Date:         Thu, 25 May 2006 20:56:56 +0200
Reply-To:     Robin Oomkes <roomkes@ZONNET.NL>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robin Oomkes <roomkes@ZONNET.NL>
Subject:      Re: Dometic
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
              reply-type=original

Roger and others,

you're mostly right in saying that extra heat to the back of the fridge
won't make it cool any better. But in certain non-optimum situations (like a
propane burner that's not fully functional) having it run on propane AND on
12V DC (which is a non-optimum source of heat as well) you can get better
cooling. In most situations you shouldn't do this though because it will
just overheat and damage the fridge.

There is no feature that prevents you from running propane and AC or DC at
the same time. Simply light the fridge on propane, then switch to AC or DC.
This won't kill the flame - the flame will only be killed when you interrupt
the propane supply (anyway, that's how it is on European Westies). The only
thing you can't do is run it on 12V DC and AC at the same time.

Like Roger says, too much heat is not good for the fridge and inside temps
of the van. That's why the fridge usually cools better with the thermostat
at two thirds rather than full!

Hope this helps,

< gulp of cold belgian Chimay munk-brewed beer > cheers,

Robin



----- Original Message -----
From: "Roger Sisler" <rogersisler2000@YAHOO.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, May 25, 2006 7:03 PM
Subject: Re: Dometic


>I dont think the switches will let you run electricity and propane at the
> same time. Dont know, never thought of trying it.  The ammonia solution
> needs to be a rather specific tempature. Ammonia needs heat to seperate
> from it's companion chemicals. It is this pure ammonia vapor that absorbs
> the heat as it then condenses at the top of the evaperator pipe.
>
> This black pipe is where the aluminum ice cube tray holder is clipped.The
> top of this dead end pipe is behind the ice cube tray area. This is the
> coldest part of the pipe,and the highest ,physically for the ammonia
> vapor.
> The vapor collects here in a cloud, and condenses.The ammonia "rain" runs
> back down the pipe and into the rest of the soultion, that it had left,
> when first heated.If there is any uncondensed ammonia, it will condense a
> few inches further down the slope,were there is more heat to absorb.If
> your
> system is working properly, frost should form all the way(and quickly)
> across the black pipe that is inside the frig.Frost should form around the
> 90 degree bend and stop at the place where it enters the rear of the frig
> box.Still, it is far colder at the top of the slope.Good place to make
> ice,huh?Extra heat may only make,the sloution  overheat, and crystalize
> somewhere in a small passage. Same, I am told if you operate the frig off
> level and the van is not being driven.This is supposed to be rare,though.
> Anyway, the added heat will not seperate out this ammonia solution any
> better. It will add extra, unneeded heat load to the frig,and reduce it's
> capicity.Also this extra heat will make you warmer than necessary. The
> waste heat is only exited the van by the flue,and not all if it gets out.
>
> Seems that a heat shield between the ammonia pipes and frig box is a good
> idea. Kinds like muffler or exhaust pipe heat shield. Just a small break
> of
> space to reduece the heat actually getting to the box. How bout a piece of
> aluminum roof flashing?