Bathroom sinks slow to drain

[Gabe]

We own a 2019 solitude 372 WB-R. In our bathroom we have two sinks. Neither one is draining, very slow. To date we’ve tried the following,
cleaned out the p trap
replaced the air admittance valve.
cleaned out any gunk in the drains.
Still will not drain effectively, in fact when one side fills up to an inch of water, the other sink begins to fill with water. When we loosen the the air admittance valve the water does drain out of the sink. Suggestions???

[TedS]

A bad air admittance valve? Did you remove the plastic covering new valve intake.

[Cate&Rob]

Gabe


Welcome to our owners technical forum. When you have a chance, have a look at our welcome post. https://gdrvowners.com/forum/main-fo...to-new-members . This will help you set up your signature and navigate the forum.

Is this a recent problem or has it always been this way? Assuming that the AAV is working correctly, I wonder if your grey tank has a plugged (or missing) vent stack connection? To put water into a tank means that there has to be an exit path for the air displaced from the tank. Removing the AAV might be creating a vent path allowing air out so that the water can drain in. When you remove the AAV, is there a tank odour present? (Indicating that air is coming out of the tank rather than going in . . . which the AAV allows)

Does this problem occur when the grey tank is completely empty or only after it is partially filled? The reason that I ask is that sometimes, the vent stack is pushed too far into the tank and as soon as the liquid level covers the end of this vent pipe, air can no longer get out of the tank to allow liquid in.

Rob

[Gabe]

The plastic was removed, I actually tried two different ones that I purchased at Lowe’s

[Country Campers]

When you remove the AAV and the sink drains can you tell if air is coming out from the threads on the AAV or is air being sucked into the threads?

If the sink drains when you loosen the AAV then I would guess bad AAV, but you have already tried that. The next thing would possibly be the vent pipe. Check the roof exit of the vent pipe, there is a screw that holds it on, watch for bees when doing this there is a member here, Yoda , that found a bees nest in his. Also try to shine a light down the vent pipe. The next thing might be that the vent pipe is inserted too far into the tank.

Brian

[ncitro]

Gabe Does the shower drain normally? They should drain into the same tank, so if the vent stack was clogged or inserted too far I would think the shower would drain slow as well.

[TedS]

I have a curious condition regarding full grey tank, shower and sink. So far just a curiosity. In my previous trailer, the shower would stop draining indicating it was time to dump the rank. In this Reflection, the sink stops draining when it's time to dump the tank. What makes it curious is that the sink is higher than the shower pan and the shower does not back up. ?

[Gabe]

Gang thanks for your thoughts and suggestions. The shower drain was not draining as well but we did clean the drain and all is well with the shower. I did remove the roof vents I didn’t see a blockage but I didn’t shine a flashlight down the pipe which I will do. One related or maybe unrelated item. When I pulled the black to dump, it was harder than normal to open and it took all the pushing I could muster to close. So I’m thinking it’s like a vapor lock or major blockage. We do flush the black tank after each camping stay. At some point the Grey and black converge so I’m wondering if I have a major blockage in the main drain? However we have no problems drawing the kitchen or shower.

[Cate&Rob]

I have a curious condition regarding full grey tank, shower and sink. So far just a curiosity. In my previous trailer, the shower would stop draining indicating it was time to dump the rank. In this Reflection, the sink stops draining when it's time to dump the tank. What makes it curious is that the sink is higher than the shower pan and the shower does not back up. ?

Hi Ted,

You likely have a "Hepvo" one way valve instead of a conventional P trap on the shower drain. This is often used when there is not room for the P trap. This one way valve will stop water from backing into the shower and the next lowest overflow point is the sink.

Rob

[Cate&Rob]

Gang thanks for your thoughts and suggestions. The shower drain was not draining as well but we did clean the drain and all is well with the shower. I did remove the roof vents I didn’t see a blockage but I didn’t shine a flashlight down the pipe which I will do. One related or maybe unrelated item. When I pulled the black to dump, it was harder than normal to open and it took all the pushing I could muster to close. So I’m thinking it’s like a vapor lock or major blockage. We do flush the black tank after each camping stay. At some point the Grey and black converge so I’m wondering if I have a major blockage in the main drain? However we have no problems drawing the kitchen or shower.

Hi Gabe,
The sticking black tank gate valve is a relatively common problem and is not likely related in any way to the grey tank filling problem. If the grey tank drains quickly, the vent stack is not likely plugged. It is still possible that the vent pipe is pushed too far into the tank. The best way to determine this is to see if the sinks drain more quickly when the tank is completely empty than they do when the tank is partially filled.

Rob

[TedS]

Cate&Rob , the hepvo valve is interesting. Ads for that valve claim it eliminates the need for an air admittance valve. Replace the p-trap and eliminate the aav.

[Cate&Rob]

Cate&Rob , the hepvo valve is interesting. Ads for that valve claim it eliminates the need for an air admittance valve. Replace the p-trap and eliminate the aav.

The AAV prevents "suction" by way of water dropping down the drain pipe from pulling the water out of a P trap. Since the Hepvo valve closes to back flow of either water or air (from the tank/drain) it makes sense that an AAV is not required.

Rob

[TedS]

The HepvO valve allows air to follow the water like an aav. The tanks still need a vent to the outside so water can flow into it and displace tank air.

[JBill9694]

To reiterate, Gabe two vanity sinks drain slowly, but the shower drains just fine. Does this indicate a problem between the sinks and where their drain connects with the shower drain? Or does the sink drain have it's own separate run to the gray tank? Does the shower drain working while the sink drain doesn't indicate that the problem isn't with the gray tank vent? No horse in the race just following along out of curiosity,

[Cate&Rob]

JBill9694
Hi John,

Good catch that the shower drain is now flowing properly after cleaning (per Gabe's post #8 . . . I missed that part ) This would point to something in the sink drain line rather than the tank vent pipe, as you suggest. The shower drain and the vanity sink drain often T together before going into the grey tank. Since this is a 5th wheel, pulling the aft wall panel in the pass through storage (just a few screws . . . designed to be removed) will provide access to all this plumbing.

Rob