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Saturday, October 31, 2009

Waste Plumbing Clearance

My question is concerning the ground clearance for the sewer hose coupler and dump valves. Mine seems to be insufficient. I have had to replace the gray water valve twice and reattach the coupler above the black water valve about three times in the past 18 months. I have thought of skid plates as an option. Also I have thought of using individual drain outlets, but that seems inconvenient. This is a very poor design, the termination point is just forward of the rear bumper and hangs pretty low. It is a mandatory inspection item after every trip. Driveways and dips can be a challenge at times. I have to be very selective of which gas stations I go in and out of. I wrote to the manufacturer about the design problem but never got a reply. Any suggestions or advice would be appreciated. Carlos, (San Diego, CA)

Carlos, indeed some waste system designs can be somewhat lacking, especially when the coach has a long overhang behind the rear axle. The holding tanks, dictated by the floor plan design, are sometimes positioned beyond the rear axle. Here's an idea that just might gain some ground clearance.

Completely empty and flush out each holding tank first. Then remove both the dump valves and all the termination plumbing. Begin by installing the dump valves directly to the tank outlets. Remember that every inch of drain line from the outlet on must drop a half inch or so for every foot of run. With the dump valves attached directly to the tank outlets, the remainder of the assembly will not hang as low.

Then, just like a puzzle, connect the two outlets together as high as possible using a "wye" or sweep "tee" fitting and other ABS fittings. Be sure to "dry fit" all the pieces first. Then, mark their placement and remove them all and cement them back into place. If you cannot reach the valves once they are positioned directly on the tank outlet, consider using electric dump valves instead of the manual type. Check out the Drain Master electric waste valve. Easily installed, they are operated by a simple push of a button.

I do not recommend installing skid plates or bumper casters which only leads to other chassis related ills. Getting the plumbing as high as possible is your best bet. And keep after the manufacturer. They need to be made aware of design discrepancies! Most coach makers welcome such input.

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