Air Lock in Kitchen Sink Drain?

[marant]

Here is the scenario:

1. Filled fresh water tank with water and one cup of bleach to sanitize. Ran water through all lines with drains open.
2. After a day or so turned on the pump to run all of the fresh water out of the tank into the grey tank to both somewhat sanitize the grey tank and drain grey tank. Grey tank empty when started.
3. While filling the grey tank (toward the end, probably only 4-5 gallons left) the kitchen sink stopped draining, filled 1/2 full when discovered (whew). Bath room sink still draining. Thought possibly the grey tank was overfull, but no water up in the shower.
4. Drained the grey tank fully. Water level in kitchen sink did not change. Bath sink never did back up, continued to drain until out of water in fresh tank.

Got a small plunger and used it on the kitchen sink, thinking there might be a clog somewhere, though do not know how, as it had drained properly until fresh tank nearly empty. When using plunger it was difficult to force water through drain, though some moved, apparently only the amount actually in the plunger. Sink did not drain on its own. I made sure the plunger contained no air and pumped it up and down several times. When lifting the plunger (still under water) air would come up into the plunger and some water would drain, but not all.

About the only thing I can think of is an air block somewhere in the drain line, but cannot find anything. We have never put grease or anything like that down the drain, and there are no apparent leaks.

Any ideas?

[Chamberman]

Do you have a Hepvo or standard trap on the kitchen sink? I would expect a piece of debris, possibly left from initial build, to be blocking the pipe somewhere. Because a Hepvo uses a diaphragm if you have one then I'd start by looking there.

[marant]

Standard sink drain.
Waited a while, sink drained. Will run another test to be sure it is ok.

[Iowa Dave]

If possible I would take the trap apart and make sure it’s clean.
Iowa Dave

[marant]

Taking Dave's suggestion I went to pull the trap to see if there was a blockage. Lo and Behold, I learned ETI is installing Hepvo traps in the newer trailers. I had never seen one before.

Took it all apart (quite easy) and discovered the plastic diaphragm was wadded up in the pipe, preventing proper drainage. Straightened it out, reassembled and everything works as it should (and did).

No idea what caused the diaphragm to bunch up originally. Could be caused by my use of the plunger, but I choose not to think so since the problem pre-dated usage of the plunger, and I can make enough mistakes without going looking for them.

Thanks to Chamberman and Dave.

[Iowa Dave]

Next up, removing sun tan oil bottles flushed down the toilet at public swimming pools and other maladies at public facilities. ( Comedy routine at rallies after I’ve quaffed a few.)
Iowa Dave

[Chamberman]

Originally Posted by marant

Taking Dave's suggestion I went to pull the trap to see if there was a blockage. Lo and Behold, I learned ETI is installing Hepvo traps in the newer trailers. I had never seen one before.

Took it all apart (quite easy) and discovered the plastic diaphragm was wadded up in the pipe, preventing proper drainage. Straightened it out, reassembled and everything works as it should (and did).

No idea what caused the diaphragm to bunch up originally. Could be caused by my use of the plunger, but I choose not to think so since the problem pre-dated usage of the plunger, and I can make enough mistakes without going looking for them.

Thanks to Chamberman and Dave.

I'm sure the diaphragm got bunched up when you put the plunger on it.

However, the fact the water stopped flowing at some point before you used the plunger says that the pressure equalized across the hepvo diaphragm. In other words the pressure in the tank was not venting as the tank was filling. I have to wonder if Escape eliminated the vent in the gray tank when they started installing hepvo valves. The hepvo valve is a great air admittance valve (one way valve) but it's not going to let the air flow in the opposite direction from the storage tank back out when the tank is filling.

[marant]

I would agree with you about venting on the grey tank, but the bath and shower drains should provide some venting. I do think it is at least partially due to the grey tank being nearly full.

I may never figure it out. Just glad the problem is solved.

[7Gentex]

Originally Posted by marant

I would agree with you about venting on the grey tank, but the bath and shower drains should provide some venting. I do think it is at least partially due to the grey tank being nearly full.

I may never figure it out. Just glad the problem is solved.

Believe the bath sink and shower drains have a shared trap which would (should) prevent the drain from acting as a vent?

I think the 21C gray tank roof vent is above the DS cabinet stack and runs up there via inside the pantry/wardrobe (inside the wall).
The black tank roof vent is above the bath - it goes up inside the sink/door wall. Curious if you see both on the roof.

Not sure where the gray tank vent ties into the gray tank - on top would make sense / and optimal...........