US20110209489A1 - Heat pump defrost control - Google Patents
Heat pump defrost control Download PDFInfo
- Publication number
- US20110209489A1 US20110209489A1 US12/932,543 US93254311A US2011209489A1 US 20110209489 A1 US20110209489 A1 US 20110209489A1 US 93254311 A US93254311 A US 93254311A US 2011209489 A1 US2011209489 A1 US 2011209489A1
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- United States
- Prior art keywords
- defrost
- cycle
- heat
- heat pump
- temp
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000004020 conductor Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000009434 installation Methods 0.000 description 2
- 239000003507 refrigerant Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 230000000153 supplemental effect Effects 0.000 description 1
- 238000010257 thawing Methods 0.000 description 1
- 238000013024 troubleshooting Methods 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B30/00—Heat pumps
- F25B30/02—Heat pumps of the compression type
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
- F25D21/002—Defroster control
- F25D21/006—Defroster control with electronic control circuits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
- F24F11/41—Defrosting; Preventing freezing
- F24F11/42—Defrosting; Preventing freezing of outdoor units
Definitions
- This invention relates to the field of heat pumps, more particularly, this Invention presents a unique defrost method for air source heat pumps.
- the present invention has timers incorporated so as to alleviate system shock by idling heat pump for a period of time and then initiate defrost cycle. At completion of defrost, it holds reversing valve in cool mode for a short time to allow pressure equalization.
- the biggest advantage to using the off-cycle system is it will have a clean coil on start-up, in addition, it is heating the entire time. It does the defrost after the thermostat has satisfied.
- the automatic emergency heat circuit will save the homeowner from manually switching to emergency heat when temperature is too low to be efficient.
- circuit board as shown on the schematic is drafted with conventional parts for better understanding of the invention.
- the manufacturer will use logic circuits such as USASI, some magnetic relays, timers designed with hexadecimal counters. Microprocessor chips could also be used at the manufacturer's discretion.
- the invention has been reduced to practice in the most basic form with board hard-wired (no etching), using relays and timers. No claim to an earlier filing date, only the provisional filing date is claimed.
- the system that is presented is a basic modification from the prior art systems that is used in most heat pumps, but after reducing it to practice in a limited way, the present invention is much quieter during change-over, and it eliminates the sudden pressure/temperature change.
- FIG. 1 consist of one off-cycle defrost schematic shown front view with all parts numbered and legends explained. This drawing is a simplified Formal Draft and is not the best mode. Reference paragraph [0009] for best mode.
- FIG. 2 is a Connection diagram for split system heat pumps, illustrating that the connections are the same for split units as it is for a package unit.
- the PCB will operate in heat or cool mode, defrost in off-cycle when temperature around forty degrees or below when system shuts down, either on normal off-cycle or forced off-cycle.
- FIG. 1 a schematic diagram is shown front view of an off-cycle heat pump defrost control 12 embodying the present invention with circuits to be etched and parts mounted on a PCB to be installed in the junction box of a package or split unit (outdoor condenser) with connections 74 through 94 made
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Defrosting Systems (AREA)
Abstract
An electronic defrost system consisting of a circuit board designed to implement defrost cycle of an air source heat pump outdoor coil during the off-cycle period. off-cycle is when the house thermostat is satisfied, heat pump is timed off for two minutes and then reactivated in regular defrost cycle if defrost sensor is calling for defrost. (Temp/off cycle). When sensor opens, heat pump will shut off for two minutes to allow pressure equalization.
The automatic emergency heat is an option that can be selected. The automatic setting will activate the same circuit as the manual switch at the indoor house thermostat.
Defrost control board designed to activate all heat strips during defrost cycle if desired.
Description
- Title: Defrost system and method for heat pumps
- Inventor: Shaw, David N.
- Date: Mar. 10, 2009
- Application Ser. No. 12/401,136
- Specific reference: Paragraph [0002]-[0005]
- The description goes into great detail how a heat pump defrost system operates.
-
- 12—Heat pump defrost control circuit board drawing
- 13—Split unit connection drawing
- 14—K-1 Defrost relay coil—24 volts
- 16—K1-1 Energizes main contactor on heat pump
- 18—K1-2 Energizes auxiliary heat during defrost cycle
- 20—K1-3 Activates blower motor relay
- 22—k1-4 Shifts reversing valve to cool mode for defrosting outdoor coil
- 24—K1-5 Interlocks K-2 during defrost cycle
- 26—K1-6 Interlocks Y-2
- 28—K1-7 Energizes TD-4
- 30—K1-8 Prevents voltage feedback in running mode
- 31—K1-9 Activates all heat strips
- 32—K-2 Normal running mode coil—24 volts
- 34—K2-1 Interlocks defrost coil K-1
- 36—K2-2 Interlocks K-3 to prevent K3-1 from opening during defrost cycle
- 37—K2-3 Energizes Y-1 in normal running mode (heat or cool)
- 38—K-3 Emergency Heat relay coil—24 Volts
- 40—K3-1 De energizes compressor and outdoor fan motor when emergency heat activates automatically or manually
- 42—K3-2 Prevents voltage feedback
- 44—K-4 Outdoor fan motor relay coil—24 volts/10 amps
- 46—K4-1 Stops outdoor fan motor during defrost cycle
- 48—SW-1 Overrides K3-1 if heat strips are inoperable, or not installed, enabling switch to run heat pump while automatic emergency heat is on
- 50—SW-2 Disables off cycle defrost
- 52—SW-3 Disables automatic emergency heat
- 54—SW-4 Disables thirty-minute defrost circuit. By placing switch on, it will put secondary defrost circuit in thirty-minute time-on. Place switch in off position for sixty-minute time-on
- 55—SW-5 Selector switch for energizing all heat strip sequencers
- 56—TD-1 Thirty-minutes on-make timer for automatic emergency heat. Activates when House thermostat is approximately two degrees below setting.
- 58—TD-2 Two-minute on-make timer for pressure equalization
- 60—TD-3 Thirty-minute on-make timer time/temp. secondary defrost circuit
- 62—TD-4 Two-minute off-timer reversing valve holding circuit for pressure equalization
- 64—TD-5 Three-second on-make timer resets TD-2
- 66—TD-6 Time delay-on two-minute timer. Holding circuit for pressure equalization
- 68—TD-7 Sixty-minute on-make defrost timer time/temp. secondary circuit
- 70—TD-8 Ten-minute off-break timer—terminates defrost cycle if ambient temperature too cold for adequate defrost
-
- 72—NOTE: LVJB-Low voltage junction box
- 74—G—Connect to green wire in LVJB
- 76—Y-1 Connect to CC coil (main contactor on heat pump)
- 78—Y-2 Connect series with yellow wire in LVJB
- 80—O-R—24V—Connect parallel to red wire in LVJB
- 82—O Reversing valve—Connect parallel to orange wire from house thermostat in LVJB
- 84—W1 Auxiliary heat—Connect parallel to white wire in LVJB
- 86—E Emergency heat—Connect brown wire parallel in LVJB
- 88—DFT Defrost sensor—Connect to DET on circuit board
- 90—T1 Disconnect from defrosts relay N.C. contacts input side, connect to T1 on defrost control board
- 92—DR Defrost relay—Connect to DR N.C. contacts input side that connects to outdoor fan motor.
- 94—C Common—Connect parallel to blue wire in LVJB (blue on most models)
- This invention relates to the field of heat pumps, more particularly, this Invention presents a unique defrost method for air source heat pumps.
- There are patent applications that is referenced that describe an inherent problem with the prior art defrost system.
- The present invention has timers incorporated so as to alleviate system shock by idling heat pump for a period of time and then initiate defrost cycle. At completion of defrost, it holds reversing valve in cool mode for a short time to allow pressure equalization.
- The higher SEER rated heat pumps that has been mandated uses a higher pressure refrigerant which could wear more on the reversing valve on systems where the compressor continues to run during defrost cycle. Even a small blow-by leak can reduce the efficiency of a heat pump considerably.
- Some heat pump manufacturers have designed their units with just the basic parts necessary. This gives the heat pump an increased reliability and less service call-outs. Switching to a defrost board that adds additional functions could be viewed as counter to what they have accomplished, but by utilizing the Off-Cycle Defrost System presented in the claims section, I believe it would increase reliability for the reversing valve and the entire system. A reversing valve is one of the more expensive repairs to make when leaks occur.
- The biggest advantage to using the off-cycle system is it will have a clean coil on start-up, in addition, it is heating the entire time. It does the defrost after the thermostat has satisfied.
- The automatic emergency heat circuit will save the homeowner from manually switching to emergency heat when temperature is too low to be efficient.
- Supplemental heat stage one sequencer energizes when defrost initiated as in most prior art units. What's different about this system is the entire strip heat unit can be turned on during the entire defrost cycle if desired.
- The circuit board as shown on the schematic is drafted with conventional parts for better understanding of the invention. The manufacturer will use logic circuits such as USASI, some magnetic relays, timers designed with hexadecimal counters. Microprocessor chips could also be used at the manufacturer's discretion.
- The invention has been reduced to practice in the most basic form with board hard-wired (no etching), using relays and timers. No claim to an earlier filing date, only the provisional filing date is claimed.
- Safety precautions will be printed for installers concerning using all heat strips with unit running during defrost without first checking breaker size, ampacity of conductors, also check register temperature if fibrous ducts installed. (max.125*)
- To simulate defrost cycle when troubleshooting, unplug outdoor fan motor, check for 24 volts AC between DFT and common, turn thermostat down until heat pump shuts off.
- The system that is presented is a basic modification from the prior art systems that is used in most heat pumps, but after reducing it to practice in a limited way, the present invention is much quieter during change-over, and it eliminates the sudden pressure/temperature change.
-
FIG. 1 consist of one off-cycle defrost schematic shown front view with all parts numbered and legends explained. This drawing is a simplified Formal Draft and is not the best mode. Reference paragraph [0009] for best mode. -
FIG. 2 is a Connection diagram for split system heat pumps, illustrating that the connections are the same for split units as it is for a package unit. - The Off-Cycle Defrost Board will replace most existing PC boards in use, primarily the more basic boards used in residential package units and split systems.
- The PCB will operate in heat or cool mode, defrost in off-cycle when temperature around forty degrees or below when system shuts down, either on normal off-cycle or forced off-cycle.
- During defrost cycle a selector switch can activate all heat strips. (Optional)
- In extremely cold weather the heat pump will automatically shut down and energize emergency heat which will be the same operation as manual emergency heat.
- The reverse cycle Hot—Gas defrost system for heat pumps has been the preferred method by manufacturer's for many years. There has been many patents granted concerning defrost of heat pump coils that, for the most part, have been unsucessful for varying reasons. Many patents in the defrost field have been abandoned.
- A. Shaw, David N.
-
- application Ser. No. 12/401,136
- Filed: March 2009
- Title: Defrost system and method for heat pumps
- B. Maths, Derick A.
-
- U.S. Pat. No. 5,332,028
- Filed: July 1994
- Ref: Claims 1-14
- C. Shuster, Don A.
-
- U.S. Pat. No. 5,758,507
- Filed: June 1998
- Title: Heat Pump Defrost control
- Ref.: Abstract Background of Invention Summary
- Reference US Class: 62/3; 62/81; 62/151; 62/259.1
- Referring to the drawing
FIG. 1 , a schematic diagram is shown front view of an off-cycle heatpump defrost control 12 embodying the present invention with circuits to be etched and parts mounted on a PCB to be installed in the junction box of a package or split unit (outdoor condenser) withconnections 74 through 94 made - In reference to connection diagram 13
FIG. 2 for split heat pump units, the defrostcontrol board connections 13 are the same as thepackage units 12. Thedefrost board section 13 is the only relevant part to the present invention. 13 has the the same reference numbers as 12. The remainder of drawing 13 which includes the thermostat, air handler, and the outdoor low voltage junction box, is shown for Illustration purposes. - To further clarify the connections and the purpose of the circuits in
FIGS. 1 and 2 referenced by identification numbers as follow: - G-74—Controls blower motor paralleled with existing green conductor in
LVJB 72. - Y1-76—Connects to main contactor (CC) mounted inside heat pump and controls outdoor fan and compressor.
- Y2-78—Connects series with yellow wire from house thermostat in
LVJB 72. Conductor controls many functions on the defrost board to effect defrost. - R-80—24 Volts AC power source from secondary side of 240/24V transformer. Connects parallel to red wire in
LVJB 72 in heat pump. - O-82—Reversing valve—Connects parallel to orange wire from house thermostat in
LVJB 72. Circuits will energizeREV 82 when unit is off andDFT 88 is calling for defrost. Thevalve 82 shifts to cooling mode until defrost thermostat opens. - W1-84—Auxiliary heat—Connects parallel to white wire in
LVJB 72. When unit goes into defrost, one stage of the heat strips 84 will be energized unless SW-5/55 is closed during installation or by the owner. Closed position will activate all heat strips 86 during defrost cycle, including a two-minute time delay-on between shut-down and defrost start-up 66. - E-86—Emergency heat-Brown wire connects parallel in
LVJB 72.EM HT 86 has two functions, one to furnish extra heat while in defrost, or to shut down compressor andoutdoor fan 76 automatically during extremely cold weather when thermostat approximately two degrees below balance—point for thirtyminutes 56. Closing SW-3/52 will activateEM HT 86 and is an option that the owner and installer can choose. - DFT-88—Defrost thermostat—Connects to defrost thermostat output side to
DFT 88 oncircuit boards 12/13. DET t′stat is located on refrigerant line to monitor for frost and ice build-up.DFT 88 is the primary circuit that puts most other circuits in operation to accomplish the defrost cycle. - T1-90—Connects to T1 on CC (main contactor) located in heat pump and feeds medium voltage to T1 terminal on circuit board. T1-90 runs the outdoor fan through
DR 92. K4-1 Normally closedcontacts 46 opens and will stop outdoor fan while in defrost mode. - DR-92—Defrost relay contacts control OFM (outdoor fan motor) during defrost cycle. These N.C. contacts could be eliminated if the present invention is used.
Connect DR 92 on defrost board to DR N.C. contacts input side going to OFM. - C-94—Common-Neutral side of the 24 volt
AC power source 80. Connect common to blue conductor (blue on most models) parallel inLVJB 72. - Since certain changes may be necessary in the foregoing disclosure without departing from the scope and spirit of the invention herein involved, it is intended that all matter contained in the above description and depicted in the accompanying schematic draft be construed in an illustrative way and not in a limiting sense.
Claims (3)
1. A defrost control apparatus designed to activate defrost cycle during off-cycle period,
A. The circuit board is designed to defrost the outdoor coil every time the heat pump shuts down if defrost sensor is closed, This is a temp/off cycle mode, The unit will have a frost-free coil on start-up,
B. Another board design function is if ambient temperature is too cold for house thermostat to satisfy, a selector switch set on 30/60 minutes will force the unit off on time/temp, and perform the same off-cycle defrost as the temp,/off cycle.
2. An automatic emergency heat circuit will energize all heat strip relays or sequencers if balance-point stays approximately two degrees below indoor thermostat set-point for thirty minutes. Compressor and outdoor fan motor will be off during this time.
3. As in prior art defrost cycles, the auxiliary heat (normally one heat strip) energizes. The present invention will give owner an option to energize all heat strips for entire defrost cycle,
A. This will eliminate cold-blow for an acceptable temperature.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/932,543 US20110209489A1 (en) | 2010-03-01 | 2011-02-26 | Heat pump defrost control |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US33904110P | 2010-03-01 | 2010-03-01 | |
US12/932,543 US20110209489A1 (en) | 2010-03-01 | 2011-02-26 | Heat pump defrost control |
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Publication Number | Publication Date |
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US20110209489A1 true US20110209489A1 (en) | 2011-09-01 |
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Family Applications (1)
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US12/932,543 Abandoned US20110209489A1 (en) | 2010-03-01 | 2011-02-26 | Heat pump defrost control |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103016325A (en) * | 2012-12-07 | 2013-04-03 | 江苏永钢集团有限公司 | Water supply pump control device |
US9239183B2 (en) | 2012-05-03 | 2016-01-19 | Carrier Corporation | Method for reducing transient defrost noise on an outdoor split system heat pump |
CN110131836A (en) * | 2018-02-09 | 2019-08-16 | 开利公司 | Defrosting control method and heat pump system |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4627484A (en) * | 1984-01-09 | 1986-12-09 | Visual Information Institute, Inc. | Heat pump control system with defrost cycle monitoring |
US4727727A (en) * | 1987-02-20 | 1988-03-01 | Electric Power Research Institute, Inc. | Integrated heat pump system |
US6263686B1 (en) * | 2000-07-10 | 2001-07-24 | Carrier Corporation | Defrost control method and apparatus |
US20030116637A1 (en) * | 2001-11-15 | 2003-06-26 | Ellingham Jeffrey R. | Heat pump defrost control |
US20080190131A1 (en) * | 2007-02-09 | 2008-08-14 | Lennox Manufacturing., Inc. A Corporation Of Delaware | Method and apparatus for removing ice from outdoor housing for an environmental conditioning unit |
-
2011
- 2011-02-26 US US12/932,543 patent/US20110209489A1/en not_active Abandoned
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4627484A (en) * | 1984-01-09 | 1986-12-09 | Visual Information Institute, Inc. | Heat pump control system with defrost cycle monitoring |
US4727727A (en) * | 1987-02-20 | 1988-03-01 | Electric Power Research Institute, Inc. | Integrated heat pump system |
US6263686B1 (en) * | 2000-07-10 | 2001-07-24 | Carrier Corporation | Defrost control method and apparatus |
US20030116637A1 (en) * | 2001-11-15 | 2003-06-26 | Ellingham Jeffrey R. | Heat pump defrost control |
US20080190131A1 (en) * | 2007-02-09 | 2008-08-14 | Lennox Manufacturing., Inc. A Corporation Of Delaware | Method and apparatus for removing ice from outdoor housing for an environmental conditioning unit |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9239183B2 (en) | 2012-05-03 | 2016-01-19 | Carrier Corporation | Method for reducing transient defrost noise on an outdoor split system heat pump |
CN103016325A (en) * | 2012-12-07 | 2013-04-03 | 江苏永钢集团有限公司 | Water supply pump control device |
CN110131836A (en) * | 2018-02-09 | 2019-08-16 | 开利公司 | Defrosting control method and heat pump system |
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