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Date:         Sun, 17 May 2015 11:01:26 -0500
Reply-To:     Jim Felder <jim.felder@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Jim Felder <jim.felder@GMAIL.COM>
Subject:      Re: Fridge problem... which thing is malfunctioning?
Comments: To: David Beierl <dbeierl@attglobal.net>
In-Reply-To:  <vanagon%2015051703490000@GERRY.VANAGON.COM>
Content-Type: text/plain; charset=UTF-8

Thanks for the information, David.

I made a manometer and hooked it up. With the stove off it was lifting an 11.5 inch difference. Turned on the stove, it's at 11.375. Is that in normal range?

Thanks,

JIm

On Sun, May 17, 2015 at 2:15 AM, David Beierl <dbeierl@attglobal.net> wrote:

> Don't do that. Ever. You're rated for six degrees (maybe eight?) >> out of plumb in either direction, which is far more than most >> absorption fridges. Running it on a hill when you're driving is ok, >> but not stationary. And the damage is cumulative and can only be >> repaired by opening up the unit and rebuilding it. I'll explain in next >> email. >> > > It's pretty simple. The cooling unit contains, all under pressure of > around 350 psi: hydrogen gas. Water. Water vapor. Ammonia > dissiolved in water, and ammonia dissolved in water vapor; both at > various strengths. Possibly some free ammonia, I forget. And > finally, some sodium chromate powder suspended in the liquid bits, > meant to protext against corrosion (and intentionally or not to show > when a system has leaked, as there will be a spray of the powder at the > leak. > > The heat source heats the boiler which contains strong ammonia water, > sending water vapor and ammonia up to the top of the system where it > begins to fall down through the various parts I won't talk about > this; many complex and fascinating things happen including ammonia > condensing to liquid at the right place to extract heat from the box > and various other interactions, all dirven by gravity, the internal > slopes of the cooling unit, and the varying densities of the > components and mixtures. Ultimately it all ends up down at the > bottom where it's fed back into the boiler, but during > operation there are distinct areas where one or another material or > phase predominates. > > If you run the thing far enough off level that the cycle is > disrupted, the boiler will eventually boil dry and the heat sosurce > with nothing better to do will bake the sodium chromate powder onto > the boiler wall, insulating it. There's no non-invasive way to get > the caked material off, and as it grows thicker the fridge struggles. > > The burping thing is simple and has been blow3n way out of proportion > by folklore. Dometic suggest that if the fridge has been out for > service and in unusual attitudes where the stuff in the cooling > unit may have ended up in odd places, just before you re-install it > turn it upside down a couple times so it all gets mixed > together. That will eliminate any possibility of it having to > struggle to get the cycle going again when it's lit. There's no such > thing as letting it soak upside down or whatever, you are just giving > it basically a shake. > > Yrs, > d > > > Yrs, > d >


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