Universal heat pump defrost controller

Abstract

A universal heat pump defrost controller device can be configured to determine when and for how long to cause a heat pump to enter defrost mode to remove ice from the outdoor heat exchanger coil. The defrost controller of this disclosure is configured to work with a variety of heat pumps which may implement a variety of defrost approaches, such as demand or timing. The arrangement and form factor of the defrost controller, along with break-away tabs, may allow the defrost controller to fit in the limited space available in many heat pumps. The simple dual display and controls of the device provide for intuitive configuration and troubleshooting during setup and installation.

What is claimed is: 
     
         1 . A defrost controller device, the device comprising:
 a housing;   processing circuitry positioned within the housing;   a user interface, comprising a display and controls operatively coupled to the processing circuitry, and   a plurality of electrical connectors operatively coupled to the processing circuitry and supported by the housing,
 wherein a first connector of the plurality of connectors is configured to provide power to an auxiliary heat exchanger and a second connector of the plurality of connectors is configured to receive a signal from a temperature sensor, and 
 wherein the plurality of connectors is arranged adjacent to the user interface and each connector of the plurality of connectors is aligned in the same direction, 
   wherein the processing circuitry is configured to control a defrost cycle for a heat pump based on the configuration of the heat pump.   
     
     
         2 . The device of  claim 1 , wherein the processing circuitry is configured to control the defrost cycle in a timing mode, wherein the processing circuitry is configured initiate a defrost cycle based on an accumulated run time of the heat pump, and wherein the defrost cycle comprises a defrost mode. 
     
     
         3 . The device of  claim 2 , wherein the processing circuitry controls the heat pump to exit the defrost mode after a set length of time. 
     
     
         4 . The device of  claim 1 , wherein the processing circuitry is configured to control the defrost cycle in a demand mode, wherein the processing circuitry controls the heat pump to enter a defrost mode based on a signal from one or more sensors. 
     
     
         5 . The device of  claim 4 , wherein the one or more sensors comprises the temperature sensor, wherein the temperature sensor is configured to send a signal to the processing circuitry indicating a temperature of a coil of the heat pump. 
     
     
         6 . The device of  claim 5 , wherein the processing circuitry is configured to imitate the defrost cycle based on a period of time while the coil is below a threshold coil temperature. 
     
     
         7 . The device of  claim 5 ,
 wherein the temperature sensor is a first temperature sensor, the one or more sensors further comprising a second temperature sensor configured to indicate an outside air temperature to the processing circuitry, and   wherein the processing circuitry is configured to initiate the defrost cycle based on a difference between the indicated coil temperature and the indicated outside air temperature.   
     
     
         8 . The device of  claim 7 , wherein the processing circuitry comprises a fail-safe timer configured to limit a length of time of the defrost cycle. 
     
     
         9 . The device of  claim 4 ,
 wherein the one or more sensors comprises a first pressure sensor located at a first position on the heat pump and a second pressure sensor located a second position on the heat pump, and   wherein the processing circuitry is configured to initiate a defrost cycle based on a pressure difference between the first pressure sensor and the second pressure sensor satisfying a predetermined pressure threshold.   
     
     
         10 . The device of  claim 9 , wherein the first pressure sensor is located at an input side of an outdoor coil of the heat pump and the second pressure sensor is located at an output side of the outdoor coil of the heat pump. 
     
     
         11 . The device of  claim 1 , wherein the processing circuitry is configured to automatically switch between a first operating mode and a second operating mode. 
     
     
         12 . The device of  claim 1 , wherein the processing circuitry is configured to cause a relay  220  to shut off a fan of the heat pump during a defrost mode of the defrost cycle. 
     
     
         13 . The device of  claim 1 , further comprising a main circuit board and a second circuit board, wherein the second circuit board includes one or more additional options for the device. 
     
     
         14 . The device of  claim 13 , wherein a first option of the one or more options is wireless communication. 
     
     
         15 . A system for controlling the environment of a building comprising:
 a heating, ventilation and air conditioning (HVAC) system a heat pump comprising a heat exchanger coil and coupled to the HVAC system;   an HVAC controller configured to control the HVAC system to circulate cold or warm air; and   a defrost controller configured to communicate with the HVAC controller, the defrost controller comprising:
 a housing; 
 processing circuitry positioned within the housing; 
 a user interface, comprising a display and controls operatively coupled to the processing circuitry, and 
 a plurality of electrical connectors operatively coupled to the processing circuitry and supported by the housing,
 wherein a first connector of the plurality of connectors is configured to provide power to an auxiliary heat exchanger and a second connector of the plurality of connectors is configured to receive a signal from a temperature sensor, and 
 wherein the plurality of connectors is arranged adjacent to the user interface and each connector of the plurality of connectors is aligned in the same direction, 
 
 wherein the processing circuitry is configured to control a defrost cycle for the heat pump based on the configuration of the heat pump. 
   
     
     
         16 . The system of  claim 15 , wherein the processing circuitry is configured to control the defrost cycle in a timing mode, wherein the processing circuitry is configured initiate a defrost cycle based on an accumulated run time of the heat pump, and wherein the defrost cycle comprises a defrost mode. 
     
     
         17 . The system of  claim 15 , wherein the processing circuitry is configured to control the defrost cycle in a demand mode, wherein the processing circuitry controls the heat pump to enter a defrost mode based on a signal from one or more sensors. 
     
     
         18 . The system of  claim 15 ,
 wherein the temperature sensor is a first temperature sensor, the one or more sensors further comprising a second temperature sensor configured to indicate an outside air temperature to the processing circuitry, and   wherein the processing circuitry is configured to initiate the defrost cycle based on a difference between the indicated coil temperature and the indicated outside air temperature.   
     
     
         19 . The system of  claim 15 ,
 wherein the one or more sensors comprises a first pressure sensor located at a first position on the heat pump and a second pressure sensor located a second position on the heat pump, and   wherein the processing circuitry is configured to initiate a defrost cycle based on a pressure difference between the first pressure sensor and the second pressure sensor satisfying a predetermined pressure threshold.   
     
     
         20 . A method for controlling a defrost cycle comprising:
 operating, by processing circuitry, a defrost controller in a demand mode during a first time,
 wherein the defrost controller is configured to control a defrost cycle for a heat pump based on the configuration of the heat pump; 
 wherein the processing circuitry is configured to initiate a defrost mode of the defrost cycle based on a difference between a first measurement of a first sensor and a second measurement of a second sensor satisfying a measurement threshold; 
   operating, by processing circuitry, a defrost controller in a timing mode during a second time different from the first time, wherein during the second time, determining, by the processing circuitry, that the first sensor is not providing the first measurement or the second sensor is not providing the second measurement.