Gray water tank odor problem solved

[Rick 2005 Dolphin 5376]

Good morning from overcast San Juan Bautista Ca. Julia and I have been enjoying our first 6 weeks of full timing in the new coach. As I work through some of the normal issues associated with a new RV , odor from the tanks had been our most "noticable" problem.
The black water tank odor was solved by adding a RV360 turbo vent and sealing the extra large hole that the vent pipe was routed through on the roof. The gray water odor was still a mystery. This morning I discovered a vent under the lavatory sink. A vent pipe with a cap on it. The cap had a few slots to allow venting but I also have a vent on the roof. Why would anyone place a vent that is exposed to the interior of the coach??? I placed taped over the vent slots and emptied the tank. The odor is GONE !!! It was quite normal to get a dose while the shower was running but not any more. I just can't figure out some of this high end engineering that goes behind the building of our RV. I hope this might help anyone looking for a solution of the same problem.

[Rick 2005 Dolphin 5376]

Good morning from overcast San Juan Bautista Ca. Julia and I have been enjoying our first 6 weeks of full timing in the new coach. As I work through some of the normal issues associated with a new RV , odor from the tanks had been our most "noticable" problem.
The black water tank odor was solved by adding a RV360 turbo vent and sealing the extra large hole that the vent pipe was routed through on the roof. The gray water odor was still a mystery. This morning I discovered a vent under the lavatory sink. A vent pipe with a cap on it. The cap had a few slots to allow venting but I also have a vent on the roof. Why would anyone place a vent that is exposed to the interior of the coach??? I placed taped over the vent slots and emptied the tank. The odor is GONE !!! It was quite normal to get a dose while the shower was running but not any more. I just can't figure out some of this high end engineering that goes behind the building of our RV. I hope this might help anyone looking for a solution of the same problem.

[Ed Gardiser]

Rick
You may want to consider taking that tape off that vent under the sink,check with National RV to see if the vent going thru the roof is only for the " black tank "if so that vent is needed for the grey tank.I use the same chemical in both the black and grey tanks to minimize smells.
Ed Gardiser
Escondido,Ca.
04 Vectra
87 Nissan PickUp
FMCA

[Rick 2005 Dolphin 5376]

There is a vent for both Gray and Black tanks on the roof. It seems almost hidious to have a vent in the coach for the gray tank. So far no ill effects from taping off the vent. I even filled the gray water tank to the top and emptied it and all seems fine. I've read about the same problem on the Nationalrv usergroup on Yahoo. Am I missing something?

[Gary RVRoamer]

The plumbing codes probably require that "vent", which is called an anti-siphon device. They are installed in a lot of new construction and not just in RVs. It's not supposed to let fumes vent back into the rig, but sometimes they do. I wonder if your gray tank roof vent is blocked?

[Rick 2005 Dolphin 5376]

Roof vent is not blocked, so I'm going to leave the under the vanity vent taped over, code or no code. The odor while running the shower is not acceptable.

[GStream40]

The "vent" under the sink has a check valve or flap built into it. It should not be letting odor back into the coach.

You should be able to unscrew the unit off the pipe and check the "flap"/check valve to make sure it is not stuck open. This unit is actually is called a "vacuum breaker". It prevents a vacuum from forming in the lines that will slow down the flow of the water to the tank. It also does not allow a vacuum to form in the tank. It also allows the vent pipe on the roof to do it's job, therefore I would not tape it.

We had an odor problem after I installed Max air covers over our vents in the bathroom. The vent pipes were right behind the skylight roof vents and I guess I changed the air flow and caused the odor to come back into the vents when we opened them to take a shower to get the moisture out.

What we did was install RV360 vents on both the black and gray tank pipes. That took care of the odor problem.

The RV 360(s) rotating back & forth on the roof with wind changes looks neat.

Ron

[Rick 2005 Dolphin 5376]

Is this the best site for all things RV or what? I'll check the flap again when I get home tonight. I found another vent under the kitchen sink and it is not allowing any odor in to the coach. Your idea that the flap / valve might be stuck is a good one. I'll also add an other RV360 for the gray tank as I am very happy with the results from the one I added to the black tank vent pipe. Thanks to all of you for your insightful information.

[DSouthw524]

The vaccum breaker is able to be screwed off and a repllacement can be obtained at your local hardware store or at the big box stores like Lowes or similar. They are not expensive.

[GStream40]

Rick,

Let us know how you make out. The RV360 on the gray vent should take care of the smell and checking the vacuum breaker also. Mine was not seated and I just had to move it around and it seated properly, but if bad, they can be replaced as mention in the above post.

Ron

[Rick 2005 Dolphin 5376]

I'll check the vent tonight and will head over to CW to pick up one more RV360 vent for the gray tank. I must say that for the first time in 6 weeks it's nice NOT to have that odor in the house.

[Digital Boy]

The vent flapper sticking is not an uncommon problem. It occured in my rig once last year.

However, you might also consider running water periodically through all your sinks and showers. It is also known that sometimes the water in p-traps escapes allowing grey tank odor into the coach.

We have an on board kenmore washer & dryer. When the washer empties after wash and rinse cycles it will suck the p-trap water right out with it! Our fix was to close the kitchen sinks and add some water to the sinks when doing laundry. Grey tank stink can be very nasty.

[Rick 2005 Dolphin 5376]

Being that we full time right now, "periodically" is, well, everytime we use the head, take a shower, wash the dishes,,,,you get the idea. The vent / valve under the lav is /was stuck open but sinse there's an other one in the kitchen, I left the tape over the vent holes. It's been 4 days with no odor and what a nice change that is. Saturday I'm installing our new SunShades on the windshield and side glass, now that all my plumbing issues have benn resolved.

[Scooter]

We had this on our old Arctic Fox truck camper under the sink. Even tho there was a roof vent, this was supposed to "pop" when excessive gas pressure built up in the gray water tank.

The rubber disc inside the cap was not working so there was a constant odor. We taped the cap and all was well henceforth. No excessive pressure built up inside the tank.