Sponsored by Fridge Defend
Knowing Which RV Refrigerator You Have Matters
Today’s modern RVs are equipped with all the niceties and technology you’d find at home. Of course, this includes refrigerators. While very large RVs have gravitated towards residential refrigerators, most smaller RVs still rely on the gas/electric absorption refrigerator that has been used in RVs for decades. This is due to the cost, efficiency, and power requirements of smaller RVs. Knowing which RV refrigerator you have is vital.
While a residential refrigerator might not operate at its highest efficiency when off-level, a gas/electric absorption RV refrigerator may not operate at all. At worst, it can be a dangerous fire hazard.
What is an absorption RV refrigerator?
The absorption refrigerator goes all the way back to the year 1850 when Edmond Carre invented an absorption cycle fridge. So, why is it called “absorption”?
Absorption is actually a part of the refrigeration cycle. An absorption fridge has a boiler that produces the refrigerant, and there is a fluid in the cooling unit that absorbs the refrigerant, completing the cycle.
Why are propane absorption fridges dangerous?
The absorption cycle has to complete the cycle so that the fridge runs continuously. When the absorption cycle is disrupted, the heat going into the system will start destroying the fridge rather than cooling the contents of the fridge.
The danger lies in repeated disruptions of the cycle. Repeated damage occurs until the cooling unit that contains the refrigeration cycle ruptures, often leading to a fire. We would like to clarify that these absorption RV refrigerators typically fail while on shore power, not on propane.
Although absorption refrigerators run on both electricity and LP gas, electricity puts more stress on the boiler assembly; this is why the fridge tends to fail on shore power.
I have a gas-electric RV refrigerator, what should I do?
If you do in fact have an absorption RV refrigerator that runs propane or electric, there are a few things you can and should do to ensure your safety and enjoyment, while protecting the environment. We will move on to the golden rule of the absorption fridge, but first, we will start with a few operation pointers to increase enjoyment.
Start your fridge 24 hours before leaving on a trip. One thing we do is prepare meals at home, then freeze the meals so that they can be used to help cool the fridge. For example, you may freeze a meal, let’s say chicken enchiladas, and put them into the refrigerated space to thaw out for the first night on the road. Depending on how much frozen food you put into the fridge, you may be able to turn on your RV refrigerator just before leaving on a trip.
Another idea is to use a wireless fridge and freezer thermometer to keep an eye on the temperatures. Opening and closing the fridge to check the temperature just makes the fridge work harder.
A local power company had a TV commercial where they put ping-pong balls in the fridge to demonstrate how the cold comes out of the fridge, so keep your ping-pong balls in your fridge by keeping the door shut!
1. Make sure you are always level
One may say that the golden rule is to keep the fridge level. But, we are talking about RVs here; staying level is not always practical.
For example, let’s say that you are climbing a pass and the traffic stops for something like an accident. You are now operating your fridge off-level, but most likely not thinking about it. Rather, you are focused on arriving at the campground to get that perfect campsite.
You may find that when you get to that perfect RV campsite, your RV refrigerator is warm inside. This is a common problem—one with a solution. It was a situation like this that destroyed our perfectly good 35-year-old absorption refrigerator, practically a family heirloom.
2. Identify your RV refrigerator & check for recalls
Identifying exactly which refrigerator you have is vital in determining whether you are at risk or not. Both of the primary brands of absorption RV refrigerators used in RVs in this country have had a series of recalls, so the first thing you need to do is check to see if your fridge requires a recall. To do that, you need to first capture the exact brand and model number of the RV refrigerator you have.
Next, you’ll want to contact the manufacturer or visit their website in search of a recall, specifically pertaining to your brand and model number. Note that even a recall isn’t a perfect solution. One major manufacturer wrote to us, stating:
“[Our] Recall Kit xx4737 does not and cannot address off-level tilting conditions. Kit xx4737 functions only to address extremely limited, catastrophic conditions in which liquid is drained from the system (e.g. as a result of a leak). Heat input to the cooling unit is not adjusted until a sensed temperature of over 800°F.”
3.The Fridge Defend Solution
As mentioned above, we destroyed a family heirloom. One does not cook the family fridge without getting a bunch of static from the rest of the family! We instrumented a working absorption fridge and came to find that the boiler temperature increases when the fridge is operated off-level.
The irony was that we received a recall notification for our second camper when we were designing a protective controller for absorption RV refrigerators. Our fridge was on a list of 100,000 units that were recalled due to fire issues. This made me realize that what I was doing would not only protect the fridge from failure, it would save lives.
Our design work paid off, and we were awarded a patent for our efforts. The Fridge Defend was born, creating a reliable safety controller for your Norcold RV refrigerator or Dometic RV refrigerator. The RV refrigerator manufacturers tried to file their own patent, but they were rejected because you cannot patent the same thing twice.
Turning back to the recall letter we received, let’s point out some facts:
- If the fridge turns off at 800°F, your fridge is already being destroyed. As a matter of fact, we tested this recall and it actually turns off at 1200°F. This may be why the recalls did not stop fires. The Fridge Defend will not allow the boiler to get over about 400°F during normal use with typical settings.
- The Fridge Defend controls off-level tilting damage to the fridge.
The recall does not really protect the boiler from overheating. The idea is to prevent a leak because a leak is what results in a fire.
“I’ve had an ARP (Fridge Defend) on mine for a year now and it works as advertised. I’ve also used an optional data collection package to monitor boiler temperatures via the ARP temp sensor and can see how quickly the boiler shoots up when seemingly minor things occur, like a brief stop that is not so level or the effect of stop & go traffic in a town.
We literally sleep a lot more comfortably at night knowing that ARP is watching for potential overheating.”
Gary Brink – iRV2.com
Conclusion
The gas-electric absorption RV refrigerator is a bit of an engineering marvel. With the onset of new 12-volt RV refrigerators, powerful new batteries, and robust solar solutions, perhaps its days are numbered. But we at Fridge Defend feel that the cost of operating electrical refrigerators is very high, and most RV manufacturers are not willing to put in the solar, batteries, and chargers that are required to run these units off the grid.
Even if every manufacturer goes electric, this means that there will be millions of the practical absorption units out in the field for years and years to come. Knowing and mitigating the potential dangers is important for your enjoyment, and most of all, for your safety.
Fridge Defend will continue to offer solutions that focus on that safety as long as those fridges exist. Visit arprv.com for more information.
About the Author
Paul and Mao Unmack are practitioners of engineering science that have committed themselves to RV safety. They are the founders, engineers, and inventors of the Fridge Defend solution.
