Integrated Heating System

The present invention relates to an integrated heating system and in particular, but not limited to, an to an integrated heating system for providing space heating and domestic hot water (DHW) for compact accommodation such as caravans, mobile homes, cabins, lodges, site offices, and motor powered applications such as motor homes, boats, horse transporters, emergency vehicles, trucks, coaches or other motor powered situations.

Current heating systems which are adapted/suited for use in motor homes and other compact living spaces are of a design that is more complicated than heating systems for a conventional household. There are several reasons for this but in general it results from conflicting requirements of compactness, low weight, limited and varied fuel availability.

In an attempt to overcome problems with limited and varied fuel availability a few of the designs have multiple fuel sources but these systems have other fundamental problems.

The above-mentioned problems are exacerbated by user perspective & user requirements. Users now tend to expect a system that performs to the standards of conventional household systems but existing products do not meet this expectation.

The present invention is suited to leisure applications and may be based around a number of fuel sources, for example Liquefied Petroleum Gas (LPG), natural gas, diesel, electricity or solar thermal energy. A majority of existing systems rely on a single fuel source although a number of systems do include immersion heaters to provide a back up heat source for supply of DHW, but these can only be used where there is sufficient mains electricity current available. Switching of these back up systems is manual and can be prone to repeated current overload trip out. Effective operation of these systems requires the user to ensure that the fuel supply is adequate for the purpose. In certain circumstances the power supplied may be so low that it can materially affect the comfort of the user, or may trip out the common power supply causing disruption & inconvenience to other users on the circuit.

This is the type of problem that led to the development of duel fuel systems such as a gas

burner and electricity based system. However whilst these are available they are still relatively new in the market place and there are significant problems with their design, operation and efficiency. Further they do not satisfy increasing user demand for space heating and Domestic Hot Water. Current systems cannot provide DHW heating while on the move (regulations prevent the use of gas while travelling and mains electricity is clearly not available). Therefore on arrival at a site the heating has normally been turned off for a considerable time, so the space is not heated and the water supply is cold. A user therefore has to wait for the system to engage and heat up the space and the hot water before they can be comfortable. Depending on the design, power input & efficiency of the system this can take several hours

Existing systems are not the most efficient in design or operation. One example aims to heat both water (for DHW) and air (for space heating) directly and simultaneously. The physical arrangement of the heat sources, heat exchangers, and the air and water media leads to a complex and fundamentally flawed arrangement of concentric annular chambers, giving poor efficiency and very slow heat up of both air and water. Furthermore most of the heat generated by the gas burner goes straight up the smooth sided vertical flue and out to atmosphere, transferring little of its heat through the heat exchanger. In addition, the unit is large & heavy (in comparison to the volume of water being heated), it therefore absorbs much of the heat and this also contributes to slow heat up and poor efficiency.

The present invention is concerned with providing a system where these problems are overcome.

According to the present invention there is provided a heating system for use in space heating applications which heating system is provided in conjunction with an engine, and which heating system includes

a vessel for holding a volume of a heating fluid medium and having at least one inlet and at least one outlet:

a first means for heating the fluid in the vessel deployed in the heating fluid medium, which

source utilizes excess energy produced by an engine: and

a second means for heating the heating fluid medium:

wherein the second means for heating the heating fluid medium comprises means for increasing the surface area of the external surface of the vessel and the hot gases generated from a burner or an engine are caused to flow over the external surface of the vessel so that the energy in the flowing gases is transferred from the gases to the vessel and thereby to the heating fluid medium

The heating system may be provided with a suitable control means for controlling and adjusting the operation of the system.

In accordance with a second aspect of the invention there is provided a heating system for use in space heating applications which heating system is provided in conjunction with an engine and which heating system includes:

a vessel for holding a volume of a heating fluid medium and having at least one inlet and at least one outlet:

a first means for heating the fluid in the vessel deployed in the heating fluid medium:

a second means for heating the heating fluid medium which means comprises means for increasing the surface area of the external surface of the vessel and the hot gases generated from a burner or an engine are caused to flow over the external surface of the vessel so that the energy in the flowing gases is transferred from the gases to the vessel and thereby to the heating fluid medium: and

a control system:

wherein the control system monitors the environment and demands on the system and

controls the energy supplied to the first and second means in response thereto.

The heating system in accordance with the second aspect of the invention may include as the first means for heating means that utilises excess energy from the engine.

The advantages with this type of system revolve around the actual design of the system in that it has been designed to utilise energy that would normally go to waste and in that the source of energy in this example may be used while the engine is running and therefore whilst the for example motor home with the system fitted is in transit. Further it is intended that a control system is fitted that controls variables such as fuel feed to the system depending on the surrounding circumstances.

The heating fluid may be any suitable heating medium and may be held in a closed system, and used to transfer heat or energy to other systems or parts of the same system. Such a system may include heat exchangers to transfer the heat or energy to the other systems. In this arrangement of the present invention the heating medium may be an Ethylene Glycol and water mix, in for example a 50:50 mix, or simply water with corrosion inhibitors.

In an alternative arrangement of the invention the heating medium may be the Domestic Hot Water supply. In this arrangement of the invention the domestic hot water supply is heated directly in the primary heat exchanger.

The heating system may be made from any suitable heat conducting material but typically is formed from standard materials used for this type of system such as copper pipes with an aluminium casting or extrusion for the vessel (primary heat exchange vessel).

The heating of the present invention may include other additional heating sources for the heating medium, for example, there may be a waste energy or excess energy recovery component to recover energy from a suitable source such as waste pipe or gas flow from an engine. Further a heat source such as a solar panel may be employed to provide renewable and free heat to the vessel.

The first means to heat the heating medium may be any suitable means for example a DC

immersion heater that may be powered from the alternator of the engine. Alternatively, fluid from the cooling system of the engine may be circulated through a tubular coil within our primary heat exchanger. In this case the system may include a pump to pump the engine coolant about the system.

The second means to heat the heating medium utilises energy or heat supplied through the wall of the vessel by direct contact of the vessel wall with a hot (gaseous) medium and therefore relies directly on the heat conduction properties of the material of the vessel as well as the flowing medium. Preferably the vessel is formed from a good conductive metal material such as aluminium, and the walls of the vessel that are to be contacted have an increased surface area over that of a standard tube.

The walls of the vessel may have an increased surface area by provisions of a convoluted surface or is provided with fins. The adaptation of the walls of the vessel may also act to slow the flow of the gases over the surface area so as to maximise the heat conduction transfer that occurs between the flowing hot medium and the vessel.

The vessel may be formed by any suitable manufacturing technique, for example where the vessel is formed from a material that may be readily extruded the vessel may be extruded and cut to an appropriate length.

The vessel for use with the invention may comprise an elongate section having an internal space sealed at its ends and walls which are suitably adapted both internally & externally to enhance the heat transfer between the vessel and a medium outside of said vessel and in contact with the external surfaces of the vessel, wherein suitable means are provided through the wall of the vessel to connect other heating sources or to allow for the flow of heating medium to and from the vessel to heat output units such as a calorifϊer, panel radiators and/or fan assisted convector heaters.

The heating system may include a burner located so that the flue gases created by burning are caused to flow over the external surface of the primary heat exchange vessel. The burner may be any suitable type of burner for example a natural gas burner, LPG burner or diesel burner.

The burner may be provided with an associated fan so that the hot flue gases are forced against the external walls of the vessel so as to enhance the heat transfer, and avoid cool spots or the risk of condensate forming.

The control means for the system may be any suitable system whether analogue or digital. Preferably the control means is a computer/microprocessor based control means. The use of a microprocessor based system enables criteria for the operation of the system to be adjusted and altered to meet the particular requirements of the user and also to suit the particular energy source supply of a particular site. This provides a high degree of control in the use of the system.

The heating system may be provided with appropriate sensors mounted about the system to monitor particular operating conditions of the heating system (such as temperature, pressure, flow rate, current, voltage) and feedback the information to the control means. Further the control system may also have manual programming capability so that the user can alter and adjust the base line operating conditions of the system, for example the drawing of energy from the various sources to power the system.

As will be appreciated the above system has a particular use with motor homes, caravans and like vehicles and therefore freely enables the user to park at various sites. Each site will have varying energy source availability, (variable electrical supply if any; varying solar energy depending on latitude, orientation, season, tree cover etc; gas availability depends on gas type; regulator type; bottle size; stock etc). These are factors that need to be taken into consideration when setting the operating criteria for the heating system. In addition it is possible that the user is in a country, or part of a country where the fuel, for example LPG gas, is not readily available and therefore there is a need to conserve the fuel stock. The programmability of the control means will enable a user to set the energy source priority, enabling the system to use a particular fuel exclusively or in preference to another. For example, the user may set the control means to prioritise mains electricity exclusively, or preferentially, only using gas where extreme demand warrants some use of gas.

In one arrangement of the invention the control means may also vary the supply of heat to the

various systems demanding energy or heat from the system in line with certain preset priorities. For example the control system may supply energy or heat to the domestic hot water supply in preference to the space heating capability under certain criteria, for example use of a shower or vice versa when the temperature sensed in the space falls below a certain threshold level. These types of criteria would be programmable into the system by the user.

A system made in accordance with the present invention provides the user with a simple to use and operate system. In addition the use of excess heat from the engine provides the user with free DHW & heated space on arrival, without using valuable & limited onboard energy. Furthermore, the reverse condition could be set up where energy/heat generated in the primary heat exchange vessel could be used to pre-heat the engine or in the case of a diesel vehicle prevent waxing in the fuel.

The invention and its alternative configurations will now be illustrated by way of description of an example heating module and heating system including a heating module, with reference to the accompanying drawings in which:

Figure 1 is a schematic representation of a heating unit for a heating system made in accordance with the present invention;

Figure 2 shows a schematic representation of an alternative heating unit to that shown in Figure 1;

Figure 3 shows a schematic representation of a heating system in accordance with the present invention and the controller set up therefore; and

Figure 4 shows an adaptation suitable for use with the present invention

Configuration 1 - Figure 1 of the drawings shows a heating unit 1 suitable for use with a heating system that is suited for use in heating a space and /or the domestic hot water supply in a motor home or other motorised vehicle.

The heating unit 1 comprises the basic heating source and heater for a heating system and

includes a vessel 2 formed as a tubular body with sidewalls 3 and end closures 4 to form an enclosed space 5, and inlet I and outlets O to connect the heating unit 1 into a heating system. A heating fluid medium, for example 50:50 ethylene gly col/water mix is stored in the space

5.

The heating output of the primary heating unit can be increased by extending the length of the primary heat exchange vessel and the associated burner unit. The volume of the space is about 2 litres in the arrangement being described and this volume is pumped about the heating system to provide the energy for downstream pieces of equipment.

The side walls 3 of the vessel 2 may be provided with fins and enclosed flow paths to enable ready flow about the, and over the external surface of the vessel 2, to facilitate the heat transfer between the vessel and the outside environment.

A burner 6, for example a gas burner (or diesel, natural gas, paraffin etc) is located in the proximity of the vessel 2 so that hot flue gases created by the use of the burner 6 are caused to flow over the external surface of the vessel 2, so that heat is transferred from the flowing flue gases of the burner to the vessel 2 and through the walls of the vessel to the enclosed heating medium in the space 5 of the vessel 2. The fins and flow paths increase the surface area available for heat transfer so increasing the efficiency and increasing the proportion of heat/energy from combustion/flue gases utilised by the heating unit.

Further to enhance the heat transfer a fan 7 may be located in the air inlet flow path to draw air into the system and increase burner output.

The outlet fitting O from the primary heat exchange vessel 2 allows circulation of the heating medium to space heating units (panel radiators, fan assisted convectors, etc) and to an indirect coil cylinder for the heating and storage of Domestic Hot Water. The heating medium 5 returns to the vessel 2 via the inlet tube I. This tube is directed to the far end of the heat exchange vessel where it will create turbulence to aid heat transfer and temperature uniformity, and will also create a contra flow to the combustion gases optimising heat transfer.

A heating coil 8 may also be provided which extends into the space 5. The heating coil 8 is connected to the cooling system of the engine of the vehicle or possibly a separate generator. The engine coolant is pumped around a circuit by pump 8a and whilst the engine is running provides heat to the heating fluid in the vessel 2. Further the pump in this circuit may be controlled so that it is operational until the engine temperature falls to a certain level so the energy in the engine is utilised for a period after the engine has been turned off.

The use of a heating coil 8 provides a direct heating source from the engine and means that heat can be supplied to the heating system for space heating & DHW while the vehicle is in transit. This provides a distinct advantage over current systems, which have to be turned off whilst in transit.

Further, due to space demands in the environments where it is intended to use these types of devices there is a trade off between the system output and the physical size of the system. Existing systems have relatively low output and poor efficiency giving rise to long delays in producing adequate DHW AND space heating.

The present invention means that the heat from the engine supplies heat so that if the j ourney is of sufficient length the heating system will be up to full operating temperature, but at very least if the journey is not sufficiently long the system will be warm reducing the heat up time on arrival.

Further the vessel 2 is also provided with a 230V immersion heater 9 that can be connected to the mains electricity supply available for heating the heating fluid in the space 5. The immersion heater could for example comprise a IkW element and a 2kW element to which electricity may be supplied separately. With this arrangement therefore the immersion could be configured to use 0, 1 , 2 or 3 kW depending on the supply available.

The heating unit 1 is suited for use in a heating system and typically a heating system that can be used in a motor home where the engine is the main engine of the vehicle. Figure 2 of the drawings shows an adapted heating unit similar to that described above and like numbers have been used to describe like components. The description of these components is

incorporated here by way of reference.

Configuration 2 - The heating unit 1 shown in Figure 2 of the drawings differs only in the provision of heat/energy from the engine. In this particular example of the invention the heat/energy source from the engine is powered from the alternator of the engine and comprises a 12V immersion heater 9 instead of a mains voltage element, to use the excess power generated by the engine via the alternator. In all other aspects the heating unit 1 is the same. This would eliminate the need to link into the engine cooling system. The 12V immersion element could still be used with mains 230V hook up via an inverter (common on motor homes etc)

In Configuration 3 of the heating unit, the coil 8 used in the original of the heating unit for heating the system from surplus engine heat is used instead to heat DHW by passing fresh cold water through this coil 8, transferring heat from the primary heat exchange vessel 2 through the coil 8 into the fresh water providing DHW without the need for a calorifier (hot water cylinder). The heating medium in the main reservoir 5 remains an ethylene/glycol or corrosion inhibitor solution for circulation to the space heating circuit as with configuration 1 & 2.

In configuration 4, the heating medium in the space 5 is water and not a mix with Ethylene Glycol or corrosion inhibitor, the water comprises the Domestic Hot Water for the motor home/vehicle/caravan/boat/cabin so the heating unit 1 is heating the Domestic Hot Water directly & exclusively. This configuration provides a powerful, instantaneous DHW heater, where space heating is not required or already provided by a separate, existing system.

Now referring to Figure 3 of the drawings there is shown a schematic representation of a typical heating system including a heating unit 1 as described above. The heating system includes a heating unit 1 and like numerals have been used to show component parts of this to those used above and the description thereof is incorporated here by way of reference.

The outlet O of the heating unit 1 is connected to a primary heating circuit including a domestic hot water module 20 and/or a space heating module 30. The space heating system

can be an air blown space-heating module 30 which and/or panel radiators, ideally connected in parallel configuration to dissipate heat/energy into the space in the motor home/vehicle/caravan/boat/cabin. The primary heating circuit then returns to the space 5 of the heating unit 1.

A pump 12 is included in the system, in this example at a point where the inlet to the heating unit 1 is located. The pump 12 pumps the heating medium around the heating system.

The domestic hot water module 20 is connected into a branch line that connects the module to the outlet and inlet sides of the primary heating circuit. The module 20 includes a vessel 21 having inlet and outlet ports 22 and 23 for the domestic hot water supply, and the branch line in the body of the vessel 21 is formed into a coil 24.

The heating medium from the heating unit 1 is pumped through the coil 24 and the heat dissipated to the water in the vessel 21.

The fan assisted convector heater module 30 comprises a heat exchanger 31 connected into the branch line that as with the domestic hot water module 20 is connected between the inlet and outlet sides of the primary heating circuit. The heat exchanger 31 is a high area exchanger, similar to a vehicle radiator. The heat exchanger 31 has associated therewith a fan 2 and associated cowling. In use the fan is caused to either draw air over the surfaces of the heat exchanger or blow air over these surfaces. A flow of heated air is then directed in to the space to be heated.

The space heating capabilities of the system may not always be required. Therefore a valve 26 may be located below the branch line for the domestic hot water supply so that the supply of heated heating medium from the heating unit 1 is not directed through the radiators or space-heating module 30.

Further, coil 8 in the primary heating unit 1 which is connected to the engine of the vehicle may also be used to transfer heat from the heating system to the engine to provide an engine pre-heat facility for use on cold mornings and to reduce wear & tear on the engine. With

diesel vehicles this system element may also be extended to include a coil that warms the diesel fuel to prevent waxing in the fuel.

In addition in Figure 3 there is also shown a schematic representation of the controller set up for the system. The system should be capable of being operated without mains electricity so the whole system, including the controller is designed to run on a 12V or 24V automotive type system. The system as illustrated includes sensors as follows:

temperature sensor 100 in the inlet side to the exchanger 8 in the heating unit to detect the temperature of the fluid flow to the vessel 2

heating medium temperature sensor 101:

domestic hot water temperature sensor 102:

control switched supply 103 to the electric immersion heater 9. (controller will sense if mains hook up is available or has been selected by user). Control switched supply may supply 0,1,2,3 kW depending on power available and user pre-selection; and

temperature sensors 104 to detect the temperature in the space to be heated.

The controller has direct control over the function and operation of the pump 12; and also the valve in the primary heating circuit so that it can vary the flow to the space heating modules.

The controller includes a microprocessor that may be programmed with preset data including the desired temperature of the space. The system may further be provided with at least one frost thermostat (not shown) and the controller may be further configured to monitor the frost thermostat and to issue control signals accordingly to protect vulnerable parts of the system from freezing in cold weather. This may be of particular value and importance for use in boats to eliminate the need for full winterisation, in turn enabling the user to take out the craft/vehicle at any time.

The controller may be configured to control the heating system in accordance with both pre-

programmed and user programmed criteria. Accordingly the controller includes a user programmable timer for allowing the modules of the system to be switched on and off automatically at different times of day depending on user requirements. The controller may also be configured to provide user programmable zones, where applicable, to allow individual control of temperature in different areas of the accommodation.

The controller may also be provided with user programmable functionality to allow user prioritisation of different heating modules according to requirements. For example, the onboard combustion fuel supply (gas, diesel etc) may be low, so mains electricity may be prioritised to conserve onboard combustion fuel supply. Alternatively, the electrical supply available may be very expensive, and so the user may wish to prioritise use of onboard combustion fuel for cost economy. Further, mains electricity available may be limited to 4 or 8 amps, so the user can preset this limit into the controller to minimise the risk of mains supply trip out.

It will be appreciated that default prioritisation may be pre-programmed, and may include decision making capability to allow priorities to be changed automatically in response to analysis of the signals received from the sensors and changes in availability of fuels, for example gas runs out or mains electricity trips out.

The controller may also be provided with a plurality of user controls for manually overriding the programmed priority, timing, and/or zoning. The manual controls typically include domestic hot water, and central heating on/off overrides.

Hence, the controller is able to prioritise the use of heater modules according to availability, cost, demand etc. Similarly the module can prioritise heat outlets according to demand, and where applicable manual overrides.

It will be appreciated that the controller may be further programmed to switch on the modules in a predetermined or user specified order to ensure maximum efficiency. Solar power may, for example, be used to preheat the fluid in the primary circuit before other modules are used to increase the fluids temperature further.

Now referring to Figure 4 of the drawings there is shown an adaptation to the system suitable to be incorporated if the circumstances are acceptable and a benefit will be achieved. In this example of the invention the adaptation to the system is shown as being made to the calorifier or domestic hot water supply module 20. The module 20 includes an extra immersion heater 27 as well as the connection to the primary heating circuit, labelled here simply as P for convenience.

In addition the system may also include a heating source, which is connected to a solar panel.

This is designated with an S Oon Figure 4 of the drawings. The solar panel works in the conventional manner heating a flowing medium passing over an internal surface to pick up the heat caught from the sunlight. This flowing medium in turn is then pumped around a circuit and through a coil in the lower section of the vessel 21 of the calorifier to heat the water in the vessel.

If the system includes a solar based heating means the controller will be connected to the pump for the solar panel and include a temperature sensor to detect the temperature of the pumped fluid leaving the solar panel. There will also be an anti-siphon check valve to prevent thermo-siphoning of heat from the cylinder 20 to the solar panels at night.