Date: Wed, 12 Aug 2009 13:51:55 -0400
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: cognitive dissonance and refrigerators
In-Reply-To: <vanagon%2009081211445804@GERRY.VANAGON.COM>
Content-Type: text/plain; charset="us-ascii"; format=flowed
Hi Roger --
At 11:39 AM 8/12/2009, Roger Sisler wrote:
>Being unlevel is more critical front to back than side to side.
Many RV fridges are spec'ed +/-3 in one direction and +/-6 in the
other. Ours is +/-8 either way.
> Either way
>is not as much of an issue as seems to be written about. I read a book on RV
>and mobile refrigeration, and the old author said that he had seen a damage
>refrigerator from this unlevel operation only once in his experience.
I wouldn't bet on it myself. Damage from off-level operation is
cumulative. I bet if you ask the people at http://rvmobile.com (who
rebuild cooling units) they could give you a realistic estimate.
>Personally, I think the reason that the Dometic sucks is that the hydrogen
>that is mixed with ammonia has leaked out, leaving only the ammonia behind.
>Hydrogen is very light and must be difficult to contain.
Troubleshooting:
http://rvmobile.com/Tech/Trouble/CoolingD.htm -- the hydrogen is at
~350 psi. If it has leaked out, the unit will make a loud percolating noise.
>Can't see any other reason for the poor performance, as I have tried
>and tried everything to get mine to work like it should and cannot
>get the results I want.
What results do you want, specifically? The fridge as designed and
as specified in the manual will only cool to 40F below its
surroundings, will take a long time to cool, and survives best on a
diet of pre-cooled food. It also requires air circulation inside the
box, which can be improved by a FridgeMate battery-operated (or 12v)
fan -- but if you pack the thing solid the results will not
please. It will not operate as well when the van is in motion as
when it is standing still. It operates *best* when it is dead-nuts
level. Here's how it works:
http://rvmobile.com/Tech/Trouble/cooldoc.htm -- by all means get the
larger graphic printed or in a separate browser window to follow along with.
If it isn't operating up to spec, you may need a rebuilt cooling unit.
http://rvmobile.com/CU/process.htm
Unfortunately RV Mobile seems to have used up all their stocks of
RM182 parts and aren't rebuilding the cooling units any more.
> I don't
>understand how someone could sell a unit like these and have them not work
>reasonably good,somewhat similar to like we are used to at home, when they
>are new. Many of them sure don't work good now, and I think this is
>the reason.
If you're expecting performance like a compressor fridge, you're
doomed. You get to pick between home-fridge performance (compressor
units) or silent long-duration (weeks) operation on propane
(absorption units). Some Vanagon people pick one way (Norcold, for
example -- a somewhat larger box that can still be fitted into the
Vanagon cabinetry), some the other -- but notice how the compressor
folks are struggling to put several hundred pounds of batteries into
the van to get the same longevity as five pounds of propane gives the Dometic.
Personally for the best of both worlds I'd be looking at a cold-plate
unit with engine-driven compressor. It's been a while since I
looked, but my recollection is that half an hour a day would keep a
properly insulated (see below) fridge cold (maybe not a
freezer). But the box would have to be custom-built, and there's
piping from the compressor to the box. This is how boats do it, mostly.
Our van is so small, though, that anything will be a compromise --
like the Dometic, which judging from the pictures in the installation
manual was built specifically for the Vanagon. The key to efficient
refrigeration is insulation -- the sailboat folks (not the boat
builders!) think that six inches on all sides is *minimum* -- we'd
have to hang it from the rear hatch, and then the raccoons would be
helping themselves to beers. My personal opinion is that people who
want seriously good refrigeration would be better off with a
Sprinter-size vehicle. Or maybe one of those super-insulated beer
coolers, hung from the rear hatch when under way. However: a)
there's an outfit out west that makes vacuum-filled insulation (at
huge expense) that could be very useful for a small installation and
b) I just heard a rumor that the nano- boys are looking into
construction insulation. A bunch of silvered nanobubbles full of
nothing could be just the ticket, and five or ten years from now we
might have it.
So realistically, if I ever have a Westy again, I'll probably go for
the Norcold. Or live with the Dometic. It served me fine for well
over ten years, not as a home fridge but as way the heck better than
nothing and always there and always cold within its limits, at the
cost of ten pounds of propane every three weeks or so.
Cheers,
--
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'89 Po' White Star "Scamp"
