HEAT PUMP WITH REFRIGERANT DETECTION AND TEMPERATURE-BASED OPERATION

Description

TECHNICAL FIELD

The disclosed systems and methods relate generally to a heating and cooling device (e.g., a heat pump) having a heat exchanger, a refrigerant sensor to detect refrigerant leaks proximate to the heat exchanger, a temperature switch to detect a temperature proximate to the refrigerant sensor and shut off operation of an auxiliary furnace in the heating and cooling device when the temperature in the heat exchanger rises too high, and a latch to control operation of the temperature switch.

BACKGROUND

A heating and cooling device (e.g., a heat pump) will generally include a heat exchanger, which may include coils through which a refrigerant flows, e.g., an A-coil. One common type of refrigerant used by such heating and cooling devices is an A2L refrigerant. The designation A2L indicates that the refrigerant is non-toxic (A), is flammable (2), and has a low burning velocity (L). Other refrigerants may also be used, with varying parameters.

In the heating and cooling device, the refrigerant is cooled in a cooling operation and heated in a heating operation, and air is passed over the coils. This causes the air to exchange heat with the refrigerant passing through the coils and be either heated or cooled depending upon the type or operation being performed.

During heating and cooling operations, a coil-based heat exchanger can leak refrigerant into the air surrounding the heat exchanger. This often happens where pipes are brazed, though other types of leaks are also possible.

Leaks in a heat exchanger coil are undesirable for several possible reasons. First, if the refrigerant used in heating and cooling devices is toxic, leaked refrigerant may cause a health hazard to people in the building containing the heating and cooling device. Leaked refrigerant from the heating and cooling device can be blown into the area being heated or cooled and may be breathed by those inside that the building containing the heating and cooling device. Second, if the refrigerant is flammable, leaked refrigerant can increase the fire risk in the building containing the heating and cooling device. Third, since the proper operation of a coil-based heat exchanger requires sufficient refrigerant pass through the coils, a leakage of refrigerant can cause the heating and cooling device to function less efficiently. Fourth, leaked refrigerant must be replaced, meaning that a refrigerant leak will result in additional costs for operating the heating and cooling device.

As a result, many heating and cooling devices contain one or more refrigerant sensors to detect refrigerant leaks so that they can be identified and corrected quickly, and so avoid or minimize the problems identified above.

In addition, in some instances, a heat exchanger may be insufficient on its own to provide the necessary level of heating, e.g., when the ambient temperature is particularly cold. As result, many heat pumps also include an auxiliary furnace, which can operate to augment the operation of the heat exchanger during heating operation when the heat exchanger loan cannot provide the required level of heating. In some instances, the furnace may heat the air to a temperature high enough that it will interfere with the operation of certain temperature-sensitive circuits within the heat exchanger, e.g., refrigerant sensors, temperature sensors, thermistors, or the like.

It therefore may be desirable to provide a circuit to automatically shut down the furnace when the air inside the heat pump becomes too great and provides desirable control for restarting the furnace when appropriate.

SUMMARY OF THE INVENTION

In some aspects, the techniques described herein relate to a heat pump, including: a furnace; a heat exchanger; a refrigerant sensor located proximate to the heat exchanger and configured to detect a presence of refrigerant in air adjacent to the refrigerant sensor; a first temperature switch located proximate to the refrigerant sensor and configured to open when a first temperature at the first temperature switch exceeds a first threshold temperature; and a latch circuit configured to close the first temperature switch upon execution of a human-initiated resume command, wherein the first temperature switch is further configured to prevent operation of the heat pump when the first temperature switch is open.

In some aspects, the techniques described herein relate to a heat pump, wherein the heat exchanger is located adjacent to the furnace.

In some aspects, the techniques described herein relate to a heat pump, wherein the first temperature switch is located within 3 inches of the refrigerant sensor.

In some aspects, the techniques described herein relate to a heat pump, wherein the refrigerant sensor is located within 3 inches of the heat exchanger.

In some aspects, the techniques described herein relate to a heat pump, wherein the first threshold temperature is between 150° F. and 195° F.

In some aspects, the techniques described herein relate to a heat pump, wherein the latch circuit includes a physical button configured to close the first temperature switch when pressed, and a pressing of the physical button forms at least a part of the execution of the human-initiated resume command.

In some aspects, the techniques described herein relate to a heat pump, further including: a controller configured to control the operation of the furnace, wherein the latch circuit is contained within the controller.

In some aspects, the techniques described herein relate to a heat pump, wherein the controller is located inside a casing surrounding the controller.

In some aspects, the techniques described herein relate to a heat pump, further including: a communications circuit connected to the controller via a remote connection, wherein the communications circuit is configured to allow an operator to execute the human-initiated resume command.

In some aspects, the techniques described herein relate to a heat pump, wherein the remote connection is a wired connection.

In some aspects, the techniques described herein relate to a heat pump, wherein the remote connection is a wireless connection.

In some aspects, the techniques described herein relate to a heat pump, wherein the communications circuit is a remote controller for the heat pump, the remote controller including a touch screen, the remote controller is configured to display a virtual button on the touch screen, a pressing of the virtual button forms at least a part of the execution of the human-initiated resume command, and the controller is further configured to close the first temperature switch after the pressing of the virtual button.

In some aspects, the techniques described herein relate to a heat pump, wherein the communications circuit is a smartphone that includes a touch screen, the smartphone is configured to display a virtual button on the touch screen, and a pressing of the virtual button forms at least a part of the execution of the human-initiated resume command, and the controller is further configured to close the first temperature switch after the pressing of the virtual button.

In some aspects, the techniques described herein relate to a heat pump, further including: an alert circuit configured to provide an alert to an operator when the first temperature switch is open.

In some aspects, the techniques described herein relate to a heat pump, wherein the alert is one of a constant light, a blinking light, a constant alarm sound, a periodic alarm sound, an email sent to a stored email address, a text message sent to a stored telephone number, or a message displayed on a screen.

In some aspects, the techniques described herein relate to a heat pump, further including: a thermistor attached to a heating coil in the heat exchanger; and a second temperature switch located proximate to the thermistor and configured to open when a second temperature at the second temperature switch exceeds a second threshold temperature, wherein the latch circuit is further configured to close the second temperature switch upon the execution of the human-initiated resume command, and the second temperature switch is further configured to prevent operation of the furnace when the second temperature switch is open.

In some aspects, the techniques described herein relate to a heat pump, wherein the second threshold temperature is between 150° F. and 195° F.

In some aspects, the techniques described herein relate to a heat pump, wherein the second temperature switch is located within 3 inches of the thermistor.

In some aspects, the techniques described herein relate to a heat pump, wherein the refrigerant sensor is attached to a first side of a sheet metal plate, and the first temperature switch is attached to a second side of the sheet metal plate opposite the first side.

In some aspects, the techniques described herein relate to a heat pump, including: a furnace; a heat exchanger; a refrigerant sensor located proximate to the heat exchanger and configured to detect a presence of refrigerant in air adjacent to the refrigerant sensor; a first temperature sensor located proximate to the refrigerant sensor and configured to detect a first temperature at the first temperature sensor; and a controller including a heat pump control circuit configured to stop operation of the furnace when the first temperature exceeds a first threshold temperature, and a latch circuit configured to restart the operation of the furnace upon execution of a human-initiated resume command.

In some aspects, the techniques described herein relate to a heat pump, wherein the first temperature sensor is located within 3 inches of the refrigerant sensor.

In some aspects, the techniques described herein relate to a heat pump, wherein the refrigerant sensor is located within 3 inches of the heat exchanger.

In some aspects, the techniques described herein relate to a heat pump, wherein the heat exchanger is located adjacent to the furnace.

In some aspects, the techniques described herein relate to a heat pump, wherein the first threshold temperature is between 150° F. and 195° F.

In some aspects, the techniques described herein relate to a heat pump, further including: a communications circuit connected to the controller via a remote connection, wherein the communications circuit is configured to allow an operator to execute the human-initiated resume command.

In some aspects, the techniques described herein relate to a heat pump, wherein the remote connection is a wired connection.

In some aspects, the techniques described herein relate to a heat pump, wherein the remote connection is a wireless connection.

In some aspects, the techniques described herein relate to a heat pump, wherein the communications circuit is a remote controller for the heat pump, the remote controller including a touch screen, the remote controller is configured to display a virtual button on the touch screen, a pressing of the virtual button forms at least a part of the execution of the human-initiated resume command, and the controller is further configured to restart the operation of the furnace after the pressing of the virtual button.

In some aspects, the techniques described herein relate to a heat pump, wherein the communications circuit is a smartphone that includes a touch screen, the smartphone is configured to display a virtual button on the touch screen, and a pressing of the virtual button forms at least a part of the execution of the human-initiated resume command, and the controller is further configured to restart the operation of the furnace after the pressing of the virtual button.

In some aspects, the techniques described herein relate to a heat pump, further including: an alert circuit configured to provide an alert to an operator when the heat pump control circuit stops the operation of the furnace.

In some aspects, the techniques described herein relate to a heat pump, wherein the alert is one of a constant light, a blinking light, a constant alarm sound, a periodic alarm sound, an email sent to a stored email address, a text message sent to a stored telephone number, or a message displayed on a screen.

In some aspects, the techniques described herein relate to a heat pump, further including: a thermistor attached to a heating coil in the heat exchanger; and a second temperature sensor located proximate to the thermistor and configured to detect a second temperature at the second temperature sensor, wherein the heat pump control circuit is further configured to stop the operation of the heat pump when the second temperature exceeds a second threshold temperature.

In some aspects, the techniques described herein relate to a heat pump, wherein the second temperature sensor is located within 3 inches of the thermistor.

In some aspects, the techniques described herein relate to a heat pump, wherein the second threshold temperature is between 150° F. and 195° F.

In some aspects, the techniques described herein relate to a heat pump, wherein the refrigerant sensor is attached to a first side of a sheet metal plate, and the first temperature sensor is attached to a second side of the sheet metal plate opposite the first side.

In some aspects, the techniques described herein relate to a method of controlling an operation of a heat pump, including: detecting a temperature proximate to a refrigerant sensor; determining that the detected temperature is above a first threshold temperature; stopping the heating operation of a furnace associated with the heat pump in response to determining that the detected temperature is above the first threshold temperature receiving a human-initiated restart command; and restarting the operation of the furnace in response to the human-initiated restart command.

In some aspects, the techniques described herein relate to a method, further including: providing an alert after the stopping of operation of the furnace.

In some aspects, the techniques described herein relate to a method, wherein the alert is one of a constant light, a blinking light, a constant alarm sound, a periodic alarm sound, an email sent to a stored email address, a text message sent to a stored telephone number, or a message displayed on a screen.

In some aspects, the techniques described herein relate to a method, wherein providing the alert further includes displaying a text message on a touch screen, and displaying a virtual button on the touch screen, and the receiving of the human-initiated restart command occurs when an operator presses the virtual button.

In some aspects, the techniques described herein relate to a method, wherein the receiving of the human-initiated restart command occurs when an operator presses a physical button attached to the heat pump.

In some aspects, the techniques described herein relate to a method, wherein the first threshold temperature is between 150° F. and 195° F.

In some aspects, the techniques described herein relate to a method, wherein the stopping of the operation of the furnace further includes opening a switch, and the restarting of the operation of the furnace further includes closing the switch.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, where like reference numerals refer to identical or functionally similar elements and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate an exemplary embodiment and to explain various principles and advantages in accordance with the present disclosure.

FIG. 1 is a perspective view of a heat pump system according to an exemplary device;

FIG. 2 is a perspective view of the heat exchanger circuit of FIG. 1 according to an exemplary device;

FIG. 3 is a diagram of the heat exchange circuit and control circuitry of FIG. 1 with a physical latch according to an exemplary device;

FIG. 4 is a diagram of the heat exchanger circuit and control circuitry of FIG. 1 in which the controller performs the function of the latch according to an exemplary device;

FIG. 5 is a perspective view of the latch circuit of FIG. 3 according to an exemplary device;

FIG. 6 is a view of a communications circuit of FIG. 3 according to a first exemplary device;

FIG. 7 is a view of a communication circuit of FIG. 3 according to a second exemplary device;

FIG. 8 is a flowchart of the operation of monitoring a heat pump for overheating with one temperature switch according to an exemplary method; and

FIG. 9 is a flowchart of the operation of monitoring a heat pump for overheating with two temperature switches according to an exemplary method.

DETAILED DESCRIPTION

The instant disclosure is provided to further explain in an enabling fashion the best modes of performing one or more embodiments of the present invention. The disclosure is further offered to enhance an understanding and appreciation for the inventive principles and advantages thereof, rather than to limit in any manner the invention. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.

It is further understood that the use of relational terms such as first and second, and the like, if any, are used solely to distinguish one from another entity, item, or action without necessarily requiring or implying any actual such relationship or order between such entities, items or actions. It is noted that some embodiments may include a plurality of processes or steps, which can be performed in any order, unless expressly and necessarily limited to a particular order; i.e., processes or steps that are not so limited may be performed in any order.

In one or more embodiments, a non-transitory computer readable medium may be provided which comprises instructions for execution by a computer, the instructions including a computer-implemented method for controlling an air-conditioning system to defrost a condenser coil, as described above. The non-transitory computer readable medium may comprise, for example, a read-only memory (ROM), a random-access memory (RAM), a programmable ROM (PROM), and/or an electrically erasable read-only memory.

Heat Pump System

FIG. 1 is a perspective view of a heat pump system 100 according to an exemplary device. As shown in FIG. 1, the heat pump system 100 includes a heat exchanger circuit 110, a furnace circuit 120, a blower circuit 130, an inlet duct 140, a flue 150, an air inlet 160, and an air outlet 165. The heat exchanger circuit 110 further includes a heat exchanger coil 170 and a drain pan 175. Furnace circuit 120 further includes a furnace 180. The blower circuit 130 further includes a blower fan 190.

The heat exchanger circuit 110 is a circuit configured to heat or cool air that passes through it using the heat exchanger coil 170. In the exemplary device of the FIG. 1, the heat exchanger circuit 110 is primarily responsible for heating or cooling the air that passes through the heat pump system 100.

The heat exchanger coil 170 contains a refrigerant that circulates through it. This refrigerant is heated during a heating operation and cooled during a cooling operation. Input air (typically return air from an area to be heated or cooled) is passed over the heat exchanger coil 170, which allows the refrigerant passing through the heat exchanger coil 170 to transfer heat between itself and the air passing across the heat exchanger coil 170. During a heating operation, heat from the refrigerant is transferred to the input air, while during a cooling operation heat from the input air is transferred to the refrigerant.

The drain pan 175 is located below the heat exchanger coil 170 and is configured to gather condensation that falls from the heat exchanger coil 170 and direct that condensation to an external drain.

The furnace circuit 120 is provided as an auxiliary heating element for when the heat exchanger circuit 110 alone is insufficient to heat the input air to a desired temperature during a heating operation. If the ambient temperature is sufficiently low, the efficiency of the heat exchanger coil 170 may not allow for sufficient heat to be transferred from the warmed refrigerant to the input air. In such case the furnace circuit 120 operates to provide additional heat that is transferred to the input air.

The furnace 180 is a device that generates heat using a direct power source such as burning natural gas, burning oil, burning kerosene, running electricity through a heating coil, etc., and transfers that heat to the input air. It runs in place the heat exchanger coil 170 to transfer heat to the input air when the heating demand rises above what the heat exchange circuit 110 can provide. In the exemplary device shown in FIG. 1, the furnace 180 is a natural-gas-burning furnace. However, this is by way of example only. Other exemplary devices could use different types of furnace 180. The furnace 180 may have two modes of operation: a heating operation (including both heating and ventilation), and a ventilation mode (including only ventilation).

The blower circuit 130 operates to circulate air through the heat pump system 100. In the exemplary system shown in FIG. 1, the blower circuit 130 draws air into the inlet duct and pushes air through the furnace circuit 120 and heat exchanger circuit 110. However, this is by way of example only. Alternate exemplary devices could move the blower circuit 130 to any desirable point along the air flow of the heat pump system 100.

The blower fan 190 is located in the blower circuit 130 and is a rotary fan configured to move air through the heat pump system 100. In the exemplary system shown in FIG. 1 the blower fan 190 draws air in through the side and expels air from the top.

The inlet duct 140 is arranged between the air inlet 160 and the blower circuit 130. It provides a channel for input air to pass from the air inlet 160 to the side air input of the blower fan 190.

The flue 150 provides a channel for smoke, gas, or other products of combustion to be expelled from the furnace 180 in the furnace circuit 120 to outdoors. The flue 150 serves to protect the structure containing the heat pump system 100 from the heat and the byproducts of combustion caused by a fire in the furnace 180.

The air inlet 160 is located at the farthest point upstream of the air path through the heat pump system 100 and is located where input air can be drawn into the heat pump system 100. For example, the air inlet 160 can be located where it can draw return air from inside an area that should be heated or cooled such that the inside air is recirculated and its temperature adjusted. In the alternative, the air inlet 160 can be located near a supply of outside air.

The air outlet 165 is located at the furthest point downstream of the air path through the heat pump system 100 and is located where heated or cooled air can be expelled as supply air from the heat pump system 100 into an area that should be heated or cooled.

In the exemplary device of FIG. 1, the flow of input air through the heat pump system 100 passes from the air inlet, through the inlet duct 140 to the blower circuit 130, then to the furnace circuit 120 and to the heat exchanger circuit 110. Heated or cooled air is then provided from the heat exchanger circuit 110 via the air outlet 165 as supply air to an area that should be heated or cooled. However, this orientation is by way of example only. Other exemplary devices could change the order in which the heat exchanger circuit 110, the furnace circuit 120, and the blower circuit 130 are arranged.

In operation, air is drawn in through an air inlet 160 and passes through the inlet duct 140 to the blower circuit 130. The air moves because the blower fan 190 in the blower circuit 130 operates to draw the air through the inlet duct 140 and blow it towards the furnace circuit 120 and the heat exchanger circuit 110.

Air moves through the furnace circuit 120 from the blower circuit 130 to the heat exchanger circuit 110. If the heat pump system 100 is operating in a cooling mode or is operating in a heating mode in a situation in which the heat exchanger circuit 110 alone is sufficient to provide the desired level of heating, the furnace 180 in the furnace circuit 120 will be shut off and the input air will simply pass through the furnace circuit 120 unchanged.

If, however, the heat pump system 100 is operating in a heating mode and the heat exchanger circuit 110 alone is insufficient to provide the desired level of heating, the furnace 180 in the furnace circuit 120 will be turned on and will operate to heat the input air as it passes through the furnace circuit 120.

In operation, when the furnace 180 is turned on, the blower circuit 130 will continue to operate to blow air from the furnace circuit 120 to the air outlet 165. When the furnace 180 is no longer needed for heating, it will shut off to allow its heating elements to cool down, but the blower circuit 130 will continue to operate in a ventilation operation for a time. Each time the ambient temperature becomes low enough that the heat exchanger circuit 110 is insufficient for heating, the furnace circuit 120 will turn on the furnace 180.

If the blower circuit 130 is operating properly, the furnace circuit 120 will follow this normal sequence of operation and will cool off the heating elements. If the blower circuit 130 is defective, however, it will take longer for the heating elements to cool off. Nevertheless, once a temperature-limiting device (not shown) in the furnace circuit 120 determines that its temperature is below a set temperature maximum value (e.g., 30° F.), the temperature-limiting device enables furnace heating and ventilation to restart the furnace 180 working. If the cause of another overheating (e.g., because of a defective blower circuit 130), this on-off cycle may continually repeat.

Since the furnace 180 in the exemplary device of FIG. 1 is a natural-gas-burning furnace, natural gas passes through the flue 150 to the furnace 180 so that it may be burned to generate heat at the furnace 180. In alternate exemplary devices in which a different type of furnace 180 is used, the flue 150 can be replaced with an appropriate supply element, e.g., an oil line, a kerosene line, an electrical wire, etc.

When the input air passes from the furnace circuit 120 to the heat exchanger circuit 110, the heat exchanger coil 170 can either heat or cool the input air by transferring heat between the refrigerant passing through the heat exchanger coil 170 and the input air. In a heating operation, this heat transfer may be the sole method of heating the input air, or it may be provided in addition to the operation of the furnace circuit 120.

Given that in some exemplary devices, the heat exchanger circuit 110 may be located adjacent to the furnace circuit 120, it is possible that during a heating operation, the temperature of the heat exchanger circuit 110 may rise to an undesirably high level. This can be undesirable because the heat exchanger circuit 110 may have circuits within it that are particularly sensitive to high temperatures, e.g., the refrigerant sensor, a thermal switch, a thermal sensor, a thermistor, etc.

It is therefore desirable to monitor the temperature of the heat exchanger circuit 110, or temperature-sensitive parts of the heat exchanger circuit 110, to determine if the temperature either in the heat exchanger circuit 110 in general or proximate to temperature-sensitive circuits within the heat exchanger circuit 110 are undesirably high. If this monitored temperature or temperatures rises above a set threshold temperature, either the furnace 180 or both the furnace 180 and a furnace ventilation operation can be shut down so that the furnace 180 will not heat the heat exchanger circuit 110 to such a degree that the temperature-sensitive circuits within the heat exchanger circuit 110 will be damaged. Shutting down the furnace 180 involves stopping the furnace from burning its fuel to generate heat.

This undesirable temperature within the heat pump system 100 may occur since a temperature sensor used to regulate air temperature is typically located proximate to the air outlet 165 to ensure that supply air output from the heat pump system 100 is not greater than a maximum allowable output temperature, e.g. 200° F. However, given that the heat exchanger circuit 110 is located immediately adjacent to the furnace circuit 120, i.e., between the furnace circuit 120 and the air outlet 165, some or part of the heat pump circuit 110 may become warmer than the air at the air outlet 165.

For example, if the heat pump system 100 is designed such that supply air output from the air outlet 165 cannot rise above 200° F., it is possible that portions of the heat exchanger circuit 110 will rise above 200° F. in temperature, or air passing through these portions of the heat exchanger circuit 110 will be at temperatures above 200° F., given the closer proximity of words of the heat exchanger circuit 110 to the furnace 180. It is even possible that portions of the heat exchanger circuit 110 may be occasionally exposed to temperatures reaching 250° F. or to air having temperatures greater than 250° F., a temperature at which some temperature-sensitive circuits may be damaged.

It is because of this danger of overheating portions of the heat exchanger circuit 110 that the heat pump system 100 is designed to turn off the furnace 180 the heating operation in general when it determines that a temperature-sensitive part of the heat exchanger circuit 110 has been exposed to a sufficiently high temperature. Furthermore, given the danger of damaging these temperature-sensitive circuits, it is desirable to limit the ability of the heat pump system 100 to automatically restart the furnace 180 after an excessive temperature is reached within the heat exchanger circuit 110.

Allowing the heating operation in general or the furnace 180 specifically to restart automatically after a shut down may cause the temperature-sensitive circuits to be repeatedly exposed to excessively high temperatures. For example, if there is a systemic problem, the heat exchanger circuit 110 may reach the undesirable temperature every time the furnace 180 is automatically restarted. Even though the furnace 180 or the heating operation may be shut down every time this undesirable temperature is reached, repeated brief exposure to this temperature may damage portions of the heat exchanger circuit 110.

As a result, the disclosed heat pump system 100 is designed such that when the heating operation or furnace 180 is turned off, it requires human intervention to restart the heating operation or furnace 180. In other words, when the disclosed heat pump system 100 shuts down due to excessive heat in the heat exchanger circuit 110, either the heating operation or the furnace 180 due to excessive temperature, the heating operation or furnace 180 will be disabled until an operator confirms that the problem causing the overheating has been addressed. For example, this could involve repairing the broken furnace, correcting the airflow through the heat pump system 100, etc.

However, when a furnace heating operation stops without enabling the furnace 180 to restart, there is the risk that a structure serviced by the heat pump system 100 will be subject to freezing temperatures inside, particularly when the structure is not occupied. Under such circumstance water pipes can freeze and then burst when the structure is reheated. Other undesirable events can occur when heating stops completely.

Overheating of the furnace 180, which can cause overheating in the heat exchanger circuit 110, can be caused by a defective furnace (e.g. furnace blower) or an issue with ducting. When the overheating is due to a furnace defect, the manufacturer of a heat pump manufacturer may not want to share liability with the furnace manufacturer for any damage that occurs as a result of that defect. In such a case, the heat pump manufacturer may not want to replace or stop the fault diagnostic and safety measures for the furnace 180.

However, if the heat pump system uses a flammable refrigerant, the heat pump manufacturer may be concerned by the danger of fire damage caused by the leaked refrigerant. Thus, in such heat pump systems it may be desirable to stop the furnace 180 or a furnace heating operation until an operator manually restarts the heat pump after refrigerant leak sensors get damaged by excessive temperature. This is why a heat pump controller may have the capability to override or disable the furnace 180 or a furnace heating operation until an operator manually enables it again when the controller considers that the repeated overheating can cause permanent damage to the refrigerant leak sensor.

This leads to two differing concerns: the manufacturer of a heat pump with non-flammable refrigerant not wanting to limit furnace safety, and the manufacturer of a heat pump with flammable refrigerant wanting to limit the number of times a furnace heating operation can restarted to avoid the risk of fire. Because of these differing requirements, some exemplary devices may enable a controller to override or disable a heating operation of the furnace circuit 120 until heating is manually enabled by an operator, while other exemplary devices may limit the ability of the controller to indefinitely disable the heating operation of the furnace circuit 120.

Heat Exchanger Circuit

FIG. 2 is a perspective view of the heat exchanger circuit 110 of FIG. 1 according to an exemplary device. As shown in FIG. 2, the heat exchanger circuit 110 includes a heat exchanger coil 170, a drain pan 175, a casing 210, one or more side panels 220, a refrigerant sensor 230, a liquid thermistor 240, a gas thermistor 245, a first temperature switch 250, and a second temperature switch 255.

The heat exchanger coil 170 and the drain pan 175 operate as described above with respect to FIG. 1 and their description will not be repeated.

The casing 210 is a metal housing surrounding the heat exchanger circuit 110. It provides both insulation for the air inside the casing 210 and helps define the air channel for air passing through the heat pump system 100.

The one or more side panels 220 and are formed between the heat exchanger coil 170 and a wall of the casing 210. By placing multiple side panels 220 adjacent to the heat exchanger coil 170, the air channel can be further defined such that it passes through the heat exchanger coil 170 and allows an access panel or wall in the casing 210 to be removed to allow access to the inside of the heat exchanger circuit 110 without interrupting the airflow past the heat exchanger coil 170. The side panels 220 can be sheet metal plates in some exemplary devices.

The refrigerant sensor 230 is a circuit configured to detect the presence of refrigerant in nearby air. It can be configured to identify a quantifiable level of refrigerant in the nearby air, or it can be configured to identify when the level of refrigerant in the nearby air rises above the threshold refrigerant level in various embodiments. In an embodiment in which the refrigerant is an A2L refrigerant, the refrigerant sensor 230 is an A2L refrigerant sensor.

In the exemplary device of FIG. 2, the refrigerant sensor 230 is located adjacent to an end of the heat exchanger coil 170, though it could be placed anywhere in the heat exchanger circuit 110 where a refrigerant leak is considered most likely. In the exemplary device of FIG. 2, the refrigerant sensor 230 is attached to one of the side panels 220, though this is by way of example only. In alternate exemplary devices, the refrigerant sensor 230 could be located in other parts of the heat exchanger circuit 110.

The liquid thermistor 240 is located near an evaporator coil in the heat exchanger coil 170 and serves to measure the temperature of the refrigerant in the heat exchanger coil 170 when it is in the liquid state. Similarly, the gas thermistor 245 is located near a condenser coil in the heat exchanger coil 170 and serves to measure the temperature of the refrigerant in the heat exchanger coil 170 when it is in the gas state.

The first and second temperature switches 250, 255 each operate as a temperature controlled switch that can disable or prevent the operation of the furnace 180. The first and second temperature switches 250, 255 can determine a temperature proximate to themselves, and will open their respective switch should the respective detected temperature rise above a set temperature threshold.

This threshold may be the same for both temperature switches 250, 255 or may be different for the two temperature switches 250, 255. In some exemplary devices, the first and second temperature thresholds may each be between 150° F. and 195° F. The first and second temperature switches 250, 255 may be either normally-open or normally-closed switches.

The first temperature switch 250 is located proximate to the refrigerant sensor 230 and operates to detect a temperature proximate to the refrigerant sensor 230. In the exemplary device of FIG. 2, the first temperature switch 250 is located within 3 inches of the refrigerant sensor 230. However, this is by way of example only. Alternate exemplary devices may locate the first temperature switch 250 closer or farther away to the refrigerant sensor 230 depending upon system parameters and the sensitivity of the first temperature switch 250. In some exemplary devices, if the refrigerant sensor 230 is attached to a thermally conductive material, e.g., a metal sheet, the first temperature switch 250 could be placed on the opposite side of the thermally conductive material from the refrigerant sensor 230.

The second temperature switch 255 is located proximate to the liquid thermistor 240 and operates to detect a temperature proximate to the liquid thermistor 240. In the exemplary device of FIG. 2, the second temperature switch 255 is located within 3 inches of the liquid thermistor 240. However, this is by way of example only. Alternate exemplary devices may locate the second temperature switch 255 closer or farther away to the liquid thermistor 240 depending upon system parameters and the sensitivity of the second temperature switch 255. In some exemplary devices, if the liquid thermistor 240 is attached to a thermally conductive material, e.g., a metal sheet, the second temperature switch 255 could be placed on the opposite side of the thermally conductive material from the liquid thermistor 240.

Although in the exemplary device of FIG. 2, the first and second temperature switches 250, 255 are configured to disable operation of the furnace 180 when the threshold temperature is reached, alternate exemplary devices could configure the first and second temperature switches 250, 255 to disable both the operation of the furnace 180 and a ventilation operation associated with the furnace 180.

Although in the exemplary device of FIG. 2, first and second temperature switches 250, 255 are provided, adjacent to the refrigerant sensor 230 and the liquid thermistor 240, respectively, alternate exemplary devices could include a third temperature switch proximate to the gas thermistor 245 and operating in a manner similar to the second temperature switch 255. In such an exemplary device, a controller could stop relevant heating operations when any of the first through third temperature sensors were open.

FIG. 3 is a diagram 300 of the heat exchange circuit 110 and control circuitry of FIG. 1 with a physical latch according to an exemplary device. As shown in FIG. 3, the heat exchanger circuit 110 includes a heat exchanger coil 170, a drain pan 175, a casing 210, a plurality of side panels 220, a refrigerant sensor 230, a liquid thermistor 240, a gas thermistor 245, and first and second thermal switches 250, 255. The control circuitry includes a controller 310, a latch circuit 320, alert circuit 330, and a communication circuit 340. The controller 310 and the latch circuit 320 are connected to the heat exchange circuit 110 by a local connection 350. The controller 310, the alert circuit 330, and the communication circuit 340 are connected to the heat exchange circuit 110 by a remote connection 360.

The heat exchanger coil 170, the drain pan 175, the casing 210, the plurality of side panels 220, the refrigerant sensor 230, the liquid thermistor 240, the gas thermistor 245, and the first and second thermal switches 250, 255 operate as described above with respect to FIGS. 1 and 2. Their description will not be repeated.

The controller 310 is configured to control the operation of the heat pump system 100, including the heat exchanger circuit 110. It can include a processor that generates signals to control the circuits within the heat pump system 100 and any other element that requires control signals and a memory that stores information and operation programs.

The processor can be a microprocessor (e.g., a central processing unit), an application-specific integrated circuit (ASIC), or any suitable device for controlling the operation of all or part of the heat pump system 100.

The memory can include a read-only memory (ROM), a random-access memory (RAM), an electronically programmable read-only memory (EPROM), an electrically erasable programmable read only memory (EEPROM), flash memory, or any suitable memory device.

The latch circuit 320 is configured to determine when either or both of the first or second temperature switches 250, 255 is placed in an open position, i.e., disabling the operation of the furnace 180, and to maintain the respective switch 250, 255 in the open position until a human operator manually confirms at the latch circuit 320 that normal heating operations can resume. When this is done, the latch circuit 320 will close the respective temperature switch 250, 255.

In the exemplary device of FIG. 3, the human operator manually confirms that normal operation can resume by performing a physical action at the latch circuit 320. This can include pushing a button, flipping a switch, moving a lever, etc. In this way, a full heating operation cannot resume until the human operator has confirmed that the heat pump system 100 is operating properly.

During a time when the furnace 180 or the heating operation is disabled, the control circuitry will continue to operate. In other words, it can still control various aspects of the heat pump system 100 and can continue to monitor temperatures during this time.

The alert circuit 330 is configured to provide one or more of a visual alert, an audio alert, or a text alert when one or both of the first and second temperature switches 250, 255 disable operation of the furnace 180. For example, the alert circuit 330 could include a constant light, a blinking light, a constant alarm sound, a periodic alarm sound, a text message that could be displayed on a control screen, a text message that could be sent to a telephone number of record, an email that could be sent to an email of record, etc.

The communication circuit 340 is configured to allow for communication with an operator. In various exemplary devices the communication circuit 340 could be a cell phone, a remote controller, a computer, or the like.

The local connection 350 is configured to transmit and receive communications between the controller 310, the latch circuit 320, and elements in the heat exchanger circuit 110. Although it is only shown in FIG. 3 as having signal lines connecting it generally to the heat exchanger circuit 110, this is simply for ease of disclosure. The local connection 350 would also have a communication connection to any element in the heat exchanger circuit 110 that requires instructions from the controller 310 or needs to give information to the controller 310. This could include, but is not limited to, the refrigerant sensor 230, the liquid thermistor 240, the gas thermistor 245, and the first and second temperature switches 250, 255. The local connection 350 could be wired or wireless in various exemplary devices and may include both wired and wireless connections.

The remote connection 360 is configured to transmit and receive communications between the controller 310, the alert circuit 330, the communication circuit 340, and elements in the heat exchanger circuit 110. Although it is only shown in FIG. 3 as having signal lines connecting it generally to the heat exchanger circuit 110, this is simply for ease of disclosure. The local connection 350 would also have a communication connection to any element in the heat exchanger circuit 110 that requires instructions from the controller 310 or needs to give information to the controller 310. This could include, but is not limited to, the refrigerant sensor 230, the liquid thermistor 240, the gas thermistor 245, and the first and second temperature switches 250, 255. The remote connection 360 could be wired or wireless in various exemplary devices, and may include both wired and wireless connections.

In addition, although a separate local connection 350 and remote connection 360 are shown in FIG. 3, this is by way of example only. Alternate exemplary devices could use different wired or wireless connections between the various elements in the control circuitry as desired.

FIG. 4 is a diagram 400 of the heat exchanger circuit of FIG. 1 in which the controller performs the function of the latch according to an exemplary device. As shown in FIG. 3, the heat exchanger circuit 110 includes a heat exchanger coil 170, a drain pan 175, a casing 210, a plurality of side panels 220, a refrigerant sensor 230, a liquid thermistor 240, a gas thermistor 245, and first and second temperature sensors 450, 455. The control circuitry includes a controller 410, an alert circuit 330, and a communication circuit 340. The controller 410 further includes a latching circuit 420 and a heat pump control circuit 425. The controller 410 is connected to the heat exchange circuit 110 by a local connection 350. The controller 410, the alert circuit 330, and the communication circuit 340 are connected to the heat exchange circuit 110 by a remote connection 360.

The heat exchanger coil 170, the drain pan 175, the casing 210, the plurality of side panels 220, the refrigerant sensor 230, the liquid thermistor 240, the gas thermistor 245, the alert circuit 330, the communication circuit 340, the local connection 350, and the remote connection 360 operate as described above with respect to FIGS. 1-3. Their description will not be repeated.

The first and second temperature sensors 450, 455 are each respectively configured to measure a temperature proximate to themself.

The first temperature sensor 450 is located proximate to the refrigerant sensor 230 and operates to detect a temperature proximate to the refrigerant sensor 230 and send that temperature information to the controller 410. In the exemplary device of FIG. 2, the first temperature sensor 450 is located within 3 inches of the refrigerant sensor 230. However, this is by way of example only. Alternate exemplary devices may locate the first temperature sensor 450 closer or farther away to the refrigerant sensor 230 depending upon system parameters and the sensitivity of the first temperature sensor 450. In some exemplary devices, if the refrigerant sensor 230 is attached to a thermally conductive material, e.g., a metal sheet, the first temperature sensor 450 could be placed on the opposite side of the thermally conductive material from the refrigerant sensor 230.

The second temperature sensor 455 is located proximate to the liquid thermistor 240 and operates to detect a temperature proximate to the liquid thermistor 240 and send that temperature information to the controller 410. In the exemplary device of FIG. 2, the second temperature sensor 445 is located within 3 inches of the liquid thermistor 240. However, this is by way of example only. Alternate exemplary devices may locate the second temperature sensor 455 closer or farther away to the liquid thermistor 240 depending upon system parameters and the sensitivity of the second temperature sensor 455. In some exemplary devices, if the liquid thermistor 240 is attached to a thermally conductive material, e.g., a metal sheet, the second temperature sensor 455 could be placed on the opposite side of the thermally conductive material from the liquid thermistor 240.

The controller 410 is configured to control the operation of the heat pump system 100, including the heat exchanger circuit 110. It can include a processor that generates signals to control the circuits within the heat pump system 100 and any other element that requires control signals and a memory that stores information and operation programs.

The processor can be a microprocessor (e.g., a central processing unit), an application-specific integrated circuit (ASIC), or any suitable device for controlling the operation of all or part of the heat pump system 100.

The memory can include a read-only memory (ROM), a random-access memory (RAM), an electronically programmable read-only memory (EPROM), an electrically erasable programmable read only memory (EEPROM), flash memory, or any suitable memory device.

The latching circuit 420 is configured to determine when a temperature detected by either or both of the first or second temperature sensors 450, 455 is above their respective temperature thresholds, and disable the operation of the furnace 180 when this happens. The latching circuit 420 is also configured to maintain this disabled state until a human operator manually confirms that normal operation can resume. When this is done, the latching circuit 420 will again instruct the furnace 180 that it may operate as necessary. The latching circuit 420 may be a portion of the controller 410, e.g., a microprocessor, ASIC, etc.

The temperature threshold may be the same for both temperature sensors 450, 455 or may be different for the two temperature sensors 450, 455. In some exemplary devices, the first and second temperature thresholds may each be between 150° F. and 195° F.

Although in the exemplary device of FIG. 4, the latching circuit 420 is configured to disable operation of the furnace 180 when a detected temperature from at least one of the first and second temperature sensors 450, 455 exceeds a respective threshold temperature, alternate exemplary devices could configure the latching circuit 420 to disable the heating operation when a threshold temperature is detected by one or both of the first and second temperature sensors 450, 455.

In the exemplary device of FIG. 4, the human operator manually confirms that normal operation can resume by performing a physical action either at the controller 410 or via the communication circuit 340. This manual confirmation can include pushing a button, flipping a switch, moving a lever, etc. the physical action may be pressing an electronic button on a touchpad rather than manipulation of a physical button. Furthermore, the physical action may involve pressing a button or other physical manipulation on the communication circuit 340, which operation is reported to the latching circuit 420 via the remote connection 360. In this way, a full heating operation cannot resume until the human operator has confirmed that the heat pump system 100 is operating properly.

The heat pump control circuit 425 is a portion of the controller 410 configured to control operation of the heat pump system 100. In various exemplary devices it can be a portion of a microprocessor, ASIC, or the like.

Latch Circuit

FIG. 5 is a perspective view of the latch circuit 320 of FIG. 3 according to an exemplary device. As shown in FIG. 5, the latch circuit 320 includes a first physical button 510 and a second physical button 520.

The first physical button 510 is configured as a start button such that when the first physical button 510 is pressed, the latch circuit 320 will close both the first temperature switch 250 and the second temperature switch 255 regardless of their current configuration. Thus, the first physical button 510 allows a human operator to affirm that the heat pump system 100 is safe to operate.

The second physical button 520 is configured as a stop button such that when the second physical button 520 is pressed, the latch circuit 320 will open one or both of the first temperature switches 250, 255, stopping operation of the furnace 180. In this way, the second physical button 520 provides a way or a human operator to manually stop operation of heat pump system 100 regardless of what the various temperature sensing circuits determine. Once operation of the furnace 180 is stopped by the operator pressing the second physical button 520, it will remain stopped until the air presses the first physical button 510.

In alternate exemplary devices, the second physical button 520 could stop operation of the furnace 180 through some other mechanism.

Communication Circuit

FIG. 6 is a view of a communications circuit 330 of FIG. 4 according to a first exemplary device. As shown in FIG. 6, the communications circuit 330 in this exemplary device is a remote controller including a touchpad 610.

The touchpad 610 operates as an input/output device, displaying text, and receiving touch input.

When one or both of the first and second temperature sensors 450, 455 exceeds a respective temperature threshold and the latching circuit 420 has disabled operation of the furnace 180, the remote controller will display a message 620 and a restart button 630 on the touchpad 610.

The message 620 will provide a text indication that the heat pump system 100 has overheated and will request that the operator confirm that it is safe to restart the heating operation by pressing the button 630.

The button 630 is a virtual button on the touchpad 610 (i.e., electronic button). Pressing the button 630 will serve as the physical action by a human operator required by the latching circuit 420 to restart operation of the furnace 180.

FIG. 7 is a view of a communication circuit 330 of FIG. 3 according to a second exemplary device. As shown in FIG. 7, the communications circuit 330 in this exemplary device is a smartphone 710.

The smartphone 710 operates as an input/output device, displaying text, and receiving touch input.

When one or both of the first and second temperature sensors 450, 455 exceeds a respective temperature threshold and the latching circuit 420 has disabled operation of the furnace 180, the smartphone 710 will display a message 720 and a restart button 730 on a screen of the smartphone 710. In some exemplary devices, this message/button 720/730 may appear within an application on the phone, which requires a human operator to open the application.

The message 720 will provide a text indication that the heat pump system 100 has overheated and will request that the operator confirm that it is safe to restart the heating operation by pressing the button 730.

The button 730 is a virtual button on a screen of the smartphone 710 (i.e., electronic button). Pressing the button 730 will serve as the physical action by a human operator required by the latching circuit 420 to restart operation of the furnace 180.

Methods of Operation

FIG. 8 is a flowchart 800 of the operation of monitoring a heat pump for overheating with one temperature switch according to an exemplary method.

At step 810, a first temperature T₁ proximate to a refrigerant sensor is detected. In one exemplary method, the proximity may be within 3 inches, though this may vary in alternate exemplary methods.

At step 820, it is determined whether the detected first temperature T₁ is above a first threshold temperature T_TH1. If it is determined that the detected first temperature T₁ is not above the first threshold temperature T_TH1, operation will return to step 810. If, however, it is determined that the detected first temperature T₁ is above the first threshold temperature T_TH1, operation will proceed to step 830. In some exemplary devices, the first temperature threshold T_TH1 may be between 150° F. and 195° F.

At step 830, operation of a furnace associated with the heat pump is shut down.

At step 840, an alert is provided to operator that the furnace has been shut down. This alert may be visual, auditory, text, or any combination of the three.

At step 850, it is determined whether a human-initiated restart command has been received. This human-initiated restart command may be represented by the pressing of a button, the flipping a switch, the pulling of a lever, or the like.

If no human-initiated restart command has been received, operation will remain at step 850, continually determining whether a human-initiated restart command has been received. In this way, the furnace will remain shut down until it is determined that a human-initiated restart command has been received.

If it is determined that a human-initiated restart command has been received, operation will proceed to step 860.

At step 860 operation of the furnace will be restarted, allowing a normal heating operation to proceed for the heat pump system.

Although in the method of FIG. 8 the various operations disclose shutting down the operation of a furnace and restarting the operation the furnace, this is by way of example only. Alternate exemplary methods could shut down/restart the furnace heating operation.

FIG. 9 is a flowchart 900 of the operation of monitoring a heat pump for overheating with two temperature switches according to an exemplary method.

At step 810, a first temperature T₁ proximate to a refrigerant sensor is detected. In one exemplary method, the proximity may be within 3 inches, though this may vary in alternate exemplary methods.

At step 910, a second temperature T₂ proximate to a temperature-sensitive circuit is detected. This temperature-sensitive circuit may be a thermistor in some exemplary methods. In one exemplary method, the proximity may be within 3 inches, though this may vary in alternate exemplary methods.

At step 920, it is determined whether the detected first temperature T₁ is above a first threshold temperature T_TH1 and whether the detected second temperature T₂ is above a second threshold temperature T_TH2. The first and second threshold temperatures T_TH1, T_TH2 may be the same or different in various exemplary methods. In some exemplary devices, the first and second temperature thresholds T_TH1, T_TH2 may each be between 150° F. and 195° F.

If it is determined that the detected first temperature T₁ is not above the first threshold temperature T_TH1 and that the detected second temperature T₂ is not above the second threshold temperature T_TH2, operation will return to step 810. If, however, it is determined that either the detected first temperature T₁ is above the first threshold temperature T_TH1 or the detected second temperature T₂ is above the second threshold temperature T_TH2, operation will proceed to step 830.

At step 830, operation of a furnace associated with the heat pump is shut down.

At step 840, an alert is provided to operator that the furnace has been shut down. This alert may be visual, auditory, text, or any combination of the three.

At step 850, it is determined whether a human-initiated restart command has been received. This human-initiated restart command may be represented by the pressing of a button, the flipping a switch pulling of a lever, or the like.

If no human-initiated restart command has been received, operation will remain at step 850, continually determining whether a human-initiated restart command has been received. In this way, the furnace will remain shut down until it is determined that a human-initiated restart command has been received.

If it is determined that a human-initiated restart command has been received, operation will proceed to step 860.

At step 860 operation of the furnace will be restarted, allowing a normal heating operation to proceed for the heat pump system.

Although in the method of FIG. 9 the various operations disclose shutting down the operation of a furnace and restarting the operation the furnace, this is by way of example only. Alternate exemplary methods could shut down/restart the furnace heating operation.

Conclusion

This disclosure is intended to explain how to fashion and use various embodiments in accordance with the invention rather than to limit the true, intended, and fair scope and spirit thereof. The foregoing description is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications or variations are possible in light of the above teachings. The embodiment(s) was chosen and described to provide the best illustration of the principles of the invention and its practical application, and to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims, as may be amended during the pendency of this application for patent, and all equivalents thereof, when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled. The various circuits described above can be implemented in discrete circuits or integrated circuits, as desired by implementation.