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What are your thoughts on this Rube Goldberg system I may try this spring in Wilmington, NC.

A shallow well about 15 feet to the well point; static water at 10 feet.

Water temp at 58-60 degrees out of the ground.

Solar powered magnetic water pump drawing water from this well and pushing it about 20 feet through an insulated pex line that connects to stacked finned copper tubing encased in a 3'x2' frame, with 4 (?) large desktop computer fans blowing across it continuously while the sun shines. The fans are also solar powered, from the same 100 watt (?) panel driving the pump. Water cycles through the tubing and exits to a PVC waste water line under the house. The goal is to cool one room about 300 sq ft by 8 feet height (2400 cubic feet.)

  • Are you looking to build an open system where you have evaporative cooling or closed were the air never touches the water? – Gary Bak Dec 6 '18 at 23:48
  • Closed system. Summertime temps here are frequently above 90 degrees, with high humidity. – MrEd Dec 7 '18 at 12:09
  • Sounds a bit like a Canadian well/ Provencal well. You are maybe over-engineering the solution. – Sean Houlihane Jul 22 at 14:47
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Someone with an engineering background can do the math. But keep in mind that, in general, air conditioning is based on a large temperature difference and a lot of air being forced through. Typical (I think - just a quick search) is ~ 40 degrees for the refrigerant, which would be on the order of 30 degrees difference from the desired temperature. So right away you are at a disadvantage because the difference will be much less. The second problem is the fan speed. A quick search found one window unit with 570 CFM. On that front, you may have a chance - I found computer fans anywhere from 30 - 200 CFM, though most are on the lower end of things. But the biggest problem is that an air conditioner works by expansion/compression to transfer heat. You don't have that here. What you have is simply cool (not "cold") water and trying to cool the air passing over the pipes.

Can't tell for sure without doing the math, but I am very pessimistic.

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    It depends on the unit size, but fans >250W are not uncommon. Higher temperatures also means worse dehumidification, which is an important part of aircon. – Someone Somewhere Dec 6 '18 at 11:22
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Some heat pumps use a similar method to harvest the constant tempatures of ground water but they use deeper wells and put the water back at a 2nd well location. Look up geothermal to get a better idea but these systems save energy but have higher maintenance costs because of using ground water. Your system will provide some cooling but depending on the distance returned into the ground it could warm up after running with a shallow well or water source.

  • BealThe "used" water would be returned to the ground at a distant location, without causing any environmental problems. We live on high ground 34' above sea level; the lot gently slopes to a riverine forest (aka "swamp") and then 600 feet out to the NE Cape Fear river. – MrEd Dec 7 '18 at 12:32

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