Nov 1st, 2008
Your refrigerator works on an interesting principle: When you put a gas under pressure, its temperature goes up. When you release the pressure the temperature goes down. In your fridge, there is a compressor that pushes the gas into a tube under great pressure. That is the coil behind your fridge that is warm. As the gas moves through this tube, it gives of its heat to the room. Then, it goes through a little nozzle into a tube that has very little pressure. The gas becomes cold. That is the coil inside your fridge. As the gas moves through the cold tube, it becomes warmer. And then it reenters the compressor. (Confused? Here’s a better description)
This also how air conditioners work: The warm coils are outside inside that noisy blower thing, the cold coil is in your basement cooling the air in your ducts.
If you have an air conditioner that also works in reverse to heat your house, this is called a heat pump. A heat pump can be made much more efficient (think twice as efficient) if you use the ground (instead of outside air) as a source or dump for the heat. This is known as a ground-source heat pump.
In the building industry, heating and cooling capacity is discussed in tons. A ton is about 12,000 BTU per hour. My facility needs about 30 tons. For each ton, a ground-source heat pump needs a 200′ deep hole. Drilling 30 of these holes (called “loops”) can be rather expensive — each hole costs about $2200 assuming you are buying in bulk like me.
As a result, a ground-source heat pump system will cost about twice as much as a normal heating and cooling system to install. I have decided to spend the extra money for a ground-source heat pump. Here are my reasons:
- It is efficient. The electricity for the ranch will come from burning coal. It seems like anything I can do to keep a little more coal in the ground is a good thing for us all. Over the long run (think 10 years) this efficiency will also save me money.
- It is quiet. Having several noisy blower things outside would totally harsh my mellow.
- It lasts longer. By keeping all the equipment inside, it should run for centuries.
- It makes hot water. When the heat is sucked out of the room, it can be pumped into cold water (instead of the ground) making hot water for showers.
- Tax credits. Remember the 700-billion bailout? It had a clause that gives a 10% investment tax credit for businesses that buy ground source heat pumps. And Georgia gives a 35% property tax credit for businesses that buy ground source heat pumps. Ah, beautiful socialism!
The tricky part is who should design and install the system for me? The technique is new and there is a lot of money involved. Thus, this is an important and difficult decision. I’ve got it down to two companies: GeoThermal Energy Solutions or Coolray. Anyone have an opinion?