GB2431228A

GB2431228A - Heating system for hot water and space heating comprising a solar panel and a fuel fired boiler

Info

Publication number: GB2431228A
Application number: GB0605648A
Authority: GB
Inventors: Matthew Lee
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-11-19
Filing date: 2006-03-21
Publication date: 2007-04-18
Anticipated expiration: 2026-03-21
Also published as: GB0523602D0; GB0605648D0; GB2431228B

Abstract

A heating system comprises a water tank 10 adapted to receive cold water and having a hot water outlet. The tank contains at least a first heat exchange coil 12 connected to a circuit 18 including at least one solar panel, a second heat exchange coil 14 connected to a circuit including a fuel fired boiler unit 20, and a third heat exchange coil 16 connected to a space heating circuit 28. The first and/or second coils operate to heat the water within the tank to provide hot water. The third coil operates to transfer heat energy from the hot water to the space heating circuit. Preferably, the space heating circuit incorporates a series of radiators (54, fig.2) and/or an underfloor heating system (52, fig.2). A control valve 44 may be provided in the system operable to supply the space heating circuit directly from the boiler unit. Temperature sensors 64, 66 and pumps 22, 30 may also be provided to control the operation of the heating system. Preferably, separate additional heat exchange coils (50, fig.2) are provided in the water tank which may be connected to different parts of the space heating system; one coil may be connected to a series of radiators whilst another coil may be connected to an underfloor heating system. Preferably, an additional heat exchange coil is connected to the water heating system of a swimming pool. An additional coil (62, fig.3) may be provided towards the bottom of the water tank to allow the use of a ground source heat pump. The water tank may also incorporate an electrically powered immersion heating coil supplied with electricity from a wind powered turbine or photovoltaic cells.

Description

I

Hting System This invention relates to a heating system, and in particular to a heating system enabling solar energy to be used to provide heat and/or hot water to a building. Although suitable for use in the provision of domestic hot water and/or heating, the invention is also applicable to commercial hot water and heating systems.

Heating systems whereby a boiler unit, for example a gas fired or oil filed boiler, is used to heat water which is then pumped through a series of radiators to heat a building are well known. It is also well known for the water heated in this manner to be passed through a heat exchanging coil of a hot water tank or cylinder to provide hot water, for example for washing and bathing purposes.

To reduce the quantity of fuel used in providing heating and hot water, it is also known to capture solar energy using solar panels. The heat energy captured in this manner is used to provide hot water or space heating. As the quantity of solar energy available to be captured varies seasonally and with atmospheric and weather conditions, systems making use of solar energy are generally provided in addition to, rather than as alternatives to, boiler unit heated systems. The provision of two independent systems to allow hot water and heating to be provided using solar energy and using a fuel fired boiler unit is cumbersome and undesirable.

A system is known in which solar energy and, when rcquircd, a boiler unit are used to heat a heat storage medium which, in turn, is used to provide hot water and to provide heat via a series of radiators. However, the system is of' limited flexibility and does not permit the storage of a significant quantity of hot water According to the present invention there is provided a heating system comprising a water tank adapted to receive cold water and having a hot water outlet, the tank containing at least a first heat exchange coil connected to a circuit containing at least one solar panel, a second heat exchange coil connected to a circuit containing a fuel fired boiler unit, and a third heat exchanger coil connected to a space heating circuit, the first and/or second coils operating, in use, to heat the water within the tank to provide hot waler, and the third coil operating, in use, to transfer heat energy from the hot water to the space heating circuit The space heating circuit may incorporate a series ofradiators, Alternatively, it nmy comprise an underiloor heating arrangennL Further, it could incorporate a coirtination of radiators and underfloor heating systenis.

Such a system is advantageous in that hot water and/or heating can be provided using solar energy or the operation of a fuel fired boiler unit or the combination of these energy sources. It will be appreciated that this allows optimisaiion of the use of solar energy. topping up with the operation of the fuel fired boiler unit when insufficient solar energy can be captured to meet the system requirements.

Where the boiler unit is being used, valves provided in the system may be operated to supply the space heating circuit directly from the boiler unit.

Additional heat exchange coils may be provided in the tank. For example, the tank could include four or five heat exchange coils.

Such a system allows separate coils to be connected to different parts of the space heating system. For example, one coil may be connected to a series of radiators and another coil connected to an underfioor heating system. A further coil could be connected to, for example, the water heating system of a swimming pool. The temperature/heat energy requirements of such system parts differ from one another, and the coil or coil positions to which they are connected can be chosen accordingly, bearing in mind the temperature gradient between the top and bottom of the tank.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagraimnatic view illustrating a system in accordance with one embodiment of the invention; Figure 2 is a view similar to Figure 1, illustrating an alternative arrangement; and Figure 3 is a view illustrating a modification.

The heating system illustrated diagrammatically in Figure 1 comprises a hot water tank 10 provided with three heat exchanging coils 12, 14, 16. The tank 10 is provided with a cold water inlet to allow the supply of cold water thereto and a hot water outlet to allow the extraction of water heated whilst in the tank 10 for subsequent use, for example in a domestic hot water system for washing or bathing purposes. The manner in which cold water is supplied to the tank 10 and extracted therefrom is conventional and will not be described in further detail.

A first one of the coils 12 is connected to a solar panel-type arrangement 18 for capturing solar energy. Fluid in the form of a solution of a material having a low freezing point is heated by solar energy in a solar panel (not shown) and is pumped to the first heat exchange coil 12 where heat energy from the fluid is transferred to the water within the tank 10. The fluid Leaving the coil 12 is returned to the solar panel ready to be re-heated by solar energy.

The second coil 14 is connected to a gas fired boiler unit, for example in the form of a condensing boiler. The boiler unit 20 includes a pump 22 whereby fluid heated by the unit is pumped through line 24 to the second coil 14, the second coil 14 serving to transfer heat from the liquid heated by the boiler 20 to the water within the tank 10. The line 24 mcorporates a check valve 46 and a control valve 44. The liquid leaving the coil 14 is returned through a return line 26 to the boiler unit 20 for subsequent reheating.

The third coil 16 is connected to a space heating circuit 28. As illustrated, the circuit 28 includes a pump 30 arranged to pump fluid heated by the hot water within the tank 10 as the passes through the coil 16, the fluid being pumped by the pump 30 through a check valve 32 to line 24, and through the control valve 44 to a sub-circuit 34 containing a series of radiators and a sub-circuit 36 used in the provision of under floor heating. A further sub- circuit 38 is also provided to allow heat extracted from the tank 10 in this manner to be used in the heating of, for example, a swimming pool or other heat using arrangement. Each of the circuits 34, 36, 38 includes associated control arrangements to allow the independent operation thereof and to control the relative amount of extracted heat used by each of the circuits.

Each of the subs-circuits 34, 36, 38 includes an associated return line connected to a return line 40 whereby the fluid from which heat energy has been extracted is returned to the coil 16 for reheating by the hot water contained within the tank 10.

A bypass return line 48 is provided between the return line 40 and line 26.

In use of the arrangement illustrated in Figure 1, solar energy captured by the solar panel of the arrangement 18 is transferred to the water within the tank 10 by the first heat exchange coil 12. If sufficient solar energy is captured to allow the full operation of the heating system, then the boiler unit 20 is not operated, and the pump 22 is not driven.

During this mode of operation, the second heat exchange coil 14 is redundant. The water within the tank 10 heated by the first exchange coil 12 is used to provide hot water, for example for bathing or washing purposes and is also used to heat the fluid within the third heat exchange coil 16 thereby allowing heat energy from the tank 10 to be extracted and used in the operation of the sub-circuits 34, 36, 38. Fluid from the sub-circuits 34, 36, 38 is returned via the return line 40 to the third heat exchange coil 16 for subsequent re-heating by the hot water contained within the water tank 10.

If it is deternimed that the solar energy capture arrangement 18 is unable to meet the full heat energy requirements of the system, then the boiler unit 20 is operated to supplement the heat energy captured by the arrangement 18. The boiler unit 20 heats liquid which is pumped by the pump 22 through the line 24 and control valve 44 to the second heat exchange coil 14 at which point heat energy is extracted from the liquid and serves to assist the solar energy in heating the water within the water tank 10. Liquid from the coil 14 is returned via the return line 26 to the boiler unit 20. It will be appreciated that in these circumstanc the provision of hot is achieved by the combination of the captured solar energy and the operation of the boiler unit 20, the boiler unit 20 serving to make up the difference between the amount of energy captured by the arrangement 18 and the system energy requirement.

Rather than use the third coil 16 to extract heat from the hot water in this mode of operation, the circuit illustrated in Figure 1 may be operated, by appropriate control of the control valve 44 to allow fluid heated by the boiler unit 20 to be supplied directly to the sub- circuits 34, 36, 38 such that the heat energy requirements of these sub- circuits can be met directly from the boiler unit 20 rather than by the boiler unit 20 being used to supplement the heating of water within the water tank 10, the hot water then being used to provide the heat energy requirements of these circuits through the third heat exchange coil 16. When operating in this mode, liquid is returned from the sub-circuits 34, 36, 38 via the bypass return line 48 to the boiler unit 20. In this mode of operation the third coil 16 may be redundant.

It will be appreciated that the arrangement illustrated in Figure 1 is advantageous in that all available solar energy captured by the arrangement 18 can be used throughout the year, the operation of the boiler unit 20 being used to provide additional heat only when insufficient solar heat energy can be captured.

To permit effective control over the operation of the system, a series of temperature sensors or thermostats are provided. For example a first sensor 64 may be provided to monitor the water temperature close to the top of the tank 10. When hot water is required, if the first sensor 64 indicates that the water temperature is sufficient the boiler 20 is switched off If it is insufficient, the boiler unit 20 is switched on and the control valve 44 operated to supply the boiler output to the second coil 14 until the sensed temperature is

acceptable.

If heating is required the pump 30 is driven and a sensor 66 located close to the pump 30 determines, after a predetermined time interval of, say, 30 seconds, whether the temperature is acceptable. If it is, the pump 30 continues to operate and the control valve is operated to supply at least a proportion of the liquid to the heating circuit. A sensor 68 associated with the heating circuit is used to control the operation of the valve 44 to divert the desired quantity of liquid to the heating circuit. If sensor 66 determines that the temperature is insufficient then pump 30 is switched off and the boiler unit 20 is used to supply hot liquid to the control valve 44 and heating circuit.

The arrangement described and illustrated hereinbefore is of simplified form, and it will be appreciated that in a real installation, further components are likely to be provided.

For example, the water tank 10 may be provided with an electrically operated immersion heater, indeed the provision of two or three such heaters is envisaged. Thermostats and other devices for use in controlling the operation of the system will also be provided. The thermostats could be located within the water tank 10, or alternatively could be located within adjacent parts of the connecting lines. A number of other modifications and alterations are possible.

Figure 2 illustrates an alternative to the arrangement illustrated in Figure 1. The main difference between the two illustrated arrangements is that in the arrangement of Figure 2 an additional heat exchanging coil 50 is provided. The heat exchange coil 16 is used to provide heat energy to an under floor heating circuit 52 whilst the fourth heat exchange coil 50 is used to provide heat energy to a radiator system 54. Additional bypass feed and return lines 56, 58 are also provided, suitable valves 60 being provided in the bypass feed line. Operation of this arrangement is largely as described hereinbefore.

One advantage of the arrangement illustrated in Figure 2 is that, as the water temperature within the water tank 10 is hottest towards the top of the tank and lowest towards the bottom thereof, the amount of heat energy able to be extracted by the fourth heat exchange coil 16 is greater than that available to be extracted by the third heat exchange coil 16. As a consequence, the circuit 54 can be provided with more heat energy than the circuit 52. It will be appreciated, therefore, that the heat energy requirements of the circuits 52, 54 can be tuned to the available heat energy from the water tank 10 by connection to appropriately positioned ones of the coils.

Although the arrangement in Figure 2 illustrates the provision offour coils within the water tank 10, if required a fifth coil could be provided, for example to provide heat energy to the water heating system of swimming pool or another heat energy using circuit.

Figure 3 illustrates a modification to the water tank 10 of the arrangement shown in Figure 2, in which an additional coil 62 is provided towards the bottom of the water tank 10 to allow the use of a ground source heat pump to provide some heat energy to the water in the tank 10. Further, the fourth coil 50 extends generally vertically from the top of the tank to a position part-way along the height of the tank and is used to provide heat energy to a series of radiators, a swimming pool, a plated heat exchanger and/or any other ancillaiy heating equipment, the third coil 16 providing heat to an underfloor heating circuit. This arrangement is thought to be most suitable for light commercial, commercial or industrial use, whereas the arrangements of Figures 1 and 2 are more suitable for domestic applications in which the cylinder input is below 45kW.

A modification which could be made to any of the above described arrangements is to incorporate an electrically powered heating coil, for example in the form of an immersion heater, into the cylinder. A wind powered turbine could be used to generate some or all of the electricity used by the coil. Although the use of a wind powered turbine is envisaged, it will be appreciated that a number of other electrical generation techniques could be used to provide the electrical power for the coil, for example an array of photoelectric cells could be used. Further, if desired, the electrical energy provided by the turbine, cells or the like could, if desired, be stored in, for example, a battery or other storage device, for use at a subsequent point in time under the control of a suitable control arrangement, if desired.

It will be appreciated that a wide range of modifications and alterations may be made to the arrangement described hereinbefore without departing from the scope of the invention.

Claims

1. A heating system comprising a water tank adapted to receive cold water and having a hot water outlet, the tank containing at least a first heat exchange coil connected to a circuit containing at least one solar panel, a second heat exchange coil connected to a circuit containing a fuel fired boiler unit, and a third heat exchange coil connected to a space heating circuit, the first and/or second coils operating, in use, to heat the water within the tank to provide hot water, and the third coil operating, in use, to transfer heat energy from the hot water to the space heating circuit.

2. A system according to Claim 1, wherein the space heating circuit incorporates a series of radiators. * ** * S S S... **. * S *.

3. A system according to Claim 1 or Claim 2, wherein the space heating circuit

S

S.....

* comprises an underfloor heating arrangement.

I..... * . S..

:

4. A system according to any of the preceding claims, further comprising valves provided in the system operable to supply the space heating circuit directly from the boiler unit.

5. A system according to any of the preceding claims, further comprising additional heat exchange coils provided in the tank.

6. A system according to Claim 5, wherein separate coils are connected to different parts of the space heating system.

7. A system according to Claim 6, wherein one coil is connected to a series of radiators and another coil is connected to an underfloor heating system.

8. A system according to Claim 5, wherein a coil is connected to the water heating system of a swimming pool.

9. A heating system substantially as hereinbefore described with reference to the accompanying drawings. * S. * . S S... S... * S *555

*SSSS5 * S * . p555

S S S.. *.S. *5 *

SS S S.