Date:         Sat, 25 Aug 2007 11:23:49 -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 high altitude lighting tips

I think at high altitudes the LP comes through the low altitude orifice
jet at a higher velocity than is useable. Higher than at low altitude.
Less air pressure up there to hold it back. What may be happening, is like
in that John Wayne movie " Hell fighters". The flame gets blown right off
the LP stream, and the fire goes out. In Hellfighters, they actually used
explosives to blow the flame off the gas well head. That put it out. I
think that this  method of extinguishing well fires is actually used in
Texas,too.

In the Dometic, maybe the LP is coming out so fast that the flame head
gets blown right off. A smaller jet may reduce this back to normal LP
velocity. OEm jet is a number 22 and high altitude is #24. #24 is smaller.

I think this lower high altitude velicity can be duplicated by reducing
the regulator pressure from 11 inches. Dont know how much changing is
needed though. Maybe 10 inches will keep the flame agoing. Actual window
of useable LP pressure is about 11.5 , down to 9 inches, and still get the
same end results.The stove should still work ok with this lower
pressure.LP supply will last longer.

People with Vanagon Westfalia with a regulator that seems to work ok at
high altitude, may have never had it adjusted during its entire lifetime.
Driving over rough roads for 20 years may cause the adjusting disk to back
off, and actually lower the LP pressure.This would make operation at high
altitude ok and still cool at sea level. My theory. The regulator in my 85
was a half inch of WC too low, when first tested.

There is no lock nut like device to keep the adjusting disk at the
setting, measured. The adjusting disk is only a plastic disk about 1/8
inch thick and the diametrer of a quarter. It has a opening for a hex
screw driver bit in the center ( like a donut hole- Mmmm donuts) for
adjustment.The disk is threaded on the outside rim, and screws into the
hole. Fine threads. It pushes against a spring, which inturns pushes on a
bellows.This bellows is contained in the wide circular area on the
regulator. There is always simple mechanical pressure on the disk
to "loosen up, or unscrew.This will reduce the pressure of the LP gas.It
only takes about a 1/2 turn to change the LP pressure an inch of water
column. Perhaps driving over bumpy roads for 20 years may be enough to do
this loosening. Especially roads at high altitiudes, as the roads in
Colorado  which I have seen( at high alitutde) are gravel and dirt, and
Westys like to go camping frequently. I think this is what is happening
with westy owners that  say their Dometics cool ok with the low altitude
jet. If they adjusted their regulators to 11 inches of WC, the Dometic
would poop out and get replaced with a NORCOLD.

www.rverscorner.com for instructions for use and building a $2 manometer
for checking your regulator. It is as easy to do as is  the $2 for buying
the materials.