Half Bath Odor When Traveling

[LK23]

2017 Dutch Star 4369

We are experiencing black tank odors in the half bath when traveling.

I suspect one of two things.

1) I replaced the leaking, plastic black tank sprayer vacuum breaker under the sink with a brass Watts LF-288A, see photo. In another thread, they said this vacuum breaker will allow odors to pass. Is this true? If so, is there a better vacuum breaker to use?

2) Another post mentioned a defective air admittance valve on the macerator toilet. Note: our problem is while traveling when no one is flushing the toilet. Is this valve a possibility if the toilet is inactive and, if so, how do I replace it?

Rex

[BFlinn181]

The AAV can allow tank odors into the RV is bad. It is there to prevent the P-trap from being drained and allowing air back up the drain.

If the toilet has the round ball-like valve, if it is working properly leaving a little water in the bowl should not drain past the valve. If the water does leak out, it could allow odors back up the toilet drain.

Run a little water into every drain, including the washing machine drain. Loss of the water in the P-trap can allow odors into the RV.

Make sure all windows and vents are closed when driving, movement of air causes negative pressure that can draw odors out of the tanks and into the RV.

[BirchyBoy]

Do you have a roof vent near your black tank vent pipe? It’s possible that the odor is coming in if the vent is open when traveling. Our Winnie has the black vent pipe right by the roof vent, and I have to close it when flushing.

[LK23]

Sink p-trap has water and the toilet has water. Toilet is not being used when traveling, yet the odor enters the half bath.

And, the window and ceiling vent is closed tightly.

[NealC]

Put happy camper deodorizer powder in your sinks so the gray tank gets deodorized. I get this from time to time.

[LK23]

Neal, I am pretty certain it is a black tank odor and not the grey tank. We get grey tank odor in the rear bath shower occasionally.

[wishalls]

Check your black tank flush anti siphon valve located under the sink in the 1/2 bath. There is a spring load ball valve that is suppose to stop black tank odors.

[BFlinn181]

Many RV manufacturers dump one lavatory sink into the black tank instead of the gray tank. I don't know what Newmar does when there are two lavatory sinks.

The AAV, or 'cheater valve' eliminates the need for a vent pipe connected to a roof vent. They unscrew from a T fitting and verticle pipe coming up from the P-trap under the sink. They aren't expensive, available at most home improvement or large hardware stores.

In post #1 OP said he changed out the plastic vacuum breaker with the brass one pictured.

[dukenrock]

Put one of these on your vent....it’ll pull the smell from the tank while your going down the road.

[LK23]

Originally Posted by wishalls

Check your black tank flush anti siphon valve located under the sink in the 1/2 bath. There is a spring load ball valve that is suppose to stop black tank odors.

That was the leaking plastic valve that I replaced with the brass Watts valve.

[Rcwaz]

I finally pulled the toilet and found the floor flange seal not set right. So one was too speedy to install it correctly.

[balvert]

Originally Posted by LK23

2017 Dutch Star 4369

We are experiencing black tank odors in the half bath when traveling.

I suspect one of two things.

1) I replaced the leaking, plastic black tank sprayer vacuum breaker under the sink with a brass Watts LF-288A, see photo. In another thread, they said this vacuum breaker will allow odors to pass. Is this true? If so, is there a better vacuum breaker to use?

2) Another post mentioned a defective air admittance valve on the macerator toilet. Note: our problem is while traveling when no one is flushing the toilet. Is this valve a possibility if the toilet is inactive and, if so, how do I replace it?

Rex

Add this check valve to the outlet side of your Watts vacuum breaker. The Watts does not have a check valve built in. Easy install.

https://smile.amazon.com/Valterra-P2...29+Check+Valve

[tom chelbana]

Might try the old sink stopper on the sink to see if the order is coming from grey or black tanks.
Newmar Man

[FatChance]

As a belts and suspenders guy, I put a back flow preventer between the anti-siphon valve and the black tank to stop sewer gas from entering the coach.