My old mans house sits in a area of our state that has a very high water table. The house has a well and the water comes in right next to his furnace. Maybe a foot away from the duct work. As you may know water below the earth stays about the same temp through out the year. About 50 degrees I was thinking I could make a coil out of copper pipe or install a pre made coil into the return air system and install a electronic valve controlled by the thermostat to open and close the water source. I would discharge the water either to the sprinkler system or when needed to the hot water tank. I would set the sprinkler system to open so when ever the thermostat triggers the water opens up and I get cheap AC, paying for the electricity for the blower and pump. This will water the lawn at the same time. In the winter I could have the water cut off completely to the coil and diverted to the water heater with another valve
Everything is already there all I would need is a coil and some plumbing work.. maybe a bit of tin work too.
Unfortunately you can only use cooled water to remove a small amount of heat before you have to start dealing with condensation. That may be a critical issue in this, but I do like the idea!
I thought of that. I could install a drain tube on the bottom of the return air duct and feed it to the sump pump. The forced air will push it down the drain tube. Maybe even a removable panel to clean off the coil. Put a valve in the drain tube so in the winter no forced air feeds through the tube.