When ac is running the rv smells like black tank

[lesterw]

i thought of this. as soon as the weather cools here, i intend to do this. thanks

[desertcottage40cck]

Here is the guarantees solution to this problem. The reason for the smell has nothing to do with check valves, p-traps etc. It is simply that the A/C's are pulling in sewer smell from the grey tanks when being left open (the gases trvel straight up through your sewer drain outside and through your entire system. You have 2 choices to resolve the issue. 1) Keep your grey tanks closed (very inconvenient) OR what I did was an instant solution:

Extend your roof-top sewer outlet by approximately 12 to 15" with new abs pipe. Be sure that you extend the pipe so that it sits a few inches above the height of the air conditioners. I only needed to do this to my bedroom one; however you may need to do this to all of them. This solved the issue immediately and permanently.

[JohnD10]

Good idea to NOT leave your gray tanks open, anywayzzzzz

[desertcottage40cck]

I think one can go either way on this.....I'd say a 50/50 split on opinions on this topic lol.

[Zak1]

Originally Posted by carlknowles

We have a 2018 cck with 2 acs and have noticed when the acs are running there is a smell of the black holding tank throughout. Any ideas why? is the ac sucking in air from the tank vent?

It is absolutely your air admittance valve (s). This happened to me a few weeks ago and ended up replacing all three in my tt. zero smell. I did the the good ones from Home Depot.


STUDOR
Mini-Vent 1-1/2 in. - 2 in. PVC Air Admittance Valve Adapter
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[desertcottage40cck]

Where are these air admittance valves exactly located at? Where's the laundry one, the bathroom one and the kitchen one at?

Thanks

[Zak1]

Originally Posted by desertcottage40cck

Where are these air admittance valves exactly located at? Where's the laundry one, the bathroom one and the kitchen one at?

Thanks

They should be close to your pea traps. they mount on top of a vertical pipe (looks like an endcap.

[desertcottage40cck]

Do you have a photo of one of the original one's installed from the factory? I do not have any in my coach anywhere.

[JohnD10]

I have heard of them being mounted in the access panel for the shower plumbing...

[Zak1]

Here you go!

[ependydad]

Interesting. I'm having the same issue, but only when a toilet is flushed and the main A/C is running.

[Zak1]

Originally Posted by ependydad

Interesting. I'm having the same issue, but only when a toilet is flushed and the main A/C is running.

Same fix,
I only had one fail but replaced all three (on my rig) with good ones just
to fix once and for all (I hope!)

[Rich5117]

Went thru this ordeal on our 2016 Silverback. Replaced both air admittance valves, no luck. Sealed around roof vents, no luck. Tried closing gray tanks, problem went away. I like leaving the gray tanks open when we are out for awhile. So now I form a trap in my sewer hose as it comes off the connection. Have not had this odor since. Our odor was most noticeable when using the shower. Our sinks both have traps, but while investigating I found our shower does not, but has a check valve

[cavie]

Originally Posted by desertcottage40cck

Here is the guarantees solution to this problem. The reason for the smell has nothing to do with check valves, p-traps etc. It is simply that the A/C's are pulling in sewer smell from the grey tanks when being left open (the gases trvel straight up through your sewer drain outside and through your entire system. You have 2 choices to resolve the issue. 1) Keep your grey tanks closed (very inconvenient) OR what I did was an instant solution:

Extend your roof-top sewer outlet by approximately 12 to 15" with new abs pipe. Be sure that you extend the pipe so that it sits a few inches above the height of the air conditioners. I only needed to do this to my bedroom one; however you may need to do this to all of them. This solved the issue immediately and permanently.

I fail to understand what you accomplished. The rooftop air conditioners do not draw air inside the trailer. They simply recirculate the air inside the trailer. the AC does use outside air to cool the coils within the rooftop unit. No outside air enters the trailer.

[Comanchecreek]

Originally Posted by Rich5117

Went thru this ordeal on our 2016 Silverback. Replaced both air admittance valves, no luck. Sealed around roof vents, no luck. Tried closing gray tanks, problem went away. I like leaving the gray tanks open when we are out for awhile. So now I form a trap in my sewer hose as it comes off the connection. Have not had this odor since. Our odor was most noticeable when using the shower. Our sinks both have traps, but while investigating I found our shower does not, but has a check valve

I always do the sewer hose trap setup. Easy and also prevents roaches etc from getting into your holding tanks.

[JohnD10]

Originally Posted by Rich5117

I like leaving the gray tanks open when we are out for awhile. So now I form a trap in my sewer hose as it comes off the connection. Have not had this odor since.

Originally Posted by Comanchecreek

I always do the sewer hose trap setup. Easy and also prevents roaches etc from getting into your holding tanks.

Creating your own P-trap in the sewer hose is only half the solution...

I know most here don't care...but this video is a must see for all RV'ers and you must watch all 5 minutes of it:

https://www.youtube.com/watch?v=Q4A-41EdBBc

[WyomingJack]

I have heard of the black tank vent pipe having a crack somewhere between the black tank and the roof vent inside of a wall. It needed to be replaced.

[cavie]

Originally Posted by WyomingJack

I have heard of the black tank vent pipe having a crack somewhere between the black tank and the roof vent inside of a wall. It needed to be replaced.

Yes, I have seen pictures of this happening. the vent pipe stoppes short of entering the vent cap. the smell then coms up the stack and INTO the ceiling if the trailer/coach not going thru the cap and out. The remedy is to remove the cap. seal up the space between the vent pipe and the roof. replacing the cap.

[Buzzard1967]

That is what I was thinking.

[jz5w63]

We had a problem with black water tank odor coming in from the annular area around the tank vent stack pipe where they go through the roof. The holding tank vents release hot odor laden air above the rv but if you are running an exhaust fan in the bathroom, over the stove, or elsewhere then air needs to come from some where. When you are running AC then everything is pretty much closed up and makeup air to replace exhausted air will leak in. In our case the air path was around these vents down the wall between the kitchen and the bath and then into the kitchen are through the grill for the furnace intake air at the bottom of the cupboards. After I took off the roof vent caps and its mating flange from the roof I could see the 3/4 inch or so of clearance around each pipe. I stuffed some 1 inch square window air-conditioner foam seal around the pipe for support and then filled above it the gap/annular opening with silicone caulk to still allow some pipe movement for expansion yet fully seal off the leak path. Then I put the flanges and vent caps back on. This has 100% solved this issue for us. You could buy the wind activated rotary swivel vane caps but I'm told these eventually break off from travel turbulence, low campground branches, hurricanes, squirrels (LOL) etc. and only work when there is wind so why put out the price for these band aids? Might not be your issue, but give it a check!