Keeping your cool off the grid 2005 article updated June 2007 – new larger 12volt Solar Chill cooler installed!
Read This Disclaimer First I’ve written what I personally did, and my opinions. Don’t assume what I did was safe, and don’t assume it will work for you. Do more research, and make your own choices. I’m not responsible for your outcomes!
I don’t like to be hot at home. You see, I grew up in the South, and we didn’t have air conditioning until I was 17 years old. So I don’t like to sweat in the house, especially when I sit down to dinner. This limits dry camping options by climate. Our goal was to follow the “good” weather around and never have to use the AC. Of course, plans don’t always work out.
I saw a demonstration at an RV Rally in Summer, 2005 of a swamp cooler made for installation on an RV. The brand name is TurboKOOL and was previously called the Rec-Air.
If you’re not familiar with them, a swamp cooler (correctly called an “evaporative cooler”) is a simple appliance. It pulls in hot, dry, outside air through a water soaked material and the evaporation of the water causes the air to be cooled. The chart on the right shows how cool. For example, at 100 degrees and 10% humidity a typical swamp cooler should put out 73 degree air. It only works in low humidity, but you’ll find low humidity all over the Southwestern US. If you visit that part of the USA you’ll see a swamp cooler on the roof of most older houses and a lot of lower income areas (they are inexpensive to operate).
The best thing is, this one runs on 12 volt DC power. That’s right, no cranking the generator to run the AC, and no need for a hookup site. It draws less than 5 amps DC, so run it 10 hours and you’ve used 50 Amp Hours of battery power. How cool is that!? (Yes, pun intended).
I didn’t buy it right away, but I did some more research looking for other comparable systems and found none. A couple months later we were in Reno Nevada, and it was getting pretty hot (low 90′s) but dry. It happens that they build the TurboKool in Reno, so I called them up (the owner answered) and I told them I wanted one. These aren’t cheap, cost around $600, but they’re the only commercial product made specifically for RV’s so with no competition they can price them up a little. We felt the benefits were worth the expense.
Installation wasn’t hard, I did it myself. Their web site has the installation instructions so you can review them and decide whether you can DIY before you buy. I learned a few things that might help you:
- You’ll need to tap into a water line. I used the one for the ice maker and ran it out the fridge vent and over the roof.
- If your roof is crowned, not flat, you’ll have to build up a mounting surface because it needs to be installed flat. I used some wooden molding strips, and planed to replace them with some nice aluminum when I got around to it.
- Our experience with performance of this unit: We have a 37′ MH with no slides. We installed the TurboKool in the kitchen, roughly in the middle of the RV. It cooled the front half well if we closed off the bedroom. Up to low/mid 90′s outside, and we were fairly comfortable inside.
- NOTE: This was with the bedroom closed off, and with RV parked east/west but in direct sun. If we parked with a long side facing the sun it can heat things up really fast. Since we have to be in the sun for the solar panels it’s a trade off.
- If it was high 80′s outside and under 10% humidity we could get the whole RV pretty comfortable. Over 95 and it was time to look for a hookup site, or move to a cooler part of the country!
- Water usage was about 10 to 15 gallons a day max
- There is no provision for flushing out this unit, so you get lots of mineral buildup in heavy usage and have to disassemble it and clean it every month or so.
- Update – 2007 – also see bottom of this page. I still recommend the TurboKOOL, but you need to go into it with realistic goals. I think it’s probably ideal for a smaller RV, say up to a 26′ Class C, or if you avoid 95+ weather. We have installed a different swamp cooler now – see below.
June 2007 – Our new, larger swamp cooler
I learned from someone on the Escapees forum about a company in Tucson, AZ that manufactures 12v and 24v evaporative coolers for solar applications. The company is Solar Chill and is owned by Bill Cunningham. I researched this and made plans for several months, eventually calling Bill and talking about my plans for his product. Bill is a very interesting person to talk with and a wealth of knowledge when it comes to all things solar, especially DC powered evaporative coolers. I made plans to visit him and buy a unit in the spring of 2007.
Here’s a link to the Southwest Solar web site and see the photos below. First one is Bill with two small units and several larger ones that will cool a whole house. Second is me installing ours on the motorhome. Ours is the model 1412XP.
The unit we have wasn’t designed for installation on an RV, it was made for cooling a room of a home, or a workshop, or small outbuilding. But the size is just right for us — large enough to do the job, and small enough to fit on the roof. Our forward AC unit had failed, so it was an easy choice to remove it and replace it with the Solar Chill. The unit measures 19 1/2 inches high, 21 long, and 24 wide. It adds about 6 inches to the height of our RV (above the height of the rear AC unit). Below are a couple of photos that show how it looks. I plan to paint it white, or maybe beige to match the RV.
Deminsions: 19 1/2 high x 21 long x 24 wide
Fan Diameter: 14″
Power Requirement: 52 Watts (12 to 15 volts DC)
Gallons per Hour Max: 3.5
Recommended cooling area: 350 – 400 Sq. Ft.
This unit really cools! It also uses a lot of water. So far we’ve camped in temperatures up to 115 degrees with the RV sitting in full sun. At 105 to 115 in the mid to late afternoon we need to close the bedroom off, but the front of the RV stays livable at around 85-90 degrees. At lower temps, around 100 depending on the humidity, we can keep the whole RV comfortable and the front cooled down to about 80. That’s very good. Compare these results to using one 15000 BTU roof AC unit and the Solar Chill out performs the AC in 100+ degree weather. Note that our RV is 30 amp service, so even when we’re plugged in we can only run one roof AC unit at a time. And the Solar Chill runs from our batteries and solar panels 100%, no generator use necessary! The Solar Chill has a timing board that cycles the internal water pump off and on at intervals. This saves water, saves power, and actually cools better I’m told. When the fan alone is running it draws about 3.5 amps, and when the pump kicks in it’s around 4.7 amps.
The Solar Chill uses an advanced “pad” that’s 8 inches thick and is supposed to get the air cooler than other pads. In our case, I was initially somewhat disappointed that the output air from the unit wasn’t as cool as advertised; however, I now feel that it’s plenty cool. Colder air would probably mean more water used, and this unit uses a lot of water already. In my experience, with temperatures 105 to 115 degrees, running constantly for 12 hours a day and cycling off/on for a few more hours, it uses around 25-40 gallons of water daily! We have a 100 gallon fresh tank, and 28 gallons portable for fetching water in the car. Our plan for next year involves two methods of addressing this issue. One is to plan our travels to avoid the higher temperatures. The other is to add another 100 gallon fresh tank giving us 200 gallons total capacity. We’ll have to lighten our load when leaving Florida in the spring so we’re not overweight.
Here are some random thoughts about how we adapted this unit for our use and installed it.
I needed to buy an elbow to duct the output air into the RV. This is a custom part, 15×15 inches, so I went to a sheet metal shop in Tucson and had it made. I ordered a 3 inch flange at the roof, and 2 inch at the unit. To install it I sealed around the AC roof vent hole with 2 inch butyl rubber tape, then placed the duct on top of that. The duct is screwed down to the metal frame of the AC vent with eighteen self tapping #8 screws. I then sealed around it with Eternabond tape.
After installing the duct I applied rubber tape to the other end as before, and attached the chiller unit to the duct with fifteen #8 sheet metal screws. This formed a very rigid unit.
Next I cut 4 pieces of aluminum angle stock 12 inches long and attached them to the vertical corners of the unit, being careful not to install screws below the water line! I made feet with 1 inch aluminum angle, and attached them to the roof with molly fasteners (I have thin plywood under a rubber roof). I then screwed these feet to the “legs” of the unit and it’s very solidly installed.
In a home installation the cooler would have a drain hole in the bottom and stand on legs. I eliminated this drain to install it as low as possible, so I had to cut an overflow drain hole above the water line on the side of the unit. For fresh water, I used the same source as before, the line for the icemaker, and ran new water line. The wiring I ran through the fridge vent and used a PVC conduit to route it up to the cooler. I had purchased a control box with the cooler including a thermostat and various control switches, but it was very large, and I couldn’t find a convenient spot for it in our small space. I disassembled it and installed the components on the wall.
We love our Solar Chill!
Since starting our annual western trips in 2005 I’m amazed at how few people who camp in desert areas make use of swamp coolers. I’ve only seen one other RV in all this time equipped with a TurboKool, and only heard from one person online with a larger unit like ours. Maybe it’s different out in the remote areas, BLM land, etc. but most blacktop boondockers aren’t using them. In our case, the Solar Chill actually out-performs our old 15000 BTU air conditioner. So even while hooked up we us it exclusively in dry climates.
Another update — July 28, 2007: We’ve been in Reno for a couple of weeks and the Solar Chill has worked GREAT here! With temps in the 90 to 100 range we’re parked in full sun and we can easily keep the inside of the RV down to below 80 degrees. Several people have visited us and been impressed by how cool it is, and the fact that it’s all done with under 5 amps of 12v DC power. By being frugal we go through about 15 gallons of water a day. I can live with that!
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