GB2342146A

GB2342146A - Heat exchanger

Info

Publication number: GB2342146A
Application number: GB9919634A
Authority: GB
Inventors: Robert Findlay
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-08-21
Filing date: 1999-08-20
Publication date: 2000-04-05
Also published as: GB9818185D0; GB9919634D0

Abstract

Heat exchange apparatus for transferring heat from waste water to fresh water comprises an exchanger element 6, a waste water supply 5, a fresh water supply 10 and self cleaning filter of the cross flow type (18, Fig 4). Typically the apparatus is used in connection with domestic hot water installations, for example a shower, a bath, a dishwasher or washing machine.

Description

1 2342146 1 HEAT EXCHANGER 2 3 This invention relates to a heat exchanger

for use in 4 reclaiming heat from waste water especially but not 5 exclusively from installations of showers, baths, washing 6 and dishwashing machines and the like. 7 8 Heat exchangers are well known and have many applications 9 for reclaiming waste heat. There are however 10 difficulties which have prevented their widespread 11 application in domestic hot water systems. Efficiency 12 levels are low where heat is extracted from a general 13 waste outlet and transported to the point of use and 14 installations generally require regular cleaning and 15 maintenance to maintain performance. 16 17 There is therefore a need for a simple and effective 18 means of extracting heat from waste hot water especially 19 but not exclusively in domestic situations. 20 21 It is an object of the present invention to provide 22 apparatus for use in extracting heat from domestic waste 23 water supplies. 24 2 1 According to the present invention there is provided heat 2 exchanger apparatus for use in extracting heat from waste 3 water supplies comprising a heat exchanger element having 4 waste water inlet and outlet means, fresh water inlet and outlet means, heat transfer means for transferring heat 6 from the waste water to the fresh water and having self 7 cleaning filter means associated with the waste water 8 inlet.

9 The filter means is preferably a mesh type filter.

11 12 More preferably the mesh is of brass or plastics 13 material.

14 Preferably also the self cleaning is promoted by 16 providing an element of waste water flow across the 17 surface of the filter to dislodge any impurities.

18 19 Preferably the arrangement is such that the proportions of waste water flow into and across the filter can be 21 adjusted to provide a cleaning flow appropriate to the 22 level of impurities in the waste water flow.

23 24 Preferably also the heat exchanger apparatus is incorporated into the supply and waste of a domestic hot 26 water installation.

27 28 The domestic hot water installation may for example be 29 but is not limited to a shower, bath, dishwasher or washing machine.

31 32 The heat exchanger may be provided as a stand alone unit 33 for retro fitment to existing installations or may be 34 incorporated into waste heating apparatus associated with 3 1 the installation to preheat the incoming fresh water 2 supply.

3 4 Embodiments of the present invention will now be described by way of example with reference to the 6 accompanying drawings in which:- 7 8 Figure 1 illustrates a heat exchanger of the present 9 invention incorporated in a shower installation; 11 Figure 2 is a sectional plan view of a heat 12 exchanger of the present invention; 13 14 Figure 3 is an end view of a heat exchanger of the 15 present invention; and 16 17 Figure 4 is a side view of an end portion of the 18 heat exchanger of Figure 2 19 Referring to the drawings, a heat exchanger in accordance 21 with the present invention is illustrated incorporated in 22 a shower installation in Figure 1.

23 24 A shower installation shown generally at 1 comprises a shower head 2 supplied by a heater unit 3. A shower base 26 4 has a waste outlet 5 which connects up to a heat 27 exchanger 6 at an inlet 7. An outlet 8 from the heat 28 exchanger 6 connects to a drain pipe 9. A cold water 29 supply pipe 10 connects to the heat exchanger 6 at an inlet 11 and a supply pipe 12 for the heater unit 3 31 connects to an outlet 13. As can be seen the heat 32 exchanger 6 and assorted fittings fit within the shower 33 base 4. This ensures that standard conventional shower 34 components can be used.

4 2 In use the shower functions initially as normal with the 3 heater unit 3 operating to raise the temperature of the 4 incoming cold supply to the required temperature level. 5 As the waste water drains from the shower base 4 through 6 the waste outlet 5 it passes through the heat exchanger 6 7 on its way to the drain pipe 9. The cold water supply 8 also passes in and out of the heat exchanger 6 via inlet 9 11 and outlet 13 and is pre-heated to some extent by 10 virtue of heat transfer from the waste water. As a 11 result the temperature of the water in the supply pipe 12 12 to the heater unit 3 is raised as compared to the basic 13 cold waste supply pipe 10. Accordingly the heat input 14 required in the heater unit 3 to raise the temperature- of 15 the water to the required temperature level is decreased. 16 17 By virtue of the heat exchanger 6 being installed within 18 the shower base 4 there is minimal heat loss from the 19 waste water before it enters the heat exchanger 6 and the 20 distance to the heater unit 3 is also kept to a minimum. 21 22 The construction of the heat exchanger 6 is illustrated 23 in Figures 2-4. The heat exchanger 6 is constructed from 24 a tubular body 14 provided with brass end caps 15, 16. 25 An in/out assembly 17 is provided at one end of the body 26 14 and has the waste water inlet 7 and outlet 8. The 27 fresh water inlet 11 and outlet 13 are provided on the. 28 end cap 16. A mesh filter assembly 18 is provided within 29 the in/out assembly 17. The flow paths within the heat 30 exchanger 6 for the waste water and the fresh water are 31 shown at 19 and 20 respectively. 32 33 The mesh filter assembly 18 filters out any impurities in 34 the waste water flow which could otherwise in time 1 restrict the flow through the heat exchanger 6. The 2 filter assembly 18 itself is provided with a self 3 cleaning effect by virtue of a small quantity of the 4 waste water flow forming a by pass flow across the-filter assembly 18 which tends to flush off any impurities which 6 would otherwise restrict the filter. The need for 7 maintenance of the heat exchanger is thus minimised.

8 9 In the example described the heat exchanger is incorporated in a shower installation but is not limited 11 to such use. For example heat exchangers of the type 12 described in the present invention might be incorporated 13 into waste outlets of baths, dishwashers, washing 14 machines and other installations where a considerable amount of heat may be otherwise lost in waste water.

16 17 Depending on the type of installation the heat exchanger 18 and the inlet water heater may be mounted separately as 19 in the shower example, adjacent to one another or within a single combined unit. The choice of arrangement will 21 depend on various factors such as the relative positions 22 of the waste water outlet and the fresh water supply.

23 24 Further modifications and improvements may be incorporated without departing from the scope of the 26 invention herein intended.

Claims

6 1 Claims:

2 3 1. Heat exchanger apparatus f or use in extracting heat 4 from waste water supplies comprising a heat exchanger element' having waste water inlet and outlet means 6 fresh water inlet and outlet means, heat transfer means 7 for transferring heat from the waste water to the fresh 8 water and having self cleaning filter means associated 9 with the waste water inlet.

11. 2. Apparatus as claimed in Claim 1 wherein the filter 12 means is preferably a mesh type filter.

13 14 3. Apparatus as claimed in Claim 2 wherein the mesh is of brass or plastics material.

16 17 4. Apparatus as claimed in any of the preceding Claims 18 wherein. the self cleaning is promoted by providing an 19 element of waste water flow across the surface of the filter to dislodge any impurities.

21 22 5. Apparatus as claimed in any of the preceding Claims 23 wherein the arrangement of said apparatus is such that 24 the proportions of waste water flow into and across the filter can be adjusted to provide a cleaning flow 26 appropriate to the level of impurities in the waste 27 water flow.

28 29 6. Apparatus as claimed in any of the preceding Claims wherein the heat exchanger apparatus is incorporated 31 into the supply and waste of a domestic hot water 32 installation.

33 7 1 7. Apparatus as claimed in any of the preceding Claims _ 2 wherein the heat exchanger is provided as a stand alone 3 unit for retro fitment to existing installations.

4 8. Apparatus as claimed in Claims 1-6 wherein the heat 6 exchanger is incorporated into waste heating apparatus 7 associated with the installation to preheat the 8 incoming fresh water supply.