IE890475L

IE890475L - Central heating installation with a circuit for domestic hot water

Info

Publication number: IE890475L
Application number: IE890475A
Authority: IE
Inventors: Rene Prevot
Original assignee: Depalma Mark S
Priority date: 1988-02-16
Filing date: 1989-02-15
Publication date: 1989-08-16
Also published as: NL193470B; IE61549B1; NL8900354A; FR2627263B1; GB8903463D0; DE8901485U1; FR2627263A1; IT8967075A0; GB2216241A; NL193470C; GB2216241B; BE1006641A5; IT1232573B; ATA33289A

Abstract

Central heating apparatus provided with a circuit for hot water for domestic use comprises a heating apparatus having a heating chamber whose lower part is provided with a burner and finned piping of the heating circuit traversing a group of fins located in the upper part of the chamber, the domestic hot water circuit having a second circuit traversing the group of fins and intimately thermally connected with first pipe. In the passage through the group of fins, the central heating water pipe (10') has a generally oval section and the domestic water pipe (12') a circular section and the domestic water pipe is incorporated into the heating water pipe and joined to a wall of the latter. Heat recovery fins (16) are located between the domestic water pipe and the healing water pipe. <IMAGE> [GB2216241A]

Description

P481 5. IE £ -J 54 9 CENTRAL HEATING APPARATUS This invention relates to a central heating apparatus.

Central heating apparatus is known in which a domestic hot water circuit comprises a pipe passing through a group of 10 fins and in intimate thermal connection with another pipe in »hich the heating water circulates. French Patent 1 33 2 607 describes such an installation in which the intimate thermal connection between the first pipe (heating water circuit) and the second pipe (domestic hot water 15 circuit) is obtained by joining the two pipes in such a way as to form a double passage tube which passes through the fins, said tube having an appropriate sectional shape, e.g. circular or elliptical.

Heating installations are also known in which the intimate thermal contact between the two pipes, respectively of the heating water circuit and the domestic water circuit,' is obtained by incorporating one of the pipes into the other, said two pipes then being realised in the form of two 2 5 concentric tubes passing through the group of fins of the heating apparatus.

It is an object of the present invention to provide a central heating apparatus with domestic water and heating 3 0 circuits making it possible to improve the heat exchanges between these two circuits and to increase the efficiency of the apparatus.

According to the present invention, there is provided a central heating apparatus having a circuit for hot water 6 1049 ~ 2 - far domestic use and including heating means comprising a heating chamber with finned piping passing through the heating chamber, the finned piping including a first pipe and a • second pipe incorporated in and in intimate contact with said first pipe, there being at least one heat exchange fin located between the walls of the two pipes and one of the pipes being for the passage of central heating water and the other pipe being for the passage of domestic hot water.

Preferably, the • central heating water pipe has a substantially oval cross-section and the domestic water pipe is located in the central heating water pipe in such a way as to be in contact with the two longer side walls of the central heating water pipe and two heat recovery fins are positioned longitudinally in the central heating water pipe.

Preferably, the domestic water pipe has a circular cross-section and is joined to the central heating water pipe on the circular surface common to both pipes, the two pipes being optionally welded along said common circular surface.

The heat recovery fins may be welded to the two pipes and may have a longitudinal partition located along the axis of the central heating pipe, a circular portion welded to the domestic water pipe and two lateral fins.

Preferably, the domestic water pipe can be welded or brazed to the central heating water pipe wall or walls and preferably the heat recovery fins have a thickness exceeding the thickness of the actual tube in order to further improve heat exchanges.

The central heating circuit pipe may have a flared part at •its exit from the group of fins of the heating apparatus, in order to permit the connection of the two circuits to the cold and hot water supply and discharge pipes respectively., For a better understanding of the inventionr and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Pigure 1 is a side view partly cat-a--'ay shoving two pipes of a central heating installation passing through a group of fins of a heating apparatus, Figure 2 is an end view of the apparatus of Figure 1, with the two pipes being shown in section, Figure 3 is to a larger scale and shows a view in longitudinal section taken along line 3-3 of Figure 2f Figure 4 is a section taken along line 4-4 of Figure 3, Figure 5 is a side elevation of a heater means of the apparatus, Figure 6 is a plan view of the apparatus shown in Figure r Figure 7 is a variant of the apparatus shown in Figure 2, and 4 Figure 8 is a vertical sectional view of the two pipes of the apparatus in the case in which longitudinal fins are provided having a thickness greater than that of the tubes.

Referring to the drawings, it can he seen that the heating apparatus has, in known manner, a first pipe 10 for heating the water of the central heating circuit and a second pipe 12 for heating the water for domestic usage 10 (sanitary water)- In order to improve the heat exchanges between these two pipes, the latter are in intimate thermal contact in the upper part 14 of the heating apparatusr where a group of fins of a heat exchanger of the heating apparatus is located™ The heating apparatus 15 includes a heating chamber with a burner in a lower region thereof and the finned piping in the upper region thereof - In the embodiment illustrated in Figures 1 to 6 in the 20 upper part 14 of the heating chamber, the central heating water pipe 10® has a substantially oval section (in the example illustrated in the drawing, the section is not a perfect oval and is constituted by a curve having two semicircles connected by two planar portions) and the 25 domestic water pipe 12' has a circular section. The two pipes 10E and 123 are incorporated into one another, the pipe 129 being placed within the pipe 10', so that it is joined along one of the semicircular walls of the pipe 101, as can be seen in Figure 2. The two pipes 10'» 12" 30 are preferably welded to one another by their respective common semicircular portions.

In order to aid the heat exchange between the two pipes 10% 12' in their passage through the group of fins of the heating ■ apparatus,. heat recovery fins 16 are provided, which are located within the heating water pipe 103 , so as to be in contact on the one hand with pipe 10 s and on the other with the domestic water pipe 12 V, In the example illustrated in the drawings, the heat recovery fins are welded to the two pipes and have a longitudinal partition 18, a circular portion 20 welded to pipe 12 and two lateral vanes 22, 228 _ Figures 3 to 5 show the way in which tubes 10, 12 are connected to the corresponding pipes 10% 12® at the inlet and outlet of the group of fins. The pipe 10® has flared portions 24, 24s ensuring the positioning and connection by welding of pipes 10% 12° to the supply and discharge tubes.

In the embodiment of apparatus illustrated in Figure 7, the domestic water pipe 12 ® ,J is located in the heating water pipe 10* % so as to come into contact with the two side walls of the pipe 10® 5 to which it is optionally welded. Moreover, there are then two fins 24, 24s arranged longitudinally in the pipe 10' % in order to further increase heat exchanges- ;According to a preferred embodiment illustrated in Figure 7, the heat recovery fins 24, 24® located between the domestic water pipe 12'® and the heating water pipe 10s " have a thickness greater than that of the tubes, in order to further improve the heat exchanges. ;_ g — ;This preferred embodiment has characteristics resulting from the following considerations. In order that the domestic water flowing in the pipe 12'e is able to remove all the thermal power supplied by the burner of the 5 heating installation without, in the inoperative position, the water of the heating eircuit 10"' rising to above 100°C? it is necessary on the one hand for the exchange surface between the tube constituting the domestic water pipe 129 * and the tube constituting the 10 heating water pipe 10'9 to be large and on the other hand for the shape of the tube for the domestic water, as well as its positioning in the tube of the heating water pipe to make it possible to begin a thermal syphon between the top and the bottom of the tube constituting the heating 15 water pipe™ However, it is difficult to satisfy these two requirements™ In order to return to simple geometries making it possible to achieve an automatic assembly of heat 20 exchangers, the basic idea of this preferred variant consists in obtaining freedom from the constraints associated with the convection field within the heating water in the inoperative state by directly transmitting by conduction part of the heat flow to the domestic 25 water.

As can be seen in Figure 7, this result is obtained in this variant by making the tube constituting the domestic water pipe 12'' tangential to the tube constituting the 30 heating water pipe 10'5. Under these conditions, in order to permit a correct heat exchange between the fluids circulating in the different pipes, longitudinal fins 24,. 24 s of a relatively great thickness are provided, which are placed between pipes 10" ' and 12®% as shown in Figure 7, in order to bring about a thermal connection between the domestic water and the fins,, 5 Preferably the thickness to length ratio of the fins is equal to or greater than 0.8.

The present apparatus permits a good heat exchange between the fluids contained in these two pipes , as a 10 result of a large contact surface between them obtained via their relative positioning and due to the presence of recovery fins and the characteristics of the latter™ Thus, in the case of water not flowing for a long time in one of the pipes, its temperature cannot exceed that of 15 the moving water, all the heat collected by the water which is not flowing being transmitted to the flowing water - The arrangement also makes it possible, by stopping the 20 flow of water in one of the pipes, to obtain the total power developed by the heating apparatus in the other pipe„ Through a flow of water in both pipes, it also makes it possible to distribute the total power of the apparatus between the two circuits, as a function of the 25 desired hot water flow, rates.

Claims

1. A central heating apparatus having a circuit for hot water for domestic use and including heating means comprising a heating chamber with, finned piping passing through the heating chamber, the finned piping including a first pipe and a second pipe incorporated In and in intimate contact with said first pipe, there being at least one heat exchange fin located between the walls of the two pipes and one of the pipes being for the passage of central heating water and the other pipe being for the passage of domestic hot water.

2. An apparatus according to claim 1, wherein said second pipe is joined to said first pipe on a common circular surface of the two pipes.

3. An apparatus according to claim 2, wherein the two pipes are welded to one another in the region of their common circular 'surfaces.

4. An apparatus according to claim 3, wherein the or each said heat exchange fin is positioned so as to extend longitudinally of said first pipe. 5 - An apparatus according to any one of the preceding claims, wherein the or each said heat exchange fin is welded to both said pipes.

5. An apparatus according to any one of the preceding claims, wherein the or each said heat exchange fin has a thickness which exceeds the thickness of each said pipe. 7. An apparatus according to any one of the preceding claims except claim 4, wherein the or each said heat exchange fin has a longitudinal partition located along the axis of said first pipe, & circular portion welded to said second pips, and two lateral -veins™ 8. An apparatus according to claim 7, wherein said second pipe is located tangentially relatively to said first pipe and the or each said heat exchange fin extends between said two pipes. 9. An apparatus according to claim B, wherein the thickness to length ratio of the or each said heat exchange fin is equal to or greater than 0.8. 10. An apparatus according to any one of the preceding claims, wherein said first pipe is for the passage of the central heating water and said second pipe is for the passage of the domestic hot water. 11. An apparatus according to any one of the preceding claims, wherein said finned piping follows a tortuous path through the heating chamber. 12. An apparatus according to any one of the preceding claims, wherein said first pipe has a substantially oval cross-section and said second pipe has a circular cross-section. 13. An apparatus according to claim 12, wherein said second pipe is positioned in said first pipe in such a way as to contact the longer side walls of said first pipe. 14. A central heating apparatus according to claim 1P substantially as hereinbefore described with reference to any one of the embodiments shown in the accompanying drawings. MACLACHLAN & DONALDSON Applicants5 Agents, 47 Merrion Square, DUBLIN 2.