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Old 06-03-2015, 06:56 AM   #1
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Atwood Helium refer replacement for RM1303

Has anyone replaced their ammonia refer with an Atwood Helium?
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Old 06-03-2015, 07:54 AM   #2
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Hmm- says they work better when not level yet it includes a built in level "for maximum efficiency".
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Old 06-04-2015, 10:21 PM   #3
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Decided to go with the new generation Dometic
New Generation RM 3762 RB - 7 cu. ft. - Dometic Corp
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Old 06-04-2015, 11:13 PM   #4
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Has anyone replaced their ammonia refer with an Atwood Helium?
From the wording of your question I infer that you believe that the Atwood Helium refrigerator does not contain ammonia. I do not believe this is the case.

Absorption refrigerators typically are filled with a mixture of ammonia and hydrogen. I'm pretty sure the Atwood Helium refrigerator uses helium instead of hydrogen, but the ammonia is still there. The ammonia is the actual refrigerant; the helium or hydrogen is a ballast gas that controls the pressure of the system (and hence the boiling point of the ammonia).

I don't know what the advantages of helium over hydrogen might be.
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Old 06-04-2015, 11:33 PM   #5
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This is worth a read.
http://rvrefrigeration.com/wp-conten...eport-rev4.pdf
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Old 06-05-2015, 01:49 AM   #6
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From the wording of your question I infer that you believe that the Atwood Helium refrigerator does not contain ammonia. I do not believe this is the case.

Absorption refrigerators typically are filled with a mixture of ammonia and hydrogen. I'm pretty sure the Atwood Helium refrigerator uses helium instead of hydrogen, but the ammonia is still there. The ammonia is the actual refrigerant; the helium or hydrogen is a ballast gas that controls the pressure of the system (and hence the boiling point of the ammonia).

I don't know what the advantages of helium over hydrogen might be.
Yep! All gas/absorption (G/A) refrigeration units contain ammonia (along with water, sodium chromate and either hydrogen or helium). The Atwood simply replaces that hydrogen with helium. Better? They say so, but my field reports say that they are still as inefficient at cooling as those units with hydrogen.

And there is technically no 'refrigerant' in an absorption fridge, unlike a compressor based fridge. The cold is produced as the gaseous ammonia (which is heated by either an LP burner or electric element) condenses back to liquid and causes a chemical reaction with the hydrogen (or helium) located mostly in the condenser section at the top of the unit.

I'll still take a Danfoss-based 12VDC compressor fridge 100% over any G/A fridge!!!
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Old 06-05-2015, 02:06 AM   #7
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Just read Ford's report.

As an aside, the hydrogen (or helium) has NO BEARING on the possibility of a fire caused by a refrigerant leak, as neither gas is found at the lower levels of the heating section at any time. The fire hazard is from the AMMONIA!!!!

I was involved in a Norcold refrigerator fire several years ago. Having placed the Norcold recall kit on this particular fridge which was designed to mitigate a fire while on LP (as I had done over 200 times on other units), the owners insurance company threatened to sue me for improper installation of the recall kit, as a fire in the fridge severely damaged the coach. The unit was, however, operating on 120VAC electric heating elements at the time of the fire.

After $8000 in legal fees and much time expended, I was eventually cleared at a quasi-judicial inquest by several paid fire inspectors (and my attorney). Turns out that the recall kit will do NOTHING to mitigate a fire hazard while the fridge is running on 120VAC, as I tried in vain to explain to the insurance company.

The rep from Norcold explained to me after the inquest (and off the record) that in a super heated situation (which happens in a blockage or one where the flow of ammonia is disrupted), the ammonia becomes a flammable plasma and is ejected from the cooling unit under high pressure thru a very small crack in a weld or pinhole in the tubing.

This pressurized, very hot ammonia is what becomes a torch and fuels the fires that have become more frequent in RVs. And you wonder why I'm not a fan of gas/absorption refrigeration????
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