Date: Tue, 8 Nov 2005 11:54:55 -0500
Reply-To: Roger Sisler <rogersisler2000@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Roger Sisler <rogersisler2000@YAHOO.COM>
Subject: Re: dometic 182b question
I finished insulating the exhaust vent on my dometic. It was much more
difficult that I first believed it would be.The problem was odor from the
insulating material.I finally solved this issue though.The heat exiting the
vehicle from the insulated vent was 70 degrees warmer than stock.This is
heat that would other wise be dumped into the passenger compartment.Now it
exits the vehicle.Bake potatos, not people ,I say. I used my "parts
dometic " as gunnie pig.A gas grill propane tank/regulator did the heating.
I removed the factory insulation that is contained by the galvanized
shield. Here, I first used a fire block fiberglass that is used between
floors of a building. It is green and smelled to high heaven.Operating the
frig overnite caused a smell that needed 4 days to go away.I found out
that the #1 compaint in newly delivered moterhomes is smell from the
frig.Dealers are supposed to operate the friges first to get the fiberglass
smell out.It needs to scorch proper , I think. Dont think this fire block
would pass any test here-ever.Dont know what dometic used for the origional
material , but savewhat you got at all costs.Dometic cant even tell me what
they used.
Well,after this beginning, I tried insulation from a dishwasher. Insulation
from a old oven .Insulation from a westy wall.Insulatiom from a house. R-
13, I believe.My flagship insulation that I thought would save the day was
a product called inswool. This is a high temp insulation that is used in a
forge or to insulate exhaust manifolds. $7/sq ft. Type in "inswool"in yahoo
to get the low down.They claim , no smell, but I still got it.I rubbed the
exterior of the refrig pipes with muritic acid after each insulation that I
tried, to get any residue off before the new test.Well, the inswool smelled
too, but not as bad, and this odor got better after a week.Still ,you could
not sleep in this space where the frig would eventually be. I cycledthe
frig on and off several times/day ,if I had time, as this spead up the
scoraching process.
I finally gave up on fiberglass, though not entirely. Here is what finally
worked.I kept the origional fiberglass that was origional material.Around
the upper vent I wrapped crumpeled aluminum foil .This well crumpelled foil
was wrapped to a thickness of 1 inch around the vent the entire legnth ,to
the aluminum collector at the exit of the vehicle.Around this, I used the
inswool.My theory was that the tempature was now reduced enough to not get
any smell from the inswool.It worked.To contain the aluminum foil/inswool,I
used roofers copper flashing. This is like 4 thicknesses of foil and very
tough. I secured everything with zip ties. The lower vent was wrapped with
1 inch thick inswool on top of the galvanized stove pipe,and wrapped with
the copper foil/zip ties.
The tempature is 70 degrees higher at the exit.The other fiberglass
insulations gave me about 90 degrees higher exiting gas,but the smell was
to much.Aluminum is not so good an insulater,butI found it necessary.I see
several benifits from this insulation.First, the heat is reduced that would
have gone into the passenger compartment.Second, the heat load on the top
and rear of the frig is reduced. The heat transfer to the amonia pipe is
increased as the inlulation keeps it warmer in there.I also put an inch of
fiberglass on the top of the frig to reduce heat load at the top of the
frig.I removed the insulation on the wall of the westy to allow the rear
heat to conduct out the metal wall of the van(3.5 sq ft).By lowering the
tempature at the rear of the frig. the fans will not come on as often. This
will save the starting battery is vehicles not equipped with an auxillery
battery.Dont want a dead battery in the morning in the middle of
nowhere.Every little bit helps. No one procedure will hit a homerun in
dometic improvment.Roger
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