Date: Thu, 5 Jun 2008 11:55:48 -0400
Reply-To: Roger Sisler <rogersisler2000@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Roger Sisler <rogersisler2000@YAHOO.COM>
Subject: Re: Dometic condensation drain
I think the vent that exits on the side of the Vanagon can allow water to
get inside the combustion area. Perhaps in a driving rain or some other
nonsence like when washing the vehicle.
If your refrigerator wont stay lit while driving try to see if the
combustion/vent system is sealed. A leaking system will cause the flame to
blow out and for the unit to be hard of starting. To determine if you have a
leaking system, close up that condensate drain, and remove the chrome vent
cover from the exterior. Plug up the inner most of the two vents and blow
into the other one. If you have a good seal, you will know it. Same for a leak.
Leaks can come from many areas. To find the leak, every connection of the
burner/vent system needs to be considered. One biggie can be checked with
the refrigerator installed. A common leak area, if the refrigerator has been
previously removed, is in the corragated vent tubing. This stuff is very
brittle and can crack when the refrigerator is jockyed during installation.
You wont know that it has happened except for the blow out while driving and
hard ignition.Otherwise, this is not a problem. The break is small and may
not be visible. You might be able to find it by removing the brown vent
grill that is on the side of the refrigerator cabinet and feeling along the
venting while someone blows into the outside vent. The fix would be JB weld
on the crack, and you could probably reach inside through the cabinet vent
hole to mush on the JB. The condensate plug is another leak area.
The corragated vent is joined to the black vent piping via a collar nut and
a split washer. This assembly is used on the intake in the 182b. It is
usually trouble free. On the earlier 182a the collar nut system is installed
only on the exhaust vent; the intake piping is connected together by some
rubber gromet thing. It can become detached and the usual problems then
exist. Got to remove the unit from the van to fix this. These 182a's are all
dead now, right?
That burner box can leak like a sieve. The 182a box gasket is Rubegoldburg's
finest, and I ended up using RTV profusely to get at "all of them leaks" It
looked a mess when I was done RTVing, but it worked. Tastes like chicken.
The 182a box is definately better and leaks less. How the orifice attaches
to the box is not usually a leak area on either the 182a or b.
The gasket that is between the burner box and black vent pipes is probably
ASBESTOS so look out! I know that it is very fragile and will crack without
whim. Maybe it will seperate apart in several places if you try to mess with
it. Where would you get another( Maybe Bus Boys)? If this gasket is not
seated well, it will leak, so try to find your leak elsewhere, first.
Heat from the burner box is transfered to the ammonia water piping mostly
via a 4 inch area just above the burner box. This conduction conduit is a
thin line of weld between the exhaust piping(now rust) and ammonia/water
pipe. That's it! Heat will transfer about 25 times as efficiently via
conduction than with radiation, so every millimeter of this weld is
critical. This conduction heat accounts for about 80 percent of the total
heat in the refrigerant solution of the Dometic. The balance of needed heat
comes from radiation between the vent pipe and the solution pipe, and is
essential if the unit is to function. The insulation that is surrounded by
the galvanized shield shows the area where this radiation occurs. It is
about 12-14 inches. The vent piping and refrigerant lines diverge from each
other in this area so that the corragaged tubings will have space to attach.
The insulation here is essential for this needed radiation to occur. Without
the insulation, refrigeration will not occur. I have tried several
replacement insulations but have not found one as good as the original. To
get better radiation heat transfer you might try capping the top of the
galvanized cylinder, and use aluminum foil in the space between the top of
the burner box and lower part of the galvanized heat shield. Then add some
insulation to the exterior of the galvanized heat shield.