evaporative air cooling, made better than HVAC

jimmyhackers

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a few years ago i made a diy evaporative cooler.

works ok, drop air temps abotu 5 - 7 degrees C.

better than hvac etc as it hydrates the air rather than drying it out. uses waaay less power, was waay cheaper.

it was essentially a ducted fan blowing through a plastic box full of car wash sponges (that have been finned) that get sprinkled in water by a small aquarium pump n sprinkler head.

today i did some tweaking and managed to get it to drop temps by 10-12 C.

essentially all i did was route the water through a small 120mm pc rad before the sprinkler head, and place the rad infront of the boxes output.

despite me being an air con technician a while ago, im still slighly perplexed asto exactly why his addition of a rad has worked so well...

i figure that the main body of water....is sub ambient in tempreture due to evaporation, and this water in a rad is more surface area to interact with.....i thought this would of been counterproductive as it should essentially put heat back into the water.
which it probably is....but then again the hotter the water the more likely it is to phase change....which is the main cooling part.

which again.....makes me realise that this is just another phase change air-con system.

in proper evaporative coolers.....this rad stage is missed out and im not sure why.

bit of a ramble, not really sure what im asking, something like is my rad part a new insight to evap coooelrs? and why arnt more aircon installs evaporative.
 
Only work in low humidity scenarios.

And even then not as effective in say a Phoenix full sun spot, 'Muricans want to flip a switch to get predictable result every time.

Personally I say relocate, follow the sixties
 
I saw one experimental system that ran the house air through a de-humidifyer to dry the air, and then a conventional swamp cooler cooled the air. It was all run by a large solar panel.

There is a youtube where a guy shows how to do the same thing. It is the compressor on an A/C unit that sucks a lot of watts, the fans do not draw much.
 
I would be interested to know if the water is warmer or cooler after passing through the rad. Could you put a thermometer in the reservoir and note the temp then put it in output that’s wetting the pads.

Johm61ct, I disagree with you. On a hot dry day in Phoenix standing in front of a Mastercool feels pretty darn good. It will give you goosebumps😁
 
essentially all i did was route the water through a small 120mm pc rad before the sprinkler head, and place the rad infront of the boxes output.

i figure that the main body of water....is sub ambient in tempreture due to evaporation, and this water in a rad is more surface area to interact with.....i thought this would of been counterproductive as it should essentially put heat back into the water.
If the rad is infront of the cooled air output, i would have thought that it would be taking heat OUT of the water ?
Then , that would give a bigger “delta T” to the air in the sponges.
It like a positive feedback system, the more you cool the water, the better the cooling effect (t/T) in the heat exchange section .
 
Just be careful. For any sort or regular or long term use, "...plastic box full of car wash sponges..." can loosely be defined as "mold/mildew/bacteria/legionella breeder and incubator"
 
its yet to mould, even after over a years use.

it gets cleaned once every two months. there is a lot of limescale depositing on the sponges and the walls. it comes out/off quite easy though.

its strange as the when cleaning my hands feel rather dry and wrinkle quickly. i can imagine over the course of a month the water gets quite concentrated in whatever makes that "limescale"

it does worry me some as i drink a lot of tap water....and that limescale stuffs in there.

that's interesting about how it works hillhater... i was thinking more the opposite.

that as the water is sub ambient due to the evaporative part, making the rad also sub ambient.
when air passes over the rad, it is hydrated and at ambient.
this means the water in the air has a chance to condense on the rad, cooling the air further.
this also means some heat is put back into the water, right before it is sprayed, making it even more likely to want to expel hot water molecules.

the other possibility is my fan airflow is too high to begin with. the rad has increased the effective surface area of the water in contact with air, and i could get a similar effect if i increased the sponge surface area or reduced the air flow.
 
I'm also a big fan of the swamp cooler and the wicking humidifier..
Great results using them in conjunction with AC out here in Utah where the humidity ranges from 10-100%..

Biological buildup on the wicking elements of both can be an issue during certain temperature, use, and humidity conditions. A long period of heat while the unit is not in use ( stale water ) is the perfect condition for this buildup. Hence, i remove the filters on either during periods of non-use during hot temps.

I am very sensitive to mold, dust, allergens, pollution.. so I use these devices with more caution than most.
 
jimmyhackers said:
today i did some tweaking and managed to get it to drop temps by 10-12 C.

essentially all i did was route the water through a small 120mm pc rad before the sprinkler head, and place the rad infront of the boxes output.

This is really interesting and i'd like to see what kinda results you could have with a commercial unit.
I also wonder if this boost works in certain conditions or if it poops out in others.

If it works well then there is a market for you to sell an add on.
 
im too lazy to comercialize this :)
i live in the uk and most households dont use a/c and if they do its usualy a small freestanding unit thats on wheels. they still use 1 -3kw power draw which is ridiculous. my totalpower usage is under 100w and it keeps my entire loft space cool enough.

between the two im sure i could bumble a proffessional looking version together for under 200 quid, but again, im lazy.

i suppose its possible that if i put the "pre-sprinkler" rad on the intake rather than the outtake.

its has potential to dehumidify the incoming air. maybe giving the unit a chance to work in more humid climates.

although in 100% humidity im not sure if the water would get sub ambient to facilitate this.

i just think it's mad that for the addition of plumbing in a rad i got better effiiency......why dont comercial/domestic evaporative coolers do something similar?
 
I’m interested in trying this idea out, I don’t have a pc radiator to try so I will scrounge up some scrap copper or aluminum tubing and make a coil in front of the fan. If there is an actual improvement to the coolers performance it seems like the manufacturers would have been doing it all along. What I suspect is that humidity changes have the most effect and the testing would have to be performed under identical humidity levels.
Does anyone have an opinion on using plastic tubing? I know copper would be best but it’s getting hard to find.
 
Oh god standalone units are garbage and such electricity hogs.

I put together a webpage for an Italian air conditioner company selling these mini split units with amazing EERs and got the idea that Europe isn't as stupid as us, but you just popped that bubble, lol.

I see missed opportunities all over air moving devices in efficiency and think there's still a lot of room to improve these things.

I have a big interest in producing super efficient and extensive air filters, so i've been studying things that move air for a while.
I may end up testing your idea in a much drier climate out of curiosity. This has inspired me.
 
One of the biggest scams. Evaporative coolers only work with LOW humidity.
Thieving asshats!
 
by neptronix » Sep 15 2021 5:14pm

Oh god standalone units are garbage and such electricity hogs.

I put together a webpage for an Italian air conditioner company selling these mini split units with amazing EERs and got the idea that Europe isn't as stupid as us, but you just popped that bubble, lol.

I see missed opportunities all over air moving devices in efficiency and think there's still a lot of room to improve these things.

I have a big interest in producing super efficient and extensive air filters, so i've been studying things that move air for a while.
I may end up testing your idea in a much drier climate out of curiosity. This has inspired me.

Bought a mini-split 3 yrs ago to test it out. Will never go back. Not cooling the whole house with it. Just use to control a hot room and the humidity in the Spring and fall.

It's a Bosch paid $1,500 US. Only a 9k btu on 240v uses about 3a. Here you can buy a 5-6k btu window unit for $200 and get 2-3yrs.
The good points: Mounts close to celling, the only is hole is 2.5". The outside unit can be mounted on a wall if you live in an apt or had a two story.

These are heat pumps, with independent and variable DC fan inside and out with a variable speed compressor.
They run by remote, modes: fan, heat, cool, dehumidify and auto that decides if you need heat or cool and varies the fans and compressor. Timers, sleep mode. And they are quite.

Lived in Phoenix (Amberwolf's city) they have both HVAC and evaporative coolers, depends on time of year.
They have evaporative systems that use a median to dry the air and make them usable but it gets compilated and costly.
 
Yup.
Mini splits with reversible heat pumps are the most badass thing i've heard of, and i'm surprised they're not everywhere.

What would be really cool is a combination evaporative and AC system that worked in different ratios depending on inside conditions. Could keep humidity and temperature constant in places that have unpredictable weather. And save money even in places where you can only use an evap cooler intermittently.

But that makes sense to me in Utah where the yearly temp swing is -20f to +110f and humidity ranges from 15% to 100% and experiences major shifts all day long. Almost every building out here is intermittently uncomfortable to be in.

If you want to cool your house efficiently here then you use both a swamp cooler and evap cooler together. But you always have to dick around with the knobs on both to get optimal cooling per kilowatt hour. Pain in the ass.
 
by neptronix » Sep 15 2021 8:27pm

Yup.
Mini splits with reversible heat pumps are the most badass thing i've heard of, and i'm surprised they're not everywhere.

What would be really cool is a combination evaporative and AC system that worked in different ratios depending on inside conditions. Could keep humidity and temperature constant in places that have unpredictable weather. And save money even in places where you can only use an evap cooler intermittently.

But that makes sense to me in Utah where the yearly temp swing is -20f to +110f and humidity ranges from 15% to 100% and experiences major shifts all day long. Almost every building out here is intermittently uncomfortable to be in.

If you want to cool your house efficiently here then you use both a swamp cooler and evap cooler together. But you always have to dick around with the knobs on both to get optimal cooling per kilowatt hour. Pain in the ass.

This last year was looking for a humidistat integrated with a thermostat. So the HVAC system would respond to humidity changes (bothers me more than tempter swings) and they don't make one. The reason i'm guessing is the HVAC system would freeze the coils and damage the compressor. (Unlike my mini split, that cycles between hot and cold)

I spend a few years looking at all of this and had an interest in absorption chillers. Hybrid systems are doable but complex.
 
Interesting change adding a condenser- radiator on the output stage. Looks to me that its condensing more moisture in the output air which would increase the ability of the air to absorb more heat. A few of these sensors would go a long way explaining what is going on in the various stages for little funds. https://www.ebay.com/itm/324773028369?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649
 
i suppose effectiveness mostly comes down to humidty.

which is where evap systems fail.

i may sound stupid, but i guess my ideas merits depend on if the water in the air will condense on the surface of colder than ambient water.

if it does not.....the extra sub ambient surface of the radiator is where it could be condensing.

again....i dont know if the water could ever get below sub ambient in a high humidity climate. this might be worth testing by someone who lives in one.
 
Live in one of them high humidity environments. Devoted some time to this years ago. Don't remember the numbers now. The cooling effect here is so low it's not worth doing. Only a few degrees drop. I have learned that lower humidity is better than lower temperature to a point.

You're findings have merit. Just that there is so many factors. Consider the water temperature coming out of the pipes in the ground. Depending how deep the pipes are as to how cool the water will be. Here in south Texas at 7ft deep the ground is +/- 72 deg. This is lower than than the ambient temperature day/night. This in itself has a cooling effect. If you ran this water thru coils to cool the air and bring the water closer to evaporation. I could see a benefit.

Have looked at many different water cooling designs. You can get most to work. The bottom line here where I live it takes to much water and system to drop the air temperature 25 -30 degrees in a high humidity environment. What I do remember is on our more humid days a evaporative cooler would only drop the air temperature 3-4 deg. Not that it did not feel good in front of the blower but the next room would be humid.

Live in 4 corners area of New Mexico for a few years (North of DogMan Dan). Had a whole house evaporative cooler, no HVAC. Did good during the day and would freeze you out at night. The water was from a snow melt stream/river. The water pipes would sweat up getting a glass of water (Source lake would be 38 deg year around. Went water sking once). This was in the high desert. Low humidity, hot during the day and cold at night.



by jimmyhackers » Sep 19 2021 12:50pm

i suppose effectiveness mostly comes down to humidty.

which is where evap systems fail.

i may sound stupid, but i guess my ideas merits depend on if the water in the air will condense on the surface of colder than ambient water.

if it does not.....the extra sub ambient surface of the radiator is where it could be condensing.

again....i dont know if the water could ever get below sub ambient in a high humidity climate. this might be worth testing by someone who lives in one.
 
it would appear the condensor rad is condensing the water out of the air.

as it gets wet.

ive also noticed my throat being drier the past week or so, and i am having to fill the unit with water less often.

i kinda wanted the humid air to help my throat.

i can just swap the air in/out, with the condensor on the intake dehydrating incoming air rather than the outgoing.

i really need to link up some humidity/tempreture meters to see whats what.
 
it would appear the condensor rad is condensing the water out of the air.

Exactly! That is how I am understanding it also. It is "fogging" the air, by bringing it closer to the dew point.

I picked up some of those mini temp-humidity sensors I linked earlier for another app recently and they are great so far. 10 of them for $17 with the postage. :) I do think you could nail down what exactly is going on with a few of them.
 
Unless I can just buy one rather just hit the hvac guy up and spend money to get one installed.

Just buy a good one
https://youtu.be/XDvViz42vaw?t=369
Yes - American Standard, Trane, Mitsibushi - Dont rust dont and dont have coil leaks
No - Carrier, LG, Goodman

I don't understand why that mansion has many many smaller units then just one big unit for the entire mansion. Must be a Florida thing, or hot, humid area thing. Does Cali do the same thing? 10 units for a mansion.
 
It's zone control. Different areas have different cooling needs. The house i'm in is not that big. The east part is hotter during the midday than the west side. The west side heats up during the afternoon. We have a 5ton ducted AC with one thermostat in the center. If you keep the east rooms cool during the day the west is to cold. In the evening the west turns warm to keep it cool need to make the rest of the house cold. You need zones to cool the parts that need it while not cooling the rest.

Bigger AC's are more energy efficient. Then you lose that efficiently thru long ducts and blower's trying to push the air around. Fans use a good percentage of an AC's energy usage. That is why you have multiple units.

Our house has a 9k btu unit on each side. West side is just a cheap window unit thru the wall. On the east side put in a mini split. This unit does heating, cooling and works as a dehumidifier. The small units will not keep the house cool during the summer. They do keep the larger unit from over cooling the parts that do not need it. Saves quit a bit of money. The big unit pulls 35a at 230v, the mini-split is setup on 230v and pulls 3a. The window unit is 115v and pulls 9a.


by markz » Oct 22 2021 11:34pm

Unless I can just buy one rather just hit the hvac guy up and spend money to get one installed.

Just buy a good one
https://youtu.be/XDvViz42vaw?t=369
Yes - American Standard, Trane, Mitsibushi - Dont rust dont and dont have coil leaks
No - Carrier, LG, Goodman

I don't understand why that mansion has many many smaller units then just one big unit for the entire mansion. Must be a Florida thing, or hot, humid area thing. Does Cali do the same thing? 10 units for a mansion.
 
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