# US 2014/0150479 A1 · Secondary Defrost for Heat Pumps > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0150479 A1 - Document ID: US20140150479A1 - Status: Published application - Kind: A1 - Application number: 13/690,645 - Filed: 2012-11-30 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: Lennox Industries Inc. - Inventors: Yi Qu; Bruce Perkins; Chris Mchugh; Mark Olsen - Web page: https://patentgrep.com/patent/US20140150479A1 ## CPC - F25D 21/008: {by timer} - F25B 47/025: {by reversing the cycle} - F25B 13/00: Compression machines, plants or systems, with reversible cycle (defrosting cycles F25B47/02) - F25B 2600/01: Timing - F25B 2600/112: of evaporator fans - F25B 2700/2117: of an evaporator - Y02B 30/70: Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating - F25D: REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR (refrigerated showcases A47F3/04; thermally-insulated vessels for domestic use A47J41/00; refrigerated vehicles, see the appropriate subclasses of classes B60 - B64; containers with thermal insulation in general B65D81/38; heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants, or materials for the production of heat or cold by chemical reactions other than by combustion C09K5/00; thermally-insulated vessels for liquefied or solidified gases F17C; air-conditioning or air-humidification F24F; refrigeration machines, plants, or systems F25B; cooling of instruments or comparable apparatus without refrigeration G12B) - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract Frost may accumulate on a heat pump. In various implementations, a primary defrost operation and/or a secondary defrost operation may be utilized to remove at least a portion of the frost from the heat pump. ## Claims ### Claim 1 A computer-implemented method for defrosting a heat pump, the method comprising: allowing a primary defrost operation of a heat pump; determining whether to allow a secondary defrost operation of a heat pump, wherein the secondary defrost operation of the heat pump comprises allowing one or more fans of the heat pump to operate at a low speed, wherein at least one of the fans comprises the low speed and at least one higher speed; and allowing the secondary defrost operation if the determination is made to allow the secondary defrost operation of the heat pump; wherein an amount of frost accumulation disposed proximate one or more parts of the heat pump is at least partially reduced. ### Claim 2 (depends on 1) The method of claim 1 further comprising restricting at least a portion of the primary defrost operation during the secondary defrost operation. ### Claim 3 (depends on 1) The method of claim 1 wherein the primary defrost operation comprises: allowing a cooling cycle of the heat pump; and restricting operation of at least one of the fans of the heat pump. ### Claim 4 (depends on 1) The method of claim 1 wherein the determination of whether to allow the secondary defrost operation is based at least partially on at least one of: a setting of the heat pump; or an identification of an ice event, wherein an identification of an ice event is at least partially based on at least one of weather proximate the heat pump, measurements from one or more sensors, or one or more properties of at least one of the fans. ### Claim 5 (depends on 1) The method of claim 1 further comprising: determining a change in temperature of a portion of a heat exchanger of the heat pump; and identifying whether an ice event has occurred at least partially based on the determined change in temperature; wherein the determination of whether to allow the secondary defrost operation is based at least partially on identifying the ice event. ### Claim 6 (depends on 1) The method of claim 1 further comprising: determining a first temperature proximate a portion of a heat exchanger of the heat pump during the secondary defrost operation; determining whether the first temperature exceeds a predetermined initiating temperature; and allowing the secondary defrost operation when the first temperature exceeds a predetermined initiating temperature. ### Claim 7 (depends on 1) The method of claim 1 further comprising: determining a first temperature proximate a portion of a heat exchanger of the heat pump during the secondary defrost operation; determining whether the first temperature exceeds a predetermined ending temperature; and restricting operation of the secondary defrost operation, if the determination is made that the first temperature exceeds the predetermined ending temperature. ### Claim 8 (depends on 7) The method of claim 7 further comprising: determining whether to allow one or more additional secondary defrost operations; rebalancing at least a portion of the heat pump if a determination is made to allow one or more of the additional secondary defrost operations, wherein rebalancing the heat pump comprises de-energizing a reversing valve for a first period of time; adjusting a predetermined ending temperature; allowing at least one additional secondary defrost operation after rebalancing at least a portion of the heat pump; determining a second temperature proximate a portion of a heat exchanger of the heat pump during at least one of the secondary defrost operations; comparing the second temperature to the adjusted predetermined ending temperature; and restricting operation of the secondary defrost operation if the second temperature exceeds the adjusted predetermined ending temperature. ### Claim 9 (depends on 1) The method of claim 1 further comprising: determining an operation time comprising at least one of: an operation time of the primary defrost operation, or an operation time of the secondary defrost operation; comparing the determined operation time to a predetermined maximum operation time; and restricting operation of the secondary defrost if the determined operation time exceeds the predetermined maximum operation time. ### Claim 10 An article comprising machine-readable medium storing instructions for managing an air conditioner, the instructions operable to cause data processing apparatus to perform operations comprising: allowing a primary defrost operation of a heat pump, wherein the primary defrost operation comprises restricting operation of at least one fan of the heat pump; and determining whether to allow a secondary defrost operation of a heat pump, wherein the secondary operation of the heat pump comprises allowing at least one of the fans to operate at a low speed, wherein at least one of the fans comprises the low speed and at least one higher speed; allowing the secondary defrost operation if the determination is made to allow the secondary operation of the heat pump; wherein allowing at least one of the primary defrost operation or the secondary defrost operation at least partially reduces an amount of frost accumulation disposed proximate one or more parts of the heat pump. ### Claim 11 (depends on 10) The article of claim 10 wherein the instructions are further operable to cause data processing apparatus to perform operations comprising: determining a change in at least one property of the heat pump; and determining whether an ice event has occurred based at least partially on the determined change in at least one of the properties of the heat pump; wherein the determination of whether to allow the secondary defrost operation is based at least partially on the determination of whether an ice event has occurred. ### Claim 12 (depends on 10) The article of claim 10 wherein the instructions are further operable to cause data processing apparatus to perform operations comprising: determining a first temperature proximate a portion of a heat exchanger of the heat pump during the secondary defrost operation; determining whether the first temperature exceeds a predetermined initiating temperature; and allowing the secondary defrost operation when the first temperature exceeds a predetermined initiating temperature. ### Claim 13 (depends on 10) The article of claim 10 wherein the instructions are further operable to cause data processing apparatus to perform operations comprising: determining a first temperature proximate a portion of a heat exchanger of the heat pump during the secondary defrost operation; determining whether the first temperature exceeds a predetermined ending temperature; and restricting operation of the secondary defrost operation if the determination is made that the first temperature exceeds the predetermined ending temperature. ### Claim 14 (depends on 13) The article of claim 13 wherein the instructions are further operable to cause data processing apparatus to perform operations comprising: determining whether to allow one or more additional secondary defrost operations; rebalancing at least a portion of the heat pump if a determination is made to allow one or more of the additional secondary defrost operations, wherein rebalancing the heat pump comprising de-energizing a reversing valve for a first period of time; adjusting a predetermined ending temperature; allowing at least one additional secondary defrost operation after rebalancing at least a portion of the heat pump; determining a second temperature proximate a portion of a heat exchanger of the heat pump during at least one of the secondary defrost operations; comparing the second temperature to the adjusted predetermined ending temperature; and restricting operation of the secondary defrost operation if the second temperature exceeds the adjusted predetermined ending temperature. ### Claim 15 (depends on 10) The article of claim 10 wherein the instructions are further operable to cause data processing apparatus to perform operations comprising: determining an operation time comprising at least one of an operation time of the primary defrost operation or an operation time of the secondary defrost operation; comparing the determined operation time to a predetermined maximum operation time; and restricting operation of the secondary defrost if the determined operation time exceeds the predetermined maximum operation time. ### Claim 16 (depends on 10) The article of claim 10 wherein the instructions are further operable to cause data processing apparatus to perform operations comprising: determining whether an ice event has occurred; wherein determining whether to allow a secondary defrost operation is based at least partially on the determination of whether an ice event has occurred. ### Claim 17 (depends on 10) The article of claim 10 wherein the instructions are further operable to cause data processing apparatus to perform operations comprising: determining whether an ice event will occur; wherein determining whether to allow a secondary defrost operation is based at least partially on the determination of whether an ice event will occur. ### Claim 18 A heat pump comprising: one or more heat exchangers; one or more fans, wherein at least one of the fans comprises a low speed and at least one higher speed; a primary defrost operation module adapted to: restrict operation of at least one of the fans; and allow a cooling cycle of the heat pump; wherein the primary defrost operation module is adapted to at least partially reduce an accumulation of frost proximate at least a portion of the heat pump; and a secondary defrost operation module adapted to: allow operation of at least one of the fans during the cooling cycle of the heat pump; wherein the secondary defrost operation module is adapted to at least partially reduce an accumulation of frost proximate at least a part of the heat pump. ### Claim 19 (depends on 18) The heat pump of claim 18 further comprising a memory storing a predetermined initiating temperature, and wherein the secondary defrost operation module is further adapted to: determine a first temperature proximate a portion of at least one of the heat exchangers during the secondary defrost operation; determine whether the first temperature exceeds a predetermined initiating temperature; and allow secondary defrost module operation when the first temperature exceeds the predetermined initiating temperature. ### Claim 20 (depends on 18) The heat pump of claim 18 further comprising a memory storing at least one of a predetermined ending temperature or a predetermined maximum operation time, and wherein the secondary defrost operation module is further adapted to: determine at least one of a first temperature proximate a portion of a heat exchanger of the heat pump or an operation time during the secondary defrost operation, wherein the operation time comprises at least one of an operation time of the primary defrost operation or an operation time of the secondary defrost operation; and restricting operation of the secondary defrost module, if at least one of: the first temperature exceeds the predetermined ending temperature; or the determined operation time exceeds the predetermined maximum operation time.