Patent ID: 8176971

Claim:
A method for transferring heat between the earth and a heat transfer fluid, the method comprising flowing heat transfer fluid into an earth loop heat transfer system, the earth loop heat transfer system comprising a heat transfer loop extending from an earth surface down into the earth, the heat transfer loop having a first loop portion extending down into a first part of the earth, the first part of the earth at a first temperature and a second loop portion below the first loop portion and in a second part of the earth, the second part of the earth at a second temperature, the second loop portion in fluid communication with the first loop portion, heat transfer fluid flowable down to the first loop portion and therefrom to the second loop portion, heat transfer fluid flowable up from the second loop portion to the first loop portion and then to the earth surface, valve apparatus in the second loop portion for selectively controlling flow of heat transfer fluid into the second loop portion, and the valve apparatus activatable in response to heat transfer fluid pumped at a pre-determined rate so that when heat transfer fluid is pumped at or above the predetermined rate into the earth loop, the valve apparatus is activated, heat transfer fluid flows to and through the second loop portion, and said heat transfer fluid is exposed to the second temperature, the earth loop heat transfer system including pump apparatus for pumping heat transfer fluid in the heat transfer loop, pumping the heat transfer fluid to the first loop portion of the heat transfer loop at or above a predetermined rate, activating the valve apparatus in response to the pumped heat transfer fluid, and transferring heat at the second loop portion between the earth and the heat transfer fluid at the second temperature, and wherein in the earth loop heat transfer system the valve apparatus includes a first valve and a second valve, the first valve in an inlet to the second loop portion of the heat transfer loop, the second valve in an outlet of the second loop portion of the heat transfer loop, and the first valve and the second valve selectively operable to permit heat transfer fluid flow only through the first loop portion or through the second loop portion, the method further comprising selectively flowing heat transfer fluid through the first loop portion or through the second loop portion by adjusting flow rate of the heat transfer fluid.