best swamp cooler location

[tanuki.himself]

Having finished the camper structural build, i'm now thinking about add ons, including evaporative cooling. Key question is: do these things work best recirculating air inside the space, or should they be mounted in a window or vent where they can pull in and cool fresh air in from outside the camper?

 

[WeLikeCamping]

Swamp coolers do not recirculate air. They need windows cracked to work most efficiently. They also need water. Think of a fan blowing air through a wet towel. Higher humidity kills efficiency.

Maybe you mean A/C? I would suggest rooftop for that

 

[Porkchopexpress]

Yeah, swamp coolers need dry air and cool by evaporation adding moisture to the air. You would definitely need to mount it outside the vehicle and bring air into the vehicle and it would need to be someplace very dry to be at all effective. You would also need a water supply like a garden hose or use your own supply of water which seems inefficient. I have been in small buildings in the desert that use swamp coolers and I was not impressed with their performance.

 

[NatersXJ6]

I’ve lived in houses that were only cooled by swamp coolers in the desert. They will take a decent water flow and need to flow quite a bit of air (big fan).

if the air isn’t moving through without dead spaces it will just feel wet, not cool. In a small space like a camper, you could probably create a decent cooling effect just by covering one shaded side window with burlap and spraying or dripping water on it while running a fan. Arrange the system so the air can blow in one end and out the other and adjust until you hit a good balance of power, water, cooling. It won’t work always, because the outside temp has to be hotter with drier air than inside, but it will work all over the west and southwest as long as it isn’t monsoon season.

The faster the air is moving the cooler you will feel. It gets wet/sticky really quick if the air isn’t moving efficiently.

 

[DaveInDenver]

We have a swamp cooler on our house. For 1,000 sq-ft (about 9,000 cubic feet of volume turned over at 4,500 CFM) we use roughly 100 gallons and 4,800 watt-hours per day (about 8 to 10 hours of use) to keep it about 75°F at about 20°F delta. For about a month every year we get hot and stay hot well into the evening so those days are about 12 hours of cooling some of which requires high fan, which increases electrical use by about 35%.

A comparable A/C would be more like 24,000 to 30,000 watt-hours per day, obviously no water. Ours is a 12" thick medium and other than midday it could cool the house to the point of needing a comforter. But we live where single digit relative humidity is typical so adding humidity is actually welcome and complete evaporation is definitely not a problem. The only time we get water draining is during a flush cycle.

For a camper the electrical energy saving is interesting but finding a water source or using up your stored would be a serious downside. Figuring about an 1/8th of a gallon per 100 cubic feet per hour you're consuming perhaps 5 or so gallons every day to cool it for a few hours.

 

[MiamiC70]

Swamp coolers suck especially anywhere humidity is high.

 

[DaveInDenver]

Swamp coolers suck especially anywhere humidity is high.

True. You know what's interesting though is the unit we have on our house was made by Essick (Champion, Mastercool, etc) who's in Denison, TX, which is near Dallas I think. I surmise they moved from Little Rock, AR. Neither of those spots seem to me well suited for swamp coolers so I can't imagine they sell many locally. I grew up in eastern Missouri where A/C was a Godsend and never even really heard of them until I moved to Colorado. OTOH perhaps the idea is with high humidity just moving air fast enough is cheap cooling, I dunno, maybe for industrial and commercial it's an option.

 

[tanuki.himself]

Swamp coolers do not recirculate air. They need windows cracked to work most efficiently. They also need water. Think of a fan blowing air through a wet towel. Higher humidity kills efficiency.

Maybe you mean A/C? I would suggest rooftop for that

Yeah, swamp coolers need dry air and cool by evaporation adding moisture to the air. You would definitely need to mount it outside the vehicle and bring air into the vehicle and it would need to be someplace very dry to be at all effective. You would also need a water supply like a garden hose or use your own supply of water which seems inefficient. I have been in small buildings in the desert that use swamp coolers and I was not impressed with their performance.

I do mean a swamp cooler, and i do understand their limitations in humid environments. I don't have the weight or power budgets to carry or run a heat pump when i'm off grid, but if i can carry an evaporative unit that is compact and lightweight (and cheap) and can run off 12v solar / battery for a short while to cool the camper down for sleeping in the right conditions then it might be better than nothing.

There are car coolers on the market that can run on 12v , and even more portable units that run off USB/internal batteries. I could just get one of those to try, and they inherently recirculate the air. Or i could make something from a couple of cheap 12v computer fans and a small aquarium pump to circulate air past/through an evaporative pad, and make a frame/housing/ducting that can clip into the opening of a top hung window, sealing around the rest of the window, that can pull fresh air in. Either way, the roof vent/fan would be running to extract warm humid air at the same time.

I did a very quick test last summer with a spare PC fan running under a wire basket supporting a wet mop head draped over it, and I measured a temperature drop from 31c to 24c in the airstream - this was near the Spanish coast in the mid afternoon - not a particularly humid day but not a dry desert environment either

I plan to try filtering grey water from the shower to flush the cassette toilet (self contained) which could also be used for the swamp cooler, so i'm getting two bites at much of the water i can carry. As long as filters and tanks are easily rinsed of any residue when i have access to a hosepipe hopefully there won't be much smell from reusing the water like this.

So, to clarify the original question, as my only practical option is a swamp cooler, is it better to recirculate air that may already have been cooled but that my have higher humidity, or use fresh air at ambient temperature?

 

[tanuki.himself]

Swampcoolers have enough problem with muck growing and mineral deposit in the absorbant material.
Dont be surprised if using greywater makes it worse.

i would look to rinse the pads every time i refilled my main tank - at least once a week

 

[susswein]

When I used grey water in my home made solar swamp cooler at burning man I treated with alum to settle the participants and a small bit of bleach to sterilize. Worked great

 

[Porkchopexpress]

They are literally just a fan unless the air is very dry. Also, in the type of climates where they are effective, it is usually cool at night anyway. I'm not even sure a swamp cooler would work at night.
If you are mostly concerned with temperature while sleeping, I will throw out one other consideration that I plan on using in my camper when it is finished. I have a mattress pad with surgical tubing running through it that circulates water through a small radiator to cool it down. You could experiment with a DIY version by filling a cooler with ice water and circulating the water with a small pump. Maybe one designed for an outdoor fountain?

 

[1000arms]

Having finished the camper structural build, i'm now thinking about add ons, including evaporative cooling. Key question is: do these things work best recirculating air inside the space, or should they be mounted in a window or vent where they can pull in and cool fresh air in from outside the camper?

"Manufacturers recommend providing enough air-moving capacity for 20 to 40 air changes per hour, depending on climate." is from the link:

Evaporative Coolers

In warm climates with low humidity, evaporative coolers can be a cost-effective cooling strategy.

www.energy.gov

 

[NatersXJ6]

Pull fresh air, don’t try to recycle it. After 1 pass through it will have picked almost all the water it can, thus the second and third passes and so on will have severely diminishing returns... that is my guess. If that wasn’t true, home units would have return ducts, instead they just go bigger to get more cool air and move it faster to get more perceived cooling.

Some portable industrial units use ice to supply the water. If you have plenty of power, a small ice maker charging up the tank with a big pile of ice will make the effect much better. Freshly melting water takes more energy to evap, so it theoretically cools more, but you have to have the flow rates balanced right.

 

[tanuki.himself]

They are literally just a fan unless the air is very dry. Also, in the type of climates where they are effective, it is usually cool at night anyway. I'm not even sure a swamp cooler would work at night.
If you are mostly concerned with temperature while sleeping, I will throw out one other consideration that I plan on using in my camper when it is finished. I have a mattress pad with surgical tubing running through it that circulates water through a small radiator to cool it down. You could experiment with a DIY version by filling a cooler with ice water and circulating the water with a small pump. Maybe one designed for an outdoor fountain?

I did a very quick and dirty test of a radiant cooling panel last summer using ice, some garden irrigation tubing and a 12v fuel transfer pump, which i thought was a success. I plan on following up on that this summer with some more tests in the house with a better-made panel mounted over my normal bed, and if that works then i'll fit it to the roof of the camper. That would involve more expenditure and weight in the camper - ice maker, vacuum flasks, mains inverter - so i want to be sure it works well enough to be worth doing. It would also only work once you are in the bed. The swamp cooler idea is to try and cool the space down a bit before that - belt and braces....and could also use ice if i have the ice maker.

 

[dbhost]

If you will only be in Desert environments go ahead with the evap cooler. But if you have any intention at all of being comfortable in coastal / southern climates then go with Air Conditioning. Evaporative coolers are effectively a wet towel with a fan. Cooling is created by the expansion of the water into dry hot air via effectively a venturi effect. HOWEVER in humid climates, above 45% RH all you are doing is adding more humidity to the air, and you can't possibly cool the air down enough to make it comfortable.