Plumbing questions: Moving P-Trap

[tred0956]

I have a small Class C that is great for us except the kitchen area lacks storage, particularly drawers. Under the sink is a cupboard, but I want to install 3 sliding drawers in the cupboard. The p-trap for the sink drain is in the way for the top drawer, so:

1. Can I move the p-trap closer to the outside wall by putting a 90 degree elbow on the sink drain to run a drain pipe horizontally about 6 inches, then install the p-trap? I would like the horizontal drain pipe to be as close to the bottom of the sink as possible, to allow for clearance for the drawer. In other words, does the p-trap need to be directly under the sink drain?

2. The p-traps in my house use a slip joint to adjust for height, but the class C has everything glued. Any problem using a slip joint? I was thinking vibration might be the reason the RV is glued?

Thanks

[myredracer]

Thx. A pain as in having to open the door then a drawer? Not really. We didn't have a slideout in the old TT and when opening any cabinet door it intruded into the walking space. And if you take a door off, unless you have drawers down to the floor, you may have an unattractive open space at the bottom. I couldn't install drawers down to the floor because of the wheel well under the sink.

The problem with taking a door off is you have holes to fill somehow. You could use the little round stick-on patches if you're not too worried about looks.

If you do a face frame style like I did, and you take the door off, it can be really hard to get even gaps all around the original opening. TTs typically aren't really very plumb and square and even and you might want to check yours first to see what you have to deal with. As you work through the project, you need to measure and remeasure and test fit each piece. I remember everything being slightly off from start to finish...

tred0956 wrote:
Thanks for all the replies. Doughere, the top drawer will still have to be short at 10 inches but the p-trap as is would mean that I could only put in ONE full depth drawer; with the trap moved I can fit in 2 or 3. And yes, I agree about the good full extension hardware.

Erstanfo, you did pretty much what I intend to do. Glad to see that the horizontal slip joints don't leak, makes installation much easier.

Myredracer, your drawers are what I want to build-looks great! Question: do you find the cupboard door a pain? I'm debating about removing the door and making regular kitchen drawers, or doing what you did.

Thanks, all!

[tred0956]

Thanks for all the replies. Doughere, the top drawer will still have to be short at 10 inches but the p-trap as is would mean that I could only put in ONE full depth drawer; with the trap moved I can fit in 2 or 3. And yes, I agree about the good full extension hardware.

Erstanfo, you did pretty much what I intend to do. Glad to see that the horizontal slip joints don't leak, makes installation much easier.

Myredracer, your drawers are what I want to build-looks great! Question: do you find the cupboard door a pain? I'm debating about removing the door and making regular kitchen drawers, or doing what you did.

Thanks, all!

[myredracer]

I added 3 drawers underneath our sink in our last trailer. I relocated the P-trap and waste pipe out of the way as much as I could. I ended up making the top drawer "L" shaped to jog around the waste piping. The short side (on the right) worked out good for spices and salt & pepper. Here's a couple of pics below. I kept the original door in place and used flush pulls. For the drawer slides, I used Knape & Vogt "stay close" RV slides from www.drawerslides.com. They stay closed and you give them a tug to release them. I also had to relocate the PEX water pipes under the sink as they were really in the way. They seem to just throw the waste and water piping under sinks without any thought to functionality.

We only ended up keeping the TT for a year before we got "two-foot-itis" and a new TT. BIL now has the TT and the benefit of the kitchen drawers and lot of other mods I did.

[Harvey51]

Heck of a good idea!
After experiencing a broken elbow on the sink drain way down low connecting the rigid six feet of pipe under the sink to the 8 foot run across to the grey tank, I figure our unit needs slightly more flexible piping to handle bumps in the roads. I replaced the elbow with a rubber one, and put a rubber joint in the under sink cupboard. The latter will make it easier to do this fine mod anyway.

[Ductape_Dave]

The picture erstanfo is a good example of an offset trap and does not create any problems. It is now a running trap instead of a P trap and does the same thing, sealing out sewer gases. Some European style sinks have no room for a P trap and instead are installed in the wall. The trap nut will not vibrate loose and is good to have to service a clogged drain or access an item that might have slipped into the drain. 20 year master plumber.

[erstanfo]

Been there, done that, works great!

Slip joints, added strap against the wall for added support. It never leaked.

I also recovered a lot of room by putting shelf over water heater.

[Clay_L]

Jerry9n wrote:
Here is an option. Saw it, but don't know anything about it.

Clicky

That is the one I mentioned above but I didn't know the name.
They started showing up in new motor homes two or three years ago.

[Jerry9n]

Here is an option. Saw it, but don't know anything about it.

Clicky

[mobeewan]

If you have double sinks, one sink drain always runs horizontal at least 12 to 18 inches before connecting to the other sink drain going to the P-trap, so there shouldn't be a problem.

My sink has a large and small bowl. There is also a shelf under the entire sink area. The P-trap was under the larger sink which is on the left and positioned so that it ran immediately left leaving 40 percent of the shelf storage space under the sink useless. I cut the pipe, removed the glued in p-trap and flipped the drain pipes connecting to the sink drains 180 degrees. Then I put in a new P-trap on the right side with the P-trap pointing toward the wall. I added new pipe and additional elbows to run the pipe back to the wall and then along the wall. I also had to move the air admittance valve to the left rear corner and reconnected to the existing pipe. Gained back the 40 percent lost space.

[bguy]

Generally speaking the trap is put as close to the fixture as possible. Aside from sewer gasses smelling, long horizontal runs can have smells from the pipe itself. A 6" horizontal run however would likely not be an issue.

[doughere]

Had about the same problem; just made the top drawer shorter. Used GOOD full extension ball bearing hardware, works great.

Doug

[Clay_L]

I have seen a type of check valve being used in new RV construction instead of a P trap. I have no idea how well they work but it might be something to take a look at.

[lanerd]

I agree with Scott... Our previous coach (Safari Simba DP) had slip joints in kitchen and bath... Never a problem. In fact, came in handy a couple of times when DW dropped an ear ring down the bath drain (not sure why she took out the screen).

I too, will be moving my kitchen plumbing to the back was and then install a p-trap there, and... will be using slip joints.

Ron

[ScottG]

1 Yes.
2 No, every RV I've had used the appropriate slip joints and worked fine. Vibration is not an issue.