grey tank stink

[deprived]

Recently the motorhome stinks whenever we run any water to the grey tank: washing dishes, showering, etc.

I couldn't figure out where the smell was coming from. I thought maybe it was coming from the p-traps or perhaps even under the floor. But it was coming from the air conditioning vents.

How on earth can running water to the grey tanks cause it to vent to the A/C duct work?

I'm very, very puzzled.

[deprived]

mobeewan wrote:
If you've done all that tank cleaning it sounds like the air conditioning has become stagnent. .

No, it's definitely grey tank smell being sucked, somehow, through the AC. If I add something like Pine-Sol to the grey tank, I can smell Pine-Sol though the AC system when we run, say, the shower or sink.

Good guess, though.

[deprived]

down home wrote:
I had someone tell me he reversed the three fans to pull in and closed up all the windows etc and the pressure was enough to blow out the junk.

I wish I could have seen that.

[deprived]

Lynnmor wrote:
Check under the shower for broken or leaking plumbing. Maybe the air in that area is drawn up thru the wall and into the ceiling where the A/C can distribute it.

Some version of this seems most likely.

Will continue looking.

[Lynnmor]

Check under the shower for broken or leaking plumbing. Maybe the air in that area is drawn up thru the wall and into the ceiling where the A/C can distribute it.

[down_home]

Are you operating the fans sucking air out of the coach and creating a negative pressure drawing in the odors through the pipes?
Still should not be if there are water traps on the trains to prevent this.
They also sell lemon scented and other additives for the gray tank but they just sorta hide a problem.
We always flush our tanks whenever leaving, or most of the time,a site for next destination or if sitting for a while.
Wife does not allow grease into the gray tank which can cause all kind of wicked smells as it deteroriates and potential tank drain problems.
Even if she did we take two showers every day with liquid shower soaps with nice smells, and wash clothes every three days at least with detergent, that smells good and softeners. Final flush is gray after black tank and the sewer hose smells great as does the tank, not that I sniff them.
If you have loose birds nest etc blocking the vent tube exiting above the coach, which I don't see how could happen, I had someone tell me he reversed the three fans to pull in and closed up all the windows etc and the pressure was enough to blow out the junk. The only exits for the pressure would be though the shower drain and other drains and out the tank vents. You would have to open the valve in the toilet of course.
I'm not vouching for this, or attesting that it will work.Perhaps I shouldn't even mention it. Just another hare brained idea perhaps.

[Mont_G_J]

Unless your AC is different from mine or any other one I have seen, the air that circulates is not drawn from the outside or attic, but directly into the AC grill on the inside ceiling. Leads me to believe it's an inside gray tank venting problem .

[BFL13]

This should not make any sense, but anyway--- the kitchen double sink has one P-trap. Make sure both sinks are clear and clean to the trap. I have had "issues" with that, but not to do with the A/C.

[mobeewan]

If you've done all that tank cleaning it sounds like the air conditioning has become stagnent. I would put some type of strongly fragrant liquid freshener into the tank through the roof vent pipe then see if you could smell it comming from the air conditioning. Using the roof vent would keep from presaturating the inside of the trailer with scent by pouring it down the drains. If the air conditioning still gave off a bad smell and you can't detect the fresener then it could be the air conditioner or vents has something bad growing in it due to excess condensation. I had a 24000 btu window air conditioner from the house that got really stagnent. Had to remove it to wash and scrub the coils and clean the drip pan. It was starting to smell like rotting leaves.

[deprived]

So, it's definitely NOT the air admittance valves. The smell is definitely coming through the ducted A/C system.

I removed the grey vent and the pipe has not dropped in to the tank.

I shot a high-pressure blast of water into the vent thinking if there was a crack or leak somewhere along the vent pipe I would see water running down the outside of the vent pipe, which is visible (inside a cabinet) at the point where it goes through the floor and in to the tank.

Further puzzling things: I was able to block the AC return duct on either side of the where the vent pipe enters the roof. The think being that I could isolate the section of the AC ducts that are close to the vent stack.

So I can't be sure at what point along the ductwork the smell is being drawn in and I really can tell from what point the tank is leaking. It has to be somewhere in the ceiling because the smell isn't present at any of the drains or admittance valves.

I'd replace the pipe at this point except that the location where the pipe meets the tank is right under a major wall.

Perhaps I can cut the pipe at the point where I can see it under the cabinet and then resection it from there. Or insert a smaller pipe inside the bigger one.

Like I said, it's a puzzler.

Also: the tank has been cleaned and cleaned and cleaned. Bleach, Fabuloso, Oxy-Clean, baking soda, etc etc. It's as clean as it's ever going to get.

[mikestock]

We were getting a smell through the air admittance valve. In our case it was located behind the washing machine. I changed out the valve and it still smelled. My solution was to fill the gray water tank a few times via the shower, then drain completely.

Now we scrape away as much food waste as possible before washing dishes. That has seemed to work. No more smell.

[RJsfishin]

A grey or black tank should not stink. Quit being so cheap....dump some holding tank chemical down it,....works for me.

[newman_fulltime]

Its your toilet ball seal leaking

[eHoefler]

Pull down yout A/C grill inside, check to see if the return air is completly sealed off from the attic space. In RV's that had a second A/C insalled, mostly by dealer or owner, do not seal off the attic space. The sewer vents are not sealed to the roof where they protude, if the attic is not sealed off, the A/C will draw air from the attic space. With the vents not being sealed to the roof, sewer gas can/will be drawn into the attic space and into the A/C.

[deprived]

Lynnmor wrote:
The vent pipe that goes thru the roof may have dropped down into the tank. Check the top of the pipe on the roof to see if it is still up where it should be.

Will do.
Thanks!