohhh I got an "atta girl"