AU642126B2

AU642126B2 - Hot water supply

Info

Publication number: AU642126B2
Application number: AU64262/86A
Authority: AU
Inventors: Arthur Maurice Meredith
Original assignee: HEATMASTER TECHNOLOGY Pty Ltd
Current assignee: HEATMASTER TECHNOLOGY Pty Ltd
Priority date: 1985-11-12
Filing date: 1986-10-20
Publication date: 1993-10-14
Anticipated expiration: 2006-10-20
Also published as: AU6426286A

Description

TWENT 1 2LR 6 COMMONWEALTH OF AUSIIALIA 0N N REN 0D 1, LMA PATENTS ACT 1962 COMPLETE SPECIFICATION

(QIRIGINAL)

64 .49/4 Application Number: PH03374 Lodged: 12/11/85 Complete Specification-Lodged: Accepted: Published: Priority: FOR OFFICE USE Class tV O~1986 Int. Class Related Art: Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: TO BE COMPLETED BY APPLICANT ARTHUR MAURICE MEREDITH 45A Monash Avenue, Como~, in the State of' Western Australia, O'ommonwealth of Aus tral ia ARTLHUR MAURICE MEREDITH Wray &.Associates, Primary Industry House, 239 Adelaide Terrace, Perth, W.A. 6000 Complete Specification for the Invention entitled: "HOT WATER SUPPLY" The following statement is a full desc'ription of this inlventiong intludlng the best method of performing It known to me 2 THIS INVENTION relates to a hot water supply utilising a burner as the heat source.

A difficulty which has been encountered with hot water supplies relates to the poor quality of the mains water supply due to the presence of salts which may promote corrosion of the components of the hot water system especially under high temperature. A further difficulty with hot water systems utilising a burner as the heat source relates to the uneven heating of the water within the reservoir resulting in unnecessary stresses being placed on the components of the system. A further difficulty with hot water systems utilising, burners has arisen from the generation of carbon-monoxide which can be extremely hazardous especially if the hot water system is not adequately flued.

It is an object of this invention to at least partially overcome some of the disadvantages referred to above.

o eo The present invention provides a hot water supply comprising a reservoir capable of accommodating a heat exchange liquid, 0.

.0 a combustion chamber mounted within the reservoir to be surrounded by said heat exchange liquid, and to be in heat exchange relationship therewith, a forced air draught burner associated with said combustion chamber and a heat exchanger also located within the reservoir in heat exchange relationship with the heat exchange liquid, the heat exchanger having an inlet connected to a water supply line and an outlet connected to a hot water delivery line, wherein said combustion chamber is shaped and dimensioned to enhance convectional flow of heat exchange liquid around the combustion chamber and to at least minimise contact of the flame generated by said burner with the walls of the combustion chamber, and wherein the operation of the burner 3 is controlled by a thermostat located at or near the lower portion of the heat exchanger.

The burner is controlled by a thermostat located at or near the lower portion of the heat exchanger.

According to a preferred feature of the inventioi said reservoir is vented to atmosphere and is associated with an expansion reservoir.

According to a further preferred feature of the invention the outlet of gases from said combustion chamber is angularly off-set from the direction of projection of the flame from said burner.

:The invention also provides an instantaneous hot water supply comprising a reservoir capable of accommodating a heat exchange liquid, a combustion chamber mounted within the reservoir to be surrounded by said heat exchange liquid, and to be in heat exchange relationship therewith, a forced air draught burner associated with said combustion chamber and a heat exchanger also located within the reservoir in heat exchange relationship with the heat exchange liquid, the heat

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exchanger having an inlet connected to a water supply line and an outlet connected to a hot water delivery line, wherein said combustion chamber is shaped and dimensioned to enhance convectional flow of heat exchange liquid around the combustion chamber and to at least minimise contact of the flame generated by said burner with the walls of the combustion chambez, and wherein the burner is controlled by a thermost.at located at or near the lower portion of the heat exchanger.

Preferably, the reservoir has an upper wall and the portion of the hot water supply above thQ upper wall defines a plenum chamber into which combustion gases exhaust.

3a Further, the burner is preferably a high fire/low fire burner such that the supply has a sufficiently fast recovery rate in order that the supply may be used effectively as an instantaneous hot water supply.

The invention will be more fully understood in the light of the following description of one specific embodiment. The description is made with reference to the accompanying drawings of which: Figure 1 is a general schematic view of the embodiment; and Figure 2 is a schematic sectional elevation of the boiler of the embodiment.

The embodiment is directed to a domestic hot water supply comprising a boiler 11 having a forced air draft burner 12 providing the heat source for the boiler. Fuel for the burner 12 is delivered via a delivery line from a suitable reservoir 13. The boiler 11 is provided with a flue 14 to allow for the escape of exhaust gases from the burner in a safe manner. The boiler 11 comprises a storage reservoir for a heat exchange liquid 15 which will not promote and preferably will inhibit corrosion of the components with which the liquid will come into contact during normal operatioi of the system. The reservoir 11 further accommodates in its lower portion a combustion chamber 16 which has an elbow configuration such that one arm 16a of the elbow opens to one side of the reservoir 11 and the I. 4 other arm 16b is directed upwardly within the reservoir.

Each arm 16a and 16b of the elbow is of a substantially circular cross-section.

The upwardly directed arm 16b of the combustion chamber 16 opens into a series of heat exchange tubes 17 which extend between the uppermost end of the combustion chamber 16 and the upper wall 18 of the reservoir. The upper portion of the boiler 11 above the upper wall 18 of the reservoir defines a plenum chamber 19 into which the combustion gases exhaust. The plenum chamber 19 is provided with a flue outlet 20 for connection with the flue 14. The burner 12 which is of the forced air draught type is mounted to the outer face of the horizontal arm 16a of the combustion :i chamber 16 to direct its flame horizontally into the combustion chamber. The burner is preferably matched to the volume of the combustion chamber such that there is minimal or no flame contact with the walls of the combustion chamber 16. Such contact is likely to result in V incomplete combustion and the generation of carbonmonoxide. The burner is also preferably matched to the volume of the combustion chamber in order to maximise the radiative heat transfer to the walls of the combustion chamber. The elbow configuration of the combustion chamber 16 facilitates the maximisation of the contact of the heated combustion gases with the walls of the combustion chamber and consequent heat transfer. The circular crosssectional configuration of the arms 16a and 16b of the combustion chamber 16 has the advantage in that it serves to enhance the convectional fluid flow of the heat exchange liquid around the combustion chamber during operation of the burner to minimise the boiling of liquid which is in contact with the external surface of the combustion chamber 16.

The reservoir of the boiler 11 further accommodates a heat exchange coil 21 which is disposed substantially vertically 5 within the reservoir and surrounds but is not in contact with the heat exchange tubes 17. The coil 21 has an inlet which is connected to the mains water supply 22 and an outlet which is connected to a domestic hot water line which may have a plurality of outlets 24.

The operation of the burner 12 is controlled from a thermostat 25 which is sensitive to the temperature of the heat exchange liquid adjacent the lower portion of the heat exchange coil 21 whereby on the heat exchange liquid falling below a predetermined temperature the burner is activated. Preferably the volume of heat exchange liquid within the boiler 11 is minimised such that when in use .a substantially minimal amount of energy is consumed in maintaining the heat exchange liquid 15 at the desired temperature. On hot water being drawn from any one of the domestic outlets 24 cold water will enter the coil 21 and become heated during its passage through the heat exchanger 21 resulting in a reduction in temperature of the heat exchange liquid 15. If that reduction in temper, ture causes the temperature to drop below the desired temperature the burner 12 is then activated to provide a heat input to the heat exchange liquid to ensure that water flowing from the outlet of the heat exchange coil 21 falls within the desired temperature range.

As a result of the embodiment a hot water system is provided which has some storage capacity but has a sufficiently fast recovery rate in order that it may be used effectively as an instantaneous heater without the creation Of hot spots in the heat exchange coil which may cause descaling or like deposition and/or corrosion.

The heat exchange liquid 15 in the case of the embodiment comprises water containing suitable additives to retard or eliminate corrosion of the surfaces with which the heat Sexchange liquid comes into contact. The reservoir 11 is krr tEO ,t 6 vented through an expansion tank 26 which is maintained at a substantially constant level through a float controlled valve 27 to the mains water supply 22.

The boiler 11 is preferably dimensioned such that it may be readily installed within a domestic situation and does not need to be disassembled to be carried through standard doorways.

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment described above. In particular the invention need not be limited to the particular domestic application described in relation to the embodiment or to the particular physical configuration of the embodiment.

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Claims

1. A hot water supply comprising a reservoir capable of accommodating a heat exchange liquid, a combustion chamber mounted within the reservoir to be surrounded by said heat exchange liquid, and to be in heat exchange relationship therewith, a forced air draught burner associated with said combustion chamber and a heat exchanger also located within the reservoir in heat exchange relationship with the heat exchange liquid, the heat exchanger having an inlet connected to a water supply line and an outlet cor'-^cted to a hot water delivery line, wherein said combustion chamber is shaped and dimensioned to enhance convectional flow of heat exchange liquid around the combustion chamber and to at least minimise contact of the flame generated by said burner with the walls of the combustion chamber, and wherein the operation of the burner is controlled by a thermostat located at or near the *lower portion of the heat exchanger. C

2. A hot water supply according to claim 1 wherein the reservoir is vented to atmosphere and is associated with an expansion chamber.

3. A hot water supply according to claim 1 or claim 2 wherein the outlet of combustion gases from said combustion chamber is angularly offset from the direction of projection of the flame from said burner. l..e

4. A hot water supply according to any one of claims 1 to 3 wherein the combustion chamber comprises a first portion of substantially circular cross-section which is substantially hcrizontal and opens at one end to the exterior of the reservoir, and a second portion also of substantially circular cross-section which connects with the other end of Ifsj '2 Vify 8 the first portion and extends upwardly therefrom, said burner being supported at the one end of the first portion.

A hot water supply according to claim 4 wherein the upper end of the second portion is in fluid communication with a plurality of upwardly extending heat exchange tubes located within the reservoir which are in fluid communication at their other end with an exhaust flue.

6. A hot water supply according to claim 5 wherein the heat exchanger comprises a coil surrounding, but not in contact with, the heat exchange tubes.

7. A hot water supply according to any one of claims 1 to 6 wherein the reservoir has an upper wall and wherein the portion of the hot water supply above the upper wall defines a plenum chamber into which combustion gases exhaust. 5*

8. A hot water supply according to any one of claims 1 to 7 wherein the burner is a high fire/low fire burner such that the supply has a sufficiently fast recovery rate in order that the supply may be used effectively as an instantaneous hot water supply.

9. A hot water supply according to claim 1 substantially as herein described with reference to the accompanying drawings.

10. An instantaneous hot water supply comprising a reservoir capable of accmmodating a heat exchange liquid, a combustion chamber mounted within the reservoir to be surrounded by said heat exchange liquid, and to be in heat exchange relationship therewith, a forced air draught burner associated with said combustion chamber and a heat exchanger also located within the reservoir in heat exchange relationship with the heat exchange liquid, the heat exchanger having an inlet connected to a water supply line and an outlet connected to a hot water 9 delivery line, wherein said combustion chamber is shaped and dimensioned to enhance cunvectional flow of heat exchange liquid around the combustion chamber and to at least minimise contact of the flame generated by said burner with the walls of the combustion chamber, and wherein the operation of the burner is controlled by a thermostat located at or near the lower portion of the heat exchanger.

11. An instantaneous hot water supply according to claim wherein the reservoir has an upper wall and wherein the portion of the hot water supply above the upper wall defines a plenum chamber into which combustion gases exhaust.

12. An instantaneous hot water supply according to claim or claim 11 wherein the burner is a high fire/low fire burner such that the supply has a sufficiently fast recovery rate in order that the supply may be used effectively as an instantaneous hot water supply. I

13. An instantaneous hot water supply accordirg to claim substantially as herein described in relation to the accompanying drawings. DATED this NINTH day of AUGUST 1993 ARTHUR MAURICE MEREDITH Applicant. C WRAY ASSOCIATES, SPerth, Western Austr~alia, Patent Attorneys for the Applicant.