Major DIY: Cold Water home cooling.

Old 07-23-06, 09:06 PM
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Major DIY: Cold Water home cooling.

I'd like ideas on using a cold water source to cool my home.

Background: I'm a semi-retired engineer. I can afford the time & equipment to build this project, and there's very little I can't build myself. My utility bills are going way up, and I want to invest time now to save money throughout the future. Besides, I like big projects.

My Atlanta home is 22 years old, and I expect the contractors' furnace/AC unit to quit soon. It's standard forced air gas heat & outdoor compressor. I want to replace the AC with a DIY unit that uses cold water.

My home is on a small river that is a constant 55 degrees F, and the property rights include water use for the property. My idea is to use this cold water as a heat sink to chill antifreeze, then run that to an air handler to cool the house. (Don't laugh. I can do this.)

Has anyone ever heard of such a project? Can you point me to a book or web page? What problems am I likely to run into?

I have two ways to get the cold water to my house: I could run PVC pipe & power down to the river where I'd need an inlet & pump. Then I could build a heat exchanger up by the house & either water the lawn or return the water to the river. The river gets silty from run-off when it rains. An inlet might clog, or I'd have to pipe muddy water uphill.

I might be better off running two insulated pipes down to the river and immersing a copper pipe heat exchanger in the river. With this second option, I just need to keep the pipes in the river from getting burried. I think I can do that, because I'm on an outside bend of the river, so it scours my bank. Also, with a closed loop down to the river and back up, I should be able to leave the pump at the top and pump the water down and back up. This may take some experimentation.

If I pump the cold river water up to the house, I'll need a heat exchanger outside. My first thought is to build that out of copper pipes soldered side-by-side, and maybe immersed in water, in an insulated container. Or maybe I can buy such a thing.

Now I'll have a closed loop of cold water/antifreeze into the house. I can lead this to the air handler, and probably pipe it through a standard A-frame cooler meant for freon. (Alternative: car radiator.) I'll house this in a second air handler next to my existing furnace. That way I can manually switch the ducts to the new unit for testing, and can always switch back to the exising AC until I get the new system working.

The controls could be standard analog thermostat, 24v control lines, and relays to turn on the pumps and fan. But I'll probably computerize it and run it from a PC -- or at least monitor it. That means I'll need to build in temp sensors, & flow meters and send that info back to the PC.

Big question: Is 55 degree river water going to be cold enough? No doubt it will be warmer than that by the time I get it to the air handler. Will that be cold enough to cool my house in a reasonable time?

Yes, I know this will be a lot of work. But look at it this way: in the future, my summer AC bill will be running a water pump and a fan -- no compressor. The expense of this project needs to be weighed against the cost of replacing the existing unit, and the cost of upgrading to an expensive heat pump. (But of course a heat pump would lower my winter heating bills too.)

[Note: Yes, I know I'm crazy. But I've just finished remodeling the kitchen, and moving the washer/dryer upstairs to a new utility room. The French Drain is almost finished, so I need something to do. It's either this, or a home photovoltaic system and an electric car.]
Old 07-23-06, 09:48 PM
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OH Boy : Out of the box here. First Id say just use the 55o water. Dont try and transfer the 55 over to something else to go into the home. You would have a big temp loss that way.Have the water go right into the new coil inside the home. Id look for some hot water coils and see if I could use them. They have some with blowers You need large pipes in them not the small pipes like in a AC coil. I dont think you will get a high temp drop . But this can take a lot of humidity out of the home and that is what makes you feel cooler.
This way you have just one heat exchanger Inside. Or have you looked into a DXGeoThermal set up in the ground for a heat pump

ED just my .02 cents
Old 02-28-15, 01:13 PM
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Is there an update for this thread?

I know this is an old thread, but I am thinking about something similar. My thoughts are to use clean water in a closed system and pump it through coils located in the river. When I gets to the house I am open to ideas on how to best use the cold water to cool my home.
Old 02-28-15, 01:24 PM
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Welcome to the forums.

This thread is quite old and there have been no recent additions to it. Rather than resurrecting it.... start a new thread with your question.

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