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Old 04-20-2021, 10:43 AM   #1
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Smaller 12V A/C options

The goal: to be able to keep the van interior below 80-90*F (lower would be better, but this is the target) for a period of 2-4 hours, if we had to park the van somewhere in the sun. Run off of a battery bank, not shore power. Would prefer to keep the battery bank to ~250 Ah or less, but acknowledge that this may have to grow depending on the solution.

Assumptions: Ambient temps between 75-90*F. Van will have a combo of thinsulate/havelock in the walls, thinsulate on the roof, windshield blocked, and windows at least partially blocked. Van is a high top EB but a few inches past the wheel well will be an isolated gear area, so not part of the air space. Interior heat load will be 1-2 humans and 2-3 dogs, plus the fridge, possibly a laptop.

What I've found so far:

Zero Breeze Mk II. 2k btu and can come with its own battery. The in laws have one, although it's mostly untested. If the van is already cool inside from driving, and we block/insulate the windows, 2k btu should reasonably manage temps for a period of time. The charging options are finicky however, and we'd need somewhere to mount it. 4k btu would be perfect so we could technically mount 2 of them, but then that's twice the cost and floor space.

Dometic RTX 2000. 6.8k btw. This would be more than sufficient for a stationary vehicle, but our battery storage would have to be massive with 40A consumption, although run time would be intermittent due to the size. The roof top mount is a big pro as it saves floor space. Made to go through standard 14x14 hole. Only actual a/c option that can take 12v direct from the battery.

Dometic SPX 1200C/I. 3.4k btu. Hit the size right on the money. Interior evaporator wouldn't take up floor space, could mount it on a wall. However, it's a split system, so we'd have to find somewhere to mount the condenser. Fortunately it's roughly 6"x1'x2' so the roof would be the likely candidate. Would prefer underneath but concerned about dirt filling the coil. Vastly more complex install, plus would need to run power to both condenser + evaporator, plus refrigerant lines between them, plus it's 24V. Could maybe incorporate existing rear hvac evaporator?

TurboKool Evap Cooler. btu will vary by outside conditions. Sized for RVs so probably overkill. Low amp draw, water tank is easy to upsize, and we are pretty much always camping in the desert or the Rockies so the conditions would be favorable. Pretty bulky however, and would need winterized (which basically just means drained). Cheapest option.

Any other options I'm missing?

When we had our old Trillium camper, since it was an opaque white and complete fiberglass construction, it was surprisingly easy to keep at a reasonable temp with just vents open and closing curtains. My concern with the van is that the metal body will act as an oven, even though it'll be light in color. Our previous high top van was a light tan but it never ran consistently enough for us to use it much in the summer heat (VW). If I'm over thinking this and with some popped windows and a roof fan we'll be fine, please let me know.
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Old 04-20-2021, 06:21 PM   #2
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Quote:
Originally Posted by b. rock View Post

TurboKool Evap Cooler. btu will vary by outside conditions. Sized for RVs so probably overkill. Low amp draw, water tank is easy to upsize, and we are pretty much always camping in the desert or the Rockies so the conditions would be favorable. Pretty bulky however, and would need winterized (which basically just means drained). Cheapest option.

Thanks, You gave me the idea to build a removable Evap cover for my Fantastic fan.
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Old 04-20-2021, 07:43 PM   #3
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I’m pulling out a Neglected danhard/starcool from a 06 that does blow somewhat cold.. takes up a lot of interior and a fair amount of exterior rail area.. if I was headed to Ocotillo in the off season maybe I would keep it but that’s not gonna happen�� I want to space for my Espar heater
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Old 04-20-2021, 11:54 PM   #4
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For any method you need massive amounts of insulation. I learned from trial and error in trying to stay cool in my astrovan full time. I tried the regular battery powered fans, the endless breeze fantastic fans, the roof vents (have 4 on the roof) and a swampcooler.

The swampcooler was the only thing that work, but it required me to add many layers of foam insulation to my van. I have 3 inches on the roof, 1 to 2 inches on the sides, rear/side doors, 3 inches on all my rear windows. I seperate the front and back of the van with an insulated barrier/sliding door. All that insulation made a huge difference, without it temperatures in the back of my van would be over 100f. On a hot day is southern california, with the insulation/swampcooler I can maintain about 94f in the back of my van, parked in the sun. I can live with that.

The problem with the zerobreeze is it will need alot of power to run it. Even 250 ah would be too little. I have over 500ah of batteries (220ah lifepo4 and 312ah li-ion) and I would be hesitant to run a zerobreeze, because then I would have to charge up my batteries again. Plus the 1000+ cost is a dealbreaker for me.

The only swampcooler I recommend are those that use the celdek evaporator pad, since it never gets clogged and last up to 5 years. I have to build my own since no one makes one for mobile use (that wont leak water all over the place).

In your situation you would need an AC larger then the zerobreeze but smaller then the window units. There is a website "hurriedyear" where someone uses a floor AC in his sprinter and runs it off batteries and solar. That might be something to look at.
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Old 04-21-2021, 03:31 AM   #5
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It doesn’t meet many of the requirements here but I’ll be looking into CLIMATERIGHT CR2500ACH it’s made for teardrop and the price is attractive, perhaps custom fitting into a bumper mounted box, piped into a rear door
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Old 04-21-2021, 08:08 AM   #6
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I would also look into mounting a window shaker inside and venting through roof, wall or floor. 5k btu for cheap.

-Mike
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Old 04-21-2021, 09:10 AM   #7
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Quote:
Originally Posted by jonyjoe101 View Post
For any method you need massive amounts of insulation. I learned from trial and error in trying to stay cool in my astrovan full time. I tried the regular battery powered fans, the endless breeze fantastic fans, the roof vents (have 4 on the roof) and a swampcooler.

The swampcooler was the only thing that work, but it required me to add many layers of foam insulation to my van. I have 3 inches on the roof, 1 to 2 inches on the sides, rear/side doors, 3 inches on all my rear windows. I seperate the front and back of the van with an insulated barrier/sliding door. All that insulation made a huge difference, without it temperatures in the back of my van would be over 100f. On a hot day is southern california, with the insulation/swampcooler I can maintain about 94f in the back of my van, parked in the sun. I can live with that.

The problem with the zerobreeze is it will need alot of power to run it. Even 250 ah would be too little. I have over 500ah of batteries (220ah lifepo4 and 312ah li-ion) and I would be hesitant to run a zerobreeze, because then I would have to charge up my batteries again. Plus the 1000+ cost is a dealbreaker for me.

The only swampcooler I recommend are those that use the celdek evaporator pad, since it never gets clogged and last up to 5 years. I have to build my own since no one makes one for mobile use (that wont leak water all over the place).

In your situation you would need an AC larger then the zerobreeze but smaller then the window units. There is a website "hurriedyear" where someone uses a floor AC in his sprinter and runs it off batteries and solar. That might be something to look at.
Unless I'm missing something, the zero breeze wall adapter is 240W so 20A at 12V full tilt. Since I'm talking only running it for 2-4 hours, that's only 40-80 ah. I did check out hurriedyear and he has 945w of solar and 780ah running an 8k btu a/c. Duly noted on the insulation and partition. Good to hear that the evap is effective in a van application though. Got a pic of it by chance?

Quote:
Originally Posted by Nick View Post
It doesnít meet many of the requirements here but Iíll be looking into CLIMATERIGHT CR2500ACH itís made for teardrop and the price is attractive, perhaps custom fitting into a bumper mounted box, piped into a rear door
I did see the self contained units. I like the price point, but they are definitely bulky/funky to mount.

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Originally Posted by FloridaNative View Post
I would also look into mounting a window shaker inside and venting through roof, wall or floor. 5k btu for cheap.

-Mike
Not going to run shore power, and the inverter to run one off of batteries would be huge (the batteries would also need to be huge).

Quote:
Originally Posted by posplayr View Post
Thanks, You gave me the idea to build a removable Evap cover for my Fantastic fan.
I already have a maxx air fan in the garage. I haven't diy'd an evap cooler yet but maybe this is the ticket.
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Old 04-22-2021, 03:49 PM   #8
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Found this in a $printer forum.

https://www.fresair.com/product/fres...onversion-kit/

I love that it's only 3.5" above the roof. Don't love the price tag or that it's 25 lbs. Not really sure how it wouldn't introduce moisture to the air though.
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Old 04-22-2021, 05:23 PM   #9
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Quote:
Originally Posted by b. rock View Post
Found this in a $printer forum.

https://www.fresair.com/product/fres...onversion-kit/

I love that it's only 3.5" above the roof. Don't love the price tag or that it's 25 lbs. Not really sure how it wouldn't introduce moisture to the air though.
I'm buying parts for a small cover similar to these

https://www.ebay.com/itm/37264632096...QAAOxyPLpRfn7N

but I will need to make a model to produce it out of vacuum-bagged fiberglass/epoxy (for space and low profile considerations).

It will be removable and you can then every back to the standard ceiling fan that this will cover.

It will be a miniaturized one of these we have on the roof.

MasterCool AD1C71 Ducted Evaporative Cooler

Basically, air is ducted down with a fan, and air entry is through media on only one side. It has both a recirculation and purges pump to cycle the water when it gets to briny.


I'm not going to computerized it. Just do a flush at the end of each day.

Parts on order are to do some basic sizing/prototyping before committing to building a mold for the cover.
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Old 04-22-2021, 10:06 PM   #10
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This is a picture of one of the swampcoolers I built, it has 2x 120mm fans. It works good when its not too humid. With both fan running on max and water pump it maxes out at about 3 amps. Note the 2x 4 inch output ports in front, thats so I can attach 4 inch flexible ducting and redirect the air. On the rear are also 2x 4 inch port for the air intake. Those 4 inch ports are required on swampcoolers, I learned from trial an error.

One thing I have also tested is running 2 swampcoolers at the same time and that does help in cooling the van by another 2 degrees, from 94f to 92f.

Last year it was so hot/humid that I began testing an idea someone recommended (indirect swampcooler) . Indirect swampcooler is suppose to work better in humid conditions, it uses an air to water heat exchanger to cool the air before it gets into the evaporator pad. The outside air was 115f, the exchanger was able to cool it to 102f . During the test the swampcooler was about 5 feet away from the exchanger and I was using flexible ducting, and water tubing to connect both units. All that caused losses in efficiency an all in unit would be more efficient. Something I notice was the water temperature in the reservoir always stayed the same, even though it was hotter after leaving the exchanger, it got cooled down by the evaporater pad. Now that I know that an indirect swampcooler does work, its my next project. The only thing it needs is an extra fan for the exchanger (total power usage is less then 5 amps). The 8"x8" heat exchanger (cost about 50 dollars) in the picture takes up extra space and it was the smallest one I could find, it wont be a small unit. I experimented using a heater core which are smaller but they dirtied the water too much, the heat exchanger is pure copper tubing and doesnt affect the water quality.

The last picture shows the celdek evaporater pad that I use, its cardboard base material, that never gets clogged up, and last a long time, I'm still using some 7 years later. The aspen evaporater pad falls apart easily and clogs pumps, and the blue durakool pad, gets clogged by water impurities after 3 months, this reduces airflow.

With the zerobreeze I hear good reviews and also bad reviews. I actually think it would work good in my van because of the heavy insulation I have. With heavy insulation, the smaller the AC you need. And at night time, you can run a swampcooler. Swampcoolers work good at night even when its humid.

One thing I was going to try last year was use a small 12 volt fridge, fill it with water and run it through the heat exchanger. That would be almost like AC. 12 volt fridge uses about 4 amps running constantly. The only problem is how long would it keep the water cold. The small 12 volt water pumps (6 dollars) I use had no problem moving water 5 feet away.
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celdek small.jpg   aa indirect section.jpg   cooler celdek 100_0042.jpg  
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