Picture of Free Air Conditioning
Technically it should be called a heat exchanger, we lovingly call it the water cooler, but it has been providing us with free cold air for more than 20 years now so it definitely does work.
Shortly after moving here (Montana) I noticed that the water from our well is really cold, under 50 degrees. I built this heat exchanger to take advantage of that cold source for use in the house in the summer and as a byproduct it heats up the water going to the garden a bit before it goes on the plants since the plants didn't seem to care to much for the super cold water. Good benefits all the way around and since I would be pumping the water to water outside anyway the only actual cost is the power to run the box fan that moves the air through the copper piping.
How well does it work? We hit a high temperature in July of 112F, hottest that I can remember. The temperature inside was 76F with the cooler running all the time. I almost didn't want to go out to move the sprinkler.
The disadvantages? Well, you have to move the sprinkler a lot, but it does keep the grass green. Also if the humidity gets high, water will condense on the exchanger the same as on a glass of cold water. So I keep towels underneath it to soak up the moisture. If it gets really muggy I have to change the towels several times a day. I just hang the wet set outside in the heat to dry and rotate the dry ones back under the cooler.
It will take some skill to put it together but once done it is maintenance free, except for the time I left it outside before putting it away for the winter and it froze some leftover water in a pipe and broke it. Make sure to get the water out of it and store it where its above freezing.
Another disadvantage, it isn't pretty, but it is unique and truly "green".
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Forgott3nM1 month ago

I wouldn't use that old fan for it...... even though they work better they'll be just as good as those all metal ones from 1940's and 50's soon, I'd go to a thrift store and find a fan like it to use but newer...... Anyways I've ran my 12000 btu window a/c off of solar before, and captured the drips for my plants, worked really well :)

Tampaguy8 months ago

Sorry, blightcp - The British thermal unit (BTU or Btu) is a traditional unit of energy equal to about 1055 joules. It is the amount of energy needed to cool or heat one pound of water by one degree Fahrenheit. A US liquid gallon of water weighs about 8.34 pounds - better recalculate!

blightcp8 months ago

If I remember right 1 btu is the energy to heat 1 gallon by 1 degree.

at 48F to 72F is a 24F change. 250 gallons of water an hour equals a 6000 Btu/h ac

So you need a 4.1 gallons a min flow rate to achieve the goal of 6K. That sounds about right for a well pump.

pulling that water up from a deep well takes a decent amount of
electricity from a well pump.

My 6000BTU window AC pulls about 450W. The well pump pulls more than that.

The only way this is cost effective is if you are already using the
water, as the poster is. Unless you recirculate the water back into the
well, there is an enormous amount of water needed for this to work.

But it does work and, it could also help a water heater use less energy also by pre-heating the input water. You could get a double savings there by both cooling the room and putting that heat into the water before the water heater.

nblender1 year ago

I've done this as well. My well is 10gpm and it comes out of the ground at 8 degrees C. I had a new furnace installed so I asked the installer to put in an evaporator coil while he was at it. It cost me an extra $180. I plumbed a 1/4" solenoid valve in line with the fresh water supply from the well. I insulated the water line leading to the furnace so the water going in is as close to the same temperature as groundwater as I can measure. I hooked the solenoid valve up to the A/C terminals on the furnace, so when the thermostat calls for cooling, it turns on the water and cools the house. The egress for the warm water is a faucet on the outside of the house which has long soaker hoses attached to water the flower beds. The flowers like warm water on a hot day over shockingly cold water anyway... The runoff just goes back into the ground.

The system works fairly well if I can control the solar load by closing curtains on sunny windows or putting out the awnings on the South view windows. If I set the temp to 66F in the morning on an anticipated 'hot day', I can keep the ambient temperatures in the house down to 75F by the time the outside temperature falls at the end of the day. It doesn't work as well as a true A/C system, but it's close enough to free that it pleases me. In preparation for fall/winter, I drain the evaporator coil and run some vinegar through it to clear out any mineralization... Hot air from heat during the winter would cause any solids to come out of solution I think, and eventually clog the evap coil.

The drawback to this system is the coil doesn't get cold enough to cause condensation to pool and run off so there's no net reduction in humidity within the house.

Anyway, that's my story. It was cheap to do and it's hidden from view...

lived there 6 years and I use this idea w an ice chest and a heater core for my work trk (which in CA w no a/c I'd bad bad bad) and it works well
balconio1 year ago
This is great- I conceived a similar system (not built yet- just in my head) using a heat exchanger and cheap box fan that took this a step further and used an insulated ducting system to deliver the chilled air to multiple rooms and a drip tray under the unit to collect condensate.
Have you thought of returning the water to the well instead of watering the lawn? I think the slight temp differential and the huge body of water in the aquifer would temper the return water back pretty quickly.
shortw4 years ago
You talked about this being a green concept? It is not really green, because you use quite a bit of water from the well. The green part would be to conserve water. Your well pump uses a lot of power. You would be able to run 2-3 5,000 btu air conditioners for the same power consumption as your well pump uses. You created a breeding ground for mosquitoes and fungus that has could have serious health or death issues, both could be deadly.
For Vyger its green because he's using the well pump for watering anyway. On the way he just takes some of the cold out of the water for his own comfort.
jcox241 year ago
I live in southern VA, and when storms knock out our power, the humidity and heat can be awful. I want to try this, only have it run from ice water in a cooler (pumped through a cooling coil), because I could run it on a car power inverter and have cool air in one room, even if I have to sacrifice another to run an extension cord through the window. I could have hand warmers in water in it during the winter, if a nor'easter knocks out the power.
samaddon2 years ago
mind blowing project i have also developed one similar to this it works ! bu i used good quality heatsinks and only one table fan but i am really surprised to see that it can also be made by some general household things!
Samad Haque
brittonv2 years ago
Have you thought about connecting this to a traditional Air conditioner air handler and use a thermostat to trigger your well pump? Great Idea though, wish it work here in South Florida.

I would think that the more efficient air handler with a blower would enable you to do the same thing using less water..

Awesome project!
This is a great idea! We happen to have a few old cooler consender and A/C coils (I guess also known as "heat exchangers"). I followed the setup here and it DOES work! Now, I have an old Everstar "portable air conditioner" that doesn't cool very well I figured it would look a lot more "asthetic" and it already has the fan built in. What I want to do is retrofit that into one of these coolers. Could anybody offer suggestions on how to do this if I put some pictures up? I also would need help with modifying the electronics - I just want to use BOTH exchangers withe the fans on at the same time.

spafford3 years ago
My question is ... How warm is the water when it reaches the garden? Is the hose laid on the ground after it leaves the cooler(which would make the water hotter)? I was just wondering the temp of the water that is coming out of the "cooler" as to determine if all the "coolness" is extracted from the water. I guess ideally you would only want the coldest air extracted but if the temp on exit is still the same more air flow and a larger "Radiator" could really make cold! Of course, flow rate is a major factor and I wanna couple this with drip irrigation and a large GARDEN :) This is an awesome idea! I had thought about it, but had not put it to work. Much praise 'ol mighty inventor, people such as yourself are the last line of defense in energy corruption.
Vyger (author)  spafford3 years ago
The rise in water temperature depends on a lot of factors. Even the air temperature plays a role. But the biggest factor is the flow rate of the water. If its running pretty slow, such as just a single sprinkler that is turned down, then the rise is pretty noticeable. You can tell the difference just by touching the in and out hoses. Also the out hose has very little condensation on it. If the flow rate is high then the temperature drop is pretty small.
There is about 150 feet of hose between the outlet and the garden. The water does get warmer just from the air while flowing through the hose. I have never checked the temperature at the garden end. The water is still cold, but not the bone chilling temperature that it is coming straight from the well.
garretttm Vyger2 years ago
Old i know, but just a thought...
If your water starts at 50F and you lose at most 15deg in the process, you should still be well under ambient temps and be able to reuse the same water (granted, at lower efficiency).
Times when you are only using 1 sprinkler and therefore have low flow you could have a recycle valve to loop the same water through several times before it is ultimately used.
Have you thought of/ experiment with this? It's hard to guess how effective it would be as there are so many variables, but it seems solid on paper
Vyger (author)  garretttm2 years ago
I could add extra heat exchangers in other places, and in fact have thought of doing that, but the main point of the project is not to get maximum efficiency out of it but to harness what usually just goes to waste. Outside watering is the priority, getting cool while you water is a fringe benefit. It just so happens that you usually need to water the most when its the hottest out.

There is also another factor involved and that is the more pipe you add the greater the resistance to the water flow so you drop the outside water pressure and flow amount. And of course the more pipe, the greater the chance of a leak.
Bonzoix4 years ago
For those without a well, couldn't we dig a field in the backyard to run lines through to recool the water to ground temp? Like a DIY geo-thermal A?C unit? Then we would need a pump or an impeller driven by the same motor as the fan... Love the instructable.
I think that is an excellent added addition! I think a key I would like to add is to make sure the water remained bacteria free.
they are saying run hoses underground not run water through dirt, would still be just as clean (or just as dirty i should say) as tap. also the radiator uses copper which inhibits bacteria and mold. also it is in an water tight radiator so even if there was bacteria you wouldn't come in contact with it.
sadly no. dirt doesn't have a great heat exchange so it wouldn't "cool" the water much. the only reason this system works is that it is a one way trip. the water doesn't get recycled so it doesn't need to cool back down. if you used a ground cooling method the water would not stay cool for more that a few hours because the radiator on the fad has a better heat exchange than the dirt (more heat is added than is taken away on each loop) good thought process though only about 1% of our ideas are good ones and yet humanity still moves forward, just goes to show how valuable it is to keep thinking.
tinker2343 years ago
wow could you use painters tarp for the water leaks in case
Vyger (author)  tinker2343 years ago
I haven't had any water leaks. There is condensation, just like on a glass of ice water in a warm room. But my climate is pretty arid and dry so condensation is usually only a problem a few times in the summer. If it was a constant problem I would look for better solution but I have been going on the "if it isn't broke, don't fix it" thinking for now.
If your wellhead is accessible, you could just run a hose back into the well. I'm sure the water temperature would still remain at 48.
That would be illegal in most states simply because of contamination risk
My great grand-dad (I only know from the stories of my grand-dad) had a large "sisturn" (that's how granddad says it) behind his house that collected rain water. Basically it was a big deep hole that was dug and then concreted and he pumped this water out and ran it through some 30's filtering system and actually had indoor water at a time where most people still were drinking out of the river (at least in TN). If someone had the land and equipment needed to do it, you could build a deep "sisturn" and pump water into it, and cover it with concrete. then build another one close by. They could run the water from one to another, and once one was dry the other would be cool enough to use.
eyerobot Funk_D4 years ago
The actual way we got our water in Kentucky, And Tennessee, Was to run large hoses uphill into small creeks, Where we created a small dam, And put screen filters on the end of the hose. The water ran down the large pipe, Into smaller pipes to build up pressure as the water approached our house. We then built a large cistern that was sealed on top by what resembled a submarine door, And this held in the pressure. On the bottom of the cistern was a hose smaller than the intake hoses which was filtered again with a sediment filter, And recieved a lot of pressure. So in an area where everyone had no water pressure, dirt, creatures, And god knows what else in their water, We had high pressure clean water. And it was always cold enough to turn your fingers blue. I just wish I had thought to use a radiator type system as a heat exchanger like this instructable. Great idea.
The water ran down the large pipe, Into smaller pipes to build up pressure as the water approached our house.

do people actually think that pipe size influences water pressure in that way? small pipes will reduce the pressure as they restrict the flow.

The way I understand it is that water pressure is determined by height of drop not pipe size.

just my two cents worth no big deal :P
@ josephlebold. eyrobot is correct. As a fluid [liquid or gas] flows through a pipe there is FRICTION between the flowing fluid and the pipe wall.

The longer a pipe run, the more "friction loss" and both flow rate and pressure are REDUCED.

To correct for this friction loss, piping systems are TAPERED smaller and smaller consistant with the length of the pipe run.

To SEE evidence of this phenomenon, the next time you are in a Wal-Mart, or any large building with EXPOSED ceiling FIRE SPRINKLER systems, "eyeball" the piping system and you'll see the "tapering down" of the plumbing. That way, ALL sprinkler heads receive the same amount and pressure of water, AND therefore provide a nearly identical spray pattern when in operation.
this is getting more complicated all the time.
I see I should build a system and check it out. lol
I'll supply the piping if you do the assembly. :P
Have you been to Kentucky?
Theres no such thing as flat ground there.

at our house, The water pipes came down hundreds of feet before reaching our house. So by the time you reduce the pipe size several times, You have all the weight of the water from the larger pipes pressing down. That's where you get your pressure from.

Yes placing smaller pipes in between the large hoses, And the house will reduce pressure, But blowing the faucets off the sink wasn't our plan. The large hoses can hold a lot of water, That would otherwise wash on down the creek, And during dry times, This can really come in handy.
I have been through Kentucky on the way to Tennessee though I cannot remember anything overly hilly... but maybe living in Maine for 6 years has caused me not to notice the hills.

my research came up with.433 psi. per foot height. so 100 foot drop would give you about 43.3psi. not a terrible lot of pressure.

a smaller pipe would have less inertia so when you turn your faucet off you would have less of a pressure spike. so yeah I see the advantage there. that is the principle behind the ram pump.

I can't stop laughing when I imagine the faucets blowing off the sink.
My step father decided the way to lay hose, Was to use all large hose. Being a kid, I never thought about the pressure, But once he opened the valve, He blew the spigot right off the front of the house. And after fixing that, He blew out two lines in the bathrooms. then finally an old drunk walked up the road, And saw him under the house fixing pipes. And felt sorry for him, And told him what he was doing wrong. that's when the smaller pipe came into play. So yeah you can get some serious pressure at several hundred feet of line, but eventually we shortened it to about seventy five feet, And only had small line for about thirty feet before the house.

Of course I would much rather have used something like the ram pump, but honestly ive never seen one before coming to instructables. Maybe the hillbillies don't know everything?
sounds like you could have put up a hydroelectric generator.
askjerry Funk_D5 years ago
It is actually spelled CISTERN.

They used them in many civil war fortresses... here is some more information and images:
Funk_D askjerry5 years ago
Oh! hahaha. I always assumed it was one of those words that older southern people make up; I never even thought to look it up!
 I think the construction industry uses the term "grey water" with systems like that.  I've seen some home-improvement TV shows where large plastic tanks were installed to catch rain-water for lawn watering or other non-drinking purposes.
wperry1 Funk_D5 years ago
If the first sistern were large enough you could just recirculate the water without the need for a second.
You are 100% correct on that one. I have yet to find a state that allows this at least without a permit. Some states (Idaho for one) allows water to be returned to some wells with a permit from the DNR. Water rules are quite strict and expect it to get much worse in the future here is a prime example: In Colorado Rain Barrels are illegal... Colorado Water Law requires that precipitation fall to the ground, run off and into the river of the watershed where it fell. Because rights to water are legally allocated in this state, an individual may not capture and use water to which he/she does not have a right. We must remember also that rain barrels don’t help much in a drought because a drought by its very nature supplies little in the way of snow or rain. Strange thinking in my opinion.
DISCLAIMER: THIS IS NOT LEGAL ADVICE AND IS MY OPINION NOT TO BE CONFUSED WITH "PRACTICING LAW." It takes a lot of legal courage, but all mineral rights including water from the sky; all rights remain with the land and the current owner. If one were to persue it in court to the highest levels and use all the correct legal arguements without any mistakes, one might be able to maintain the original legal precedents involved. We only get to keep those rights which we defend. We lose those which we allow to be taken from us. Rain barrels are part of survival, no agency has the right to remove your ability to survive under "color of law." (Rain barrels in Colorado would make for interesting tea parties would they not?)
(removed by author or community request)
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