AU2006201133A1 - Heat pump hot water system - Google Patents

Description

17/03 '06 FRI 13:18 FAX 61299255911 GRIFFITH HACK 003 NO AUSTRALIA o Patents Act 1990 ct COMPLETE SPECIFICATION STANDARD PATENT cI \O Applicant Pioneer International Pty Ltd Invention Title: HEAT PUMP HOT WATER SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me/us: COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 ___17/03 '06 FRI 13:18 FAX 61299255911 GRIFFITH HACK EIJ004 o A HEAT PUMP HOT WATER SYSTEM ct Technical Field This invention relates to a heat pump hot water S system.

en Suimnary of the Invention in a first aspect the present invention provides a 0 heat pump hot water system including: a heat pump circuit made up of an evaporator coil, a compressor, a condenser o coil and at least one capillary tube and adapted to hold a charge of refrigerant; an outlet of the compressor connects to an inlet of the condenser coil; an outlet of the condenser coil connects to an inlet of the at least one capillary tube; an outlet of the at least one capillary tube connects to an inlet of the evaporator coil; an outlet of the evaporator coil connects to an inlet of the compressor; and in use the condenser coil is provided in heat exchanging relationship to a body of water.

The capillary tube may be dimensioned so that, in use, refrigerant flowing out of the capillary tube is at a temperature of greater than zero degrees celsius during normal ambient operating temperatures.

The outlet of the at least one capillary tube may connect to more than one inlet of the evaporator coil by way of a distributor.

The distributor may connect to three inlets of the evaporator coil.

The outlet of the compressor may connect to an inlet of the condenser coil via an expansion chamber.

In a second aspect the present invention provides a hot water heat pump including: a heat pump circuit P60175 COMS ID No: SBMI-03059463 Received by P1 Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:18 FAX 61299255911 GRIFFITH HACK 1005 3 including a compressor and a condenser coil; in use the condenser coil is provided in heat exchanging relationship to a body of water; the heat pump is arranged to operate in a heating mode based on the temperature of the water being heated; when in the heating mode, the flow rate of the compressor is controlled based on the temperature of the water.

The inventors have found that heating water from a temperature of 500c to 600c using this arrangement can save up to 40% input power over this water temperature range.

The flow rate of the compressor may be controlled by cycling the compressor on and off.

The flow rate of the compressor may be controlled by controlling the speed of operation of the compressor.

The flow rate of the compressor may be controlled by passing discharge refrigerant back to the suction line of the compressor.

The system may include more than one compressor and the flow rate may be controlled by controlling the number of compressors that are pumping refrigerant at any one time.

In a third aspect the present invention provides an evaporator coil assembly including: a distributor having one inlet and a plurality of outlets; a coil having a plurality of inlets and a single outlet; the outlets of the distributor are connected to the inlets of the coil.

In this way, refrigerant enters the coil at two or more locations. This spreads the flow of cold refrigerant into the coil in use and assist in avoiding cold spots on the evaporator coil that might cause ice build-up.

In a fourth aspect the present invention provides a condenser coil including: an inner coil having a bore; an P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:19 FAX 61299255911 GRIFFITH HACK M006 O -4 oouter coil having a bore; the inner coil lies inside the bore of the outer coil for a substantial part of its Slength; and in use the core of the inner coil conducts refrigerant.

In this arrangement, if the wall of the inner coil is ruptured to the extent that refrigerant escapes, the M refrigerant is still held within the bore of the outer coil.

O In a fifth aspect the present invention provides a 0 o10 method of fabricating a condenser coil including the steps o of: selecting two lengths of copper tube of appropriate diameter so that one fits inside the other; inserting one tube inside the other; bending the tubes to form a coil.

In a sixth aspect the present invention provides a heat pump hot water system including: a condenser coil and a pressure vessel; the pressure vessel includes a hub having an opening, and the condenser coil is inserted through the opening in the hub.

Brief Description of the Drawings An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a top view of a heat pump hot water system according to an embodiment of the present invention; Figure 2 is a schematic illustration of the heat pump circuit of the hot water system of figure 1; Figure 3 is an enlarged detail view of area A of figure 2; Figure 4 depicts in detail the distributor arrangement of the heat pump hot water system of figure 1; Figure 5 illustrates the condenser coil of figure 1; P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:19 FAX 61299255911 GRIFFITH HACK 16007 0N o Figure SA is a detailed cross sectional view of inlet 22 of the condenser coil of figure Figure 5B depicts an alternative condenser arrangement; Figure 6 is a table used for selecting an appropriate compressor for a refrigeration circuit; enFigure 7 is a table used to select an appropriate capillary tube for a refrigeration circuit; and 0Figure 8 is a diagrammatic explanation of the change of state of refrigerant in a capillary tube.

Detailed Description of the Preferred Embodiment Referring to Figure 1, a heat pump hot water system is shown including a heat pump circuit made up of evaporator coil 12, a compressor 14, expansion chamber a condenser coil 16, and a capillary tube 18. In use, a body of water (not shown) is in heat exchanging relationship with the condenser coil 16. The heat pump can operate in a heating mode to heat the water.

The outlet 20 of compressor 14 connects to inlet 22 of condenser coil 16. The outlet 24 of condenser coil 16 connects to an inlet of capillary tube 18, being one end of tube 18. The other end of capillary tube 18 connects to an inlet of evaporator coil 12 by way of distributor 26. The outlet 28 of evaporator coil 12 connects to the inlet 32 of compressor 14 by way of suction line Prior to use, the heat pump circuit is filled with a charge of refrigerant. The refrigerant is pumped around the circuit by compressor 15. The pumping of refrigerant causes heat energy to be absorbed from the atmosphere by the refrigerant at the evaporator coil 12. The absorbed heat energy is given of f at condenser coil 16 which in turn causes heating of the body of water. Fan 34 draws P6017S COMS ID No: SBMI-03059463 Received by P1 Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:19 FAX 61299255911 GRIFFITH HACK io008

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o air across the evaporator coil 12 to assist in absorption Sof heat from the atmosphere.

Expansion chamber 26 dampens the effect of pressure pulses caused by the operation of the piston in compressor 14. This assists in reducing noise of operation of compressor 14.

e In figure 3, expansion chamber 15 is depicted in more detail. Expansion chamber 15 includes an inlet 36, an o outlet 38, and a body portion 40. The diameter of the \N 10 body portion 40 is approximately 4 times the diameter of Sinlet 36 and outlet 38. The length of body 40 is ci approximately 3mm per cubic centimetre of compressor capacity. Thus, for a compressor of 20cc capacity, an expansion chamber of about 60mm length is used. Expansion chamber 40 is mounted in a vertical position to avoid accumulation of compressor oil in the expansion chamber.

Referring to figure 4, an evaporator coil assembly is shown including distributor 26 and evaporator coil 12.

Distributor 26 has three outlets 26A, 26B and 26C.

Distributor 2G operates to split the flow of refrigerant from capillary tube 18 into three streams. These streams flow to inlets of the evaporator coil 42, 44 46. This assists in spreading the flow of cold refrigerant into the evaporator coil and assists in avoiding cold spots on the evaporator coil that might give rise to ice formation.

Evaporator coil 12 has a single outlet 28 not shown (see fig I).

Referring to figure 5, condenser coil 16 is shown in detail mounted to a pressure vessel in the form of water tank 60. Water tank 60 is surrounded by a layer in insulating material 61 and an outer skin 65. Water tank is shown in cross section. Figure 5a is a detailed view of outlet 24. Inlet 22 is constructed identically to P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:19 FAX 61299255911 GRIFFITH HACK IN109 0N o the outlet, End 24 is designated as the outlet to allow oil return to the compressor through the refrigeration circuit. Condenser coil includes an inner coil having a bore in the form of inner tube 50 having a bore 52 and an S outer coil in the form of outer tube 54 having a bore 56.

In use, tank 60 is filled with water up to about the level Mn indicated by dotted line B and bore 52 transports refrigerant. The condenser is includes a plate 62 which o is sealed air tight where the condenser passes through the plate. Plate 62 is dimensioned to fit to hub 62 of tank o 60. Hub 64 is circular and is provided with holes about its periphery. Plate 62 has holes which correspond to the holes about hub 64. To assemble, condenser 16 is inserted into tank 60 through the centre of hub 64 and threaded fasteners are used to clamp plate 62 to hub 64 to form an air tight seal. The width of the coils of condenser 16 are such that the condenser can be dropped down the aperture in hub 64.

To form condenser coil, two lengths of copper tube are selected of appropriate diameter so that one will be a close fit inside the other and so that no appreciable air gap is created between the outside of the inner tube and the inside of the outer tube. The fit between the tubes should be looser than anl interference fit to allow one tube to slide within the other for assembly. Outer tube 54.is swaged at the ends to form flared portions 58.

Inner tube 50 is then provided with gas tight couplings (not shown) at either end. The inner tube 50 is then inserted inside outer tube and together they are bent into the shape of coil 16 indicated in figure 5 which is akin to a corkscrew type shape with a straight length of tube running inside the corkscrew along the length of the condenser.- P50175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:20 FAX 61299255911 GRIFFITH HACK o010 O 8 0 When assembled, there is no appreciable air gap Sbetween the inner and outer tubes. In this way, when in use, the strength of both tube walls combine to retain the pressurised refrigerant within condenser 16. In one embodiment, the combined thickness of both tube walls is about 0.9mm.

Cn By substantially eliminating an air gap between the walls of the two tubes, heat transfer across the two tube 0 walls is made more effective. An air gap between the tube o 10 walls would serve to insulate the water being heated from o the hot refrigerant in condenser 16.

ci Outer tube 54 lies in contact with the water being heated. If the wall of inner tube 50 is ruptured and refrigerant escapes, it is retained within the bore 56 of outer tube 54. The refrigerant expands and flows along the small gap between the inner and outer tubes to escape to atmosphere at the ends of outer tube 54 indicated by arrows A. Thus, the refrigerant escapes safely and does not come into contact with the water being heated.

Referring to figure 5B, an alternative condenser 116 is shown fitted to a tank identical to the tank shown in figure 5 and like reference numerals have been used. In this embodiment the width of the coils of the corkscrew part of condenser 16 are wider than the aperture in hub 64. To insert condenser 116 it is necessary to first insert end 118 into the aperture and then to rotate the condenser a number of times corresponding to the number of turns of the condenser coil and to guide the condenser into the tank whilst turning. In this way, the condenser coil is gradually inserted into tank 60. In this embodiment, the surface area of the condenser 116 is greater than that of condenser 16 shown in figure 5. This improves heat transfer.

P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:20 FAX 61299255911 GRIFFITH HACK 1011

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o The particular components making up the heat pump Sdepend on the intended use for the heat pump and the intended operating requirements.

A method for selecting components for a particular heat, pump will now be described along with an overview of the design consideration.

Step One: Determine how much energy is needed to 0 heat up a set volume of fluid to a required temperature O 10 within a desired time frame.

ci Example To heat up water from 20°c to 600° Temperature Enthalpy Volume Energy Energy Difference 0 c 83.63kJ/kg 250L 20990kJ 600c 251.13kJ/kg 250L 62782.5kJ 41792.5kJ Therefore, energy required to do this in 4hrs (14400 sec).

Therefore 2.90kW energy is required.

Step Two: Select a refrigerant that will operate in the conditions of the design criteria. Select a compressor for the task that can produce the energy required. There are various types of compressors on the market. A compressor must be selected to give the most efficiency at the refrigerant pressures and ambient it is expected to operate in. It is vitally important for the compressor life that the compressor operates within the desired parameters as set down by the compressor manufacturer. Every compressor is different.

P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:20 FAX 61299255911 GRIFFITH HACK Z012 0 Step Three: Select an evaporator coil that is at ;4 least 1.8-1.5 times bigger in capacity to the output of the compressor. The evaporator must have no more internal resistance than pressure drop of l-2psi. To achieve this the evaporator may need more than one feed, as this slows the refrigerant velocity and reduces the number of bends M in the evaporator that the refrigerant must pass. Each 90° bend is equivalent to an extra meter of resistance of 0 a straight pipe. If multiple feeds are required, it is IO 10 important to use a distributor to feed into the evaporator Scoil. The distributor must always be vertical. The distributor will feed the same mass of refrigerant through each feed in the coil. This maximizes performance of the evaporator coil and reduces power consumption. It is important to always ensure sufficient oil return to the compressor in the evaporating design and refrigeration pipe work returning to the compressor.

Step Four: Select an appropriate capillary. This is done with the aid of an empirically derived chart (see figure 7).

1. Using the capillary tube preliminary selection table (figure 7) and the capacity of the compressor at design conditions, the capillary tube can be designed.

Capacities on this selection table are per one length of capillary tube. For multi-tube selection and/or multicircuit evaporator, divide the compressor capacity by the number of circuits to obtain the required capacity of each tube. Multi-tubes must be of identical length and bore size, and should be identical in configuration.

2. Linear interpolation is acceptable for intermediate bore size to a given length, or, given bore size to intermediate length.

P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:21 FAX 61299255911 GRIFFITH HACK 2013

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0 3. Corrections for other condensing pressures Sbetween 25°c and Increase flow capacity by 2% for each 50c higher than 0 c condensing.

Decrease flow capacity by 3% for each 5°c lower than 0 c condensing.

4. Capillary flow rates are not significantly affected by suction pressure variations that apply over C< the usual refrigeration and air conditioning temperature

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range.

0 5. To provide better stability in flow pattern, selection should always be made on the longest practical length consistent with the application and capacity required. As a rule tube lengths between 2 metres and 5 metres will give best results.

Step Five: Selecting a fan. A base for air flow is 130L/S of air across the evaporator per kW of compressor capacity.

Therefore, a compressor 2.8kW would have a 364L/S of air across the evaporator coil. More air flow is better.

To reduce noise, a larger fan blade should be used-as practically as possible. Then a motor should be selected so that the fan spins as slow as possible to produce the air flow. This reduces the tip speed of the fan, ie tip noise, thus making the fan quieter.

It is important in the design that the airflow out of the heat pump is not able to re-circulate into the air into the heat pump.

Step Six: Selecting an expansion chamber or muffler at the discharge of the compressor. This is done by using the capacity of the compressor or in cubic centimetres and P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:21 FAX 61299255911 GRIFFITH HACK l014 N-12 F0 multiplying by approximately 3. It is important that the Smuffler always be vertical for good compressor oil return and have tapered ends to reduce resistance of the refrigerant flow on expansion chamber as this reduces the pulsing of the refrigerant from the compressor. This reduces compressor noise.

Step Seven: Selecting a condenser Heat Exchanger.

0q Select a heat exchanger that is bigger than required o 10 to maximize performance. Heat exchangers should be o selected to suit the type of fluids that are being heated.

With a wide range on the market it is important to select one with good thermal conductivity and keeps the compressor efficient. The main purpose of the condenser is to provide liquid back to the capillary by condensing super heated refrigerant and expelling energy to create a phase change of the refrigerant, The bi-product of this is the heating up of the fluid described. Ensure that good compressor oil return is possible from the heat exchanger.

Step Eight: Once all the components are selected, they should be installed with the minimum amount of connecting pipe. Every 900 bend has the same resistance as im of pipe. Once all connected and wired, the unit should be evacuated to 100 microns minimum and charged with refrigerant. Ensure that there is enough refrigerant for good sub cooling back to compressor. Refrigeration lines should be kept clean by purging the system with an inert gas when welding.

One embodiment of the heat pump includes the following components: P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:21 FAX 61299255911 GRIFFITH HACK 1@015 13 Component List Rating Supplier Compressor 18cc Danfoss/Electrolux/Techumsuh/ Bristol Fan Motor 1/5hp Tori/Zeal Ebm/Teco Fan Blade 14" 4 blade Tori/Zeal Ebm/Teco High Pressure Cut out Danfoss/Actrol/Alco/Sagnamia Safety Switch 2200kpa/Cut in io00kpa Low Pressure Cut out Danfoss/Actrol/Alco/Sagnamia Safety Switch 20kpa/Cut in 200kpa Evaporator 4kW Aust Coil/Kirby/Heatcraft Coil Fan Cowling Tori/Zeal Ebm/Teco Sheet Metal A&A Industries/AFA/Marciano Base Industries Brackets Electrical Middy's/Turks/Utilux Connectors Wires Copper Tube Crane Copper/BHP/Actrol/ Including Kirby Capillary___ Explanation of Operating Temperature Range The operating temperature range is determined by the ability of the evaporator coil to supply refrigerant back to the compressor in the correct state or temperature for the compressor to safely operate. No consideration is needed on the discharge side of the compressor, as high head pressure relates to high water temperature until the thermostat is satisfied. Should the thermostat fail, the high pressure safety will turn the machine off.

Therefore, with a high ambient limit of 40 0 c. The suction pressure is designed to be approximately 460kpa, which is a refrigerant temperature of 10 0 c. This is the maximum temperature of refrigerant required to cool the P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:21 FAX 61299255911 GRIFFITH HACK I016 S- 14 0 compressor. Any higher than this temperature and the Scompressor is outside its correct operation curves and can fail. This low suction pressure at high temperature is achieved with the over-sized evaporator coil, with low internal resistance and high air flow.

Therefore, low ambient limit is 30c. This suction cn pressure is approximately 220kpa, which is a refrigerant temperature of approximately 3°c. Any lower in 0 refrigerant temperature, it could promote liquid not being o 10 evaporated in the evaporator coil and thus liquid being o returned to the compressor which could cause the compressor to fail. Refrigerant temperatures below 0°c can allow ice to form on the evaporator coil and begin to reduce the effectiveness of evaporation of the refrigerant. Thus again, liquid could return to the compressor- Working Example to Select a Capillary Tube With reference to figures 6 7, a worked example of selecting a capillary tube will now be explained.

Firstly, select a refrigerant for desired application.

For Example, R22. For the purpose of our example, an energy output of approximately 2kW is required.

Select a compressor. Using a condensing temperature that is high, ie. 55°c with an evaporating temperature of 2 0 c. A compressor can then be selected from the compressor charts supplied (see Figure 6).

Referring to figure 6, using compressor model S19UN, we find at 55 0 c condensing at 2 0 c evaporating, this compressor produces (by interpolation) 1944.8watts.

Using the capillary tube selecting table (see Figure we chose a capillary tube bore diameter that suits the capacity of compressor, ie a length between 2 P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:22 FAX 61299255911 GRIFFITH HACK E017

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0 5 metres should be selected and for simplicity, a single i strain capillary will be used.

Using a 1>50mm bore diameter, we find a 2 metre long capillary will give 1946watts.

The capillary design is complete. A capillary that is 2 meters long with a bore diameter of 1.50mm will produce en, 1945watts which is similar to the 1944.8watts the compressor will produce at our requested conditions.

0, Figure 8 illustrates the changes of state in a o 10 refrigerant as it passes through a capillary tube.

0 The heat pump includes a thermostatic arrangement which monitors the temperature of the water being heated.

The thermostat may be adjusted so that the heat pump operates until the temperature of the water is 60 0 c. When the heat pump is operating to heat the water it is said to be in the heating mode. When the water reaches 600c the thermostat operates and shuts off the heat pump until the water temperature again falls below When in the heating mode, the flow rate of the compressor is advantageously controlled based on the current temperature of the water.

The flow rate of the compressor may be controlled by cycling the compressor on and off during the heating mode.

The refrigerant slows through the metering device and equalizes the pressure between the evaporator and condenser. The compressor may be cycled off when the discharge refrigerant temperature is equal to or 5-10c above the liquid line refrigerant temperature. The refrigerant slows in the condenser and is allowed to condense (changing state), which releases energy. As the system equalizes, this process continues until the compressor is cycled on again. The process is repeated P6017S COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:22 FAX 61299255911 GRIFFITH HACK Z018 I-O 16- 0 until the liquid reaches the described temperature.

i Depending on how long the compressor can remain off while still providing energy to the fluid, will dictate energy saving. It is important that cycling the compressor on and off falls within the compressor manufacturers guidelines of number of starts per hour.

cn Alternative methods or controlling the flow rate of the compressor include: Using an invertor or other electrical methods to slow

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the revolutions per minute of the compressor to 0 change the volume of refrigerant and input power.

Using a digital compressor that unloads the compressor by bi-passing the discharge refrigerant back to the suction of the compressor to control the volume of refrigerant and reduce input power.

Using multiple compressors and staging them to cycle off to reduce volume of refrigerant and reduce input power.

Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge, unless otherwise indicated.

Finally, it is to be appreciated that various alterations or additions may be made to the parts previously described without departing from the spirit or ambit of the present invention.

P60375 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17

Claims (17)

1. A heat pump hot water system including: en a heat pump circuit made up of an evaporator coil, a compressor, a condenser coil and at least one capillary tube and adapted to hold a charge of refrigerant; San outlet of the compressor connects to an inlet of the condenser coil; an outlet of the condenser coil connects to the inlet of the at least one capillary.tube; the outlet of the at least one capillary tube connects to an inlet of the evaporator coil; an outlet of the evaporator coil connects to an inlet of the compressor; in use the condenser coil is provided in heat exchanging relationship to a body of water.

2- The capillary tube may be dimensioned so that, in use, refrigerant flowing out of the capillary tube is at a temperature of greater than zero degrees celsius during normal ambient operating temperatures.

3. A heat pump hot water system according to either claim I or claim 2 wherein the outlet of the at least one capillary tube connects to more than one inlet of the evaporator coil by way of a distributor.

4. A heat pump hot water system according to claim 3 wherein the distributor connects to three inlets of the evaporator coil. P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:22_FAX 61299255911 GRIFFITH HACK 020 O 18 0q

5. A heat pump hot water system according to any Spreceding claim wherein the outlet of the compressor connects to an inlet of the condenser coil via an expansion chamber.

A heat pump hot water system including: a heat pump circuit including a compressor and a Ce condenser coil; in use the condenser coil is provided in heat C exchanging relationship to a body of water; cO o 10 the heat pump is arranged to operate in a heating o mode based on the temperature of the water being heated; when in the heating mode, the flow rate of the compressor is controlled based on the temperature of the water.

7. A heat pump hot water system according to claim 6 wherein the flow rate of the compressor is controlled by cycling the compressor on and off.

8. A heat pump hot water system according to claim 6 wherein the flow rate of the compressor is controlled by controlling the speed of operation of the compressor.

9. A heat pump hot water system according to claim 6 wherein the flow rate of the compressor is controlled by passing discharge refrigerant back to the suction line of the compressor.

A heat pump hot water system according to claim 6 wherein the system includes more than one compressor and the flow rate is controlled by controlling the number of compressors that are pumping refrigerant at any one time.

11. An evaporator coil assembly including: a distributor having one inlet and a plurality of P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:23 FAX 61299255911 GRIFFITH HACK Bl021 NO -19 C outlets; k a coil having a plurality of inlets and a single outlet; the outlets of the distributor are connected to the inlets of the coil.

12. An evaporator coil assembly according to claim 11 en wherein the distributor has three outlets and the coil has three inlets. C

13. A condenser coil including; an inner coil having a bore; 0 an outer coil having a bore; the inner coil lies inside the bore of the outer coil for a substantial part of its length; and in use the core of the inner coil conducts refrigerant.

14. A condenser coil according to claim 13 wherein the outer coil has a flared portion at at least one end.

A condenser coil according to either claim 13 or claim 14 wherein the inner coil is a close fit inside the outer coil.

16. A method of fabricating a condenser coil including the steps of: selecting two lengths of copper tube of appropriate diameter so that one fits closely inside the other; inserting one tube inside the other; bending the tubes to form a coil.

17. A heat pump hot water system including: a condenser coil and a pressure vessel; the pressure vessel includes a hub having an opening, and P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17 17/03 '06 FRI 13:23 FAX 61299255911 GRIFFITH HACK 1022 O Sthe condenser coil is inserted through the opening Sin the hub. SDated this 1 7 th day of March 2006 PIONEER INTERNATIONAL PTY LTD By their Patent Attorneys m GRIFFITH HACK P60175 COMS ID No: SBMI-03059463 Received by IP Australia: Time 13:23 Date 2006-03-17