Personal Application of This Air Conditioning

The "air-based" system described in the Free Air-conditioning presentation works great! It is also rather simple to install, inexpensive, and almost universally applicable to homes and other buildings. A bonus is that almost nothing bad could ever happen to it in future years, so maintenance is near zero!

It happens that the Physicist/designer of this system has a small waterfall adjacent to his house, a rather unusual situation! More than that, it is not a waterfall that is fed by a surface stream (which water would be heated by the sun on a hot sunny day) but where the water is actually underground for at least a mile before coming out to be the waterfall.

If you have a fairly good understanding of the Free air-conditioning system, you might see advantages here! By having been underground for a long time, the water comes to have the 53°F temperature of the deep soil. As water, such heat/coolness can be transported in smaller pipes than the large air tubes described in our main presentation. As water, it can be passed through very common standard heat exchangers to create the desired cool air within the house.

This particular waterfall begins around 12 feet below the altitude of the house, and the water falls around 10 feet. That would normally indicate that a motorized pump would be required to pump the water UP to the house, where the coolness was captured. However, with extensive engineering, a system was designed where a second pipe paralleled the intake pipe. This pipe carried the water back down toward the waterfall, to a point in the stream below it. Since the entire water system is sealed, even with no pump involved, it acts as a "siphon" where the water flows all by itself! This even eliminated the expense of a pump and of the electricity for it!


A ten foot drop between the ends of the siphon means that there is around 1/3 of atmospheric pressure difference between the two ends, around 5 PSI pressure, which drives the siphon flow. Pipe sizes and other components were chosen which allow a maximum of around 18 gallons per minute of water to flow through the system due to this siphon action. That's around 130 pounds of water flowing through the heat exchanger every minute. Not much effort was made to insulate the buried intake pipe, so the original 53°F water commonly becomes (naturally) warmed to around 56°F as it enters the heat exchanger in the house. If house air enters the heat exchanger at 80°F, that's around 24°F temperature differential within the heat exchanger. If everything had perfect efficiency, that would represent about 24 Btu of cooling per pound of water passing through the heat exchanger. The 130 pounds of water per minute therefore represents a maximum of around 3100 Btu per minute of cooling, or 186,000 Btu/hr of air conditioning!

Few houses need more than 30,000 or 40,000 Btu/hr of cooling (normally provided by a compressor-based air-conditioning system of 36,000 to 60,000 Btu/hr rated equipment, or 3 to 5 tons). With the availability of a maximum of 186,000 Btu/hr of cooling, this system has incredible performance! (This also explains why it was not seen necessary to maximize efficiency by insulating the buried intake pipe!)

A conventional wall thermostat turns on and off the conventional furnace blower (air handler) that pushes air through the heat exchanger, so actual use is absolutely standard! About the only noticeable differences are that there is no sound of an air conditioner compressor running outside (and the associated high electric bills) and the fact that EXTREMELY cold temperatures can be set on the wall thermostat. In fact, it has been found that it can be set so low as to require wearing a coat in the house, or to go out into the 90°F outside air just to warm up! (That was done, only once, as an experiment, to have the house at around 63°F on a 90°F+ day, to see just how well it could cool!) Normally, the best design comfort temperature in the summer is 76°F, and the standard wall thermostat easily keeps the whole house exactly at that. (Remember that not even a pump is operating, with only the existing furnace blower sometimes turning on.

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It may be one of the only houses anywhere that continuously air conditions the garage, too! With so much extra cooling capacity, and with no cost of providing the air conditioning, why not? There is not currently a dog present, but plans for air conditioning the large (6' by 8') existing doghouse are also in the works!

A water-based system has more maintenance than the air-based system described in the main web-page presentation. There is junk in the water, so filters must be used and sometimes cleaned. And, without a waterfall and a unique source of huge amounts of underground water, operating cost and system performance would suffer somewhat, requiring much more design and engineering. But you can probably see why the system designer uses this adaptation rather than the described air-based system!

After the summer, a valve is opened and air is allowed into the water lines, to let them all drain, to avoid freezing during the winter. Various other such considerations make this system a little less "fool-proof" than the described air-based system, which is another reason why that is described for universal applications.

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