Thursday, August 20, 2015

Report: Dorm Style 110 VAC Compressor Refrigerators for Van/RV Use

There are always questions about what kind of cooler or refrigerator to use in vans or small RV's. While it's not necessarily a controversial issue, the topic always garners lots of thoughts from the proponents, the skeptics and the critics of each method. This report is not meant to cause controversy nor should it inspire proponents, skeptics or critics to necessarily support, question of refute my findings. I'm simply going to tell it like it is from my perspective and experience.

Four Basic Types Of Food & Beverage Cooling Devices

I will make one further stipulation. I am not including the variety of two way and three way refrigerators usually found in commercially built, larger RV's whether motorhomes, travel trailers or 5th wheels. This report is confined to those of us who enjoy life on the road in a compact space.

·      Ice chest - non-electric, requires cube or block ice
·      Thermoelectric cooler - requires 12 vdc, cools to about 40 degrees below ambient temperature and usually runs continuously
·      Dorm style, small 110 vac, compressor type refrigerator/freezer like those found in most stick & brick homes
·      12 vdc compressor type refrigerator/freezer, usually chest style designed specifically for truck, small RV and marine use

Each of the listed kinds of cooling/refrigerating units has a place in the world of the vandweller, van camper, tent camper, small travel trailer, utility trailer, box truck and school bus conversions.

Ice chest: This is, obviously, the least expensive and simplest to acquire and use. It's how I, like so many of us on the road, started out. It works pretty well, but capacity is limited, especially because you have to allow space for either block ice (which lasts longer) or bagged cube ice that's easier to acquire, but melts much faster and has to be replenished more frequently. Good as a place to start, but not optimal for the long term.

Thermoelectric cooler: This unit is very similar to an ice chest except it uses a Peltier Effect cooling device. In simple terms, it's basically a heat pump, similar to those used for heating and cooling homes. The best units will only produce about 36 to 40 degrees lower temperature than the ambient temperature. So, on a 90 degree day, the cooler may keep contents around 50 to 54 degrees. This may not be enough to keep perishables from spoiling. Additionally, these units are usually energy hogs and will deplete engine or house batteries fairly quickly. They are inexpensive to acquire.

Dorm style 110 vac compressor refrigerators: This is the kind of unit this report will focus on since that's what I'm currently using in my van. They operate like a home refrigerator. They can keep perishables down in the mid 30o F to 40o F range and if they include a freezer, can keep frozen foods frozen and make ice. Since they are thermostatically controlled, they don't operate continuously and when they are operating usually use less power than a thermoelectric cooler, so they are more energy efficient. This is important when operating from a 12 volt house battery and, typically, a modified sine wave inverter. Depending on your requirements they can be purchased in various cubic capacities and with half size, full size, separate freezing compartment or no freezing compartment. Lots of flexibility here. They are inexpensive to acquire.

12 vdc compressor type refrigerator/freezer: This, in my opinion, is the optimal way to go. This is the most efficient kind of  refrigerator/freezer you can use in a mobile situation. They are typically chest style, which is actually the most efficient way to retain cold where it needs to be, in the refrigerator/freezer. Because there is no inverter required they are more energy efficient and cost effective to use. They may not have as much capacity as some people would like. These units are considerably more expensive than any of the other units. You can expect to pay as much as six to ten times more than you might pay for a 110 vac dorm style unit. But, from all reports, they are well worth the investment, if you can justify making it.

My Experience With A 110 VAC Dorm Style Refrigerator

I have a 2.7 cubic foot, Black & Decker labeled unit, as pictured. At the time I purchased it from Walmart, it cost me about $90 plus tax. These units area available under a number of brand names including Haier, Black & Decker, Emerson, Amana and others. It's my guess they are all made in the same factory in China and are simply custom labeled. So, I don't think it makes any difference which unit you purchase, they're all pretty much the same.

As you can see from the photo, I built a wood cabinet to house my refrigerator. I didn't want the unit sailing around the van as I drove, needless to say. Additionally, although there is a small amount of air space on four sides, the back is open to allow the heat generated by the compressor to dissipate. There is actually quite a bit of heat. So, I also mounted it directly against one of the side doors of the van to allow heat to escape through the window. However, due to the less than optimal design of van windows, I'm not sure this is very effective. During cold or chilly weather, this heat can be a blessing. During the warmer weather in Yuma, it's more of a curse. But, the cold drinks sure help a lot.
One other important note is these type refrigerators do not have to be operated in a perfectly level position like the three way RV units do when they are operating off propane. That's a nice feature in my book.

What can I say other than, it has done the job I purchased it for. It keeps things cool and the freezer freezes. For the money invested, I feel like I've received the return on my investment. Does that mean I wouldn't still rather have a 12 vdc compressor unit? No! That is still the plan for sometime in the future. But, I will have to do some redesigning of the van interior to accommodate the chest style unit. So, for the time being, I'm pleased.

As you can see from this photo, I have a reasonable amount of capacity to carry just about everything I normally consume. I can carry bottled cold drinks on the door and as I deplete one bottle, I replace it with another. The condiments pictured on the upper shelf are not normally stored in the refrigerator. Catsup, mustard and salad dressings like Miracle Whip, peanut butter, many jellies and jams and similar, do not require refrigeration after opening. Mayonnaise does, however. Don't leave the mayo out or you could get pretty sick. Even eggs can be left out for quite some time, but not egg salad. You can check around a number of places and get some great info on what does and does not require refrigeration.

You can also see that I only have a half freezer inside the refrigerator. This works fine for me. I don't actually maintain any frozen foods. Ice cream is a treat I can enjoy while traveling. I like to get and use meats and fish right away, but they'll stay just fine in the refrigerator for a few days, not too long, though. Food poisoning on the road is not fun at all.

Power And Operating Efficiency

Now, here is a question everyone wants to know. How much power does it draw and how can you get the maximum efficiency from a unit like this. Like most things, you need the facts, you need some experience and there is a learning curve.

Here is the back plate from the refrigerator. As you can see, it is rated at 1.5 amps . . . BUT, it requires 6.3 amps to start up each time the compressor kicks in. That's over four times the operating current. Basically, the power used is, nominally, about 175 watts. So, I figured a 400 watt inverter would be more than adequate for the refrigerator. And, generally speaking, it is.

But, the start up surge is something else and even though the Thor TH400 inverter I installed for the purpose is rated for 900 watts at surge, it didn't always cover the start-ups. The inverter would go into fault mode and the refrigerator went without power. I solved the problem by installing the Bestek MRI100111,000 watt inverter with 2,400 watts for peak surge. No problems since I made that change. Also, remember the inverter is only about 90% efficient. I think this may cause the compressor to run hotter than it might if it were on 110 vac shore power (which is how I run the refrigerator when shore power is available) or with a pure sine wave converter. Again, a pure sine wave converter is at least two to three times more expensive than a modified sine wave unit. Another desirable future acquisition.

Here is a trick I use and I know others probably use it, too. I timed the running and off cycles of the refrigerator. They vary between about 15 minutes on and 15 minutes off to 24 minutes on and 24 minutes off plus or minus one or two minutes on either part of the on or off cycle. So, this means that while the unit momentarily uses 6.3 amps on each of the start up cycles and then settles quickly to 1.5 amps, it's not using that power for an entire hour like a thermoelectric unit might.

Additionally, and a lot of people don't take this into account, but that 1.5 amps and 6.3 amps is at 110 vac. The inverter is drawing that power from the 12 volt house battery. So, it's actually drawing approximately 16.5 amps (allowing for inverter efficiency) during running time and 69 amps for an instant when the unit is starting up. So, if the unit is running at, say an average of 20 minutes on and 20 minutes off, over two hours it's averaging 30 minutes on and 30 minutes off per hour. So, that's about an 8 or 9 AH (amp hour) draw. I have a 245 AH deep cycle AGM house battery. That allows me about 122 AH of useable battery charge. So, dividing 122 by 9 gives me about 13.5 useable hours of battery life, before I need to recharge. I don't have solar on my van, yet. Another future acquisition.

So, here's how I use my freezer. During the day, I freeze three 16.9 oz bottles of water into solid ice. I also have two freezable gel packs that I freeze. When night falls and the outside temperatures fall, I turn off the refrigerator and allow the frozen gel packs and water bottles to keep everything cool as if I were using a conventional ice chest. This saves me battery power during the cooler night time hours. There's no rocket science involved here. I didn't invent it. I just figured it out and I quite probably read it somewhere else, though I don't know who to give credit to for the idea.

The Bottom Line

My current refrigeration arrangement is not my optimal solution, however, I find it adequate for my current requirements. It's definitely better than the ice chest, although, I am actually using some of the features of an ice chest. For my purposes, it's considerably better and more efficient than the thermoelectric solution. But, it's not the optimal solution that I continue to envision for the future.

For the investment, less than $175.00, I feel I have received more than my money's worth. I don't include the cost of my 245 AH, deep cycle 8D AGM house battery as part of the investment since that is required for three of the four possible solutions I enumerated. I'll report on my house battery in another review and discuss my rational for the direction I chose for the battery.

My solution is one solution out of one. It might be the right one for you or it might not. Perhaps you can get along with a 1.7 cubic foot unit. Or, maybe you need a 3.3 or a 4.2 cubic foot unit. The interesting thing is that I believe all of these units use essentially the same compressor, so the power ratings are pretty close to the same for all of them. The difference in power consumption will most likely be based on longer or shorter running times to cool and maintain the temperature of the different capacity refrigerators.

By the way, I didn't mention this before, but you generally can find these dorm style refrigerators in black, white and stainless steel finishes. So, depending on your taste, you have a choice.

One final note. You may have noticed in the photos of my unit that the refrigerator is mounted on the floor. This was by intention. But, hindsight being what it is, it was a miscalculation on my part. I had originally planned to use the top of the refrigerator cabinet to mount a small, .7 cubic foot microwave oven. I now realize I probably will not install a microwave in the future. I haven't found that I missed one. And, even if I had installed a microwave, I could have raised the refrigerator and mounted the microwave higher. I have found having the refrigerator at floor level is extremely inconvenient in practical use. So, the plan is to rebuild the refrigerator cabinet and raise it at least a foot higher, maybe more. This will still provide a useable counter space on top of the refrigerator cabinet and room for more storage below the cabinet. I have several ideas for utilizing that storage space.

I hope through this report you gained some useful information and insight about refrigeration in a van. Perhaps you can apply some of it in your own projects, even if they don't involve a living space with wheels under it. I've included some links to scroll through for dorm style refrigerator units available at Walmart where I found the best prices for these units. As always, I want you to know I am an Amazon and a Walmart affiliate and will earn a small commission from anything you purchase through my links. You'll pay the same price either way. You can order a Walmart item on line and pick it up locally at a Walmart store you designate or it can be shipped to you. So, again, thanks for using my links if you choose to.

I solicit your thoughts on the blog so others may benefit from your comments and experiences with refrigeration. Please share this article with anyone else who may benefit. Thanks for being a subscriber, but if you're not, please do subscribe. I'll do my best to earn your readership. And don't forget to Like my Facebook fan page and connect with me on Google+. 


Steve said...

Strikes me as a high fire risk, Ed. I'd urge you to either get a 3-way refer or get a pure sine wave inverter ASAP.

Ed Helvey said...

Hi Steve,

Hot, yes, but not that hot and there's nothing directly in contact or within a foot of the compressor that's flammable. As one of my modifications I plan to add a fan to blow on the compressor and dissipate the heat faster.

Certainly, safety, especially fire safety is of utmost importance, but so far, I've not felt I have been at any risk. Additionally, the cost of a 3 way system and then having enough propane to operate it and having a propane flame burning all the time the refridge is operating is, in my mind, even riskier. The set up I have now actually operates as a two way system - 12 volts through the inverter when no shore power is available and 110 AC from shore power when available. I'm not sure investing in a pure sine wave inverter at this time will reduce the compressor operating temperature significantly enough to justify the expense. Perhaps others who have experience with this kind of set up will comment about their experiences.

Thanks for your thoughts. Definitely something anyone on the road needs to keep in the forefront - fire safety.


Rob said...

A very useful post Ed, thanks!

On a side note I hate these robot thingees that want you to play games in order to leave a comment

Ed Helvey said...

Thanks, Rob --

Your comments are always appreciated.

I also hate the "Captcha" things, too. But, for a while I was getting hit by a lot of "Anonymous" spam comments basically sent by robots with nothing meaningful to add to the blog, but attempting to draw my readers to their owner's Web sites or blogs. While I'm doing a lot of reformatting and restructuring the blog, I may turn it off for a while and see what happens. If the 'crap' starts up again, I'll have to turn it back on. Don't want to. I could also moderate the comments, but I was getting 10, 15 or 20 or sometimes more of the spam comments and it began taking way too much time to keep denying access and deleting them.

Have a terrific day,


Unknown said...

Hi Ed,
I've been following your adventures for almost a year, thanks for sharing.
I wanna follow you on Facebook but I couldn't find your fan page.

Ed Helvey said...

Hi Bruce,

Thanks for your note and for following my adventures on the blog. I almost made it to Las Vegas this past winter, but due to my engine challenge, I had to bypass on that trip. But, if all works out, I'll be back out west again this winter and Las Vegas is on my itinerary. I have a couple folks I know out there. One of them is the news anchor on KLAS, Dave Courvoisier. Perhaps when I get out there we can meet up if you're interested.

About the Facebook fan page, if you look to the right of the main text block on the blog and directly below the "Follow by Email" subscription widget, you'll see the "Follow us on Facebook"widget. You can click the like button there and also click on the link and it will take you there. My personal Facebook page can be found

Stay free and be happy,

Anonymous said...

Thank you for all the info. I've learned a lot of things from the 60s to present.
Hope to meet you someday, stay safe.

Ed Helvey said...

Thanks, Glad my info is useful. I enjoy meeting up with blog readers. So, watch the blog and it will give you an idea of where I am or where I'm heading. I'd look forward to a meet-up.


Unknown said...

Sounds good.

Unknown said...
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engelcoolers said...
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