You’ve pulled into your campsite, the RV is finally all unpacked, you’ve got everything set up and it’s time to feed the kids. As per tradition you reach for the package of hot dogs, cold macaroni salad, condiments and juice as the rest of the family gets the fire ready and finds their favorite roasting sticks. Jump forward half an hour later and everyone’s fed “ahhhh…” camping is finally settling in. You grab a nice cold celebratory beer and set up the smores station ready for a long weekend of relaxation.
But hold on, what’s keeping those hot dogs and salad from going bad? And who do we trust to keep our beers and juice cold? Edmond Carre dreamed up the very first beginnings of the RV fridge in 1850 but in wasn’t until 1956 that we had actual manufacturers. Now even though they started retailing RV fridges in 1956 the original units are akin to the dinosaurs in terms of design, space and convenience. Gone are the days when all we were equipped with was a cooler full of ice and now are the days with a dizzying choice of sizes, makes, models and even methods of cooling systems. So I’ve decided to break down two of these systems and simplify how they work and what their differences are. That way the next time you reach for your refreshing beverage you’ll know how it gets cold and why it stays that way.
There are two main refrigeration systems used in RV’s today. We have the ever trusted standard RV system (that uses hydrogen gas) and the brand new Helium system, each one presenting their own unique benefits and shortcomings. But before I start to describe what these elements are or the differences between them we need to start at the beginning and explain the actual process of cooling in its most simplified terms.
We begin with ammonia, water, hydrogen and an anti-corrosive agent in what’s known as the “boiler” where the ammonia/water solution is heated until vaporized. This heat can be caused by LP gas flame or an electric element. (Either 120 or 12V) (This is why your RV fridge will most likely have a changeover or a setting where you can choose LP or Electric.) That way if you run out of propane or there’s a shortage of power your food can still stay cold.
As this mixture is turned into vapor the evaporated ammonia and water rises. The water vapor condenses much quicker than the ammonia and falls back down into the boiler. However the ammonia vapor rises to the top of the system where it is cooled down and converts back into ammonia liquid.
Now the ammonia liquid runs down into the evaporator section of the fridge where is comes into contact with hydrogen gasses causing the ammonia liquid to evaporate again and mix with the hydrogen gas.
This mixture is heavier than the non-ammonia hydrogen and sinks down to the bottom of the system again where it is combined with a weak water/ammonia solution. Here the hydrogen gas is free to rise back up to the top of the system and then the cycle restarts. To summarize a healthy and functioning system needs the right amount of heat, good air flow (for cooling) and gravity to work properly.
Now what I just described (in this extremely simplified way) is the hydrogen gas system what we call a “conventional RV fridge”. And the only difference in process between the hydrogen gas system and the helium gas system is that instead of using hydrogen gas you incorporate helium. However functionally this can make a big difference.
The hydrogen system depends on the fridge being absolutely level to work properly. If it isn’t and you operate the fridge for a long period of time you will get a build up of heat in the system, this build up causes pressure and that can create cracks allowing the hydrogen gas to escape and eventually breaking down the cycle. Without an efficient cycle you’re left with rotten wieners and warm beer.
The helium gas system will function for a longer period of time and more efficiently (than the hydrogen system) if the fridge isn’t 100% level. However the issue with the helium system is the fridge itself. It comes with an alert and leveling system so you can see directly on the fridge if the unit is perfectly level. This sounds like a fantastic idea except that it is also equipped with an automatic shut down so if your fridge is not level for an extended period of time the unit will lock-up and you will need to take it in to be service… regardless of it being broken or not.
So to conclude whether you chose hydrogen or helium the best way to maintain your systems integrity is to of course, keep the fridge as level as possible. When you pull into your site make sure your unit is leveled off. If the fridge is in a slide then level your unit and take an extra peek to make sure the slide is also level. (Slide stabilizer jacks are very handy in this circumstance.) And the next time you’re out camping and you reach into your nice and cold fridge, smile, knowing you know exactly what’s going on behind those shelves.
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This article was originally posted here.