I believe some of the calculations for hole/trench sizing per ton used for geothermal exchange heating/cooling applications rely on the seasonal nature of heating/cooling. I have heard that if you either heat or cool on a continuous permanent basis, year-round, then you need to allow for more hole or trench since the cold/heat doesn't have an off-season to equalize from the surrounding earth. I don't have hard facts on hand, but it might be a factor worth verifying. On Wed, Mar 26, 2008 at 2:23 AM, Petri Helenius <petri@helenius.fi> wrote:
Paul Vixie wrote:
aside from the corrosive nature of the salt and other minerals, there is
unbelievable maze of permits from various layers of government since
an there's
a protected marshland as well as habitat restoration within a few miles. i think it's safe to say that Sun Quentin could not be built under current rules.
The ones I have are MDPE (Medium Density Polyethylene) and I haven't understood that the plastic would have corrosive features. Obviously it can come down to regulation depending on what you use as a cooling agent but water is very effective if there is no fear of freezing (I use ethanol for that reason). The whole system is closed circuit, I'm not pumping water out of the ground but circulating the ethanol in the vertical ground piping of approximately 360 meters. The amount of slurry that came out of the hole was in order of 5-6 cubic meters. Cannot remember exactly what the individual parts cost but the total investment was less than $10k. (drilling, piping, circulation, air chiller, fluids, etc.) for a system with somewhat over 4kW of cooling capacity. (I'm limited by the airflow, not by the ground hole if the calculations prove correct)
Pete