GB2266762A

GB2266762A - Heating domestic water

Info

Publication number: GB2266762A
Application number: GB9118985A
Authority: GB
Inventors: Nicholas Julian Jan F Macphail
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-09-05
Filing date: 1991-09-05
Publication date: 1993-11-10
Anticipated expiration: 2011-09-05
Also published as: GB9118985D0; GB2266762B

Abstract

A heating system comprising a heat exchanger 2 for providing mains pressure domestic hot water fitted externally to and drawing its heat energy from a thermal store. The thermal store 1 may be heated directly by an immersion heater (14) (Fig. 1, not shown) or indirectly using a combustion chamber heated boiler 15. The primary circuit 5/6 includes a pump 12 controlled in dependence on a thermal store thermostat (4) and a flow sensor 3 in a secondary domestic water circuit 7/8. <IMAGE>

Description

Heat Exchangers THIS INVENTION relates to improvements in systems for the supply of mains pressure hot water to, for example, plumbing systems.

It has been common practise in the tank fed supply of hot water to bulk store in a cylinder or the like the hot water which is to be drawn from the taps in a plumbing system. Recent developments have used a thermal store to enable-cold water from the mains supply to be heated indirectly via an internally fitted heat exchanger dispensing with the need for bulk colo water storage tank or the large bore distribution pipes required by the aforementioned tank fed systems.

In one currently available form a cylinder forms a thermal store which is internally provided with a heat exchanger which together with an externally fitted heat exchange boo.ting circulating pump flow switch and other ancillaries provides heated mains hot water to tap.

In another currently available form a thermal store incorporating an internal heat exchanger is positioned adjacent to a boiler inside a boiler casing, again with the required ancillaries to provide mains hot water to tap.

Other forms of boiler incorporating mains water heating via a heat exchanger but without a thermal store are available but such forms without thermal storage suffer from reduced hot water flow rates and or require boilers with larger outputs.

The currently available hot water units incorporating a thermal store and requiring the heat exchanger to be fabricated within the thermal store make variation in the storage to heat exchange ratios impossible after initial manufacture and make service or replacement complicated and expensive.

It is one of the aims of the present invention to improve or obviate the above mentioned problems.

It is a further aim of the present invention to offer an option of electrical standby or stand alone heating to the versions of the thermal store incorporated within boiler casing.

According to the present invention there is provided a system comprising a heat exchanger for providing mains pressure domestic hot water fitted externally to and drawing its heat energy from a thermal store heated integrally any or remotely.

In a preferred form the said thermal store is d copper cyl inoer.

In a further preferred form the said thermal store is formed Dy a non cuprous vessel.

In a further preferred Broiler cased form the said thermal store is wormed adjacent to or within the casing of a boiler but separate to its water jacket.

In a further preferred form-the said thermal store is formed uy an enlarged water jacket of a boiler.

In a further preferred direct fed form the said thermal store is formed by a cold tank fed cylinder having direct draw off to tapis.

Each of the said preferred forms may incorporate a control system being provided with a flow switch and/or a thermal store low temperature thermostat, either or both when actuated respectively by hot mains water flow or a reduction in thermal store temperature, transfers the output of the heat source to the thermal store.

Preferably the thermal store is a water vessel provided with an external heat exchanger having a shunt pump to assist circulation on the primary or store water side of the heat exchanger the said shunt pump may conveniently be flow sensor and/or temperature sensor activated. Mains cold water passes through the secondary side of the heat exchanger where, having absorbed heat from the heat store via the heat exchanger, it passes hot to the taps.

Advantageously a tempering valve to regulate the temperature of the mains hot water is incorporated in the outlet pipework from the heat exchanger, Advantageously the said copper cylinder has an integral or remote cold feed and expansion tank. Where sufficient strength of fabrication ailows, a sealed system with an expansion vessel may be used as a substitute for a feed and expansion tank. The water in the said cylinder form may be heated integrally and/or remotely.

Conveniently the said non cuprous vessel system is a closed system where the thermal store water remains permanently in circuit as a thermal reservoir and may be fabricated from non cuprous materials, for example, sheet steel. Where sufficient strength of fabrication allows, a sealed system with an expansion vessel is used as a substitute for a feed and expansion tank.

The water in the said vessel may be heated integrally and/or remotely.

Advantageously the said boiler cased form provides a heating and hot water supply system within one unit.

Advantageously the said boiler integral form provides a heating and hot water supply system within one unit.

Conveniently the cold tank fed cylinder form provides a thermal store which together with a heat exchanger, bronze or secondary pump with fiow and/or temperature actuation, supply mains pressure hot water to supply a shower or other mains pressure hot water requirements, for example, extra draw offs above the existing storage tank.

Advantageously each of the said preferred forms may incorporate an immersion heater boss andxor immersion heater.

Typically steel jackeed, oil fired boilers, have burners which are fitted with air shutters to prevent loss of heat from the boiler jacket to the chimney, and the thermal store may usefully incorporate an electrical immersion heater to provide a stand aione,stancy neat source.

Conveniently at least the boiler cased and boiler integral forms are provided with a control system which transfers the full heat source output to the thermal store to increase hot water output while draw off occurs and speed temperature recovery after draw off ceases. When the thermal store is adjacent to or integral with the boiler the function of the thermal store low temperature thermostat may be carried out by the boiler control thermostat.

In order that the invention may be more readily understood and so that further features thereof may be appreciated the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a diagramatic representation of a form of the present invention where the thermal store is a cylinder: Figure 2 is a diagramatic representation of a form of the present invention where the thermal store is a separate unit incorporated adjacent to or within the casing of a boiler but separate to its water jacket: Figure 2A is a diagramatic representation of a form of the present invention of Figure 2 showing a preferred water flow configuration.

Figure 3 is a diagramatic representation of a form of the present invention where the thermal store is formed by an enlarged water Jacket of a boiler: Figure 4 is a diagramatic representation of a form where the thermal store is an existing tank fed cylinder.

Figure 5 is a diagramatic representation of a control sytem which forms part of the present invention incorporating two pumps.

Figure u is a diagramatic representation of a control system which forms part of the present invention incorporating two motorised valves.

Referring firstly to Figure I of the accompanying drawings a thermal store (1) provides the heated primary medium via tappings (5 and 6) to the heat exchanger (2). The primary medium is accelerated by a pump (12) actuated by thermal store thermostat (4) any or mains water flow sensor (3). Mains water enters via mains supply (7) passes the double check valves ( flow water sensor (3) the heat exchanger (2) where it is heated and exits to the taps at (8) where a tempering valve (not shown) may be incorporated to regulate its temperature. Pump isolating valves (10) may be provided to ease pump servicing.Thermal store water expansion and cold feed is provided for by the expansion and cold feed tank (9) while an electric immersion heater (14) provides stand alone or standby heating of the thermal store water. A boiler, (not shown) may provide an alternative heat source via extra tappings (not shown) Figure 2 illustrates an embodiment of the invention wherein the thermal store is separate unit incorporated aaJacent to or within the casing of a spoiler out separate to its water jacket where the thermal store (I) which may be formed conveniently from sheet metal provides the heated primary medium via tappings (5 and > to the heat exchanger (2). The primary medium is accelerated by a pump (12) actuated by thermal store thermostat (4) and/or mains water flow sensor (3). Mains water enters via mains supply (7) passes the double check valves (11) flow water sensor (3) the heat exchanger (2) where it is heated and exits to the taps at (8) where a tempering valve (not shown) may be incorporated to regulate its temperature. Pump isolating valves (10) may be provided to ease pump servicing. Thermal store water expansion and cold feed is provided for by the expansion and cold feed tank (9) while an electric immersion heater (14) provides stand alone or standby heating of the thermal store water. The boiler (15) may act as the primary heat source for the thermal store instead of or in combination with the immersion heater (14).A central heating pump ( services a central heating circuit. This twin pump arrangement may be substituted for a single pump and twin valve or single pump and 3 port valve control configuration.

Figure 2A iliustrates a preferred heat exchanger flow and return circuit configuration as would give the longest possible delay In the cooled water returning from the heat exchanger reaching the boiler return port, to reduce boiler combustion chamber condensation probiems.

Figure o illustrates an embodiment of the invention wherein the thermal store is formed oy an enlarged water jacket of a boiler where Ine thermal store (1 > which is formes within the boilers water jacket provides the heated primary medium via tappings (5 and 6) to the heat exchanger (2). The primary medium is accelerated by a pump (12) actuated by thermal store thermostat (4) and/or mains water flow sensor (3). Mains water enters via mains supply (7) passes the double check valves (11) flow water sensor (3) the heat exchanger (2) where it is heated and exits to the taps at (8) where a tempering valve (not shown) may be incorporated to regulate its temperature. Pump isolating valves (10) may be provided to ease pump servicing.Thermal store water expansion and cold feed is provided for by the expansion and cold feed tank (not shown) while an electric immersion heater C14) provides stand alone or standby heating of the thermal store water. The boiler (15) may act ds the primary heat source for the thermal store instead of or in combination with the immersion heater ( Figure 4 illustrates an embodiment of the invention wherein the thermal store is formed by a cold water storage tank fed cylinder. The functioning of the system shown in Figure 4 is similar to that shown in Figure 1 with the exception that water is drawn from the cylinder forming the thermal store (1) to taps via a cold storage supply tank (17) requiring that the pump (12) be a bronze or direct water pump.

Figure 5 is diagramatic representation of a control system which forms part of the present invention incorporating two pumps. with the contacts closed on the fuse and isolation (2O) programmer (21i ana room thermostat (22) but open on the flo: sensor ( ana thermal store thermostat (24) the rela -ri is unenergised and contacts B. and C. are closed and theellne feed from the room thermostat (22) is therefore taken via contacts B.

and C. to energise the pump (27) and the. burner (30) via the control and limit thermostats (28'and 29). Should the flow switch (23) andfor the thermal store thermostat (24) close contact the relay (25) is energised and A. and B. close contact while B. and C. open contact. This switches off the central heating pump (27) while switching on the shunt pump for the thermal store (26) while maintaining the line feed to the burner (30) via stats (28 and 29) via the closed contacts A. and B. The effect of this control is to glve priority to recovering and servicing any thermal store load by shutting off any potential central heating load when either mains hot water flow andfor low temperature occurs in the thermal store.In the above described -control systems the flow switch makes on flow and the thermal store thermostat makes on fall in temperature.

Figure 6 is a diagramatic representation of a control system which forms part of the present invention incorporating two motorised valves. With the contacts of the fuse and isolation (20) programmer (21) and room thermostat (22) closed but with the rlow sensor (23) and thermal store thermostat (24) contacts open the relay (25) has its normally closed contacts B. and C. closed.

The motorised valve serving a central heating system (31) is therefore actuated and the contacts of its switch are closed.

This provides line feed for the pump (26) and the burner (30) via the control thermostat (28) and limit thermostat (29). If the flow sensor (23) and,'or thermal store thermostat (24) are actuated by respectively mains hot water flow or lowered thermal store temperature their contacts close and the relay (25) is actuated opening the contacts B. and C. which closes the central heating motorised valve while the thermal store motorised valve (32) is actuated and its contacts close providing power to the pump (2u) and the burner (30) via the control thermostat (28) and limit thermostat (29).

The above twin valve and pump control function may be substituted by a single flow sharing three port valve and pump.

In the above described control systems the flow switch makes on flow and the thermal store thermostat makes on fall in temperature.

Advantageously a tempering valve may be incorporated on the outlet pipework from the heat exchanger to maintain a steady temperature to the draw offs.

Conveniently the heat exchanger is of the plate type fabricated from stainless steel or copper.

Conveniently the pump, flow switch, thermal store thermostat, double check valves, cylinder, expansion tank and immersion heater are all of the common commercially available type.

Advantageously the said heat exchanger is of the multi plate type and formed from stainless steel or copper.

Typically the boiler integral form would have a water capacity greater than 6 gallons.

Claims

I. A system comprising a heat exchanger for providing mains pressure domestic hot water fitted externally to and drawing its heat energy from a thermal store heated integrally and/or remotely.

2. A system comprising a heat exchanger as defined in Claim I where the thermal store is formed by a copper cylinder.

3. A system comprising a heat exchanger as defined in Claim 1 where the thermal store is formed by a non cuprous vessel.

4. system comprising a heat exchanger as defined in Claim 1 where the thermal store is formed within the casing of the boiler but separately to the water jacket.

5. A system comprising a heat exchanger as defined in Claim 4 where the thermal store is formed by an enlarged water jacket of a boiler.

6. A system comprising a heat exchanger as defined in Claim 1 where the thermal store is a cold tank fed cylinder having direct draw off to tap/s.

6 A system comprising a heat exchanger as defined in Claims 3, 4 and 5 which incorporates an immersion heater boss and/or immersion heater.

8. A system comprising a heat exchanger as defined in any of the above Claims which incorporates a control system being provided with a flow switch and'or a thermal store low temperature thermostat either or both when actuated respectively by hot mains water flow or a reduction in thermal store temperature transfers the output of the heat source to the thermal store.