Absorption Refrigerator Options in a U270

Topic: Absorption Refrigerator Options in a U270 (Read 2415 times) previous topic - next topic

Re: Absorption Refrigerator Options in a U270

Reply #25 – December 15, 2013, 05:33:28 pm

We had the cooling unit of our Dometic replaced at the Amish factory http://rvcoolingunit.com/Default.aspx in Shipshewana, Indiana. We have been very pleased with the results. I'm sure the installation would be straightforward (for two people) if one wanted to do it himself. In our case we are close enough to Shipshewana that (given the difference between the shipping cost and the installation cost) that it made sense to drive there and have them install it. The added bonus was a delightful long weekend (with delicious food) in Amish country.

Re: Absorption Refrigerator Options in a U270

Reply #26 – January 14, 2014, 12:23:15 am

This may be of some use to other FoFum's faced with similar 7.5 cu.ft. NORCOLD replacement decisions. It is in followup to my previous post requesting input on options available to replace a failed NORCOLD Model 982 Absorption refrigerator in a 1998 U270.
With your input (and a considerable amount of additional exploration), I set and ranked the available options against the following goals (listed in strict order of importance to us):

Goal 1 Maintain dry camping ease without increasing coach system complexities (KISS)

Goal 2 Maintain (or improve) the AMOUNT of food that the refrigerator can store/maintain

Goal 3 Improve safety Factor/Features

Goal 4 Minimize installation complications and degradation of coach appearance

Goal 5 Hold the costs down

Once I arrived at the above logic, the choice was easy.
As you will see in the attached, updated spreadsheet, ATWOOD is producing a competing model (currently just 6 and 8 cubic foot refrigerators), that scores extremely well against these criteria.
The ATWOOD HE-0801:

Is a Helium/Ammonia absorption design that uses AC and Propane.

Helium is both inert and non-flammable, thus the ease of dry camping is maintained and the design safety factor is improved.

The designs of the boiler, evaporator and condenser sections are all improved and the tubing is more robust than the NORCOLD design.

While the exterior dimensions are identical, the interior is about an inch larger in all dimensions (through improved insulation) with the same or improved shelving dimensions.

When you look closely at interior shelving and bin designs, refrigerator Cu. Ft. Volume (in general) becomes nearly meaningless. Many refrigerator options use the storage volume so inefficiently, or interior arrangement/rearrangement options are so wasteful and poorly thought out, it renders the cu. ft. volume parameter nearly useless in trying to decide between options.

The ATWOOD has:

Refrigerator: 4 shelves, 4 bins on the door, 2 bins in bottom, and a 5th, shallow shelf is available,

Freezer: 1 full shelf, 1 bin on door

I added an RV Cooling Warehouse interior fan (two fans in an all SS mounting, switch for 12Vdc, powered through the drain tube) in the refrigerator, to end the defrosting nuisance. Several FT owners have reported good experience with the RVCW fan units -- 2 weeks so far with us and no visible condensation or frost on the fins and the cooling efficiency is greatly improved (more on that later).

When the coach is stationary, the ATWOOD design provides a TILT warning and records accumulated hours of use with TILT warning overridden. When enough time has accumulated, a TILT override control will alarm until serviced by an ATWOOD authorized service (good for safety: we'll have to wait and see whether it becomes problematic or not) Current owners report no problems.

The ATWOOD design also incorporates an (outside, back) 12Vdc evaporator fan. I added an LED indicator switch to the fan control, in order to be able to either turn it off or run it in automatic. Independent testing shows that the ATWOOD outperforms the NORCOLD 982, even with the evaporator fan disabled.

The external installation dimensions were a pleasure, beyond expectation. The physical dimensions are so identical (NORCOLD 986 to ATWOOD HE-0801) that even the (6) anchor screw holes in the new ATWOOD fit the holes left in removing the NORCOLD.

Also, the original wood insert panels were a direct exchange. From the outside, then, other than the new controls, one would never know that anything has been changed. Inside, the blue LED lighting and the blue tinted Lexan trays betray the change.

The old and the new refrigerators, with coils attached, fit through the door with 1/4" width to spare. After removing the screen door and the doorway wooden grab handle, it was a bulky, two man, slow and steady operation (doors down, coils up orientation). I did protect the edges of everything, with masking tape, to prevent marring any finishes, but it took three of us all of ten minutes to complete the transfer (out with the old, in with the new), once I was ready.

The ATWOOD "all-in" cost, including shipping and interior fan, was $1,139.35 which was about $200 more than installing a replacement AMISH cooling unit. However, the new box, new wiring, new controls and new propane control valve, as well as the safety factor improvement of He vs. H₂, not to mention the reduction in work involved with changing out the absorption refrigeration coil unit, all made it more desirable. PPL service was excellent, refrigerator was drop shipped from a Georgia w/house to our doorstep in 4 days. The shipping packaging was well designed and in great shape upon arrival.

Due to the need to add a third house battery and a small inverter (if I had chosen a residential option), the ATWOOD cost less than any of the residential refrigerator options. The ATWOOD was around 1/2 the cost of a direct replacement NORCOLD and the intriguing NOVA KOOL. But note that my spreadsheet does not include any of the battery tray welding and coach carpentry time, material and labor costs, if you chose any of the residential or NOVA KOOL options. Depending upon one's set of tools and DIY capabilities, the price differential above the ATWOOD cost could quickly grow to double and even triple the ATWOOD costs (with less storage, more complications and potentially, degraded appearance and quality).

All sounds pretty good, RIGHT?

Well, almost.

While the frame of the ATWOOD box is the same heavy gauge steel and the same rugged construction as the old NORCOLD box, and the cooling unit, as well as all of the NORCOLD controls are visibly robust, ATWOOD chintzes out on the door handle design as well as the gauge of the interior Lexan bins. I think that I will order spares for both. New, these components work fine, but the ATWOOD handles are plastic instead of the rugged, machined, metal parts (that still look and operate like new) on the NORCOLD. The handles also have awkward operating characteristics (that ATWOOD calls intuitive, but I personally find counter-intuitive) at least based upon the what we are accustomed to in the NORCOLD handles. I would have gladly just changed out the old for the new, but naturally, they don't quite work out, dimensions wise. I'm sure that we will become accustomed to them, eventually.
The most pleasant surprise, however, was the cooling efficiency of the ATWOOD (see attached "1st & 2nd Run" spreadsheet): Without the inside and outside fans running, the box temperature came down to <40°F in <5 hours. With both the inside and outside fans running, it pulled down to <40°F in <2 hours.
That's far faster than either the old NORCOLD (on the order of 12 hours) OR the Kenmore Elite and GE Profile residential refrigerators that we have (each around 8 hours on a good day).
We have since found that with just the interior fan running, we have to run the temperature control on its warmest setting in order to keep the interior temperatures above 34°F. When loaded with food goods, prolonged opening of the door is quickly recovered. Nice surprise in the cooling efficiency!
Sorry for the long post, but I feel that many of the older FT's are making an expensive mistake in the rush to residential refrigerators. If one carefully weighs the details , going to a residential unit degrades many important values in the original FT design, costs considerably more in the long run and unnecessarily complicates the well thought out design of the original coach.
The above is one option for those with the 6 and 8 cu.ft. class refrigerators to seriously consider. If the ATWOOD design stands the test of time and gains traction with the small boxes, they will certainly continue with larger boxes in the future.
I'm throwing the old NORCOLD box out tomorrow, but I will strip it of shelves, bins, controls, handles, propane solenoid, etc, in case anyone wants to pay for shipping of any of that stuff. I've already given some bins away here at RiverBend, Ask away if you want anything.

FWIW,
Neal

Re: Absorption Refrigerator Options in a U270

Reply #27 – January 14, 2014, 11:58:53 am

Neal thank you so much for that very informative writeup. I have been thinking of putting a residential fridge in someday but I like the idea of having the same functionality of the old unit with a newer design that is much safer. I think this is what I will do in the future.

Mark

Re: Absorption Refrigerator Options in a U270

Reply #28 – January 14, 2014, 02:37:54 pm

The ammonia is what eats out the walls of the cooling units. The Feds reduced the amount of the chemical that they put in to coat the walls too. This flakes off over time and is what causes the blockages. I decided on a residential and pulled my stove too. That means an extra battery now and maybe another later. I have no problem boondocking with the residential fridge either. I understand the desire to keep it similar but the residential is so much more efficient that I wish I had done it earlier.

Re: Absorption Refrigerator Options in a U270

Reply #29 – January 14, 2014, 04:01:09 pm

John, pictures of stove, battery , etc. please

Re: Absorption Refrigerator Options in a U270

Reply #30 – January 14, 2014, 08:14:30 pm

I will try to take them tomorrow.

Re: Absorption Refrigerator Options in a U270

Reply #31 – January 15, 2014, 04:18:36 pm

Quote from: MAZ – January 14, 2014, 11:58:53 am

Neal thank you so much for that very informative writeup. I have been thinking of putting a residential fridge in someday but I like the idea of having the same functionality of the old unit with a newer design that is much safer. I think this is what I will do in the future.
Mark

For the most part, the silence was deafening.
Thanks Mark.
Neal

Quote from: John S – January 14, 2014, 02:37:54 pm

The ammonia is what eats out the walls of the cooling units. The Feds reduced the amount of the chemical that they put in to coat the walls too. This flakes off over time and is what causes the blockages. I...........................the residential is so much more efficient that I wish I had done it earlier.

Hi John,
Thanks for responding.
There are several concepts in your response that people may wish to consider.
The absorption cycle fluid is made up of three major ingredients:

highly pure (distilled) water,

ammonia and

sodium chromate (<2% by volume)

As you point out, sodium chromate is used in an absorption refrigerator, to plate out on and protect the insides of the system from the corrosive effects of ammonia liquids and vapor.
The "Feds" reduced the sodium chromate (overburden allowance) because it is a known carcinogen, which is important to know following an absorption refrigerator failure and for disposal reasons.

Sodium chromate is hygroscopic (attracts and dissolves in water), so water content must be low or absent for sodium chromate to form crystals (solids). Absent stagnation, if the tubing is intact, water is always present and if the sodium chromate were able to "flake off" from tubing, it would simply dissolve in the weak solution.

So what does "plug" absorption refrigerator tubing?

When operating, an absorption refrigerator's fluids must continue TO FLOW in order to prevent overheating of the boiler. Overheating creates dramatically increased thermal cycle stresses and eventual failure in the boiler region. That is why "off level" operation is such a big deal. A much bigger deal than the average owner or RV dealer allows for. The conventional wisdom that "If the coach is level enough to comfortably walk around in, it's close enough" is very inadequate for an absorption refrigerator. It's also exactly why my NORCOLD failed. For several days I was having HWH leveling problems and before I could get to finding and fixing the HWH problem, the old NORCOLD unit failed.
Here's the crux of the issue:
As the percolation flow of ammonia and water slows (or worse, stops), boiler region temperatures soar. This doesn't happen in a few minutes or hours, but immediately. Unlike the new ATWOOD design, NORCOLD and DOMETIC refrigerators, without the addition of aftermarket controls, have nothing in their designs to prevent overheating by the continued application of AC Voltage heating or Propane Gas flame heating during low or no flow refrigerant conditions.
If the overheating goes on long enough, the ammonia "weak solution" becomes lower in water content and the sodium chromate concentration increases (due to the stagnant flow) Under highly elevated temperature, the concentrated sodium chromate vapors will then form stable crystals (that do not dissolve in the weak ammonia solution). They in turn settle to the bottom of the tubing. Once that has occurred, the process is not reversible and with enough accumulation, the refrigerator is worthless. The urban myth of turning the refrigerator upside down, may stir up the sediment, but it will soon clog up again. Also of concern is that with low or no flow and high temperatures, the overall system pressure increases dramatically.

The quantity of sodium chromate crystals produced (clogging) depends upon how long the low or no flow conditions are allowed to exist with AC or Propane Flame Heating still applied. So, depending upon how diligent you are in always keeping level operation, you might go 35 years or just 35 minutes without an absorption refrigerator tubing failure.

ATWOOD will only respond that their design is "Proprietary" when asked exactly how the patent pending TILT technology works.
Looking at the available schematic and the actual wiring, I suspect that the TILT control is more intelligent than a "spirit level" type tilt sensor. I believe that there is a thermal switch mounted directly on the burner tube. When the tube temperature goes high, it opens, terminating further heat application until the thermal switch cools down and recloses. Then, if the refrigerator interior thermistor is still calling for more cooling, the AC or propane heat source is reapplied to the boiler.
Thus, the TILT control is completely transparent to the user until a predetermined number of "protective TILT interrupts" cause the TILT control board logic to lockout further use and make the user go in for ATWOOD evaluation service. Normal care in leveling will prevent the feature from ever being noticed by the user.

Final point.

I'm not sure what you mean by "...... the residential is so much more efficient that I wish I had done it earlier".
Do you mean that your Dometic didn't cool well? I can't speak to that, but have certainly seen the numerous complaints. Our old NORCOLD, always cooled well and, other than taking 12 hours to cool down and frosting up in humid environments, it always worked well. Zero recalls or difficulties.

Plugged into shore power, the cooling efficiency of the ATWOOD seems to be far better than the old NORCOLD or either of our two large residential refrigerators.

If you mean power consumption when NOT plugged into shore power, surely a propane flame driven absorption refrigerator cycle is more efficient than a Powertech diesel driven generator/battery charger/battery/inverter/residential refrigerator motor/compressor energy conversion cycle all with component specific power losses/inefficiencies (or the even less efficient Cummins engine driven cycle).

Anyway, thanks for responding and the above gives a bit more info for those that have an interest.
Neal

Re: Absorption Refrigerator Options in a U270

Reply #32 – January 15, 2014, 09:21:01 pm

Neal thanks for your very detailed explanation. My Dometic is working good so far so hopefully I wont have to make up my mind too soon. Mark

Re: Absorption Refrigerator Options in a U270

Reply #33 – January 15, 2014, 09:47:18 pm

I studied this pretty closely. We have much more stable temps in all extremes outside. Say over 100 degrees the old fridge would have a warm freezer or at times it would freeze things in the fridge. The samsung stopped that. I have way more room too especially in the freezer for odd sized things. I usually turn on the generator every morning to make coffee and run the microwave. That will bulk charge the batteries. I can go all night without the generator on too. If it is really cold I turn on the generator anyway and if it is really hot it is on for ac. So I do not see the benefit of the gas units. I can remove a volatile substance from the coach too.

When the sodium chromate flakes off there is a tube that is suppose to catch it but since it is in the middle of the cooling unit that is hard to do. So it settles and will plug. The failure can be spectacular and the time between failures seems to be decreasing. That is anecdotal but it seems that when people get the new cooling unit it does not last like the old one.

Re: Absorption Refrigerator Options in a U270

Reply #34 – January 16, 2014, 12:05:36 am

Quote from: John S – January 15, 2014, 09:47:18 pm

I studied this pretty closely. ............................When the sodium chromate flakes off there is a tube that is suppose to catch it but since it is in the middle of the cooling unit that is hard to do. So it settles and will plug............................

Hi again, John

I haven't experienced the Dometic issues but, based on internet information, yours don't seem to be unique.

I also understand that many FT owners aren't as focused (DW calls it being anal) on coach operation, maintenance and corrective action analysis as I am. So, it's not unusual that we have different perspectives on keeping things simple and cost effective.

WRT sodium chromate "flaking off", I know of the urban myths that are scattered about on the RV/internet websites, but I would be curious to know if you have actual evidence of sodium chromate "flaking off" and blocking refrigerant flow in a failed absorption refrigeration coil. I ask because chromate is an extremely useful inhibitor that works in two ways:

the high oxidation state Cr (VI) causes the protected metal to pass into the passivation region, rendering the base metal essentially inert

the product of oxidation by chromate is chromic oxide Cr2O3 which itself forms an inert, insoluble surface film. In practice, though, chromate treatment of steels produces a mixed film of ferric and chromic oxides, one molecule thick, which is highly resistant to corrosion.

Neither can "flake off" and restrict flow.

The formation of crystals under TILT induced, high boiler temperatures and low water vapor in the percolation column, combined with highly concentrated sodium chromate (soluable overburden) vapors, make more chemistry sense to me.

Just curious,

Neal

Re: Absorption Refrigerator Options in a U270

Reply #35 – January 16, 2014, 07:12:44 am

Neal thanks for all the details. Knock on wood my 15 year old Dometic is still running good, but sooner or later it will die. Glad to see Atwood get in the fridge game sounds like they have made a lot of improvements. I am like you not sold on the residential refrigerator deal just yet, 1 they are not designed for mobile use power on power off road vibration and so on (we'll see how that works with warranty issues), 2 they don't fit without a good bit of modification, 3 extra batteries inverters switches and so on more things for more problems. Possably at some point GE and others will design a "mobile unit" that better fits the space in RV's they all seem to be too deep, and to tall. As far as the power issues go we dry camp 4 days every year with a friend that has a residentail fridge in a 42' SOB seems like his generator is always running, I run mine about 4 hours a day and we are not paying much attention to power useage. When mine gives up I will likely go back with a new RV unit and be done with it for 10 or 15 more years. My opinon may change when we start fulltiming next year we'll see.

Re: Absorption Refrigerator Options in a U270

Reply #36 – January 16, 2014, 07:36:15 am

A Foretravel owner here had three cooling units that he cut open in his bay. He had cut open over ten of them after his third replacement to see why. You could see the flaking. I was surprised. He yes a magnet now to try to move the particles into the doubled walled tube that the put there to capture the stuff to prevent clogs. Now I did not cot the open and caution people about doing so as it is under pressure that is pretty high. I was surprised by what I saw too and this owner put Ina new cooling unit but is making his own out of stainless steel right now so he will eliminate the issues. For how I use my coach, I am happy with a residential as it gives better cooling or I should say more even cooling and freezing. I pulled my propane tank and added an extra battery too so I can go a while before turning on the generator. I understand what you are saying about the flaking off too and for years thought it was not happening but looking at those cooling units has me thinking that it is in solution maybe then and participates out but it is what causes the plugs.

Re: Absorption Refrigerator Options in a U270

Reply #37 – January 16, 2014, 07:37:54 am

I wonder if it is part of the pipes itself coming off in a high temp situation. But it definitly plugged it

Re: Absorption Refrigerator Options in a U270

Reply #38 – January 16, 2014, 07:44:25 am

I hope Atwood changes things because the new units are not lasting like the old ones did. I runmy genny about 4 hours a day to stay charged. Usually some in the morning when I make coffee and. Some in the evening again I run two cpaps all night too. They are constant drains as is the ceiling fan. I put. In a fourth battery and all is good. If I boo docked all the time solar would rake care of my needs but as it is it is easier to run the generator about four or so hours a day. Interestingly samsung takes the 120 and converts it to 12 volt. I bet they could make a 12 volt only become much more efficient. I do not turn off the ice maker but if I did that saves a lot of energy.

Re: Absorption Refrigerator Options in a U270

Reply #39 – January 16, 2014, 11:59:55 am

Quote from: bbeane – January 16, 2014, 07:12:44 am

...................Neal thanks for all the details."...............When mine gives up I will likely go back with a new RV unit and be done with it for 10 or 15 more years...............

Thanks Bruce.
Much along my thoughts as well.
Neal

Quote from: John S – January 16, 2014, 07:36:15 am

.............A Foretravel owner here had three cooling units that he cut open in his bay. He had cut open over ten of them after his third replacement to see why. You could see the flaking. I was surprised. He yes a magnet now to try to move the particles into the doubled walled tube that the put there to capture the stuff to prevent clogs....................

Thanks, John.
I think that I understand now.
The units that he cut open were not NORCOLD or DOMETIC?
Mini bars for hotels/motels are the largest application of absorption refrigerators worldwide.
Is this what he was using?
They are inexpensive, commonly available. And seldom have a very long half life in mobile applications.
Thanks again.
Neal

Re: Absorption Refrigerator Options in a U270

Reply #40 – January 16, 2014, 12:25:33 pm

I work on the principle that" why waste a bunch of time worrying about Absorption fridge problems when I can install a simple 120v one that cost 1/4 of the Dometic or? and more than likely will last almost as long. There are no "vibration" issues to really worry about in our coaches and as we have ours on it's own dedicated circuit PS Inverter it is not "on and off" Yes I have put solar in and better batteries but that was for the freedom to be away from the RV Parks and running Generators-NOT- to run a fridge, that came after the fact! I spent a grand total of $5000 for solar and better batteries and would do it again. Think of it this way. If you fulltime and stay in a park for at least 200 days a year (because you need power) divide $5000 by 200= $25 a night!! That means my solar is paid for in 1 yr. The rest of time is free and I do not have to run as much Propane- just for heating(I do not have Aqua hot) Most fulltimers stay in sunny warm climates so charging the batteries is an easy thing with solar and sensible power management.
I am sold on this and we do not have any cooling problems with this fridge ie fans hanging all over the place, and various other ideas we have seen on the forum to keep the walls of fridge cool.
I am a simple person, fix it for once and all and go onto something else without all the decoding etc of chemicals, flaking, etc etc that seem to consume a lot of time.
FWIW
John H

Re: Absorption Refrigerator Options in a U270

Reply #41 – January 16, 2014, 04:47:30 pm

There are two Foretravels in here now that had their refrigerators die. Newer coaches and one was on his second cooling unit so now a residential unit.

Re: Absorption Refrigerator Options in a U270

Reply #42 – January 18, 2014, 06:14:28 pm

Great post Neal! Our MiFi died and we have mostly been sans internet in poor T-Mobil reception areas going through West Texas and NM so just catching up on the forum. I was looking into the helium option awhile back, but it seemed like a product that might never actually get to market. I am glad to see Attwood pull it off! It is an intriguing option, but at this point with my plans to do the solar thing and battery upgrades, I am still leaning towards the NovaKool or Vitrifrigo options using the Danfoss compressor. The off level capabilities are probably the biggest reason, but form factor plays a roll as well. Still, there is much to like about the option you chose... I am still in research mode because I have to wait until we are back in San Diego to act upon it anyway. Please keep us posted on your experiences with the Attwood.

Don

Re: Absorption Refrigerator Options in a U270

Reply #43 – April 17, 2014, 12:04:47 am

Quote from: acousticart – January 18, 2014, 06:14:28 pm

Great post Neal! .........................Please keep us posted on your experiences with the Atwood.
Don

OK
Three months of use on two ATWOOD HE-0801's:

We have not needed to use the refrigerator beyond setting #1

Setting #1 = least amount of cooling. In a test, setting #5 froze water jugs in the refrigerator within two hours.

With the (inside refrigerator) RVCW circulation fan operating and the external (condenser coil stack) fan turned off, the refrigerator operates consistently between 34°F and 37°F, while the freezer runs between -6°F and -2°F, with outside temperatures varying from 40°F to 95°F. Ice cream is very hard and beer is very cold! Life is GOOD!

All of this to say that the HE-0801 cooling has been rapid and more than abundant. The external condenser coil fan appears to be overkill (I installed a switch to turn it off and have not used it as it is both noisy and not needed for more cooling capacity). There appears to be more than enough reserve cooling capacity to handle much higher outside temperatures and more difficult cooling challenges.

The RVCW fans provide even temperature distribution and totally frost free operation with only a slight hum (see photos). I found that placing a strip of "fuzzy" VELCRO on the fan assembly (where the assembly contacts the aluminum cooling fins) makes any running noises all but disappear.

All of the ATWOOD components work well: Handles, shelves, bins, controls, lighting, condensate collection and drain, etc. The bins and handles are not as robust in design and build as the original NORCOLD, but thus far, they seem to be trouble free. The four door levels and the five interior shelf levels of the refrigerator far exceed the residential boxes that we evaluated. And they are more adjustable than even the NORCOLD was.

The fit and finish is far superior to any of the residential refrigerators that we considered. The issue is that small "apartment" residential options (that can be made to fit the available volume in a 1998 U270/U295) are low budget, no-frills, refrigerators while the ATWOOD is meant to compete favorably against the existing (NORCOLD and DOMETIC) mobile platform designs, ALL three of which are inherently more robust, rugged and mobile friendly designs (latching doors, rattle free shelf "keepers", lipped shelving, 2-way [propane and AC], etc.). As previously mentioned, the ATWOOD HE-0801 fit the NORCOLD volume precisely, right down to the location of the predrilled anchor screw locations.

I did have to rework the wooden door inserts some. The freezer door original (edge-glued) insert had failed. Biscuit routing and a re-glue resolved that. The refrigerator door insert had to be shortened by 5/8" in height and the edges had to be thinned all around by roughly 1/8", in order to fit.

So that is my good news.
The single negative may be of minor or major importance. I still do not know which:
Barely a few days into operation, a small amount of odd substance began to "ooze" through imperfections in the sealing tape on the rear exterior surface of the refrigerator. I know that it isn't chromate but I have only a vague idea what it is. It stopped about two weeks into use of the refrigerator. I suspect that it was a byproduct of the thermal mastic used to "heat sink" the evaporator coil to the aluminum fin cooling plate. I had a conversation with the head of ATWOOD refrigerator production and he asked that I have it inspected by an authorized service rep, which I did. Based on the rep's evaluation, ATWOOD provided a complete replacement unit. It arrived about ten days later. The service rep and I changed the two units out in less than three hours, including screen door removal and re-installation. We did find that both the first and second units needed to be taped more carefully around the cavity that the evaporation coil fits into. Of course we did that, with overkill, on the replacement unit, and the service rep. wrote it up profusely. Zero cost to me.
So that is the not-so-good news.
The bad news is that the replacement unit is doing the very same "oozing" thing on the very same schedule. The service rep. has filed a follow-up report and I'm still waiting for a reaction from ATWOOD. It would be nice to receive a "no-consequence" response, but who knows?
So now you are up to date on the ATWOOD. Sadly, it has the "hanging chad" to interpret.
I did do a thorough disassembly/dissection of the failed NORCOLD unit, which I will document in another, separate post.
Neal

Re: Absorption Refrigerator Options in a U270

Reply #44 – April 17, 2014, 07:25:35 am

Nice follow up. Hope the oozing us taken care of.

Re: Absorption Refrigerator Options in a U270

Reply #45 – April 17, 2014, 08:35:16 am

Another great write up Neal.

Great help to those of us that may be looking to make a future fridge change of that size/type.

D&D

Re: Absorption Refrigerator Options in a U270

Reply #46 – April 17, 2014, 11:40:58 am

Thanks Neal

Mark

Re: Absorption Refrigerator Options in a U270

Reply #47 – April 17, 2014, 12:06:33 pm

Excellent follow up!

Thanks for letting us vicariously follow another viable fridge option without actually having to do it! I would be tempted to wipe off the ooze periodically and see if it stops... since your issue has been documented already by Atwood, I would think you should be able to opt for another change out if it doesn't stop. Of course, it would be useful to know what the stuff is and why it is happening. Perhaps an overfill pressure release valve? Anyway, good luck!
Don & Tys

Re: Absorption Refrigerator Options in a U270

Reply #48 – October 27, 2014, 10:14:06 pm

Hi Guys,
The flaking material in a failed absorption refrigerator is sodium chromate (the rust inhibitor placed in the system to inhibit corrosion) which crystalizes when repeatedly over heated - usually when the refrigerator frequently is operated out of level. The preventive answer is to utilize an ARP (Absorptive Refrigerator Protection) control.

Google this product to see how it stops this over temperature condition that literally causes the system fail over time. Spending $120 to protect your absorption refigerator literally is: an ounce of precaution is worth a pound of cure.

I am affiliated with this company and the science is sound.

Affiliate Notice