Hello - We are currently construction 2 large-scale homes in Northern California where the owners want to implement Geothermal into the design. The first project has a Geothermal system that required 9 vertical wells, each about 300' deep. The system, after drilling, ducting, equipment, radiant, etc. for a 8,000 sq ft home ended-up being about $230,000. This includes domestic hot water as well climate control for a large wine cellar.

We now have another project in the same area, approx. 14,000 sq. ft. and we are looking for alternatives. Some people have talked about using the swimming pool as a "heat sink" for the system. Does anyone know anything about this? Are there any alternatives to drilling the wells, etc. We are in a planned community where a horizontal system won't work because of space requirements.

Thanks for your help!

Have you looked at the "ACES" system? Here is a pdf to get you started. http://www.osti.gov/accomplishments/pdf/DE00836858/196.pdf
You may not have enough seasonal weather in Northern California to make this work like in Tennessee.

Have you looked at the Daikin AC system?

Sounds like quite the project.
What was the total price for the complete house?
How much did just the drilling cost?
Using the pool might work if you have a really big pool and a really small house. A 14,000 sq ft house needs a lot of "heat sink". You migh need at least a 28,000 sq ft pool, more than 1/2 acre.

I am sure that you want a geo system that works flawlessly to go with what sounds like a mansion. Cutting corners will only cause you grief.

The ground loop is the foundation of the geosystem. Treat it like the foundation of the house, not a place to try and save money.

We are involved in a 14,000 sq ft project where the owner wanted a top notch system with all of the bells and whistles, radiant and forced air, domestic hot water, controls that are internet based , every option imaginable, etc,etc.
The price is up to almost $500,000.

Good luck and let us know.

Alton,
Interesting idea. Did ACES ever go mainstream? All of the info google showed me was from 20+ years ago.

The patent for ACES contains this "The ACES uses a concrete water/ice storage tank for thermal storage and glazed solar collectors to provide supplemental heating to the water/ice tank. The use of these concrete tanks and glazed solar collectors result in an initial cost that is too high to be recovered by fuel savings over a reasonable payback period."



I know of some commercial projects where they use a geo system to make ice at night ( at a lower KW rate) and then use the ice to cool during the day. But that is not the same as ACES.

Is any body doing this today?

Dewayne,
I do not know of anyone using it today. I knew about it because I worked for TVA many years ago. I mentioned it because the technology for solar and geothermal has really improved over the years. With the latest technology and the high energy prices, we need to consider everything we can to conserve.

Ice storage systems are only practical on large commercial project in areas where there is a large utility cost differential between day and night or where there is a very high demand charge. 

The resulting HVAC systems usually use very low chilled water and supply air temperatures.  Accordingly, condensation can be a big problem, so a perfect insulation job is required on the chilled water and supply air sytems.

Overall refrigeration efficiency is less than a standard system chiller or heat pump, but you save a little fan and pump horsepower because of the low distribution temps as well as the ability to use smaller primary air ducts.
 
I think there have been more problematic installations than successful ones.

xexpat