IE910330A1

IE910330A1 - Water heating arrangement

Info

Publication number: IE910330A1
Application number: IE33091A
Authority: IE
Original assignee: Baxi Partnership Ltd
Priority date: 1990-02-01
Filing date: 1991-01-31
Publication date: 1991-08-14
Also published as: WO1991011664A1; AU7231991A

Abstract

A water heating arrangement and in particular a combined water heating/central heating arrangement is provided with an enhanced water heating facility compared with existing combined water heating arrangements. The water heating arrangement comprises a primary hot water circuit and a secondary cold water circuit with both circuits including water-to-water heat exchange means located within a storage tank containing intermediate temperature water. The combined water heating arrangement is designed for cylinder/airing cupboard, floor standing and wall mounted applications and consequently provides a siting flexibility not to be found in existing combined water heating arrangements.

Description

This invention relates to a water heating arrangement and in, particular-a combined water heating/central heating arrangement. it is an object ol the present invention to provide such a combined water heating arrangement which provides an enhanced water heating facility compared with existing combined water heating arrangements, According to the present invention there is provided a water heating arrangement comprising a primary hot water circuit and a secondary cold water circuit, with both circuits including water-towater heat exchange means located within a storage tank containing intermediate temperature water (hereinafter and in the claims simply called “intermediate water).

It is to be noted here that the term intermediate water as used herein and in the claims is to be construed as including any suitable liquid, gaseous and/or solid media serving to assist in the water heating capacity of the water heating arrangement.

Preferably the water-tn-water heat exchange means is constituted by an inner· and uuter tube arrangement, one connected to the primary circuit and the other to the secondary circuit.

There may be one or more inner tubes enclosed by the outer tube.

Alternatively the water-to-water heat exchange means is constituted by a plurality of outer tubes, each of which houses one or more inner tubes.

Preferably, the inner tube or tubes Is connected to the primary circuit and the outer tube to the secondary cixxuit.

Alternatively the heat exchange tubes for the two circuits arc arranged in separate parallel array, The heat exchange tubes are preferably of coiled configuration.

Thfi primary circuit is preferably cnrinuctHd to central heating radiator means and to the heat exchange means via a diverter valve, thermostatically controlled to ensure that the supply of hot water to the heat exchange means has priority whp.n required.

The primary circuit preferably includes a hot water boiler, IE 91330 JAN '91 13=48 MARKS & CLERK M/C 061 834 1142 P.4/22 preferably gas-fired and preferably having multi-directional flue means.

Preferably, the hot water boiler is located within th« storage tank at or adjacent the top of the storage tank with at least a heat exchanger of the hot water boiler immersed in the intermediate water contained within the storage tank.

As a result the required fr-tnperature of the intermediate water within the storage tank is more easily maintained.

Preferably, the hot water boiler is a fan-assisted gas boiler with the flue products being drawn through the top (or possibly the tank wall adjacent the top) uf the boiler into a multi-directional flue means.

Preferably, the inner tube or tubes of the water-to-water heat exchange means opens into the storage tank, Preferably, the cp.ntral heating radiator means is part of a sealed central heating system including within the sLurage tank a w&ter-to-water, heat exchange means.

Alternatively, the central heating system can bc fed from a separate water supply tank.

A second and condenser type heat exchanger may he immersed within the intermediate water in the storage tank and in water flow communication with the heat exchanger t,f the hot water boiler.

Ac a result the heat Hxchange rating of the water heating arrangement is significantly improved.

TIih combined water heating arrangement according to thio invention is designed for cylinder/airing cupboard, floor standing and wall mounted applications and consequently provides a siting flexibility not tn he found in existing combined water heating arrangements.

Embodiments of the present invention will now be described, by way of example, with reference l.u the accompanying drawings, In whichiFig. 1. is a diagrammatic view of one embodiment of combined water heating arrangement according to the invention: Fig. 2. is a sectional view through one form of the heat exchange means; •Ε 91330 JAN ’91 13:48 MARKS a CLERK M/C 061 834 1142 P.5/22 Fig. 3. is a diagrammatic view of a second embodiment of combined water heating arrangement: Fig. 4 is a diagrammatic view nf a third embodiment of a combined water heating arrangement according to the present invention; Fig. 5 is a fragmentary diagrammatic view οΓ a fourth embodiment; Fig. 6 is a fragmentary diagrammatic view of a fifth embodiment: Figs. 7 and 8 arc respectively front and side views of a sixth embodiment of combined water beating arrangement; Fig. 9 is a. sectional view uf another form of the heat exchange means; Fig. 10 is a side view of the gas boiler of the. combined water heating arrangement of Figs. 7 and 8; and Fig. 11 is a circuit diagram of the control and ignition means of the combined water heating arrangements of the present invention.

The combined heating boiler arrangement (Figs.l and 2) comprises an insular. Art Intermediate waler storage tank 10 within which is huused a coiled co-axial water--to water heat exchanger 11.

The heat exchanger IL forms part of a hot water primary circuit 12 and also of a cold water secondary circuit 13.

The primary circuit 12 includes a gas-fired water boiler 14 incorporating a fan-assisted gas burner (not shown) and a flue (also not shown) which is multi-directional to suit the particular application involved in any specified premises.

A sealed expansion vp.skf.1 is is connected to the boiler 14 by a pipe 16.

The boiler hot water output is via a pipe 17 and is controlled by a pump 18 and a diverter valve 19, The latter has two outputs, namely via a pipe 20 to central heating radiators generally indicated at 21 and via a pip**. 22 into !.he inner tube 23 of the heater exchanger 11.

It is to be noted that the diverter valve. 19 directs hot water either to the radiators 7.1 nr through the pipe 22 to the heat exchanger 11 with priority being given to the latter when required.

IE 91330 JAN '91 13:4S NARKS & CLERK M/C 061 334 1142 P.6/22 The water return from the central heating radiators 21 to thfi boiler 14 ie via a pipe 24 and the pipe 16.

The heat exchanger inner tube 7.7 is also curmected to the pipe 16 fnr water return from Lhe heat exchanger 11 to the boiler 14, A blow-down pipe 25 incorporating a safety valve 26 connects the boiler output pipe 17 with the interior of the intermediate waiter tank 10, The secondary circuit 13 is connected to the cold water mains supply from which cold water ia delivered to the outer tube 27 of the coiled heat exchanger 11 via a pipe 28 and also to thft domestic water supply 20 via a pipe 30. The outflow of heated water from the heat axr.hang«r tube 27 is via a mixing valve 31 to the domestic water supply 29, the cold water supply from the pipe 30 also passing through the mixing valve 31.

The heat exchanger tube 27 may alternatively be fed from a cistern supply.

From the above it will be 3een that the intermediate water 32 in the storage tank 10, when required, receives additional heat from the boiler primary circuit 12 via the haat exchanger 11.

The diverter valve 19 and the pump 18 are thermostatically controlled.

Associated with the storage tank 10 is a ball float 32 controlling a ball valve 43 incorporated in a pipe 33 extending from the pipe 28 into the tank 10. A stop cock 34 is also incorporated in the pipe 33. The stop cock may alternatively be disposed at location 34A.

The storage tank 10 io provided, ae is usual, with an air vant. pipe 35 and a warning or overflow pipe 36.

An optional water r.np-np system fur the storage tank 10 is indicated in dutted lines and comprises ft pipe 37 connected to the boiler water output pipe 17 and the storage tank 10, a compressor 38 and a one-way non-return valve 39 with the cranprwiNiir 38 being controlled by a float switch or pressnrH switch 40.

ReCurt-mg to Fig. 3, parts identical to those on Figs. 1 and 2 are indicated by the same references with the suffix A”. Certain parts have been omitted for convenience.

In rhlK p.mhndiment, there are two distinctly separate watcr-towater heat exchangers, namely one indicated at 41 within the primary IE 91330 _———fSr‘ JAM '91 13M9 MARKS & CLERK M/C 0S1 834 1142 .7/22 circuit 12 and the other indicated at 42 within The secondary circuit 13.

The heat exchangers 41 and 42 are of single pipe construction, the heat exchanger 41 being connected between the diverter valve 19A, i.e. boiler output pipe 17A, and the boiler return pipe 16A while the heat exchanger 42 is fed from the cold water mains supply pipe 28A or a supply cistern.

Referring imw to Fig. 4 of the drawings the eomhined water hunting arrangement comprises an insulated intermediate water storage tank 50 within which is housed a coiled coaxial water to-water heat exchanger 51.

Disposed within the storage tank 50 at the top thereof is a gas fired water boiler 52 provided with a heat exchanger 53 of cast iron or copper for example.

The gas fired water bnilc.r 52 is fan assisted as indicated at. 54 and the com I ms, tion products from the gas fired water bailer- 52 are .directed through the top of the storage tank 50 into a multidirectional flue system (not shown).

Ir. this embodiment the gas fired water boiler 52 is substantially immersed in the intermediate water contained within the storage tank and it is Lu be noted that the heat exchanger 53 at. lu?ist of the gas fired water boiler 52 is always immersed within the intermediate water.

The heat exchanger 51 and the water boiler 52 constitute an intermediate heat circuit system 55 in communication with a secondary domestic hot water system 56.

A central heating system 57 constituting a primary circuit is in water flow communication with the intermediate water contained within the storage tank 50.

The intermediate heat circuit system 55 incorporates the inner Lube 51A of the heat exchanger 61, which tube 51A is open to the intermediate water within the storage tank 50 in the region of the heat exchanger 53 as indicated at. .58. the tube 51Λ being connected by a pump 59 external of the storage tank 50 and a pipe 60 tn the heat exchanger 53.

The pump 59 has at each side, as is usual, a shut-oii valve or cock 61.

The secondary domestic hot water system is connected to the IE 91330 JAN '91 13=49 MARKS & CLERK M/C 061 334 1142 P.8/2 mid water mains supply from which cold water is delivered to the outer* tube 51B uf the heat, exchanger .11 via a pipe rt? anti a.lsn tn the domestic water supply via a pipe 63. The outflow of heated water from the heat exchanger tube 51B ia via a mixing valve 64 to the domestic water supply, the cold water supply from the pipe 62 also passing through the. mixing valve 64 via a pipe 65.

The supply to pipe 62 may be either from the water mains supply or from a cistern.

A ball float 66 controlling a ball valve 67 is incorporated within the storage tank 50 to control the level nf the intermediate water, the water supply being from the pipe 62 via a pipe 68 which incorporates a control valve 6y.

The storage tank 50 is provided with an overflow pipe 70 and a top air vent 71.

The primary or central heating system 57 comprises central heating radiators generally indicated at 72, the usual flow control valves being indicated at 73.

The cenLral heating system 37 ,5 conn Anted tn the intermediate water of the storage tank SO via a pipe 74 incorporating a pump 73 with at each side shut valves 76. This pipe 74 is the water supply pipe. The return pipe 77 from the system is also connected into the storage tank 50 at a lower level than the outlet to which the pine 74 is connected.

Reference is now made to Fig. 5. Parte identical to the parts shown in Fig. 4 are indicated by the same references with the suffix A.

The water heating arrangement of Fig. 5 ia identical with that described with reference to Fig. 4 save that the centrel heating system is a sealed system, the water inlet and outlet pipes 7ΊΑ and 77A respectively being connected within the storage tank 50A by a coiled tube 78 providing a water-to-water heat exchange relationship with the intermediate water contained within the storage tank 50A.

Instead of being a sealed, system, the central heating system may be fed from 3 separate water supply tank.

Referring now tu Fig. 6, pails identical Lu Lhuse described with reference to Fig. 4 are indicated by the same references with the suffix *B.

IE 91330 JAN '91 13:50 MARKS & CLERK M/C 061 S34 1142 P.9/22 / In this embodiment there io provided a secondary heat exchanger of the condensing type indicated at 79, which heat exchanger is formed for example of aluminium or stainless steel. This heat exchanger has the pipe 60S connected to its inlet and a pipe 80 connects its outlet with the heat exchanger 53B.

The open end 58B of the water-to-water coaxial tube heat exchanger 81 (Identical to heat exchanger 51) is elevated in thin HinliDiliiiiKnl. tn the region of the gas boiler exchanger 53B.

In addition to the aforementioned enhanced water heating capacity and siting versatility, the combined water heating arrangement, compared with the existing arrangements, permits a reduction in Lite overall weight of the storage tank since it is not a sealed tank; allows a reduction in expansion vessel capacity; provides optional topping-up of the primary circuit from the intermediate tank when required.

Reference is now made to Figs. 7 to. 10 and in this embodiment the water to water heat exchanger 90 is constituted by an outer tube 91 housing four inner tubes y2.

The water-to-water heat exchanger 90 is located above the boiler 93, T.bfi gas hurner for the latter being indicated at 94, and the suction fan at' 95. The latter directs burnt gases to a multi-directional concentric flue indicated generally at 96 which handles lumibustion products from the boiler and combustion airnuw to the boiler.

The gas supply l.n the gas burner 54 is via pipe 97 incorporating a control valve 9δ.

The electrical supply to the combined water heating arrangement is indicated at 99 and is fad to a control box 100 to be described later with reference t.n Fig. 11 for controlling the gas valve 98, burner ignition and operation, pumps operation and other electrical components described with reference to Fig, 11.

The water connections are water mains supply feed 101, hot water draw off 102, central healing system flow 104 and central heating return 103.

An intermediate panel 105 is arranged above the Intermediate water to contain the latter and define a compartment 10G, A vent 107 is arranged in this compartment 106 which also houses a float 108 controlling a valve 1(J9 connected to the mains IE 91330 JAN '91 13:50 MARKS & CLERK M/C 061 834 1142 're- Λ water cold feed for topping-up purposes should this prove necessary. Any ouch topping-up water is delivered Into the storage tank 110 by a pipe iii.

Referring naw Lo Fig. 11 there is shown details of the circuitry of the control box indicated at 100 in Fig. 7.

Thi3 circuitry in addition to controlling the gas valve 98 also controls (a) ignition spark and sensing 112; (b) the fan 95} (c) the intermediate circuit, pump 113 for the boiler and domestic hot water supply - see, for example, the pump 59, boiler 52 and hot water supply via mixer valve 61 of the combined water heating arrangement of Fig. 4j (d) the central heating pump 114 - see the pump 75 of the Fig. 4 arrangement.

The electrical mains supply 99 io connected via a storage lank thermostat 115 and a double pole relay li6 to a printed, circuit board 117 to which is electrically connected the fan 95, the gas valve 98 which is of l.hn double solenoid type, a gad pressure switch 118 and the ignition 3park and sensor 112, A normally-closed overheat thermostat 119 ie in circuit with the gas valve 98. The thermostat 119 may alternatively be disposed, in series arrangement, between the storagft tank thermos Lai 115 and the double pole relay 116.

The double pole relay 116 is electrically coupled to the intermediate circuit pump lli which is provided with an overrun thermostat control 120 and a flow switch yr water heating thermostatic control 121, The ηΙκιΧγ ictty mains supply 99 ia also connected directly to the central heating pump 114 with which is also electrically coupled a room thermostat 122 and a clock control 12'5.

The circuitry is shown In Fig. ll, hi a bulk water (intermediate water) store heating made. In which mode the gas boiler Vi for example is on (operational), the intermediate pump 113 is on and the central heating pump 114 is off (non-cperational).

Other operational modes of i.hi.s control circuitry arc as follows;1. Domestic hot water run off, or intermediate pump overrun.

In this mode, pump 113 is on, pump 114 is off and gas boiler is oif.

Compared with the circuitry shown in Fig. ii, the double pnl« IE 91330 JAN '91 13=51 MARKS & CLERK M/C 0S1 834 1142 P.11/22 relay 116 is open, tank thermostat 115 is open and the pump overrun thermostat 120 and hLowswitch or hot water thermostat 121 are both closed (operational). 2. Duiueblic hot waLer and cenLial heating store (intermediate water) temperature satisfied.

In this mode, the circuitry compared with that shown in Fig. 11 has the double pole relay 116 is open, tank thermostat 115 is closed, flow switch of water heating thennosl.Hl. 121 is closed mom thermostat 122 is closed and the clock control 123 ia operational.

Briefly, other possible operational modes are:(a) all systems calling for heat-gas boiler, lnt.ftrmp.rilate pump and central heating pump, all on; (b) central heating only operational gas boiler and intermediate pump both off but central heating pump on; (c) pump overrun-gas boiler and central heating pump both off but ΐηΙ.ΗΓΓΙΙΗ,ΙίχΙ.Ρ. pinny on.

IE 91330 JAN '91 13=51 MARKS a CLERK M/C 061 834 1142

Claims

1. A water heating arrangement comprising a primary hot water circuit and a secondary cold water circuit with both circuits including watcr-to-water heat exchange, means located within a storage Lank containing intermediate temperature water,

2. A water heating arrangement as claimed in claim 1, in which the water to-watcr heat exchange means is constituted by an inner and outer tube arrangement, one connected to the primary circuit and the other to the secondary circuit,

3. A water heating arrangement as claimed in claim 2 in which the heat exchange mcanc is constituted by co-axial tubes,

4. Λ water heating arrangement as claimed in claim 2 in which the heat exchange imwris is constituted by an outer tube and a plurality uf inner tubes,

5. A water heating arrangement as claimed in claim 2, in which the water-to-water heat exchange means is constituted by a plurality of outer tubes, each of which houses one or more inner tubes. fi.

6. A water heating arrangement as claimed in any one of elaime 3 to 5, in which the inner tube or tubes is connected to the primary circuit and the outer tube to the secondary circuit.

7. A water heating Arrangement as claimed in claim 1, in which the heat exchange means comprises separate tubes in parallel array with one connected to the primary circuit and the other to the secondary circuit.

8. A water heating arrangement as claimed in any one of claims 2 to 7 in which the heat exchange tubes are of coiled configuration.

9. A water heating arrangement as claimed in any one of claims 1 to 8 in which the primary circuit is adapted to bc connected to central heating radiator means and is connected to the heat exchange means via a diverter valve, thermostatically controlled to ansurs that the supply uf hot water to the heat exchange means has priority when required.

10. A water heating arrangement as claimed in any one of claims 1 to 9, in which the primary circuit includes a hot wa.i.hi.· boiler, preferably gas-fired and preferably having multi-directional flue means. IE 91330 29 JAN '91 13=51 MARKS & CLERK M/C 061 834 1142

11. A water heating arrangement as claimed in claim 10, in which the hot water boiler is located within -the storage tank at or adjacent the top of the storage tank with at least a heat exchanger of the hot water boiler immersed in the intermediate water contained within the storage tank.

12. A water heating arrangement an claimed in claim 10 or 11, in which the hot water bolter Is a fan assisted gas boiler with the flue products being drawn through the top (or possibly the tank wall adjacent the top) of the boiler into a multi-directional flue means,

13. Λ water heating arrangement, as claimed in any one of claims 1 to 12, in which the inner tube or tubes of the water-to-water, coaxial tube heat exchange means opens or open Into the storage tank.

14. A water heating arrangement as claimed in any one of claims 1 to 13, in combination with a sealed csntral heating system.

15. A water heating arrangement as claimed in any one nf claims 9 to 14 comprising a second and condenser type heat exchanger immersHii within the intermediate water in tbs sLurage tank and in water flow communication with a heat exchanger of the hot water boiler.

16. A water heating arrangement as claimed in any οιικ of claims 9 to 15, combined with a central heating system and having control circuitry for controlling the gas-fired hot water boiler, an intermediate hot water supply pump and a central heating pump as defined with reference to th« description and Fig. 11 of the. drawings.

17. A water heating arrangement substantially as hereinbefore described with reference to one or more of Figures 1 to 11 of the accompanying drawings.