Foretravel Owners' Forum

 Well, our coach just passed its 16th birthday and, during my semi-annual propane PM's, I found indications that I need to repair/replace our NORCOLD 982 (highly reliable to date and never subject to a recall).  I found external Chromate showing at the burner stack so the unit is now placed out of service and isolated.
Looking more seriously at my options, I have several questions for those of you that have made the absorption refrigerator replace/repair decisions.
We still feel strongly about our KISS principle and we WILL continue boon-docking, from time to time, so I either have to continue with a safe Absorption Refrigerator design and installation or I have to add more battery capacity and an inverter dedicated to a residential refrigerator.  I am not willing to get into deeper battery cycles and solar panel complexities at this time.  I ran 50% draw-downs on our 12 year old MK Gels recently and they are still showing 89% original capacity, so I'm not anxious to modify our routine treatment of the coach DC systems.
Here are my questions:
 

• Has anyone had any kind of negative installation or operating experience with the Amish built "RV Cooling Unit Warehouse" (DIY replacement) Absorption Units?  From the attached MS Excel spreadsheet (work in progress), it is a clear contender.  We are NOT going to travel to Amish country at this time of year and the DIY process appears to be very reasonable, even possible within the coach.  I will do the repair myself.
   
• The WHIRLPOOL and Sears KENMORE residential units require a good amount of cabinet modification on top of the cabinet interior safety upgrades.  I'm not averse to that, but, it appears that even with cabinet modifications which will place the door significantly "off-center", the door will bear against the mirrored wall each time the door is opened.  Is that a problem and how do you guard against inadvertent mirror damage?  Will the door even open all the way?
   
• With minimal effort, our interior matching wood panel inserts look like new day in and day out, even after 16 years.  How do you keep the residential refrigerator black and SS panels looking unblemished? 
   
• What have you been able to do to accommodate the highly reduced shelving and door storage as compared with the original 7.5 Ftᵌ NORCOLD 982?  The 10.3 Ftᵌ HAIER and the 10.7 Ftᵌ WHIRLPOOL and KENMORE models have 37% more interior capacity but then they provide you with 25% less shelving which leads to more than 35% lost use of the refrigerator volume (unless goods are just stacked).
   
• What has anyone done to accommodate the lack of a shelf in the Whirlpool freezer, and the inefficient space utilization in the HAIER door design?
   
• I've seen the several attempts at overcoming the free swinging doors while underway and the shifting of refer. contents in the new "nonresidential" environment. Does anyone have other designs?
   
• Small (10/11 Ftᵌ) residential units appear to have far less robust and substantial designs when it comes to latches, controls, shelves, trays, bins and door hinges as compared to the NORCOLD 982 equivalent components.  Has anyone experienced failures?  Are replacement parts readily available?
   
• Does anyone have anything else to offer for these Whirlpool, Hanover and Haier (or other U270 compatible) repair/replacement units? 

Thanks in advance,
Neal
 

Neal,

A bunch of this is covered in past posts if you have run a search or two.

Amish will work if you are good at DIY, and will be lowest cost. Tool my Norcold apart in my OREG after 16 years. Decided I din;t want DIY and replaced with New Absorption replacement which was an exact fit.

When my absorption unit on my current 2000 U-320 started acting up, the easiest replacement from a fit standpoint was a 35 1/2 wide - 36 " wide residential. Absorption would have been more for the refrigerator and even more for the cabinet mods, since no current model came close in size for some reason.

Yes we stack stuff, and yes there is WAY more space in a residential of an equal size than absorption.

I have French doors, stainless steel. Use lemon pledge on the doors, seem to keep smudges to minimum. Only freezer door would hit opposite cabinet know, we know it and are careful.

Run referig all night on standard inverter that comes with coach, auto start never kicks on the Genny. I boon dock all the time at NACSCAR, but not afraid to run Genny a bit, read somewhere here that engine is 8,000+ hour rated, will never get there.

YMMV. Like the aqua-hot, will never go back to absorption.

Good luck with your project!

Hi Tim,
I have followed the posts carefully over time and I've, in the last few days, reviewed them all.
As you know, in the 36 foot coaches, every inch is important and most of my questions have to do with squeezing every available bit of opportunity out of our limited real estate.
The questions I've asked are ones that I haven't been able to find answers to through FoFum searches or through direct discussions with other U270 owners (as well as other coach friends).
Thanks for the input though,
Neal
PS:  Curiously, from actual measurement and careful calculation, I've noticed that many residential refrigerators are overstated in terms of volume while NORCOLD is not.  And residentals tend to squander their volume with poor interior layout and design, whereas NORCOLD makes every cubic centimeter count.

Neal, as mentioned there have been many fridge changes by members, us included, and would not go back to old. The doors on our Whirlpool are held tight by the simple latch that I fitted, and it is almost un noticed as I painted it black too.
We have no problems with loss of space and ours runs off a 1000watt Pure sine extra inverter that easily handles it and the tv etc etc. Less stand by current loss than using the Xantrex 2500. Overnight the battery loss is around 8% and of course our batteries are topped up by solar (which you do not want). The circuit for it is by way of a DPDT switch so we can change to shore/gen/inverter or to the smaller onverter.
If you want to see my latch I will send pictures, and if you email Barry and Cindy they have seen ours and I am sure they will give you an honest opinion.
Our old one was double doors and this one single so I made a slide out cabinet in space left over.
Much better use.

John H

Sorry Neal, understand the specificity of your questions.

Holding the doors not an issue, Velcro on French doors, sliding door locks on single doors.

Amish unit a really good option cost wise IF you are pretty handy. I do a lot of handyman stuff and Habitat Builds and once I took mine apart, thought better of putting in the new coil. You may be much better than I, or maybe I was just a chicken.

Yes, change out of unit can be done within coach , messy and right fit but it can be done

actually the lock I made up is not a slider and it can be made to work on french doors too. You just need around 3/8 " space between upper and lower door.
John H

FWIW,
My FT is also older and the Dometic is doing pretty well.  Freezes my drinks when cold outside on highest setting and does ok when hot out.  When it fails, I think I will go with the Whirlpool/Haier type home refer.  However, I did once in a previous SOB change out my 3 way dometic to a new replacement ( 2 way Norcold).  I will say that I owned that motorhome for about 5 more years and never had an issue with it.  If I were to consider changing refers as you are and wanted to keep the absorption type as my refer, then I probably would just go get a new Norcold or Dometic and change them out.  I frankly like just not having issues for a while, and the effort and additional costs may be worth it. 

I did the "RV Cooling Unit Warehouse" replacement two years ago for our Dometic. I did it by myself in the salon of the coach. It took a couple of days. With a little help and experience, it could be done in about four hours.

There was very little collateral damage ;D and the unit has performed well. I broke one door handle and left a couple of scratches. Both of those issues can be easily fixed. If doing the repair by yourself, make a platform in the hallway in front of the unit so that you can slide the unit out and back in. I improvised a ramp to get the unit down to the floor and then back up to height for installation.

I recently added the Fridge-Fix fan to the interior and have been pleased with the results.

The absorption refer advantages in a low power consumption use are well known.  Unless significant solar is to added or you only use your coach plugged in or do not mind the gen running you might need to replace the batteries IMO.  New deka's apparently exceed the normal rating by a fair amount.  I am not an expert but I remember my expert buddy saying something about normal gels measuring 1225 something but the new deka's frequently measured 1350 or more.

Mine showed similar percentage worn but dropped a fair amount of amp hours under medium use.  Much less drop since a put new ones in.

Its a system and if it consumes more power it has to be put back in somehow.

Duh. 

Bob 

even if you DO not add solar and drive for a few hours each day after a night on the lower 1000w inverter you will replace all lost power out of batteries. You DO not need to run genset for this loss. If you are parked with shore power then no issue. If you are parked for a few days and no shore power, then yes you will have to use genset to replace battery loss. Personally do not see a problem with it all and feel that this issue is "over thought by many" I actually speak from experience on this one!!
John H

Understand the 8%, John, but you have (3) 8D's and I have only (2), as well as a power hungry CPAP machine.  So, if I'm trying to stay in the top 25% of my capacity, I need another 8D or more generator run time.
I'd sure appreciate a good picture of your door latch design, to add to my thinking.
I agree on all points.  From my experience, though, a residential refrigerator solution to my problem, without adding to my battery capacity, would more than double my boon-docking daily generator run times, which would become tiresome.  I've  done most of my generator maintenance myself and the Isuzu/Gen set is doing just fine at 2985 hours.  I did have Powertech do a thorough evaluation a couple of years ago, in case I was overlooking anything.  It was continue on "as-is".  They told me that they have identical units on islands that were approaching 11,000 hours without overhaul.  Just unskilled maintenance, reasonable fuel and clean air.  But, I'd just prefer being as gentle on the machinery as is reasonable.
I remember when you did your repair, Dave and I looked at your posts again recently.  There are several good UTube videos available now also.  I already have the support stand built, as I'll need it either way.
I tried the DIY computer fan route and ran into long term reliability problems.  If I go with the RV Cooling Unit Warehouse solution, I want to try theirs, particularly since they offer the 5 year warranty.  Thanks for the input.
Neal

Neal, I don't know how similar our coaches are regards the refrigerator as my coach is older.  I replaced my Norcold refrigerator with a new Norcold model that was  the same size and fit the opening without any modifications.  If you do that you may want to redo the lining of the compartment with something that is somewhat fireproof like sheet metal or hardie board.  The refrig manual said the back of the refrig should be close to the wall but not touching it.  The original FT installation was not like that with about 4" of space between the outside wall and the back of the refrig.  I built out the wall with some wood framing, filled the space with fiberglass, and covered it with sheet aluminum.  If the back of the refrig is close to the wall the rising air has to move over the coils.  It worked okay in Las Vegas with the temperature over 100.  I also put some sheet aluminum on the sides of the compartment that was already insulated and added some insulation above the refrig.  I had to remove a window in order to get the old refrig out and the new one in.  I also had a platform the same height as the bottom of the compartment, that helped make it easy to slide in and out.  Although the outside dimensions of the new refrig is the same as the old one, my wife says that it is not as deep inside as the old one.  I decided to replace the whole unit as the inside of the old refrig was beginning to show its age. 

Forgot to mention that I made my own oak plywood inserts for the doors using 1/4" ply.  I had to thin the edges in order to get it to fit.  Just used a belt sander on the back side along the edge.  It's a fairly decent match with the rest of the coach.  You may have to go to more than one big box store to find some decent looking oak ply. 

I expect the fans from "Warehouse" are good quality. The folk who build Fridge-Fix claim to use high quality components. Their warranty is two years.

I can hear the hum of the motors when the refrigerator is closed, but it is relatively quiet and does not annoy. NO ice collects on the cooling fins and the temperature throughout the box is much more uniform than without the fans. The unit has a plenum that spreads the draft of the fans across the full width of the cooling fins. Installation was fast and easy.

And --- it has those way cool blue lights!!

I'll be sure that the compartment is safer when I'm done.  I've seen some cabinet interiors on SOB's that were obscenely unsafe (charred wood and dry rot from water intrusion).  While the FT's are much, much better, as Pierce and others have shown, there are easy ways to improve even the FT's.
In terms of cooling ability, we've never had any problems maintaining 0 degrees and less than 40 degrees with any outside temperature conditions.  Not sure why that has been the case.  I'm also not sure how many others have/had the NORCOLD 982 unit and whether that might be the key.  The only difficulties we have ever had were the fins frosting up under humid, heavy use conditions and the limited size.  But even with the limited size, Brenda says that neither our 23 cu. ft. bottom freezer Kenmore Elite in NH nor our 27 cu. ft. side by side GE Profile in FL will hold as much (refrigerator section to refrigerator section) as the "little" 7.5 cu. ft. Norcold does.  Those two have big freezer sections, but refer to refer............about the same.
I may be wrong but it looks to me as though removing my screen door and the handrail near the copilot chair will allow me to take the old NORCOLD 982 out.  It is tight but the tape measure says yes.  If it looks like it will mark anything up, I'm not averse to removing the dining table window.  I installed it and removal is but a hiccup away.  We have some nice staging here at RiverBend and many helping hands....so no problem if it comes to that.
I was hoping to use the present refer door inserts if I went with any of the NORCOLD options.  I've always felt that the "built in" look speaks of consistent class and elegance. But your inserts didn't fit the new box?  The door outside dimensions look to be the same.
Thanks, Jerry
Dave,
I've added that to my spread sheet.  Looks like a great option that I need to understand better
Thanks,
Neal

Neal, here are a few pics of my lock for Res fridge.
JohnH

The interior fan from Cooling Unit Warehouse has sure solved the frost-on-the-coil issue for us. I'm sure the temp is more uniform as well. Good investment so far.

Do you have a side by side dometic?  My freezer side metal parts get frost fairly quickly. Is the fan on the refer side only?

Bob

Thanks John.  Got it.
Thanks Rick.  The fan from the Cooling Unit Warehouse would be my choice.  The Fridge-Fix unit that JD pointed to looks to be too large (18" X 4" X 2" free volume on overhead, in front of cooling fins) for the small NORCOLDS.  Nice looking design though.
Neal

Neal, about 4 months ago I ordered the Amish unit for my Dometic fridge. I have a '99 270, 36 ft. Anyway I installed the unit  with the fridge laying on the couch. One problem was where the cooling unit protrudes into the freezer. It didn't fit real well but I could have lived with that. It cooled well until my maiden voyage to buy more propane which was about a month and a half after the  install. I had just left the drive when the smell of ammonia hit me. The unit had given it up.  D#%m! To make a long story short, I got my money back. They didn't even want the unit returned. I bought a new Dometic fridge from PPL and all is well. Lesson learned!

Dennis Davis

Dennis,
Was the Amish unit that you installed a refurbished Dometic unit, rebuilt to Amish specifications?

Or was it a brand new Amish unit designed and built from scratch by the Amish?  The RV Cooling Unit Warehouse sells both.  Do you have RVCUW model number(s) that would clarify which Dometic replacement unit you installed?

When you removed the Refrigerator, after the RVCUW failure, were you able to determine the point of failure and was it possibly related to the poor fit of the unit with the original box?  The RVCUW instructions regarding the need to "carefully bend things with pry bars", in order to precisely form the replacement unit into the existing box configuration, are really turning me off.
 
Also I'm being turned off by the RVCUW precautions that Freezer cooling plate holes and refrigerator cooling fin holes may not line up very well, but just force them to fit by deforming the RVCUW unit until the anchor screws can be started", then tighten everything down.

Thanks for the input,

Neal

Neal, my old fridge was a RM 3862. The "Amish" unit was new, painted white. The leak occurred near the 120 volt heating element located in the flue. The original unit leak was near the same location! I talked to the fellow who sells the unit and he had me call the Amish manufacture. They were accommodating, never dodged me etc. I hated the fact it didn't work out but so it goes.

I took off the screen door "check", so it would open farther and walked the new unit through the door.

Hope this helps...........

Dennis Davis

I thought that Amish propane refrigerators do not have the 120-volt heating element, which is very useful when shore power is available.

Our new cooling unit was a direct replacement for the original, including a place for the 120VAC heating element. The old heating element failed a few months I installed the cooling unit. I bought a new 120VAC element from RVCUW.

The only modification I had to make for the new unit to fit was to get new stainless steel screws to secure the fin unit and back of the freezer unit to the cooling unit. The new screws needed to be 1/4" longer than the original in order to get a bite on the new unit.

Our refrigerator is a Dometic NDR1062.

Barry and Cindy,
The AMISH themselves don't use refrigerators with 120 Vac, but the RV Cooling Unit Warehouse is an authorized vendor of the AMISH re-manufactured, as well as "AMISH BAND NEW",  Dometic and Norcold cooling units which are designed to use both propane and 120Vac. 

As I understand it, the AMISH, being practical, quality oriented, good businessmen, grew tired of the many absorption refrigerator problems/failures. To increase reliability and safety, they significantly redesigned the common absorption refrigerator problem areas, incorporating better burner regions/stacks, materials and fill gas processes/mixtures.  All of the AMISH units (reman'd as well as brand new) are done to AMISH spec's, which are quite different from other available reman'd or new replacement cooling units. 

The AMISH "brand new" cooling units have much heavier, more durable materials throughout, but fit the old Dometic and Norcold boxes as "plug and play" cooling unit replacements.  If one needs a new 120Vac heater, control board, gas solenoid valve, burner nozzle, etc. one still has to provide those on your own.
Neal

I even considered the Amish panel when our fridge packed up but after adding up the cost (we had double door) plus shipping by truck to Xtreme (we were there at time) and the hassle of all the change over. I figured we could buy 4 of the whirlpool ones and similar amount of work to change over to single door. We also did the slide out pantry which is a far better change than  than keeping the abs' style one. By the way a good deal of the cost saving helped toward the solar install too. The decision to go electric was for me a NO BRAINER.
John H

We had the cooling unit of our Dometic replaced at the Amish factory http://rvcoolingunit.com/Default.aspx (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.

 
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

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

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. 

John, pictures of stove, battery , etc. please

I will try to take them tomorrow.

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

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

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.

 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
 

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.

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.

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

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.

Thanks Bruce.
Much along my thoughts as well.
Neal
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

 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

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. 

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. ^.^d
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
 

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

                   Another great write up Neal. ^.^d Great help to those of us that may be looking to make a future fridge change of that size/type.

        D&D

Thanks Neal

Mark

Excellent follow up! ^.^d 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

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.