# US 2009/0260378 A1 · DX System Heat to Cool Valves and Line Insulation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2009/0260378 A1 - Document ID: US20090260378A1 - Status: Published application - Kind: A1 - Application number: 12/427,512 - Filed: 2009-04-21 - Published: 2009-10-22 - Earliest claimed: 2008-04-21 - Assignees: Earth to Air Systems, LLC - Inventors: B. Ryland Wiggs - Web page: https://patentgrep.com/patent/US20090260378A1 ## CPC - F25B 30/06: characterised by the source of low potential heat - F25B 47/006: {for preventing frost} - F25B 47/003: {for preventing corrosion} - F25B 2600/2513: Expansion valves - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS ## Abstract Alternative means of inhibiting frosting in the interior heat exchanger of a DX system when switching from the heating mode to the cooling mode, plus an improved insulation and heat transfer means for vertically oriented sub-surface geothermal heat transfer tubing, as well as a means to protectively coat the sub-surface metal tubing of a DX system in a corrosive environment. ## Claims ### Claim 1 A direct exchange heating/cooling system operable in a cooling mode, comprising: a compressor; an interior heat exchanger; a primary liquid refrigerant transport line directing a refrigerant fluid into the heat exchanger; a primary vapor refrigerant transport lien directing the refrigerant fluid out of the heat exchanger; a primary hot gas discharge line directing the refrigerant fluid out of the compressor; and a valve having an inlet port in fluid communication with the primary hot gas discharge line and an outlet port in fluid communication with either the primary liquid refrigerant transport line or the primary vapor refrigerant transport line, the valve being operable to automatically open in the cooling mode to permit at least one of hot gas/vapor refrigerant from the compressor and warm refrigerant vapor exiting the interior heat exchanger to provide supplemental heat to the refrigerant fluid entering the interior heat exchanger, and to automatically close when a temperature of the refrigerant entering the interior heat exchanger reaches a temperature limit of no more than about 5 degrees F. greater than freezing. ### Claim 2 (depends on 1) The system of claim 1, further including an oil separator positioned downstream of the compressor, and in which the valve inlet port fluidly communicates with a point of the primary hot gas discharge line that is positioned downstream of the oil separator. ### Claim 3 An automatically operating valve, which begins to close itself off at about 75 psi, and that modulates to fully close itself off when about 95 psi is reached, in the liquid refrigerant transport line leading into the interior air handler, at a point subsequent to the cooling mode TXV and prior to the distributor to the air handler. ### Claim 4 (depends on 3) Claim 3 where the automatic valve has a pressure-sensing cap filled with gas at a pressure of at least 85 psi. ### Claim 5 An electronic automatic valve, in the cooling mode, that, being otherwise fully open, fully closes itself off when about 95 psi is reached in the liquid refrigerant transport line that leads into the interior air handler, at a point subsequent to the cooling mode TXV and prior to the distributor to the air handler. ### Claim 6 Insulation surrounding the smaller sub-surface liquid refrigerant transport line in a vertically oriented DX system, where the insulation is a solid type insulation material at depths down to, and exceeding, 50 feet. ### Claim 7 (depends on 6) Claim 6 where the solid type insulation is low density polyethylene. ### Claim 8 (depends on 7) Claim 7 where the low density polyethylene is at least 0.1 inches thick. ### Claim 9 (depends on 6) Claim 6 where the heat conductivity rate of the insulation material did not exceed 0.25 BTUs/Ft.Hr. degrees F. ### Claim 10 (depends on 6) Claim 6 where expanded foam, closed cell, plastic insulation is additionally placed around the exterior of the solid state insulation coating on the liquid refrigerant transport line, which expanded foam has a minimum insulation wall thickness of at least ½ inch, and which foam is installed from the ground surface to a depth of at least 50 feet. ### Claim 11 (depends on 10) Claim 10 where the heat conductivity rate of the expanded foam does not exceed 0.25 BTUs/Ft.Hr. degrees F. ### Claim 12 (depends on 7) Claim 7 where the wall thickness of the solid-state insulation material is at least 0.2 inches thick when there is no additional expanded foam, closed cell, plastic insulation surrounding the solid-state insulation. ### Claim 13 (depends on 6) Claim 6 where about the lower 15% of the vertically oriented sub-surface geothermal liquid refrigerant transport line is not insulated. ### Claim 14 A coating for metal refrigerant transport tubing, situated in a sub-surface environment that is corrosive to the metal tubing, where the coating is comprised of a solid-state coating on both the sub-surface refrigerant transport vapor line and liquid line, where the coating is comprised of a protective coating that does not significantly impair geothermal heat transfer. ### Claim 15 (depends on 14) Claim 14 where the coating is a solid-state polyethylene coating that is between 0.01 and 0.02 inches thick. ### Claim 16 A DX system with a valve that automatically opens, in the cooling mode, to permit hot gas/vapor refrigerant, originally exiting from the system's compressor, to enter the refrigerant vapor line exiting the interior heat exchange means, before the vapor enters the system's accumulator, so as to exert a high enough back-pressure on the refrigerant within the interior heat exchanger to prevent frosting of the interior heat exchanger. ### Claim 17 (depends on 16) Claim 16 where the automatic valve has a cap filled with a gas, and where the valve has a pressure sensing/equalization refrigerant transport line situated at least about twelve inches downstream, in the refrigerant flow direction, from the point where the hot gas enters the refrigerant vapor line exiting the interior heat exchange means. ### Claim 18 (depends on 17) Claim 17 where the cap is filled with dry nitrogen at 110 psi for a system operating on an R-410A refrigerant. ### Claim 19 (depends on 17) The system of claim 17 wherein the hot gas refrigerant sent to the interior heat exchanger in the cooling mode is taken from hot gas refrigerant line exiting at least one of the system's compressor and the system's oil separator.