Adding a washer/dryer combo and plumbing

[Det107]

I'm putting in a washer/dryer combo and called Keystone to find out if they had a P-trap in the wall or somewhere for the washer drain. There is a label on the wall that says "the washer is not hooked up to a holding tank, and to make sure your hooked up to the camps sewer line". Keystone advised that there is not a P-trap installed. To me that means that nothing is preventing sewer gases from entering the RV. Has anyone had this problem or installed a P-trap on their own?

[BB_TX]

What year and floorplan do you have?

Not hooked to a tank means the washer drain line runs directly to the sewer drain pipe and you must be connected to the park sewer connection for the washer to drain. Otherwise it would back up and overflow out the drain pipe behind the washer. If the drain pipe is installed I would think it does have a P trap there though.

Some Montana washer drains are piped to the grey water tank and some, like yours, are piped directly to the drain outlet. Mine goes to the grey tank. You guess is as good as mine as to why.

[bncinwv]

Our simple solution has been to configure the sewer slinky hose in the form of a p-trap at the end of the slinky. Our 3400 was plumbed directly bypassing any tank.
Bingo

[jcurtis934]

And I would not believe that sticker. Do your own homework to see where it really drains first. John

[Carl n Susan]

X2 on the sticker. It seems to be installed in every Montana, yet most find their grey tank is involved. Be sure to test it out.

Regardless of the connection method (direct or through a tank), practical use of a washer requires a open path to the sewer line. As Bingo wrote, provide your own P trap using the sewer hose to prevent sewer gasses from coming back at you.

[PackerFan]

Ignore that sticker....Ours has the same sticker and we found out the washer is plumbed into the bathroom grey water tank.

[BB_TX]

Our washer is plumbed into the grey tank. And our grey tank valve typically stays open until I want to collect some water before draining the black tank. And I don't form a trap in the sewer hose. If fact I use one of those flexible thingies to support the sewer hose and keep a slope all the way to the drain so water does not collect in it. Now having said all that, we have never had sewer odors come up thru the washer drain inside the trailer. For that reason I think there must be a built in P trap or some other means to isolate that line.

[Det107]

Thanks for the information. I took a small camera I use for fishing and snaked it down the pipe, and Keystone was correct it is piped to the main sewer drain. I am getting a rubber reducer to seal the pipe to the washer drain hose. There just isn't enough room to put a P-trap in without tearing some of the wall out. With this pipe going straight to the main line there shouldn't be any problems of back pressure as long as the sewer line valve is open. Thanks again..

[BB_TX]

Det107 - I am curious to know if you have an open pipe with no trap from the washer closet all the way to the drain. As I mentioned, mine is piped to the grey tank. But I normally leave the grey tank valve open unless I need to collect water to flush the sewer hose after draining the black tank. But my washer drain hose just drops into the washer drain pipe with no seal. But I have never had any sewer odor come from that pipe in 8 years. Wondering if I have just been lucky, or if there is something blocking sewer odors from coming back up in my piping. I don't plan on changing anything, just wondering.

[rohrmann]

I would not recommend sealing the washer drain hose to the drain line. If you do, the water will siphon all the water from the machine and most washers depend on some water to remain in the system so the pump remains immersed and does not need to be primed each time.