Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. Today he discusses refrigerators in RVs.
Residential/compressor-driven refrigerator versus RV/absorption refrigerator
There has been quite some discussion on residential versus RV refrigerators not only on RVtravel.com but on almost every forum out there. So I thought I would climb up on my dunk tank and let everyone take a shot!
I first saw the residential refrigerators pop up in the RV market back in the late 1990s, but only on the larger diesel rigs. The reason was, people were getting frustrated with the RV refrigerators that didn’t cool very well in extreme temperatures. Also, there was the fear of fires as well as the recalls, which we will discuss later.
When I was with Winnebago we did not go the residential route as the rig needed to be plugged for 120-volt power or have a huge battery bank, which we were not known for. Plus, our test results showed they did not hold up well when the RV was rolling down the road. The larger diesel, like the Monaco, Newmar, and American Series, had much nicer-riding air suspensions and large battery banks with four 6-volt batteries, inverters and more.
How the compressor-driven refrigerator works
A residential refrigerator uses an electrical compressor to compress the refrigerant inside. The compression results in the refrigerant raising its pressure while getting very hot and traveling up through the coils on the back outside of the refrigerator. Once the hot gas meets the cooler air in the room, it turns into a high pressure liquid. It then cools down as it passes through the expansion valve and passes through the evaporator inside the freezer and refrigerator. The refrigerant draws the heat from both areas and pulls it out. Then, as it gets hot again, it turns to a gas and travels to the compressor to start all over again.
The advantages of a residential refrigerator
The electrical compression method works better in hot temperatures and cools down faster when you are getting ready to take a trip. It also works better in high altitude, although I do not think this is a fair comparison. You need to be running on electricity or inverted battery power, so you can do the same with an RV refrigerator and it will run efficiently. So I don’t compare the propane operation versus 120 volt.
Residential refrigerators typically have more interior space as they have no condenser fins inside. They also take much less time to cool down before a trip, typically 2-3 hours.
A residential fridge is a completely sealed system with no open flame, and the refrigerant is not combustible if it does leak. They also do not require ventilation to the outside and do not need to be as level.
Typically a residential refrigerator is less expensive than absorption in smaller 8-cubic-foot models from discount appliance stores.
Disadvantages of a residential refrigerator
Probably a better reference would be issues you need to know about, as everyone’s situation can be a little different. If you are planning to remove your RV refrigerator and replace it with a residential model, make sure the residential one will fit in the door. Most are wider and deeper, and sometimes you will need to take out a large window or even the windshield to get it into the RV. Also make sure it fits in the existing compartment. It is easier for product managers to design cabinetry around the larger footprint of a residential model, especially with slide rooms. Older models might not have the walking space in the aisle for a deeper unit.
Who does warranty or repair work? I talked with my Winnebago contact and several service managers and they said that warranty work must be performed by an authorized appliance dealer – which is typically not the RV dealer. Also, if the unit needs to be removed, the appliance dealer will not touch it. So the RV dealer has to remove it and then the appliance dealer can work on it. Sometimes you get lucky and the repair is on the front of the refrigerator, but not often. However, my Winnebago contact said there are very few units that fail while under warranty.
You must have 120-volt power such as a campground source or generator, or a large battery bank with inverter. In the past this was more of an issue as battery technology was not what it is today. However, even with high amp hour batteries and even lithium ion and solar panels, you can’t boondock too long without needing to fire up the generator. Having said that, I did see some great gains in this aspect at the Hershey, PA, RV show. There are 200-watt panels that can be connected with more panels, and lithium ion batteries with amazing amp hour ratings that might make it through long boondocking days. But is the price worth it? Time will tell.
RV refrigerators are commonly referred to as absorption refrigerators and run off either 120-volt power or propane. Some smaller units also run off 12-volt power. Older models, up until the mid 1980s, did, as well. But both Norcold and Dometic went to 120-volt and propane only, as the 12-volt mode did little more than turning the unit off and leaving the door shut while draining the house batteries quickly.
Here is how an absorption refrigerator works
A rich solution of ammonia, water, hydrogen, and sodium chromate is kept in the absorber vessel and flows to the boiler, where it is heated by either a flame on propane, or a heat element on 120-volt power. The ammonia turns to a vapor and travels up the pump tube to the condenser fins at the top of the refrigerator on the outside. At this time, the water separates. As you can see by the diagram, the various components go to the evaporator in the freezer and through the condenser fins in the refrigerator, going through various changes in vapor versus liquid to flash and draw heat out of each section, similar to the residential refrigerator.
I’ve always maintained that I am a handyman, not an engineer or physics expert. I’m not even sure if physics is the right word, and I did have to use “spill chick” on that one. Plus, I have not stayed at a Holiday Inn Express for more than 4 years. So before you bombard the comments, it’s just a handyman’s overview for reference and not designed to be that specific. Thanks!
Lions, Fires and Bears (Recalls) – “Oh, my!”
Sorry, couldn’t resist. However, this is probably the highest-ranking internet RV topic other than maybe tires. So let’s address the elephant in the room. Both Norcold and Dometic have issued recall notices on their refrigerators. Here is what I have been able to find on both recalls.
The issue began when some units started leaking the rich solution from tubing coming off the absorber vessel due to a variety of reasons. Since the rich solution has hydrogen and ammonia, which are flammable, the open flame used in the propane mode could cause an ignited state. It is amazing how many articles have been written about the recall and what prompted them without any factual information. Several that I read claimed it was due to excess heat that weakened the propane line that caused a rupture and leak. Not true. The propane line is downstream of the gas valve and burner assembly and is not subjected to the heat of the cooling unit. Plus, most units have an excess flow valve in the POL connection at the tank or cylinder that will shut the flow off. The issue as stated above is a leak of the ammonia and hydrogen in the cooling unit tubing. We will address more of these “Fake News” issues later.
According to my sources at Dometic and their website, they initiated a voluntary recall on units built between 1997 to May 2003, then again for units built from 2003 to 2006. This included 1.6 million units and more than 90% of these units have been contacted for the recall. Dometic also claims that the recall was voluntary and they had no reported fires or casualties. The fix was a temperature sensor/shut off mounted to the upper cooling unit tube and container kit. It covers the burner assembly area to keep any leaks contained to that area, which has been incorporated to all newer designs. To find out if your unit is included in the recall or has been addressed, visit the recall page here.
Norcold initiated a recall on all units built from 1997-2010 which also incorporates a temperature sensor and shut off. Although nobody at Norcold will go on the record as to documented fires, I know from my time at Winnebago that there were cases of units that did have these issues. Norcold also does not list the number of units affected by the recall. However, the actual documented cases were very small and my Norcold contact, that asked to not be identified, stated it was less than .01% of units. Norcold recall information.
The Real Problem!
I have talked with several dealership service managers, RV manufacturer representatives, and even owners that had issues. The underlying theme seems to be the heat generated in the cooling unit. If the unit is operated in a normal condition, the cooling unit can reach temperatures of 300 degrees. However, if the unit is out of level 3 degrees side-to-side or 6 degrees front-to-back, the solution in the cooling unit cannot flow down the zig zag pipes. Thus, it sits and gets hotter and can reach temperatures over 800 degrees! This overheats the tube and literally burns off the powdercoat paint. Prolonged use in this condition can even weaken the metal and eventually cause it to crack.
Both Norcold and Dometic have redesigned the cooling unit so the rig does not need to be perfectly level. They have provided a bubble level to help identify what is good. As long as the bubble is half way in the ring, the rig is OK.
Talking with a design engineer from Norcold a few years ago, he indicated another issue is RV manufacturers stuffing loose fill insulation around the refrigerator cavity and getting too much in the vent cavity. This was confirmed a few times from seminar attendees that told me they had pulled out their RV refrigerator that had a clogged cooling unit. They found slightly charred wood and burnt insulation on the back side. Nothing should be in the vent area, which compounds the issue of overheating the cooling unit.
Plus, neither recall swaps out the cooling unit. Rather, they install a temperature senser up on the evaporator coils that will shut the unit off when it gets uncommonly hot, to eliminate the problem.
Advantages of absorption refrigerators
Probably the biggest advantage of an absorption refrigerator is the flexibility of either 120-volt power or propane. If you do a lot of boondocking or dry camping off the grid, it’s a great choice. And understanding how it works, performing some minor maintenance, and doing the little tips to make it run more efficient makes it my preferred type of refrigerator.
The RV refrigerator was more durable in the tests we conducted at Winnebago. However, there is no test data showing the durability of the residential models out in the real RV world.
Disadvantages of absorption refrigerators
As stated above, the RV refrigerator does have some efficiency issues in hot conditions. However, in my seminars I ask attendees about their refrigerators, and the largest majority have not had issues. There is more maintenance required such as cleaning out the burner assembly and checking the roof vent. However, that is only required once a year or longer.
Then there is the price. I have talked with owners that had a cooling unit get clogged and the replacement cost was more than $2000. A new unit was $3000. Or they could go to a discount store and get a residential model for under $1000.
The bottom line: If you understand how each type of refrigerator works and the efficiencies or inefficiencies as to your type of RVing, and understand that what works for some does not work for others, means it’s your choice.