Purge Air Switch and Assoc. Plumb.

[Leroy A. Eckert]

Lengthy post.

I am posting this because I know it is correct. The details relate to
how my coach is plumbed between the purge air system used to winterize
the coach and the water system. I am posting this because another BB
owner had water back flow into the coach aux air system.

I suggest all BB owners with a purge air system check the integrity of
their system. All applications may not be the same as mine but it is
worth a look. Otherwise, it is possible(not probable, but it only
takes once)to flood the aux air system with water if a check valve
fails. As well, it is possible to introduce air into the water system
if the purge air switch fails.

General Plumbing:
On my coach there is a purge air switch on the bed support that
introduces air into the water system to blow out excess water when
winterizing. See your respective BB manual for Winterizing. The air
hose goes from the purge air switch to a check valve attached to a
pressure regulator, then to a small ball shut off valve then to the
top of the water sanitizer cylinder. I believe my ball valve is an add
on. Typically, the check valve is the line of defense to prevent water
from back flowing into the aux air system. The aux air system operates
a number of systems. The air step, front vents, driving lights, remote
oil fill, aux air for tire inflation, step cover, and who knows what
else, perhaps the air bags.

You see, there is water in the line continuously from the water system
sanitizer or where ever yours is attached to the ball valve if you
have one or the check valve to prevent the water pump or shore water
from pumping the aux air system full of water. If you have only a
check valve and prior owners have not used the air purge switch to
winterize the coach, the check valve can become corroded and leak. If
you are a full timer and sit for months it is possible to fill your
aux air system with water. Not good. The worst happens when you crank
up and head out for parts unknown and the following happens.

You empty your holding tanks and water is introduced into the dump valves.
You try to operate the step, it is sluggish and does not work properly
because it is filled with water.
You blow the air horn and it has emphysema.
It is also possible to introduce water into the aux oil tank, though
not likely because my air switch is high in the engine bay.

How does that happen. Once water passes through the various air
control valves for each system it is everywhere. I suspect my coach
had this problem before I owned it. I have a manual ball shut off
valve to prevent it from happening again. Other coaches only have a
check valve in the line.

Easy fix. (after you get the water out of the air system)

Locate the purge air switch, check valve and regulator and identify
where your air line is attached to the water system. Viewed from air
flow in with the purge switch on , install a small ball valve after
the pressure regulator if you have one, if not after the check valve
and before the connecting point to the water system. You can still
winterize the coach by opening the ball valve, and not be concerned
with water back flowing due to a faulty check valve.

On my coach, all of the plumbing is under the bed.

I replaced my Poly tube attached with those funky gray retainers with
copper tubing(the wet area tube)from the regulator to the sanitizer.

Leroy Eckert
1990 WB-40 Smoke N Mirrors
Dahlonega, GA
Royale Conversion