Direct expansion geothermal heat pump

• US 5,313,804 A
• Filed: 04/23/1993
• Issued: 05/24/1994
• Est. Priority Date: 04/23/1993
• Status: Expired due to Fees

• Current Assignee: Maritime Geothermal Ltd.
• Original Assignee: Maritime Geothermal Ltd.
• Inventors: Kaye, Glenn A.
• Primary Examiner(s): Tanner, Harry B.
• Application Number:
  US08/053,050
• Time in Patent Office: 396 Days
• Field of Search: 62/160, 62/196.4, 62/197, 62/199, 62/200, 62/222, 62/224, 62/225, 62/260, 62/238.1, 62/238.6, 62/238.7, 62/324.1, 62/324.4, 62/324.6, 165/29, 165/45, 237/2 B
• US Class Current: 62/160
• CPC Class Codes: F24T 10/10 with circulation of working fluids through underground channels, the working fluids not coming into direct contact with the ground
• CPC Class Codes: F25B 13/00 Compression machines, plants or systems, with reversible cycle defrosting cycles F25B47/02
• CPC Class Codes: F25B 2313/002 geothermal
• CPC Class Codes: F25B 2313/025 using multiple outdoor units
• CPC Class Codes: F25B 2313/0314 Temperature sensors near the indoor heat exchanger
• CPC Class Codes: F25B 2313/0315 Temperature sensors near the outdoor heat exchanger
• CPC Class Codes: F25B 2600/2513 Expansion valves
• CPC Class Codes: F25B 30/06 characterised by the source of low potential heat
• CPC Class Codes: F25B 41/385 Dispositions with two or more expansion means arranged in parallel on a refrigerant line leading to the same evaporator
• CPC Class Codes: F25B 41/39 Dispositions with two or more expansion means arranged in series, i.e. multi-stage expansion, on a refrigerant line leading to the same evaporator
• CPC Class Codes: Y02E 10/10 Geothermal energy

Abstract

A "DX" heat pump is provided herein which is based on the principle of providing optimal heat exchange in the heating mode through three parallel ground loops, two of which can be cut off from the system and evacuated of refrigerant in the cooling mode. The loops are designed in terms of volume so that the refrigerant charge is correct in the heating mode when split in three loops and also correct in the cooling mode when only one loop is used, but it contains the full system refrigerant charge.

Claims

1. A loop system for use in combination with a "DX" heat pump system comprising:

a) three loops, a first loop including a dual purpose suction/hot gas line and a liquid line, and second and third loops, said second and third loops each including a suction line and a liquid line, each loop being adapted to be buried underground in heat exchange relationship with earth;

b) a refrigerant vapor header provided with a check valve;

c) means connecting said suction/hot gas line of said first loop to said refrigerant vapor header downstream of said check valve;

d) means connecting said suction lines of each of said two other said loops to said refrigerant vapor header upstream of said check valve;

e) a liquid line header provided with an electric solenoid valve;

(f) means connecting said liquid line of said first loop to said liquid line header upstream of said electric solenoid valve;

and g) means connecting said liquid lines of each of said other two loops to said liquid line header downstream of said electric solenoid valve.

2. Said loop system of claim 1 including (h) a scavenging line connected between said refrigerant vapor header upstream of said check valve and an accumulator.

3. Said loop system of claim 1 including:

(i) a liquid line provided with a "TX" valve connected to said liquid line header.

4. Said loop system of claim 1 including (h) a scavenging line connected between refrigerant vapor header upstream of said check valve and an accumulator;

and (i) a liquid line provided with a "TX" valve connected to said liquid line header.

5. A geothermal heating and air conditioning system, comprising:

(i) a compressor means for compressing a refrigerant;

(ii) one or more indoor coils for heat exchange between said refrigerant and inside air;

(iii) at least three outdoor loops which are placed vertically or horizontally below ground for heat exchange between said refrigerant and earth surrounding said outdoor coils, said loops being so designed in terms of volume that said refrigerant charge is correct in said heating mode when split into three loops and is also correct in said cooling mode when only one loop is used;

(iv) a reversing valve which controls said direction of flow of said refrigerant as it leaves said compressor so as to direct said refrigerant header to said ground coil or to said indoor coils; and

(v) an internal heat pump solenoid valve, a check valve and an evacuation line header configuration which enables said manipulation of said heat exchange capabilities of earth exchange coils and reposition refrigerant charge to suit said heating or cooling mode as required using said same refrigerant charge in both modes of operation.

6. A "DX" heat pump system comprising:

a) three earth loops, a first earth loop including a suction line and a liquid line, and said second or third loops including a suction line and a liquid line, each loop being adapted to be buried underground in heat exchange relationship with earth;

b) a refrigerant vapor header provided with a check valve;

c) means connecting said suction/hot gas line of a first said loop to said refrigerant vapor header downstream of said check valve;

d) means connecting said suction lines of each of said two other loops to said refrigerant vapor header upstream of said check valve;

e) a liquid line header provided with an electric solenoid valve;

f) means connecting said liquid line of said first loop to said liquid line header upstream of said electric solenoid valve;

g) means connecting said liquid lines of each of said other two loops to said liquid line header downstream of said electric solenoid valve;

h) a scavenging line connected between said refrigerant vapor header upstream of said check valve and an accumulator;

i) a liquid line provided with a "TX" valve connected to said liquid line header;

j) a reversing valve having two inlets and two outlets;

k) a compressor having an inlet and an outlet, said outlet being connected to said hot gas inlet of said reversing valve;

l) an accumulator having an inlet and an outlet, said outlet being connected to said inlet of said compressor;

m) one outlet of said reversing valve being connected to said inlet of an air condenser;

n) said common suction outlet of said reversing valve being connected to said inlet of said accumulator;

and o) a second inlet of said reversing valve being connected to said refrigerant vapor header downstream of said check valve.

9. A capillary balanced feed "DX" heat pump system of claim 6 in said heating mode, said system comprising:

(a) three earth loops, a first loop including a dual purpose refrigerant vapor line and a liquid line, and said second and third loops, which are operationally idle during said cooling mode, including a suction line and a liquid line, each being adapted to be buried underground in heat exchange relationship with said earth;

(b) a refrigerant vapor header provided with a check valve;

(c) means for connecting said refrigerant vapor line of said first loop and said refrigerant header downstream of said check valve;

(d) means for connecting said suction lines of each of said other two loops to said refrigerant vapor header upstream of said check valve;

(e) a liquid line header provided with an electric solenoids valve;

(f) a bypass liquid line check valve in parallel with a first capillary tube whose inlet is connected to said first earth loop liquid line near said outlet of said first capillary tube and whose outlet is connected to said liquid line header upstream of said solenoid valve;

(g) three capillary tube restriction devices to provide balance refrigerant metering in said heating mode, each capillary tube having one inlet and one outlet;

(h) a thermostatic expansion valve to act as a primary refrigerant metering device, and having one inlet and one outlet, an equalization port and a gas filled controlling bulb;

(i) means for connecting said equalization tube of said thermostatic expansion valve to said common suction outlet of said reversing valve;

(j) means for placing said thermostatic expansion valve controlling bulb in said thermal contact with said common suction outlet of said reversing valve;

(k) means for connecting said inlet of said first capillary tube to said liquid line header upstream of said solenoid valve;

(l) means for connecting said outlet of said first capillary tube to said liquid line of said first earth loop;

(m) means for connecting said inlet ports of said second and third capillary tubes to said liquid line header downstream of said solenoid valve;

(n) means for connecting said outlets of said second land third capillary tubes to said liquid lines of said second and third earth loops, respectively;

(o) a scavenging line connected between said refrigerant vapor header upstream of said check valve and said inlet of said accumulator;

(p) a reversing valve having two inlets and two outlets;

(q) a compressor having an inlet and an outlet, said outlet being connected to said refrigerant vapor inlet of said reversing valve; and

(r) an accumulator having an inlet and an outlet, said outlet being connected to said inlet of said compressor, said hot gas outlet of said reversing valve being connected to said inlet of said air condenser coil, and said suction inlet of said reversing valve being connected to said refrigerant vapor header downstream of said check valve.

10. A capillary balanced feed "DX" heat pump system of claim 6 in said coiling mode, said "DX" heat pump system comprising:

(a) three earth loops, a first loop including dual purpose refrigerant vapor line and a liquid line, and said second and third loops which are operationally idle during said cooling mode, including a suction line and a liquid line, each loop being adapted to be buried underground in a heat exchange relationship with said earth;

(b) a refrigerant vapor header provided with a check valve;

(c) means for connecting said refrigerant vapor line of said first loop and said refrigerant header downstream of said check valve;

(d) means for connecting said idle suction lines of each of said two other loops to said refrigerant vapor header upstream of said check valve;

(e) a liquid line header provided with an electric solenoid valve;

(f) a bypass liquid line check valve in parallel with a first capillary tube whose inlet is connected to said first earth loop liquid line near said outlet of said first capillary tube and whose outlet is connected to said liquid line header upstream of said solenoid valve;

(g) three capillary tube restriction devices to provide balance refrigerant metering in said heating mode, each capillary tube having one inlet and one outlet;

(h) a thermostatic expansion valve to act as said primary refrigerant metering device having one inlet and one outlet, an equalization port and a gas filled controlling bulb;

(i) means for installing a capillary tube bypass between said inlet and outlet of said thermostatic expansion valve;

(j) means for connecting said equalization tube of said thermostatic expansion valve to said common suction outlet of said reversing valve;

(k) means for placing said thermostatic expansion valve controlling bulb in said thermal contact with said common suction outlet of said reversing valve;

(l) means for connecting said inlet of said first capillary tube to said liquid line header upstream of said solenoid valve;

(m) means for connecting said outlet of said first capillary tube to said liquid line of said first earth loop;

(n) means for connecting said inlet ports of said second and third capillary tubes to said liquid line header downstream of said solenoid valve;

(o) means for connecting said outlets of said second and third capillary tubes to said liquid lines of said second and third earth loops, respectively,

(p) a scavenging line connected between said refrigerant vapor header upstream of said check valve and said inlet of said accumulator;

(q) a reversing valve having two inlets and two outlets;

(r) a compressor having an inlet and an outlet, said outlet being connected to said hot gas inlet of said reversing valve; and

(s) an accumulator having an inlet and an outlet, said outlet being connected to said inlet of said compressor, said hot gas outlet of said reversing valve being connected to said refrigerant vapor header and to said hot gas inlet of said first ground loop, said common suction outlet of said reversing valve being connected to said inlet of said accumulator, and said suction inlet of said reversing valve being connected to said refrigerant vapor outlet of said air evaporator coil.

11. An individually "TX" valve metered "DX" heat pump system of claim 6 in said heating mode, said "DX" heat pump system comprising:

(a) three earth loops, a first loop including a refrigerant vapor line and liquid line, and said second and third loops including a suction line and a liquid line, each loop being adapted to be buried underground in heat exchange relationship with said earth;

(b) a refrigerant vapor header provided with a check valve;

(c) means for connecting said refrigerant vapor line of said first loop to said refrigerant header downstream of said check valve;

(d) means for connecting said suction lines of each of said other two loops to said refrigerant vapor header upstream of said check valve;

(e) a liquid line header provided with an electric solenoid valve;

(f) three thermostatic expansion valves to provide refrigerant metering in said heating mode, each valve having one inlet and one outlet, an equalization port and a gas-filled controlling bulb;

(g) one thermostatic expansion valve to provide refrigerant metering in said cooling mode, and having one inlet and one outlet, and equalization port and a gas-filled controlling bulb;

(h) said inlet and outlet of said heating thermostatic expansion valves;

(i) means for connecting said inlet line of one heating thermostatic expansion valve to said liquid line header upstream of said solenoid valve;

(j) means for connecting said outlet of said thermostatic expansion valve to said liquid line of said first earth loop;

(k) means for connecting said equalization tube of said thermostatic expansion valve to said refrigerant vapor header downstream of said check valve;

(l) means for placing said thermostatic expansion valve controlling bulb in said thermal contact with said refrigerant vapor line of said first loop a short distance from its connection to refrigerant vapor header;

(m) means for connecting said inlet ports of said second and third heating thermostatic expansion valves to said liquid line header downstream of said solenoid valve;

(n) means for connecting said outlet ports of said second and third thermostatic expansion valves to said liquid lines of said second and third earth loops respectively;

(o) means for connecting said equalization ports of said second and third thermostatic expansion valves to said refrigerant vapor header downstream of said check valve;

(p) means for placing said thermostatic expansion valve controlling bulbs of said second and third thermostatic expansion valves in said thermal contact with said suction lines of said second and third earth loops respectively, a short distance from said connection to said refrigerant vapor header;

(q) means for connecting said inlet port of said cooling said thermostatic expansion valve to said liquid line of said first earth loop downstream of said outlet of said heating said thermostatic expansion valve and capillary bypass tube;

(r) means for connecting said outlet port of said cooling said thermostatic expansion valve to said liquid line header upstream of said solenoid valve;

(s) means for connecting said equalizer line of said cooling said thermostatic expansion valve to said refrigerant vapor line of said air/refrigerant heat exchanger coil a short distance from said outlet of said coil;

(t) means for placing said controller bulb of said cooling said thermostatic expansion valve in said thermal contact with said refrigerant vapor line of said air/refrigerant heat exchanger coil a short distance from said vapor port of said coil;

(u) a scavenging line connected between said refrigerant vapor header upstream of said check valve and said accumulator;

(v) a reversing valve having two inlets and two outlets;

(w) a compressor having an inlet and an outlet, said outlet being connected to said hot gas inlet of said reversing valve; and

(x) an accumulator having an inlet and an outlet, said outlet being connected to said inlet of said compressor, said hot gas outlet of said reversing valve being connected to said vapor port of said air condenser, said common suction outlet of said reversing valve being connected to said inlet of said accumulator, and said suction inlet of said reversing valve being connected to said refrigerant vapor header downstream of said check valve.

12. An individual "TX" valve metering "DX" heat pump system of claim 6 in said cooling mode, said "DX" system comprising:

(a) three earth loops, a first loop including a hot gas line and a liquid line, and said second and third loops including a suction line and a liquid line, which are operationally idle during such cooling mode, each loop being adapted to be buried underground in heat exchange relationship with said earth;

(b) a refrigerant vapor header provided with a check valve;

(c) means for connecting said refrigerant vapor line of said first loop to said refrigerant vapor header downstream of said check valve;

(d) means for connecting said suction lines of each of said other two loops to said refrigerant vapor header upstream of said check valve;

(e) a liquid line header provided with an electric solenoid valve;

(f) three said thermostatic expansion valves to provide a refrigerant metering in said heating mode, each valve having one inlet and one outlet, an equalization port and a gas filled controlling bulb;

(g) one said thermostatic expansion valve to provide refrigerant metering in said cooling mode and having one inlet and one outlet, an equalization port and a gas-filled controlling bulb;

(h) means for installing a capillary tube bypass between said inlet and outlet of said heating said thermostatic expansion valves;

(i) means for connecting said inlet line of one heating said thermostatic expansion valve to said liquid line header upstream of said solenoid valve;

(j) means for connecting said outlet of said first heating said thermostatic expansion valve to said liquid line of said first earth loop;

(k) means for connecting said equalization tube of said thermostatic expansion valve to said refrigerant vapor header downstream of said check valve;

(l) means for placing said thermostatic expansion valves controlling bulb in said thermal contact with said refrigerant vapor line of said first loop a short distance from its connection to said refrigerant vapor header;

(m) means for connecting said inlet ports of said second and third heating said thermostatic expansion valves to said liquid line header downstream of said solenoid valve;

(n) means for connecting said outlet ports of said second and third said thermostatic expansion valves to said liquid lines of said second and third earth loops respectively;

(o) means for connecting said equalization ports of said second and third valves to said refrigerant vapor header downstream of said check valve means for placing said thermostatic expansion valve controlling bulbs of said second and third valves in said thermal contract with said suction lines of said second and third earth loops respectively a short distance from said connection to said refrigerant vapor header;

(p) means for connecting said inlet port of said cooling said thermostatic expansion valve to said liquid line of said first earth loop downstream of said outlet to said heating said thermostatic expansion valve;

(q) means for connecting said outlet port of said cooling said thermostatic expansion valve to said liquid line header upstream of said solenoid valve;

(r) means for connecting said equalizer line of said cooling said thermostatic expansion valve to said refrigerant vapor line of said air/refrigerant heat exchanger coil a short distance from said vapor port of said coil;

(s) means for placing said controller bulb of said cooling said thermostatic expansion valve on said refrigerant vapor line of said air/refrigerant heat exchanger coil a short distance from said vapor port of said coil;

(t) a scavenging line connected between said refrigerant vapor header upstream of said check valve and extending to said inlet of said accumulator;

(u) a reversing valve having two inlets and two outlets, a compressor having an inlet and an outlet, said outlet being connected to said hot gas inlet of said reversing valve; and

(v) an accumulator having an inlet and an outlet, said outlet being connected to said inlet of said compressor, said hot gas outlet of said reversing valve being connected to said refrigerant vapor header and to said hot gas inlet of said first ground loop said common suction outlet of said reversing valve being connected to said inlet of said accumulator, and said suction inlet of said reversing valve being connected to said refrigerant vapor port of said air evaporator coil.

13. A method for operating said "DX" heat pump system of claim 6 in said heating mode, said method comprising said steps of:

(i) placing liquid refrigerant in each of said earth loop coils in an amount which is insufficient to fill said coils;

(ii) opening said solenoid valve to permit liquid refrigerant to flow down each of said liquid lines of said loops;

(iii) allowing vaporized refrigerant to flow upwardly in each of said suction/hot gas lines to said refrigerant vapor header;

(iv) flowing warmed gas from said three suction lines and said refrigerant vapor header through said reversing valve and said to said accumulator and to said compressor;

(v) flowing compressed refrigerant gas from said compressor through said reversing valve to said air condenser; and

(vi) withdrawing liquid refrigerant from said air condenser through a liquid line having a TX valve therein.

15. A method for operating said "DX" heat pump of claim 9 in said heating mode, said method comprising said steps of:

(i) opening said liquid line solenoid valve;

(ii) maintaining said bypass check valve around said first capillary tube closed by high pressure liquid;

(iii) allowing said thermostatic expansion valve to meter liquid refrigerant to said liquid line header as per said signal of said controller bulb;

(iv) allowing said capillary tubes to restrict said flow slightly so that equal pressure is maintained on said inlet side of each capillary tube;

(v) allowing liquid refrigerant to flow down said liquid lines;

(vi) allowing vaporized refrigerant to flow upwardly in each of said suction lines and said refrigerant vapor header through said reversing valve and to said accumulator and to said compressor;

(vii) flowing compressed refrigerant gas from said compressor through said reversing valve to said air condenser; and

(viii) withdrawing liquid refrigerant from said air condenser through a liquid line towards said liquid line, said thermostatic expansion valve and liquid line header.

16. A method for operating said "DX" heat pump of claim 10 in said cooling mode, said method comprising said steps of:

(i) closing said liquid line solenoid valve;

(ii) maintaining said bypass check valve around said first capillary tube open by high pressure liquid;

(iii) evaporating and scavenging residual liquid refrigerant from idle second and third suction lines into said accumulator and said to said compressor;

(iv) passing compressed refrigerant through said reversing valve and into said hot gas line which is downstream of said check valve on said refrigerant vapor header;

(v) allowing said heat pump to reject its heat to said ground at a pressure which is high enough to force liquid refrigerant up said liquid line;

(vi) allowing said liquid refrigerant to flow through said liquid line check valve and capillary tube on said first ground loop, to said thermostatic expansion valve inlet;

(vii) allowing said thermostatic expansion valve to meter liquid refrigerant to said air coil evaporator as per said signal of said controller bulb; and

(viii) withdrawing warmed refrigerant gas from said air evaporator into said suction line and through said reversing valve into said accumulator and said to said compressor suction inlet.

17. A method for operating said "DX" heat pump of claim 11 in said heating mode, said method comprising said steps of:

(i) opening said liquid line solenoid valve;

(ii) maintaining said cooling said thermostatic expansion valve closed by virtue of its equalizer tube being connected to said refrigerant vapor port of said air coil which is under high pressure during said heating mode;

(iii) allowing said liquid refrigerant to flow into said liquid line header;

(iv) allowing said heating said thermostatic expansion valves to meter liquid refrigerant down each of said three earth loops as per said signal of said respective controller bulbs;

(v) allowing said vaporized refrigerant to flow upwardly in each of said suction lines and said refrigerant vapor header through said reversing valve and said to said accumulator and to said compressor;

(vi) flowing compressed refrigerant gas from said compressor through said reversing valve to said air condenser; and

(vii) withdrawing liquid refrigerant from said air condenser through a liquid line towards said liquid line header.

18. A method for operating said "DX" heat pump of claim 12 in said cooling mode, said method comprising said steps of:

(i) closing said solenoid valve, said preventing liquid refrigerant from entering said two loops which are downstream of said solenoid valve;

(ii) maintaining said refrigerant vapor header check valve closed by hot high pressure gas, whereby said got gas is directed only to said first ground loop;

(iii) maintaining said three heating said thermostatic expansion valves closed as a result of said equalizer tubes being connected to said currently high pressure refrigerant vapor line downstream of said check valve;

(iv) evaporating and scavenging residual liquid refrigerant from said liquid refrigerant lines which are downstream of said solenoid valve to said accumulator and said to said compressor;

(v) passing compressed refrigerant through said reversing valve and into said refrigerant vapor line which is downstream of said check valve;

(vi) allowing said heat pump to reject it heat to said ground at a pressure which is high enough to force liquid refrigerant through said liquid refrigerant line connected to said inlet port of said cooling said thermostatic expansion valve and through a by-pass capillary tube of said heating said thermostatic expansion valve;

(vii) allowing said cooling said thermostatic expansion valve to meter said correct amount of liquid refrigerant into said air evaporator by virtue of said placement of its controlling bulb and equalizer tube a short distance from said refrigerant vapor outlet; and

(viii) withdrawing warmed refrigerant gas from said air evaporator into said suction line and through said reversing valve into said accumulator and to said compressor suction inlet.

7. A "DX" heat pump system comprising in said heating mode, said system:

(a) three earth loops, a first earth loop including a suction line and a liquid line, and said second and third loops including a suction line and a liquid line, each loop being adapted to be buried underground in heat exchange relationship with earth;

(b) a refrigerant vapor header provided with a check valve;

(c) means connecting said suction line of a first said loop to said refrigerant vapor header downstream of said check valve;

(d) means connecting said suction lines of each of said two other loops to said refrigerant vapor header upstream of said check valve;

(e) a liquid line header provided with an electric solenoid valve;

(f) means connecting said liquid line of said first loop to said liquid line header upstream of said electric solenoid valve;

(g) means connecting said liquid lines of each of said other two loops to said liquid line header downstream of said electric solenoid valve;

(h) a scavenging line connected between said refrigerant vapor header upstream of said check valve and an accumulator;

(i) a liquid line provided with a "TX" valve connected to said liquid line header;

(j) a reversing valve having two inlets and two outlets;

(k) a compressor having an inlet and an outlet, said outlet being connected to said hot gas inlet of said reversing valve;

(l) an accumulator having an inlet and an outlet, said outlet being connected to said inlet of said compressor;

(m) said hot gas outlet of said reversing valve being connected to said inlet of an air condenser;

(n) a common suction outlet of said reversing valve being connected to said inlet of said accumulator;

and (o) said suction inlet of said reversing valve being connected to said refrigerant vapor header downstream of said check valve.

8. A "DX" heat pump system comprising in said cooling mode, said "DX" heat pump system comprising:

(a) three earth loops, a first loop including a hot gas line and a liquid line, and said second and third loops including a suction line and a liquid line, which are operationally idle during such cooling mode, each loop being adapted to be buried underground in heat exchange relationship with said earth;

(b) a refrigerant vapor header provided with a check valve;

(c) means connecting said hot gas line of a first loop to said refrigerant vapor header downstream of said check valve;

(d) means connecting said idle suction lines of each of said two other loops to said refrigerant vapor header upstream of said check valve;

(e) a liquid line header provided with an electric solenoid valve;

(f) means connecting said liquid line of said first loop to said liquid line header upstream of said electric solenoid valve;

(g) means connecting said liquid lines of each of said other two loops to said liquid line header downstream of said electric solenoid valve;

(h) a scavenging line connected between said refrigerant vapor header upstream of said check valve and an accumulator;

(i) a liquid line provided with a "TX" valve connected to said liquid line header;

(j) a reversing valve having two inlets and two outlets;

(k) a compressor having an inlet and an outlet, said outlet being connected to said hot gas inlet of said reversing valve;

(l) an accumulator having an inlet and an outlet, said outlet being connected to said inlet of said compressor;

(m) said suction inlet of said reversing valve being connected to said outlet of an air evaporator;

(n) said suction outlet of said reversing valve being connected to said inlet of said accumulator;

(o) said hot gas outlet of said reversing valve being connected to said refrigerant vapor header downstream of said check valve.

14. A method of operating said "DX" heat pump system of claim 8 in said cooling mode, said method comprising said steps of:

(i) closing said solenoid valve, said preventing liquid refrigerant from entering said two loops which are downstream of said solenoid valve;

(ii) high pressure hot discharge gas closes said check valve to assure that warmed refrigerant gas in refrigerant vapor header enters only said suction/hot gas line which is downstream of said valve;

(iii) scavenging residual liquid refrigerant from said liquid refrigerant lines which are upstream of said solenoid valve to said accumulator and said to said compressor;

(iv) passing compressed refrigerant through said reversing valve and into said suction hot gas line which is downstream of said check valve;

(v) allowing said heat pump to reject its heat to said ground at a pressure which is high enough to force liquid refrigerant through said liquid refrigerant line connected to said liquid refrigerant header downstream of said solenoid valve;

(vi) passing liquid refrigerant through said expansion valve and into said air evaporator; and

(vii) withdrawing warmed refrigerant gas from said air evaporator into said suction line and through said reversing valve to said accumulator.