Black Tank Vent & Bedroom AC Unit

[jdelp]

We have a 2019 Puma 31RLQS with an AC unit installed in the front (bedroom). This weekend my wife and I noticed a septic smell in our bedroom when someone would flush the toilet in the bathroom - don't notice the smell any other time. I think I may have pinpointed it, but wanted to get other's thoughts.


The black tank vent stack is about 2' or so from the AC unit in our bedroom - my thought is when the AC is running, it is pulling in the septic smell from the vent stack...IF that's the case, I'm thinking the only remedy would be to not have the AC on in the bedroom when the toilet is flushed. I try to keep the black tank as clean as possible, have used the Geo method to treat it in the past and just got some Happy Campers Organic mix to try as well - we'll see how much that helps with any odors - even though we don't use the toilet for anything other than #1. , but I think you'll always have some odor especially when temps are high.


Any thoughts or has anyone else noticed this particular problem. Thanks in advance!

[bubbles]

Not saying somehow it isn't but the air conditioner just recirculates the air within the rv. Should be no opening to outside air.

[5picker]

The roof top unit shouldn't be pulling any outside air into the R/V.

As mentioned, they simply recirculate inside air. There could be something not sealed properly but not likely.

The suction of the bedroom air conditioner, recirculating that air, 'could' be pulling sewer gasses up through the toilet when flushing. This also often happens with a ceiling vent fan. Especially one right above the toilet.

We often leave a window cracked a small amount or a vent open slightly to keep the "box' of the R/V from becoming a vacuum.

[jdelp]

Originally Posted by 5picker

The roof top unit shouldn't be pulling any outside air into the R/V.

As mentioned, they simply recirculate inside air. There could be something not sealed properly but not likely.

The suction of the bedroom air conditioner, recirculating that air, 'could' be pulling sewer gasses up through the toilet when flushing. This also often happens with a ceiling vent fan. Especially one right above the toilet.

We often leave a window cracked a small amount or a vent open slightly to keep the "box' of the R/V from becoming a vacuum.

Thanks for the info on re-circulating air not pulling in from outside.

Yea, we make sure that the vent/exhaust fan is NEVER on while flushing. Appreciate the tip of leaving a window cracked to prevent the vacuum effect - we'll give that a try in a couple weeks.

[Lins]

One issue I’ve read about and we had as well, is the vent isn’t always properly sealed where it comes out of the roof. The sewer smell seems to get pulled down into the roof/walls causing the smell in the trailer.

[Iwannacamp]

Occasionally we get a stinky smell also. I have noticed mostly after towing. I think the traps get emptied and so the smells. I think putting in the stoppers will help with that. I also discovered that part of my stinky was actually gray/grey water odors. I got some of the yellow Camco stuff and I also bleach my gray tank when I think of it.

[Scrapper]

Originally Posted by Lins

One issue I’ve read about and we had as well, is the vent isn’t always properly sealed where it comes out of the roof. The sewer smell seems to get pulled down into the roof/walls causing the smell in the trailer.

The vent stack can only be sealed at the roof with a flexible boot between the inner and outer pipe. The outer vent pipe is nothing more than a short tube going through and sealed to the roof. The roof needs to be separate from the vent stack because of the combination of expansion/contraction rates of the different materials along with the up/down movement and vibrations while traveling on the various road surfaces.

If the vent stack was sealed at the holding tank and the roof either one or both seal will fail.

[hbillsmith]

My sister and her husband bought a new 2017 26ft travel trailer that had the A/C unit installed directly over the bedroom. As it turned out, the standard sewer vent cap was fairly close and at times (we think it depended on wind direction) they would get sewer smells in the trailer after a flush.

We did some research and ordered the Camco 360 $16.02 (it's available in black or white). My BIL did the simple install and they haven't had an issue since. The thing works!!

It's sold on Amazon and at CW and other places.

Camco 40597 Black Cyclone RV 360 Sewer Vent $16.02

[Freetyme]

I experienced this once and only once, other than having max fan on during a flush. First blamed it on wind direction. Thought too of the tank vent, AC was not running. At the time I didn't know better while at our first full hookup site I had left the dump valves open. Believe this was the source, once closed I never noticed again. Still doubtful of my assumption I ordered the Cyclone directional black tank vent. Said to myself next time it happens I'll install it. It's still in the package, though sounds as if it could work.

[Kirk S]

You will like the Happy Camper tank treatment. We used every chemical on the market since 1990 and Happy Camper is the only treatment we have used where we have zero waste tank odors.

We use it in the black and grey water tanks.

When traveling we discovered it also helps to keep the stoppers in the sinks

When in storage mode we make sure to keep the sink traps full and some water in the toilet.

[jdelp]

Originally Posted by Kirk S

You will like the Happy Camper tank treatment. We used every chemical on the market since 1990 and Happy Camper is the only treatment we have used where we have zero waste tank odors.

We use it in the black and grey water tanks.

When traveling we discovered it also helps to keep the stoppers in the sinks

When in storage mode we make sure to keep the sink traps full and some water in the toilet.

I'm glad to hear that, we've tried quite a few over the years as well with mixed results. I treated the grey & black tanks yesterday with the Happy Camper - hoping this is THE one! I'll also make sure the stoppers are in when traveling as well, pretty sure we do that already but will add it to the checklist!

[AdamKam]

I have the same Puma 31RLQS' and have only had the same problem once in the last 3 years and we use the trailer 4 months every year. It only occured in one campground and only happened 2 different days during a months stay, I know it had nothing to do with the AC. This park did have a septic sewer system which might be a factor.