</font><font color="blue" class="small">( JMC,
I'm in Bloomington In as well! Small world. The lake is Monroe and can not sink coils into the lake. That is why I thought if I could use two wells very close so to use the lake as a heat sink. The stone is very soft, sand stone and shale. The down side is the contamination.
Where in Bloomington are you? Me, Ramp Creek
)</font>
My sister lives there, but we forgive her out of love. We're a Purdue family /forums/images/graemlins/wink.gif
If you already understand how this stuff works - skip this.
The heating and cooling is done based on forcing the gas back into liquid or liquid into gas. Some people have a hard time relating to this, but I think I have good examples:
Air compressors and propane tanks. The air compressor shows what happens when you pressurize a gas into a smaller space. The molecules cannot move around as much and thus are FORCED to lose their heat, transferring it to whatever is nearby. In air compressors, its that little metal tube that goes into the tank and gets very very hot. The heat is not from the motor, but from the air itself. Also, water vapor in the air is re-condensed (also releasing heat). This water then gets blown back out of the tank in liquid form and must be trapped or else muck up some air tools or applications (like painting a car). This is why Turbo'd cars have intercoolers - the air has been squeezed, but is now very hot. The air is blown through a radiator to try to cool it down to ambient temp. When the air is released, it will absorb heat, but that effect is more noticeable with propane tanks.
Propane has to be compressed to liquid form, but you aren't there to see it. Its already liquid when they fill your tank. If you use your propane tank heavily, you will notice ice forming on the outside. This is because the propane expands to many times its volume and absorbs heat from its surroundings. If it wasn't so flammable etc, you could use it to chill things (a waste since you are paying for it). In fact, propane has been used as a coolant medium like freon is. It lost favor because of little things like being very flammable.
So in a nutshell, thats how the heat pump works. When it wants heat, it compresses the medium (freon or etc) which forces the heat to leave the medium - this heat is convected into the house. This leaves the radiator fluid in pipes headed for the ground very cold and is warmed back up to whatever the ground temp is.
When it is in cooling mode, it essentially just works backwards forcing the medium to expand which makes it absorb heat, making the radiator fluid very hot and it uses the ground to cool back down. This fluid could be really hot, and 70 degree ground temps are very cool in contrast.
Geo Thermal heat pumps are essentially the same as regular heat pumps except that they use the ground as the "heat sink" vs. the air. They are generally speaking MUCH more energy efficient. Waste heat can also be used to keep the water heaters hot.
