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PanJH · 10-20-2020, 06:05 AM

[Like many others, I've had issues with odors coming into the coach via the washing machine drain pipe. It is much more prevalent when someone was taking a shower. As a stop gap, I wrapped some duct tape around the washing machine hose where it goes into the drain pipe. That helped significantly. So , a couple weeks ago, I picked up a 2" PVC cap. I drilled a 1 1/16" hole in the cap and inserted the washing machine drain hose , put sealant around the hose and put the cap on the drain pipe. I thought that should take care of it...
Well, sort of, but not... went to shower for the first time since I installed the cap and the shower pan started to rapidly fill with water.... it wasn't draining. I go over to the washing machine, pull the cap I had installed and now the shower drains. Would seem to indicate that the tank wasn't venting when the cap was on. BTW, the gray tank was maybe 1/3 full.
OK, next step I drained the gray tank , put the cap back on the washing machine drain and ran water into the shower. Shower drained fine. So, what I'm thinking is Newmar installed the roof vent pipe for the gray tank too deep into the gray tank and when it gets about a 1/3 full or so, the bottom of the vent pipe is under water and then if the cap is on the washing machine drain, the shower pan fills with water as the tank can't vent. When I pull the cap off the washing machine drain pipe, the gray tank can vent via that washing machine pipe... bringing odors into the coach. When I get back home in a few weeks, I'll do some more investigation, but I'm pretty sure that's what's going on. More fun

swduns · 10-20-2020, 06:19 AM

odor could be air admittance valve (i replaced mine with double sealed)
or
some RV manufactures don't use a conventional drain trap at a shower or washing machine, they use a waterless trap, some people call them a HepvO trap. Those can lose their elasticity.

couple of things to check

BigBillSD · 10-20-2020, 06:29 AM

Have you verified the grey tank roof vent is clear of nests, leaves or other blockages? Each of your sinks will have an air admittance valve (vent) too, your Washer drain should have one also.

Its odd that sewer gas should come up that washer drain as there should be a P trap full of water to prevent that and another Air Admittance valve there too.

Our washer seemingly was causing the same stink issue, I replace all 4 of my Air Admittance valves with new ones. https://amzn.to/3o8Wfsj (I had first bought the cheap ones they sell at home depot. Stink didn't go away. These new ones seem to be made better (and cost 4 times as much) But

No more stink.

PanJH · 10-20-2020, 08:02 AM

Quote:

Originally Posted by swduns

odor could be air admittance valve (i replaced mine with double sealed)
or
some RV manufactures don't use a conventional drain trap at a shower or washing machine, they use a waterless trap, some people call them a HepvO trap. Those can lose their elasticity.

couple of things to check

All teh air admittance valves were replaced with "good" ones previously. The Hepvo trap in in the shower and is not the problem, The odor is definitely coming from the washer drain pipe. There is supposed to be a traditional P trap on the drain pipe, but it's a straight shot down thru the floor into the wetbay, behind the wall, so I can't see if there is really one there.

PanJH · 10-20-2020, 08:05 AM

Quote:

Originally Posted by BigBillSD

Have you verified the grey tank roof vent is clear of nests, leaves or other blockages? Each of your sinks will have an air admittance valve (vent) too, your Washer drain should have one also.

Its odd that sewer gas should come up that washer drain as there should be a P trap full of water to prevent that and another Air Admittance valve there too.

Our washer seemingly was causing the same stink issue, I replace all 4 of my Air Admittance valves with new ones. https://amzn.to/3o8Wfsj (I had first bought the cheap ones they sell at home depot. Stink didn't go away. These new ones seem to be made better (and cost 4 times as much) But

No more stink.

All the air admittance valves were replaced with good ones. I can't see a traditional P trap or Air admittance valve on the washer drain pipe. It's a 2" straight pipe down thru the floor then it's behind the wet bay walls where it can't be seen.

BigBillSD · 10-20-2020, 11:09 PM

Have you called Newmar to ask where the p trap is located for your washer in the coach? I doubt it would be under the floor. Would be practically impossible to winterize that. It would normally be just a few inches from the drain hose inlet.

Maybe it was not installed? If its straight down from the washer drain line, where is the Air Admit Valve located that you replaced on the washer drain?

Behind my washer is a straight pipe coming from the floor and at the top is the air ad valve, 3/4 the way up that pipe is a T with a p-trap going over to the vertical pipe that my washer drain hose empties into. Looks like what you would expect in a house, except instead of the Air Valve, that pipe would continue up and out the roof. -Bill

PanJH · 10-21-2020, 06:39 AM

Quote:

Originally Posted by BigBillSD

Have you called Newmar to ask where the p trap is located for your washer in the coach? I doubt it would be under the floor. Would be practically impossible to winterize that. It would normally be just a few inches from the drain hose inlet.

Maybe it was not installed? If its straight down from the washer drain line, where is the Air Admit Valve located that you replaced on the washer drain?

Behind my washer is a straight pipe coming from the floor and at the top is the air ad valve, 3/4 the way up that pipe is a T with a p-trap going over to the vertical pipe that my washer drain hose empties into. Looks like what you would expect in a house, except instead of the Air Valve, that pipe would continue up and out the roof. -Bill

I sent a detailed email to newmar last week--- still awaiting their response.
There is no obvious Air admittance device on the washer drain. It's a 2" black PVC pipe going from height of the washing machine straight down thru the floor, where is enters the backside of the wetbay, I can't see that's going on back there as the paneling hides everything and looks to be a pain to take out, at least it's stay that way till we get home.
Any chance you can take a pic ? That way I can send your pic along with mine to newmar

Ljwt330 · 10-21-2020, 09:14 AM

Quote:

Originally Posted by PanJH

I sent a detailed email to newmar last week--- still awaiting their response.
There is no obvious Air admittance device on the washer drain. It's a 2" black PVC pipe going from height of the washing machine straight down thru the floor, where is enters the backside of the wetbay, I can't see that's going on back there as the paneling hides everything and looks to be a pain to take out, at least it's stay that way till we get home.
Any chance you can take a pic ? That way I can send your pic along with mine to newmar

Not familiar with Newmar, but on my coach the air admittance valve was located away from the stand pipe, near the opposite side of the washer/dryer bay. Fortunately, my coach did not have the machine installed so I could easily see both the stand pipe and AAV. If you cannot easily see behind your W/D, the AAV may be back there but hidden.

BigBillSD · 10-23-2020, 06:55 AM

Quote:

Originally Posted by PanJH

I sent a detailed email to newmar last week--- still awaiting their response. Any chance you can take a pic ? That way I can send your pic along with mine to newmar

I will do that today as I am going over to the coach this afternoon. It might be tough to see as my W/D is in front of it. I have an opening on the side of the closet for the water valves so it may be possible to get a usable pic.

Its Friday, I would call them. Based on what you can see, and the way its working for you, there is a very basic drain issue there. You must have a ptrap and either a vent thru the roof for that pipe or an Air Admittance valve period. Anything else and you get the nasty grey tank smell inside. Its way to easy for support organizations to ignore or lose emails. Or the response could just be in one of your Spam folders. -Bill

BigBillSD · 10-23-2020, 06:11 PM

Here is a poorly annotated pic of what my coach has behind the W/D. -Bill

PanJH · 10-24-2020, 05:55 AM

Quote:

Originally Posted by BigBillSD

Here is a poorly annotated pic of what my coach has behind the W/D. -Bill

Quite a bit different than ours....we just have a single 2" pipe w/o a P trap coming up from the floor.

BigBillSD · 10-24-2020, 11:01 PM

Makes sense that you cannot seal the drain pipe it if there isn't a vent. And there "must" be a vent for plumbing to work. No P Trap on the grey tank is like having a pit toilet inside the house..

PanJH · 10-25-2020, 06:37 AM

Quote:

Originally Posted by BigBillSD

Makes sense that you cannot seal the drain pipe it if there isn't a vent. And there "must" be a vent for plumbing to work. No P Trap on the grey tank is like having a pit toilet inside the house..

You got it..... one I get home in a couple weeks, I'll be able to check things out. My thought is still that the vent pipe was dropped too far down in the gray tank and when the water level gets high enough, it blocks the vent resulting in the smells in the coach.

Ljwt330 · 10-26-2020, 05:03 PM

You mentioned that your plumbing behind the washer/dryer looks much different than the photo posted by BigBillSD. Do you think it's possible that you have an incomplete plumbing set up, meaning that what you use as the stand pipe is actually the unfinished connection to the drain? I'm envisioning that the stand pipe with a p-trap was not even installed, and if it were, it would be connected to the existing pipe, once a connector T is added. Then, a AAV would be installed atop that pipe. Further, the shower line may tie in to the same drain line to which the existing pipe is connected and the AAV would allow venting for both the washer and shower.

The above still doesn't account for the failure to drain once the grey tank is 1/3 full or more.

Just a thought.