Heat pump external unit

Abstract

Provided is a heat pump external unit comprising: a housing and within the housing an evaporator, the housing including an air inlet and an exhaust outlet, a fan to move air from the inlet through / over the evaporator and out through the exhaust outlet of the housing, the air inlet being provided in a rear or side face of the housing, and the exhaust outlet being provided in an upper or front face of the housing, the exhaust outlet having a generally circular cover grille, the fan being located behind the cover grille and including a motor and / or bearing substantially at the centre of the grille, the heat pump external unit including a connection to a remote unit including a control panel and information display, the heat pump external unit including control logic for controlling the fan and a compressor connected to the evaporator, the control logic being arranged to operate with the control panel to display information on the operation of the unit and to set one or more parameters relating thereto, the heat pump external unit further comprising a status display indicator comprising a plurality of addressable illumination elements overlaid by a diffuser and / or a printed image or logo, wherein the diffuser and / or the image at least partially obscures or blurs the individual addressable illumination elements, wherein the addressable elements can be controlled to illuminate the diffuser and / or printed image or logo to render the exhaust outlet visible in darkness, wherein the addressable illumination elements include at least one element of selectable colour and / or wherein the plurality of addressable illumination elements include elements of multiple different colours and wherein intensity of at least some of the plurality of addressable illumination elements is variable in multiple steps or substantially continuously, wherein the control logic is controllable to send one of a plurality of static patterns or animation sequences to control the addressable illumination elements based on both a status of operation of the heat pump external unit and based on one or more stored configuration parameters so that different states of operation of the device are discernible from observation of the collective arrangement of the addressable illumination elements

Description

[0001] Heat Pump External Unit

[0002] Technical field

[0003] The present invention relates to an improved heat pump external unit with an integrated status display.

[0004] Background

[0005] Conventional heat pump outdoor units face several challenges related to long-term weatherproofing and accessibility. These units are often installed in hard-to-reach locations, such as behind protective cages in semi-commercial applications or awkwardly positioned areas in domestic installations. As a result, most existing units require an indoor control panel and display system, wired remotely to the outdoor device. Additionally, outdoor units may have status lights located on circuit boards that are accessible only by maintenance personnel under removable panels.

[0006] Compact or ergonomic designs present further limitations, as there is often insufficient space for a visible status indicator that can reliably be seen under various installation conditions. Consequently, verifying the operation of such a device frequently involves dismantling the external unit, accessing the building interior to reach the control panel, or making repeated trips between the two locations, resulting in a time-consuming and labour-intensive diagnostic process particularly for a technician who is working alone and unaided.

[0007] The present invention addresses these challenges by recognizing that the fan exhaust outlet, for functional purposes, must remain exposed regardless of the unit’s installation orientation to facilitate free air exhaust.

[0008] Summary

[0009] According to a first aspect, there is provided a heat pump external unit comprising: a housing and within the housing an evaporator, the housing including an air inlet and an exhaust outlet, a fan to move air from the inlet through / over the evaporator and out through the exhaust outlet of the housing, the air inlet being provided in a rear or side face of the housing, and the exhaust outlet being provided in an upper or front or angled face of the housing, the exhaust outlet having a generally circular cover grille, the fan being located behind the cover grille and including a motor and / or bearing substantially at the centre of the grille, the heat pump external unit including a connection to a remote unit including a control panel and information display, the heat pump external unit including control logic for controlling the fan and a compressor connected to the evaporator, the control logic being arranged to operate with the control panel to display information on the operation of the unit and to set one or more parameters relating thereto, the heat pump external unit further comprising a status display indicator comprising aplurality of addressable illumination elements overlaid by a diffuser and / or a printed image or logo, wherein the diffuser and / or the image at least partially obscures or blurs the individual addressable illumination elements, wherein the addressable elements can be controlled to illuminate the diffuser and / or printed image or logo to render the exhaust outlet visible in darkness, wherein the addressable illumination elements include at least one element of selectable colour and / or wherein the plurality of addressable illumination elements include elements of multiple different colours and wherein intensity of at least some of the plurality of addressable illumination elements is variable in multiple steps or substantially continuously, wherein the control logic is controllable to send one of a plurality of static patterns or animation sequences to control the addressable illumination elements based on both a status of operation of the heat pump external unit and based on one or more stored configuration parameters so that different states of operation of the device are discernible from observation of the collective arrangement of the addressable illumination elements.

[0010] In a heat pump external unit according to the first aspect, the housing may comprise a generally planar back wall containing the air inlet, and a curved front with the fan angled upwards and pointing forwards.

[0011] In a heat pump external unit according to the first aspect, the fan may have a central motor supported by the grille, the grille carrying / supporting wires / electrical conductors providing power to the motor and carrying electrical signals to the central indicator.

[0012] In a heat pump external unit according to any variant of the first aspect the status indicator may be configured to indicate at least one of the following conditions: fault condition, defrost mode, quiet mode, and normal operation mode.

[0013] In a heat pump external unit according to any variant of the first aspect the status indicator’s display may be configurable via the indoor control panel.

[0014] In a heat pump external unit according to any variant of the first aspect the status indicator provides a sequence of indications related to various parameters using an animated display.

[0015] In a heat pump external unit according to any variant of the first aspect the display may comprise at least one central element, a first radial array of elements, and a second outer array of radial elements.

[0016] In a heat pump external unit according to any variant of the first aspect the display may include a screen-printed logo or icon that obscures multiple elements of the display for aesthetic integration and enhanced functionality.

[0017] Brief description of FiguresEmbodiments of the invention will now be described, by way of example only, with reference to the accompanying figures, in which:

[0018] Figure l is a schematic showing a typical domestic heat pump installation, according to an aspect of the invention, for premises in the form of a house;

[0019] Figures 1 A to ID illustrate details of a status display arrangement according to various aspects of the invention;

[0020] Figure 2 is a schematic showing a typical multiple heat pump installation, according to an aspect of the invention, for a building housing multiple individual dwellings, such as an apartment block;

[0021] Figure 3 is a three quarter perspective view of a heat pump according to an aspect of the invention;

[0022] Figures 4A to 4D are exploded views of the housing of figure 3;

[0023] Figures 5A, 5B and 5C are three quarter perspective views of the lower housing portion of the heat pump of Figure 3;

[0024] Figures 6A and 6B are perspective views of the upper housing part of the heat pump of Figure 3; Figure 7A and 7B are perspective views of a front cover of the heat pump of Figure 3;

[0025] Figure 8A is a vertical section showing the arrangement of the fan and evaporator of the heat pump of Figure 3;

[0026] Figure 8B is a perspective view showing a possible arrangement of internal components of the heat pump of Figure 3;

[0027] Figure 9 is a plan view corresponding to Figure 8B; and

[0028] Figure 10 is a front elevation corresponding to Figure 9 with the front cover removed.

[0029] Specific description

[0030] Figure l is a schematic showing a typical domestic heat pump installation for premises in the form of a house 102, according to an aspect of the invention. The heat pump, in this case an air source heat pump, includes a heat pump external unit 104 which is coupled, by pipework 105, to a space heating (and optionally cooling) arrangement and a domestic hot water system, together indicated as arrangement 106. The heat pump external unit 104 comprises a housing that encases and protects the main components of the system. The housing is designed to withstand environmental conditions and provide structural support for the components of the heat pump. Inside the housing, the heat pump may include an evaporator, a condenser integrated with a heat exchanger, a fan motor, a fan, a compressor, and an electrical drive unit that controls both the fan motor and the compressor. The evaporator absorbs heat from the surrounding environment (air or another heat source), facilitating the evaporation of a refrigerant that circulates through the system. Positioned in the airflow path, the evaporator serves to maximize the efficiency of heatabsorption. Downstream from the evaporator, the condenser with its heat exchanger releases the absorbed heat. The heat exchanger transfers heat to either the indoor or outdoor environment, depending on whether the heat pump is in heating or cooling mode. The fan motor drives the fan, which is mounted adjacent to the condenser, ensuring airflow across the heat exchanger to enhance heat dissipation.

[0031] The compressor increases the pressure and temperature of the refrigerant before it enters the condenser. The electrical drive unit supplies power to both the fan motor and the compressor, managing their operation based on control signals from the system's control logic.

[0032] The control logic is connected to the drive unit and oversees the operation of the heat pump, including regulating fan speed, compressor activity, and monitoring system performance through various sensors. It is also linked to a remote indoor control unit 110, which allows for the setting and reading of operational parameters and modes. This control unit 110 enables users or technicians to adjust the system and monitor its status without needing physical access to the external unit.

[0033] The heat pump external unit 14 includes a compressor and an evaporator, not shown, which during a heating mode of operation together extract energy from ambient air, the energy then being supplied to the heating and / or hot water supply parts of the arrangement 106. The heat pump external unit 104 also includes a processor 108 (and associated control logic) to control the functioning of the heat pump. The processor 108 is arranged to communicate with a control panel 110 located within the premises, by means of which occupants of the premises 102 can control the heat pump. That is, the heat pump external unit includes control logic for controlling the fan and a compressor connected to the evaporator, the control logic being arranged to operate with the control panel to display information on the operation of the unit and to set one or more parameters relating thereto.

[0034] Additionally, the heat pump features a display which may be mounted coaxially within the grille of the fan. The display is connected to the control logic and provides visual indicators of the unit’s status, operational mode, and diagnostic information. This display may be illuminated and configured to show various patterns or colours, enhancing visibility in low-light conditions and improving the user’s ability to determine system status at a glance. Also, the arrangement of these components optimizes the airflow through the evaporator and condenser and maximizes the efficiency of heat exchange. The control logic, in combination with the indoor control unit and the (coaxial) display, ensures that the heat pump operates efficiently and that its status is easily discernible, even from a distance.

[0035] The control panel 110 may include or be associated with a display by means of which status, settings, and optionally other operational parameters may be displayed. The control panelmay incorporate a thermostat for setting a threshold temperature for activating the heating, and / or may be coupled to one or more thermostats each of which permits the setting of a threshold temperature for a different room or zone within the premises. The heat pump external unit 104 may include at least one RF transceiver 110, and such a transceiver may be used for bidirectional communication with the control panel 110, additionally or alternatively there may be a wired connection between the two devices. One or more of the transceivers 110 may be used to receive weather information and / or power tariff information, either or both of which may be used by the processor 108 in controlling and optionally optimising the performance and / or operation of the heat pump installation. The heat pump external unit 104 also has a fan, which may be located at or adjacent an upper or front or angled face for exhausting air from the unit. A generally circular cover grille 114, may be provided, to prevent interference with the fan, and for the passage of air exhausted from the unit by the fan. The cover grille is typically in the form of an annulus so configured that exhaust air passes through the annulus but not through a “blind” central portion. The location of the central portion may correspond generally with the location of the motor that drives the fan, the rotational axis of the fan also extending through the central portion. The heat pump external unit further comprises a status display indicator 115 that may be located at, on or adjacent the upper or front or angled face that includes the vent opening for the exhaust from the fan as will be described in more detail later. Optionally the status display indicator 115 is located within the central portion of the cover grille 104. In this position the status display indicator 115 may overlie the fan’s drive motor while leaving the annular grille part substantially unobstructed. An advantage of positioning the status display indicator 115 in this way is that, if the heat pump external unit is correctly situated, the exhaust grille will be unobstructed and facing towards an open space of some kind - so that the exhaust from the unit is able to dissipate without significant restriction - which in turn means that there is a high likelihood that the status display indicator will be unobscured and visible from at least a few metres distance, and typically from as far as away as 5 to 10 metres. This is advantageous in that it is possible to carry out status checks without the need to visit the external unit, and that awareness of the heat pump’s status can be maintained without special effort, and in particular without the need to visit and inspect the external unit.

[0036] Figure 1 A illustrates an arrangement of the annular grille 114 located in an aperture 120 in a panel 122 of the cabinet of the external unit 104. The centre portion 124 of the grille 114 underlies the status display indicator 115. The position of the fan 126 behind the grille 114 is shown schematically in outline - although in reality an aerodynamically efficient fan blade design is chosen both to improve the overall efficiency of the heat pump, but also to help minimise the sonic footprint of the heat pump. The axis of rotation of the fan is shown nominallyas 128. It will be noticed that this axis lies within the area occupied by the status display indicator 115.

[0037] Figure IB shows schematically, in partial cross section, an arrangement of a status display indicator 115 and its relationship with the fan, motor, and adjacent housing portions of a heat pump external unit, for example as shown in figure 1 A. The fan comprises a central hub or boss 126 from which extend fan blades 130. The fan hub 126 may be coupled to a drive shaft 132 of a fan motor 134 - although as will be appreciated the motor may be provided within the fan hub rather than being coupled to the latter via a drive shaft. Other configurations are also possible, of course. The rotational axis of the fan is indicated by the broken line 133. As previously mentioned, the fan may be received in aperture 120 of the housing 122 - although it may also be located upstream of the opening rather than being located within the opening 120 proper. Covering the opening 120, and the fan blades 130 is grille 114. The grille may be annular, for example as shown in Figure la, with a central region 144 which does not serve as an exhaust for air ejected from the housing by the fan. In the arrangement shown, the central region 144 within the centre of the annular grille 114 supports the status display indicator 115. The central region 144 may also house a bearing to support the shaft 132.

[0038] The fan may be supported by the grille arrangement that comprises the louvred part 114 and the central region 144. The grill arrangement may include suitable strengthening ribs by means of which the central region 144 and the fan are supported by the housing part 122.

[0039] In the arrangement shown, the status display indicator 115 comprises a layered structure. A first layer 150 may comprise a plurality of addressable illumination elements. This first layer is overlaid by a second layer 152 which comprises a diffuser and / or an image or logo (e.g. a printed, etched, moulded, or cast). The diffuser and / or the image / logo at least partially obscures or blurs the individual addressable illumination elements. The diffuser may be translucent, for example a translucent plastics material. The addressable elements are controllable (under control of the heat pump’s processor) to illuminate the diffuser and / or printed image or log. The effect of this may be to render the fan exhaust visible in darkness. The addressable illumination elements may include at least one element of selectable colour and / or the plurality of addressable illumination elements may include elements of multiple different colours. The intensity of either or both of illumination (brightness) and colour (saturation) of at least some of the plurality of addressable illumination elements may be variable in multiple steps or substantially continuously. The second layer may be overlaid by a third, protective layer, 154 through which light from the first layer may pass when the latter is illuminated, although the presence of this layer is optional.Figure 1C illustrates schematically another example of a status display indicator 115, wherein the display comprises a central element 160, a first radial array of elements 162, and a second outer array 164 of radial elements. The central element 160 may comprise a plurality of individually addressable illumination elements whose colour (e.g. hue and optionally saturation), and / or illumination (e.g. light intensity) can be controlled by control logic of the heat pump. Likewise, each of the elements of the two arrays 162 and 164 may comprise plurality of individually addressable illumination elements whose colour (e.g. hue and optionally saturation), and / or illumination (e.g. light intensity) can be controlled by control logic of the heat pump.

[0040] Figure ID illustrates schematically a further example of a status display indicator 115, wherein the display comprises a plurality of central elements 170, a first radial array of elements 172, and a second outer array 174 of radial elements. Each of the plurality of central elements 170 may comprise a plurality of individually addressable illumination elements whose colour (e.g. hue and optionally saturation), and / or illumination (e.g. light intensity) can be controlled by control logic of the heat pump. Likewise, each of the elements of the two arrays 172 and 174 may comprise plurality of individually addressable illumination elements whose colour (e.g. hue and optionally saturation), and / or illumination (e.g. light intensity) can be controlled by control logic of the heat pump.

[0041] Preferably the heat pump (e.g. the heat pump external unit) includes control logic (e.g. which may be run on the processor of the heat pump external unit) which is controllable to send one of a plurality of static patterns or animation sequences to control the addressable illumination elements based on both a status of operation of the heat pump external unit and based on one or more stored configuration parameters so that different states of operation of the device are discernible from observation of the collective arrangement of the addressable illumination elements.

[0042] Figure 2 is a schematic showing a typical multiple heat pump installation 200 for a building housing multiple individual dwellings, such as an apartment block. The heat pump installation comprises a plurality of heat pumps, each having a heat pump external unit 204. In this case the heat pumps may each be air source heat pumps. The heat pump external units 204 may each be as described with reference to unit 104 of figures 1 and la, each being coupled, by pipework 205, to a space heating (and optionally cooling) arrangement and a domestic hot water system, together indicated as arrangement 206, which provides space heating and domestic hot water for the individual dwelling units of the building, e.g. each of the apartments of an apartment block. The arrangement 206 will typically also provide space heating and hot water, for communal areas of the apartment e.g. for shared lavatories, restaurant, gym and recreational facilities of the building. Arrangement 206 may be located in a basement facility akin to atraditional boiler room. The scale of energy use in apartment blocks and other large, shared use buildings, such as those found in schools, on campuses of other educational facilities, is such that it is normal to use multiple individual heat pumps rather than trying to source a single heat pump that can meet the total energy demand of the building. This is not only more economical than sourcing a heat pump of large enough capacity, but also provides a degree of redundancy in that the building will continue to have heating and hot water even if some of the heat pumps fail - it being unlikely that all the heat pumps will fail together (absent a loss of electrical power, and even then a backup electrical power supply may be provided, to ensure at least some degree of continuity of supply). Each of the heat pump external units may be provided with its own control panel 210 within the premises 202, typically within an area of the building to which access is restricted - so that only authorised individuals (e.g. a caretaker, building manager, or service engineer) can access the control panels and therefore control (and see messages from) the respective heat pump external units 204. The individual control panels may each include or be associated with a display that may be arranged to display status and operating parameters of the respective heat pump. Optionally, the functionality of some or all of these control panels may be provided by one or more aggregate control panels, with integral or associated displays to display relevant status and performance information, and through which more than one of the heat pumps may be controlled.

[0043] The nature of the buildings served by heat pump installation of the kind illustrated in figure 2 means that the heat pump external units 204 are likely to be located in areas accessible by many people - unlike the situation likely to be experienced with domestic installations of the type described with reference to figure 1. To reduce the risk of thefts and vandalism, each of the heat pump external units 204 is protected by a locked cage - so that access to the units 204 is restricted to a keyholder - typically someone with a caretaking role for the premises, but optionally also one or more service engineers. Under some circumstances it may, of course, also be desirable to provide a cage or other secure enclosure around the heat pump external unit of an individual domestic installation such as that shown in figure 1.

[0044] As with the installation described with reference to Figure 1, each of the heat pump external units 204 has a fan on an upper or front or angled face for exhausting air from the unit, the fan having a generally circular cover grille (not shown). The heat pump external units 204 each further comprise a status display indicator (not shown) that may be located at, on or adjacent the upper or front or angled face that includes the vent opening for the exhaust from the fan (e.g. as described with reference to figure 1) - being a position at which its visibility even from a distance of several metres is likely to be good. Positioning a status display indicator in such a position means that the caretaker (or other authorised person) should be able to determinethe operating status (operating mode, fault condition, power loss, etc.) of the heat pump without needing to open the unit’s security cage 220, possibly even without needing to come within 10 metres or more of the cage, and possibly being able to determine the status of all the units simultaneously - thereby permitting quicker investigation and hence quicker rectification of any fault conditions. In this way the caretaker is quickly able to determine the operating status of each of the heat pumps. If the status indicators all indicate a regular operational status with no faults, the caretaker will be aware that any reported deficiency in the premises’ heating / hot water supplies is unlikely to be attributable to the heat pump installation - and hence that other fault causes need to be investigated.

[0045] Figures 3 to 10 illustrate a practical example of a heat pump external unit that includes a status display indicator 115 as previously described. In this example the heat pump external unit is built into a housing that may be formed of a plastics material such as medium density polyethylene which provides advantages in terms of reducing the noise footprint of the heat pump, as well as various other constructional and performance advantages as will be described. But it should be appreciated that the invention is not in any way limited in its application to the use of housings made principally of plastics materials or as otherwise described with reference to figures 3 to 10. That is, the invention finds application with otherwise conventional external units, such as those constructed with sheet metal cabinets. Rather the scope of the invention is solely limited by the scope of the appended claims.

[0046] Figure 3 is a three quarter perspective view showing the front and one side of an example of a heat pump 300 according to an aspect of the invention in a new housing arrangement. The housing is formed of a plastics material, for example a material such as medium density polyethylene. The main housing components may each be formed by a moulding process, for example roto-moulding, blow moulding, or injection moulding. The mouldings may be formed as hollow mouldings and the cavities within the mouldings may be filled with a thermal and / or sound-absorbing material such as a foamed plastics material (e.g., polyurethane foam), plastics beads (optionally of foamed plastics), or other suitable material. By thermally insulating the housing the efficiency of the heat pump may be improved. The provision of a plastics outer case or housing, in place of the more conventional sheet metal construction is likely to lead to reduced wastage and expense caused by the damage that sheet metal cases / housings all too commonly suffer in storage, transit and on site before installation. Plastics housings are also less likely to resonate during operation of the heat pump, potentially reducing the heat pump’s noise footprint. Unlike typical sheet metal housings, plastics housing will not corrode under the influence of the wind borne salt that may be experienced in installations near the sea.Some air source heat pumps may have been provided with housings made of plastics materials, typically where the heat pump is used for heating a swimming pool, but these are believed to have been based on the use of an internal metal chassis or framework to which the heat pump’s functional parts must be attached prior to the addition of the plastics cover or housing. Such a structure is time consuming and therefore expensive to construct. Conversely, embodiments of the present invention use the housing as a structural element which secures the heat pump’s internal components, some of are secured directly to the housing while others rest on or in supports provided by the plastic housing itself. By moulding (or printing) pipe-retaining features into the housing, pipework of the heat pump may be positioned, supported and held in place by the material of the housing itself. Such pipework hoi ding / supporting features may also be used to provide a jigging function to enable pipework to be held in place prior to connection of adjoining pipe ends (for example by brazing using inductive brazing). Threaded inserts may be moulded (or otherwise included) into portions of the housing during manufacture of the housing, facilitating accurate positioning of components and speedier assembly - which may lead to further cost savings.

[0047] In the illustrated example the housing is formed of three main components. In this example the main components are an upper housing part 302, a lower housing part 304, and a front panel 306. In this example the upper housing part 302 houses the fan, mounted beneath a grille or louvre arrangement 114 in an opening 122. In this example the opening 122 serves as an outlet for the air that the fan induces to flow over the air heat exchanger. In the configuration shown, the air outlet 122 is formed in a portion of the upper housing that is angled away from the vertical, so that expelled air is directed at least partially upwardly and not just horizontally, which potentially has the advantage of reducing the noise footprint and hence the amount of noise pollution suffered by neighbours. As will be seen, the axis of rotation of the fan may be arranged to be inclined about 30 to 60, e.g., 33 to 45 degrees to the horizontal. As previously explained, a status display indicator 115 is provided to display different states of operation of the heat pump. The status display indicator 115 may be positioned in the vicinity of the air outlet 122, for example within an area whose outer limits are defined by the grille 114.

[0048] The status display indicator 115 may comprise a plurality of addressable illumination elements overlaid by a diffuser and / or a printed image or logo, wherein the diffuser and / or the image at least partially obscures or blurs the individual addressable illumination elements, wherein the addressable elements can be controlled to illuminate the diffuser and / or printed image or logo to render the fan exhaust visible in darkness, wherein the addressable illumination elements include at least one element of selectable colour and / or wherein the plurality of addressable illumination elements include elements of multiple different colours and wherein intensity of at least some ofthe plurality of addressable illumination elements is variable in multiple steps or substantially continuously, wherein the control logic is controllable to send one of a plurality of static patterns or animation sequences to control the addressable illumination elements based on both a status of operation of the heat pump external unit and based on one or more stored configuration parameters so that different states of operation of the device are discernible from observation of the collective arrangement of the addressable illumination elements.

[0049] Figures 4A and 4B are three quarter views from the front and rear respectively, showing the heat pump of figure 3, with the three main components separated, revealing their individual forms. Figures 4a and 4b also reveal the location of the air heat exchanger 20, but apart from this and the fan, which is positioned in the upper part 302 beneath the grille 308, the heat pump’s internal components are not shown. The air heat exchanger 20 may be disposed generally vertically as shown. The air heat exchanger’s conduits or pipework that carry refrigerant may extend generally transversely between the two generally vertically extending sides. The air heat exchanger may also include cooling fins thermally coupled to the refrigerant-carrying conduits and these may be arranged generally transverse to the conduits - for example also extending generally vertically.

[0050] The air heat exchanger be received in a receiving structure, such as a trough or channel, not shown, in the lower housing part 304. The trough or channel may include or communicate with a drip tray arranged to catch condensate that falls from the air heat exchanger 20. The rear face of upper housing part 302 includes an opening, defined by sidewalls 400, which in the assembled state exposes the air heat exchanger, the periphery of the opening framing the air heat exchanger 20 on three sides (as shown) or optionally on all four sides.

[0051] Internally, to either side of the opening, the upper housing part 302 may include a channel 402 into which the air heat exchanger 20 may be received or slotted. Between the mounting location for the air heat exchanger 20 and the air outlet 122, the upper housing includes an air flow conduit 406. The conduit is shaped to guide the air flow that the fan induces through the air heat exchanger the fan angled upwards. The walls of the conduit 406 may define a generally straight path or may define a curved path.

[0052] Figures 4C and 4D correspond generally to Figures 4A and 4B but additionally show the fan assembly 408 removed from within the upper housing part 302. The fan assembly 408 includes the fan and its drive motor mounted inside a casing that is mounted within, and secured to, the upper housing part 302 for example using screws fastened from within the upper housing part. As shown, the fan assembly casing includes on the exhaust side a cylindrical sleeve portion 410, sized to fit snuggly within the opening 122, which at its inner end abuts against a laterally extending flange 412 that mates to the underside of the upper housing part 302. The fan motor iscentrally located in the inner sleeve portion, behind the stationary “boss” 124 that can be seen externally in the middle of the fan grille 114. The fan is largely contained within the enlarged inner end 414 of the fan assembly 408 where the casing widens.

[0053] In an alternative arrangement the fan assembly may be arranged to be mounted and demounted from the upper housing from outside the housing, so that the upper housing does not first need to be removed or “opened” before installing or removing the fan. Thus, rather the enlarged flange portion 412 on the entry side of the fan assembly could be dispensed with and there may be no sleeve 410.

[0054] Figures 4A and 4D also show the status display indicator 115 positioned within the central land of the grille. The status display indicator 115 may be coupled to the processor 108 (for the receipt of control signals, and optionally to provide feedback) and the heat pump’s power supply by means of wires or electrical conductors carried by the grille. Likewise, the grille may carriy wires / electrical conductors that in use provide power to the motor.

[0055] Figure 5 shows in greater detail the lower housing part 304. Figure 5A is a three quarter perspective view from the back left of the heat pump from which can clearly be seen the recess 500 within which the lower end of the air heat exchanger is received. The base of this recess may be in the form of a drip tray 502, as shown. The drip tray is provided with a drainage outlet 504 through which gathered condensate can escape. The floor of the drip tray to either side (left and right when viewed from the rear of the heat pump) preferably slopes downwards to the drainage outlet 504. To the front, back, and sides of the drip tray 502 a ledge or shelf 506 is provided, onto which the lower end of the air heat exchanger is placed during assembly of the heat pump. At either end of the recess 500 are upstanding flanges 508 spaced to accommodate the air heat exchanger snugly therebetween. A back wall 510 of the recess 500 may provide the lower edge 512 of the opening (otherwise defined by sides 400 of the upper housing part) through which air is, in use, sucked into the air heat exchanger by the fan. On the opposite, innermost, side of the recess 500 the lower housing part provides an air guiding feature in the form of a sloping surface 514 which is designed to match with a corresponding sloping surface, in the upper housing part 304, that in part defines the air flow conduit 406. Together these sloping surfaces are designed to guide air flow smoothly from the inner side of the air heat exchanger to the fan to reduce energy wastage and noise generation. The two sloping surfaces are preferably formed integrally with the upper and lower housing parts during the moulding (or printing) of these components. In order to facilitate manufacture of the housing parts, the sloping surfaces may each comprise multiple generally flat surfaces that angle together to define the required surface shape - rather than, for example, being in the form of curved arcuate shapes 514. This may help to reduce the cost of mould making and also possibly simplify the moulding process. Of course a suitable streamlinedair flow conduit may be formed from the sloping surfaces of the upper and lower housing parts can be designed and made using curved / arcuate surface shapes albeit possibly with a consequent increased cost of mould creation. If the housing parts are to be made by printing the use of curved / arcuate surfaces may be accommodated without significant cost increase. Figures 5A and 5B show an example in which the sloping surface 514 is defined by three sections, with an inner section flanked on either side by a side section, although of course more or fewer sections could be used. More detail about the possible configuration of the air flow conduit 406 will be discussed with reference to Figure 8.

[0056] A ledge 516 may be provided at the upper edge of the sloping surface 514, and an upstanding flange 518 may be provided around at least a portion of the ledge 516, to co-operate with corresponding features on the upper housing part. These co-operating parts, which may take other forms, enable the upper and lower housing parts to abut in such a way that there is little disruption of air flow through the composite air flow conduit, and preferably also in such a way that an effective seal can be provided between, on the one hand, the compartment that will contain the air heat exchanger and the fan, and on the other the compartment that will respectively contain the heat pump’s electronics and the compartment that will contain the compressor and its associated refrigerant pipework. Preferably a substantially gas-tight (or at least weather tight) seal is provided between the first compartment containing the compressor and the second compartment containing the fan and air heat exchanger, and between the second compartment and the third compartment containing the heat pump’s electronics, without the need to use an intermediate sealing component between the upper and lower housing parts. But in practice it may be necessary to use a suitable sealing strip or sealant in order to achieve a sufficiently good seal (e.g. a weather tight seal).

[0057] In general we want the housing to be weather tight, and care in design and assembly, particularly with respect to elements 516, 518, 534, 550, 552, (and 602 and 604 which will be mentioned later) to provide weather tight seals where surfaces meet is desirable.

[0058] Other features may be provided to enable the upper and lower housing parts to couple together and to provide structural stability to the assembled housing. One such feature, shown in Figures 5A and 5B, is an upstanding frame portion 520 provided in what will become the compartment containing the compressor. The frame portion may include at its upper end a socket 522 to receive a corresponding boss that is formed in a lower surface of the upper housing part. In the example shown, the upper end of the frame part 520, and the socket 522, are each square in section, to mate with a corresponding square section boss on the upper housing part. The socket may also be provided with one or more pairs of holes 524 to receive a bolt or the like which may pass through the paired holes and through a corresponding hole or holes in the bosson the upper housing part. The bolt or bolts being used to secure the upper and lower housing parts together.

[0059] Figure 5A shows a pair of openings 526 and 528 on the back face of the heat pump. Opening 526 communicates with what will become the chamber that houses the processor and other electronics (e.g. the inverter) of the heat pump, and is provided to accommodate electrical (and potentially optical) cables for powering the heat pump and for providing communication and control features. Conversely, opening 528 communicates with what will become the chamber that houses the compressor and the refrigerant and water pipework, to accommodate the pipes (e.g. pair of flow and return) by means of which the heat pump will be connected to a heating installation. The opening 528 preferably includes suitable sized and located channels 530 to accommodate the relevant pipework, and these channels may each include anti-rotation features (e.g. formations configured to mate to 4 sides of a 6-sided union or connector) by means of which the unions (or bodies) of compression (or other) pipework fittings may be held in place to facilitate installation. These anti-rotation features may again be formed in situ during the moulding or printing process, saving further manufacturing and labour costs.

[0060] Cover plates may be provided for each of the openings 526 and 528. Cover plate 526 may be provided with suitable glands for sealing around wiring conduit, and wiring, as appropriate to provide a weatherproof seal and to prevent ingress of rodents and other pests and also to protect the cables / pipework from human interference. The cover plate 528 for pipework may include factory-made circular openings for the male union fittings to poke through.

[0061] To the left of figure 5B can be seen an upstanding wall 532 at the top of which are channels 534 through which will pass the pipes which carry refrigerant to and from the evaporator 20 and wiring to the sensors and valve(s) within the evaporator. Also to the left of the figure a zone 535 is marked out to receive the compressor 32 and the liquid receiver 12. This zone 535 may be distinguished from the surrounding portions of the upper face (or floor) of the lower housing part 304, for example by having a flat and level base whereas the surrounding portions (or the rest) of the upper face may slope downwards towards the leading edge of the lower housing part. - a feature that is useful for ventilating the refrigerant and electrical chambers in the event of refrigerant leakage, particularly if a flammable refrigerant is being used. The zone 535 preferably includes captive nuts 536 / 537 or other fastening features to permit the ready securing of the compressor and the liquid reservoir to the lower housing part.

[0062] To the right of the zone 535 is the frame portion 520 which includes at its lower front edge a flange 538 that is spaced from the floor surface of the lower housing part to accommodate water and refrigerant pipes. The upper surface provides a support or abutment surface 540 for the condenser or water heat exchanger 34 as will be seen in Figures 8 to 10.Somewhat to the right of the frame portion one or more features 542, 543 such as grooves or flanges, may be provided to accommodate the cooling plate 46 on which the inverter will be mounted. The grooves or other features 542, 543, may be provided in the back wall and floor of the lower housing part. The cooling plate may form a partition that will separate the two compartments 544 and 546 that will house on the one hand the compressor and other refrigerant circuit, and on the other the heat pump’s processor and other electronics.

[0063] Figure 5C is another perspective view showing the base part 304 with the front panel 306 in place, viewed from above and to the right. As can be seen, the front panel 306 has at its upper edge a structure 550 to mate with the corresponding surface of a lower edge of the upper housing part 302. The structure preferably includes one or more features to aid alignment of the two parts during assembly and these alignment features, or others, preferably also provide an effective seal between the upper part and the lower part. For example the structure 550 may comprise a ledge and one or more upstanding flanges. At its back edge on either side the front panel 306 may couple at 552 with corresponding surfaces on front edges of the base part 304, again preferably to provide a substantially gas tight (or at least weather tight) seal (with or without the use of intermediate sealing members, but preferably without). Adjacent portions 554 of the back edge of the front panel 306 are also designed to mate with corresponding edges / surfaces of the upper housing part, again preferably providing a substantially gas tight (or at least weather tight) seal.

[0064] Figures 6A and 6B are perspective views showing the upper housing part 304 with the fan assembly removed. Figure 6 A shows a view looking into the aperture 310 into which the fan assembly is mounted. The aperture 301 opens into a generally cylindrical space which, once the fan assembly is installed, surrounds the cylindrical housing part 410. In the side wall that defines this space are formed channels 600 which serve to accommodate and guide the wiring that feeds the motor (and motor controller) of the fan assembly.

[0065] Figure 6B shows the generally vertical mating surface 602 that will abut the portions 554 of the back edge of the front panel 306, and the generally horizontal mating surface 604 that will abut with the upper edge 550 of the front panel, when the housing is assembled. The upper housing part includes a floor (behind sloping surface 406, and between the two horizontal mating surfaces 604) which serves as a roof to the compartment housing the compressor and the compartment housing the processor and other electronics. This helps to keep heat within these compartments so that it can be harvested using the cold plate 46, as will later be described.

[0066] Figures 7A and 7B show the front panel 306 from behind and from in front. It will be appreciated that rather than using a single housing element to cover the fronts and the sides of the chambers that house the compressor and the electronics it would be possible to provide one or more separate covers for each of these chambers. The use of a one piece cover, generally asshown, does have the advantages of reducing parts count and also eliminating the need to seal more joints between panels or housing elements. The boss that can be seen on the rear face of the cover is an artefact of the moulding process used.

[0067] Figure 8A is a vertical cross section through the centre line that bisects the front and rear faces of the housing. The fan motor 800 can be seen as part of the fan assembly 408, along with the fan 802. The condenser or heating heat exchanger 34 can be seen being supported by the abutment surface 540 on the flange 538. The drip tray 804 to collect condensate that falls from the air heat exchanger 20 is also shown.

[0068] Figure 8A also illustrates the smooth and largely unobstructed air flow path between the evaporator 20 and the fan, due to the fact that the fan is mounted to and carried by the upper housing cover 302 and that no chassis needs to be provided between the evaporator and the fan. Indeed the fan is preferably entirely supported structurally by the upper housing. The contouring of the air flow conduit 406, formed between the housing base part 304 and the housing upper part 306, which may contribute to improving efficiency and reducing noise generation, can clearly be seen in the figure.

[0069] The lower end of the evaporator 20 may include the sub-cooler 100 through which refrigerant is arranged to pass on route from the liquid receiver 12 to the heating expansion valve 16. The sub-cooler may consist of just a few vertically displaced rows of conduit (say one to four), and all or most of these may be shielded from the air flow induced by operation of the fan by an upstand 806 formed as part of the base part 304. This upstand may be on the upstream or downstream (i.e. left or right) of the sub-cooler as viewed in Figure 8A, or there may be a formation on both sides.

[0070] A peg or boss 808 extending downwardly from the lower surface of the upper housing part 302 is shown as engaging with the socket 522 on the integrally formed frame portion 520. A bolt or screw may be used to secure the boss 808 within the socket 522, thereby securing the upper and lower housing parts. The previously mentioned floor 80 of the upper housing part, that provides a roof or ceiling to the two compartments below is also shown.

[0071] Figure 8 A also shows the status display indicator 115 positioned within the central land of the grille.

[0072] Note that in Figures 8 and 10 the evaporator 20 is represented as having two featureless surfaces separated by a feature rich region, but this is merely a CAD artefact and it is without technical significance.

[0073] Figure 8B is a near three quarter view from the left front, with the front cover removed, of the heat pump that is partially populated with its internal components. The compressor 30 can be seen secured to the floor of the lower housing part. To the right of the compressor is the fluidreservoir 12 also secured to the floor of the lower housing part 304. To the right of the fluid reservoir 12 is the condenser 12 supported on the flange 538 that forms part of the lower housing part. The four way valve arrangement 32 is carried by the metal pipework that carries refrigerant and which may be clipped into place in features moulded or printed into the lower housing part. Also shown is the optional, but preferred, pump 810 that serves to pump heating fluid through the condenser 34.

[0074] To the right of the condenser 34 is the cold plate 46 to which is attached the heat pump’s electrical inverter. The cold plate 46 may be fed with refrigerant taken from the fluid reservoir 12, the refrigerant passing through expansion valve 48 before entering the cold plate. The expansion valve 48 may be controlled based upon the temperature of an IGBT in the inverter, for example targeting an IGBT temperature of 25C. Although not shown in the drawings, a cover may be provided over the cold plate and a fan provided to draw air in from towards the top of the chamber housing the compressor and to expel the air from around the lower end of the cold plate - in this way harvesting energy from warm air in the chamber housing the compressor, as well as recovering energy from the inverter. Warmed refrigerant from the cold plate then passes back into the inlet side of the compressor 32.

[0075] The thermal insulation properties of the plastics housing, which may be double skinned (hollow) and which may include insulation between the outer and inner skins, mean that harvesting heat internally in this way may make a worthwhile contribution to improving the efficiency of the heat pump. It also means that the pipework within the heat pump does not need to be separately lagged or insulated, further saving construction labour costs.

[0076] The lower housing part 304 preferably includes one or more grooves (e.g. a groove in the generally vertical wall and another in the floor) to receive and hold the cold plate 46, again doing away with the need for an internal chassis. The processor and other electronics of the heat pump may be located in the chamber to the right of the cold plate 46. The cold plate 46 acts as a barrier to separate the compartment housing the electronics from the compartment housing the compressor and most other refrigerant-handling components.

[0077] Preferably the cold plate, the lower housing part 304 and the front cover 306 are so configured that an effective gas seal is provided between the chamber containing the electronics and that containing the compressor. If the refrigerant is flammable, it is useful to have such a substantially gas tight (some leakage of refrigerant gas into the electronics chamber may be permitted by the relevant technical standards, the acceptable threshold depending upon the explosion risk posed by the electronics) barrier between the two chambers because it can reduce the need to ensure that all the electronics / electrics in the second chamber are certified flame proof. If the refrigerant is flammable, it may also be necessary to provide some form ofventilation for the chamber that houses the compressor and the refrigerant circuits, but otherwise it may be preferable to ensure that the chamber is gas tight or at least weather tight (and draft proof) to reduce energy losses.

[0078] The pipework that runs close to the floor of the compartment housing the compressor may clip into place in features integrally formed (moulded or printed) in the plastics material of the lower housing part. In this way the lower housing may act as a jig for use when connecting the various refrigerant and water pipes, for example by soldering or brazing. In addition, more anti-turn features may be provided to hold captive threaded fasteners / coupling components / valves, etc. to facilitate speedier assembly of the heat pump.

[0079] An expansion vessel for the heating circuit (pumped by pump 810) may be located in the gap between the condenser and the cooling plate 46.

[0080] Figure 9 is a plan view looking down on the lower housing part and front cover after the heat pump has been assembled. Here we see the PCB 900 that carries the heat pump’s processor, and coupled to this a wiring loom or harness 902 that is wrapped for protection and that passes from the chamber that houses the processor to the chamber that houses the compressor 30.

[0081] Suitable gas sealing (and sealing to provide weather tightness) precautions may be implemented, as just discussed. The inverter 903is mounted to the cold plate 46 whose temperature is regulated to ensure optimum performance of the inverter. The temperature of the processor may also be monitored and using by the processor in controlling operation of the heat pump and the flow of refrigerant through the cold plate 46 in order to prevent thermal damage to the processor.

[0082] Figure 10 corresponds generally to Figure 9, but shows the heat pump after assembly but with the front cover and upper housing portion removed. The space between the condenser 34 and the cold plate 46, to receive the expansion vessel for the heating system can clearly be seen. Element 1000 is a cover for the pipework-receiving opening 528.

[0083] Constructing a heat pump according to aspects of the invention starts with a bare lower housing part 304 which is then populated with the compressor and fluid reservoir, which are bolted to the floor of the lower housing part for example using captive nuts incorporated during the moulding or printing of the lower housing part. The condenser may be mounted on the flange 538 on the integrally formed frame portion, and may be held in place with a strap that secures the condenser to the lower housing part. As previously mentioned, pipework to carry refrigerant and pipework to carry water may be clipped into place in formations pre-formed on the floor of the lower housing part and elsewhere. The evaporator may be slotted into place in the receiving recess 500, and the pipework connected. The inverter may be mounted to the cooling plate 46, and the assembly then inserted into the receiving grooves (or other features) 542, 543. The electronics may then be mounted to the body of the inverter, and the wiring loom connected tothe various valves, sensors, etc. The fan assembly, which may be pre-wired with cabling for fan power and control (e.g. MODBUS), is mounted to the upper housing part 302. Once assembly and charging of the components on the lower housing part is completed the wiring from the fan is connected to the electronics and power feed on the lower housing part, and the upper housing part is placed on the lower housing part and the two connected. The front cover may then be put in place, with the heat pump awaiting despatch and installation. Such an assembly process may be significantly simpler and faster than with heat pumps of conventional construction.

[0084] Although the described embodiments have focused on a particular housing design in which the ceilings of the refrigerant and electrics chambers are provided by a floor of the upper housing part, it should be appreciated that these ceilings could be provided instead by the lower housing part, as could the majority or the whole of the lower surface of the airflow path (instead of this being split between the upper and lower housing parts). That is, it is not necessary for both housing parts to contribute to both the refrigerant chamber and the electronics chamber. The upper housing part could still contain and support the fan and its motor, and cap off the evaporator.

Claims

Claims1. A heat pump external unit comprising:a housing and within the housing an evaporator, the housing including an air inlet and an exhaust outlet, a fan to move air from the inlet through / over the evaporator and out through the exhaust outlet of the housing, the air inlet being provided in a rear or side face of the housing, and the exhaust outlet being provided in an upper or front face of the housing, the exhaust outlet having a generally circular cover grille, the fan being located behind the cover grille and including a motor and / or bearing substantially at the centre of the grille, the heat pump external unit including a connection to a remote unit including a control panel and information display, the heat pump external unit including control logic for controlling the fan and a compressor connected to the evaporator, the control logic being arranged to operate with the control panel to display information on the operation of the unit and to set one or more parameters relating thereto, the heat pump external unit further comprising a status display indicator comprising a plurality of addressable illumination elements overlaid by a diffuser and / or a printed image or logo, wherein the diffuser and / or the image at least partially obscures or blurs the individual addressable illumination elements, wherein the addressable elements can be controlled to illuminate the diffuser and / or printed image or logo to render the exhaust outlet visible in darkness, wherein the addressable illumination elements include at least one element of selectable colour and / or wherein the plurality of addressable illumination elements include elements of multiple different colours and wherein intensity of at least some of the plurality of addressable illumination elements is variable in multiple steps or substantially continuously, wherein the control logic is controllable to send one of a plurality of static patterns or animation sequences to control the addressable illumination elements based on both a status of operation of the heat pump external unit and based on one or more stored configuration parameters so that different states of operation of the device are discernible from observation of the collective arrangement of the addressable illumination elements.

2. The heat pump external unit as claimed in claim 1, wherein the housing comprises a generally planar back wall housing the evaporator and a curved front with the fan angled upwards and pointing forwards.

3. The heat pump external unit as claimed in claim 1 or 2, wherein the fan has a central motor supported by the grille, and the grille carries wires / electrical conductors that in use provide power to the motor and signals to the central indicator.

4. The heat pump external unit as claimed in any preceding claim, wherein the status indicator is configured to indicate at least one of the following conditions: fault condition, defrost mode, quiet mode, and normal operation mode.

5. The heat pump external unit as claimed in any preceding claim, wherein the status indicator’s display is configurable via the control panel.

6. The heat pump external unit as claimed in any preceding claim, wherein the status indicator provides a sequence of indications related to various parameters using an animated display.

7. The heat pump external unit as claimed in any preceding claim, wherein the display comprises at least one central element, a first radial array of elements, and a second outer array of radial elements.

8. The heat pump external unit as claimed in any preceding claim, wherein the display includes a screen-printed logo or icon that obscures multiple elements of the display for aesthetic integration and enhanced functionality.

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