[19]
`
`[11] Patent Number:
`
`4,607,787
`
`United States Patent
`Rogers, III
`[45] Date of Patent: Aug. 26, 1986
`
`
`
`[54]
`
`[76]
`
`[2 1]
`
`[22]
`
`[51]
`[52]
`
`[58]
`
`[56]
`
`ELECTRONIC CONTROL AND METHOD
`FOR INCREASING EFFICIENCY OF
`HEATING
`
`Inventor: Charles F. Rogers, III, 10 Moraga
`Dr., Chico, Calif. 95927
`
`Appl. No.: 722,516
`
`Filed:
`
`Apr. 12, 1985
`
`Int. Cl.4 .............................................. F253 19/00
`US. Cl. ........................................ 236/11; 62/231;
`165/12
`Field of Search ............... 236/10, 11, 46 F, 46 R;
`165/12; 62/231
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3,921,899 11/1975 Hamilton .......................... 236/11 X
`
`4,090,663
`.......................... 236/10
`5/1978 Bonne et a1.
`4,136,730
`1/ 1979 Kinsey .............. 165/ 12 1
`
`4,199,023
`4/1980 Phillips .......... 165/20
`4,487,361 12/ 1984 Brown ................................... 236/11
`
`Primary Examiner—William E. Wayner
`Attorney, Agent, or Firm—Leonard D. Schappert
`
`[57]
`
`ABSTRACI‘
`
`A method of increasing the efficiency of a hot air fur-
`nace by measuring the temperature differential across
`the heated air inlet and outlet plenums which occurs
`during normal operation of the furnace to raise the
`room temperature from its turn on point to its turn off
`point. The plenum temperature differential is then used
`to time cycle the burner.
`
`5 Claims, 3 Drawing Figures
`
`
`
`HONEYWELL - EXHIBIT 1024
`
`HONEYWELL - EXHIBIT 1024
`
`

`

`US. Patent Aug.26, 1986
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`Sheet] of2
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`4,607,787
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`
`
`

`

`US. Patent Aug. 26, 1986
`
`Sheet20f2
`
`4,607,787
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`
`

`

`1
`
`4,607,787
`
`ELECTRONIC CONTROL AND METHOD FOR
`INCREASING EFFICIENCY OF HEATING
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`This invention relates generally to the area of heating
`and cooling systems, and more specifically to electronic
`control systems designed to increase the efficiency of
`central heating and cooling air conditioning systems.
`2. Description of the Prior Art
`Heretofore, temperature control systems for use with
`heating and air conditioning units, hereinafter referred
`toas “HVACs,” have consisted of thermostats which
`turn the heating or cooling unit on or off when a given
`temperature is reached. Further improvements have
`been accomplished through the use of timers which
`limit the period of use of the HVAC. Additional im-
`provements have included controls using a relay to-
`gether with a time delay in conjunction with a thermo-
`stat, so that the fan operates for a preset time after the -
`HVAC unit is turned off, thereby clearing the duct of
`any available warm or cool air. Applicant is unaware of
`any prior art teaching a device or method which com-
`bines a differential thermostat sensing both the supply
`and return duct temperatures with a computerized con-
`trol unit having the unique features as taught herein.
`SUMMARY OF THE INVENTION
`
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`10
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`
`The present invention comprises a control unit for
`use with HVAC’s which is designed to increase energy
`efficiency during operation of existing equipment. The
`control unit is operationally positioned between the
`room thermostat which would normally control the
`HVAC unit and the HVAC unit itself, so that it is in a
`position to control the HVAC. The control unit could
`be modified to include a thermostat function and thus
`obviate a separate thermostat. The control unit is capa-
`ble of deactivating the HVAC equipment even though
`the thermostat is in an “on” condition; however, unless
`the thermostat indicates a demand, the control unit will
`not activate the HVAC unit except for operation of the
`fan as discussed herein. In connecting the control unit,
`the operator disconnects the thermostat and connects
`the control unit in place of the thermostat. The thermo-
`stat is then connected to the control unit as shown in the
`drawings and discussed later herein. The control unit
`senses temperature at both the supply duct and the
`return duct of theHHVAC system, compares the two
`temperatures, computes the rise and modifies operation
`of the system on the basis of the computed data. The rise
`referred to herein is the mathematical difference be-
`tween the temperatures in the supply duct and the re-
`turn duct. On the basis of the computed data, the con-
`trol unit cycles the burner or compressor of the HVAC
`unit on and off, increasing the efficiency of the system.
`As it performs this function, it also senses the supply
`and return duct temperatures and continues to operate
`the fan after the burner or compressor of the HVAC
`unit is deactivated. The fan continues to operate until
`the temperature difference between the supply and
`return ducts (“rise”) is reduced to a computed level.
`The control unit does not operate on absolute tempera-
`ture variations in either of the ducts, but rather on the
`differential (“rise”) between the ducts. Then, having
`read the demand, it operates the HVAC unit.
`In operating the HVAC in the heating mode, the
`control unit increases efficiency by preventing the heat
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`2
`exchanger from exceeding saturation (that is, the point
`at which the temperatures of the inside and outside
`surfaces of the heat exchanger wall are substantially
`equal), thereby limiting the loss of heat through a flue.
`Exceeding saturation dramatically reduces efficiency.
`Efficiency is further increased because the control unit
`leaves the fan on to clear the flue of warm air after the
`burner is deactivated.
`
`In operating the HVAC in the cooling mode, the
`control unit operates the compressor in the HVAC in its
`most efficient mode by cycling on and off, allowing
`head pressure to be equalized, and by evaporating mois-
`ture on the cooling coils, and by clearing the ducts of
`the remaining cool air during a “coasting” period with
`the evaporator fan on and the compressor off.
`One of the objects of the present invention is to pro-
`vide an electronic control unit which is capable of in-
`creasingthe efficiency of an HVAC system.
`Another object of the present invention is to provide
`a control unit for HVAC systems which is relatively
`inexpensive to build and to operate.
`A further object of the present invention is to provide
`a method of controlling HVAC systems so as to maxi-
`mize efficiency at a minimum cost.
`A further object of the present invention is to provide
`a control unit for use with HVAC systems which in-
`creases efficiency dramatically.
`Another object of the present invention is to compute
`and determine the equipment’s present level of energy
`efficiency (fuel utilization) and the increased efficiency
`resulting from the use of the control unit, and then to
`display the savings realized in percentage form.
`The foregoing objects, as well as other objects and
`benefits of the present invention, are made more appar-
`ent by the descriptions and claims which follow.
`BRIEF DESCRIPTION OF THE DRAWINGS '
`
`FIG. 1 is a perspective view of an HVAC unit with
`associated ducting and hardware.
`FIG. 2 is an operational view showing the connection
`of the control unit between the room thermostat and the
`HVAC unit.
`
`FIG. 3 is a block diagram of the control unit showing
`the basic components utilized and their interconnection.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`FIG. 1 shows a perspective View of an HVAC 14
`with flue 11 and having an outlet, supply duct 12, and an
`inlet, return duct 13. Though such is not shown in the
`drawings, HVAC 14 includes a burner for heating, an
`evaporator and condenser coils for cooling, an air circu-
`lating fan, and a transformer. For purposes of simplic-
`ity, a room thermostat 16 is shown beside HVAC 14.
`Room thermostat 16 would normally be connected to
`HVAC 14 through lines 17 and 18. However, in the
`present invention, a control unit 15 is connected to
`HVAC 14 by line 17, and room thermostat 16 is con-
`nected to control unit 15 by line 18. Control unit 15 is
`also attached by lines 19 and 42 to a temperature sensing
`means, temperature sensor 21, in the supply duct 12 of
`HVAC 14, and through lines 20 and 43 to a temperature
`sensing means, temperature sensor 22, in return duct 13
`of HVAC 14. Control unit 15 senses temperatures in
`supply duct 12 and return duct 13 and modifies the
`operation of HVAC 14 on the basis of computed varia-
`tions between those temperatures. Thermostat 16 is
`
`

`

`3
`used by control unit 15 to determine when demand is
`present, whether the demand is for heat, cool or manual
`fan, and when the demand is satisfied. While thermostat
`16 is here used as a switch to indicate demand, a manu-
`ally operated switch could be connected in place of 5
`thermostat 16 if desired. Control unit 15 is also usable
`with a convection or gravity heater rather than an
`HVAC, in which case a fan may or may not be used.
`FIGS. 2 and 3 show control unit 15 and its connec-
`tion to room thermostat 16 and HVAC 14. The actual 10
`construction of one embodiment of control unit 15 is
`shown in FIG. 3 of the drawings. Control unit 15 con-
`sists of a microprocessor 36 connected through line 47
`to a RAM chip 38. RAM chip 38 is connected to
`EPROM memory chip 39 through lines 48. In one vari- 15
`ation,
`the microprocessor 36 has an internal RAM
`which takes the place of RAM chip 38. Basic program-
`ming of the functioning of the unit
`is provided by
`EPROM memory chip 39. Display 34 is provided to
`monitor operation of control unit 15, and is attached to 20
`microprocessor 36 by lines 44. Microprocessor 36 is ,
`connected to input buffer 37 through line 49. Input
`buffer 37 is utilized to input data from room thermostat
`l6, and monitors heat demand through line 23, cooling
`demand through line 24, and the fan of HVAC 14 25
`through line 26. Input buffer 37 further monitors tem-
`perature sensor 21 in supply duct 12 through lines 19
`and 42, and temperature sensor 22 in return duct 13
`through lines 20 and 43. Output buffer 40 is attached to
`microprocessor 36 by line 50, and controls HVAC 14 30
`through the use of relays 25, 30 and 32, which route
`power to the burner, fan and compressor of HVAC 14
`through lines 28, 29 and 31, specifically controlling
`heating through line 28, cooling through line 29, and fan
`through line 31. Control voltage to operate relays 25, 30 35
`and 32, which actuate HVAC 14 through lines 28, 29
`and 31, is provided by line 60, which is attached to line
`27, which is connected to a transformer in HVAC 14 or
`other appropriate .power supply. Output buffer 40 is
`connected to constant known voltage source 41 40
`through line 51, and directs voltage to temperature
`sensor 21 through line 42 and to temperature sensor 22
`through line 43. Power is provided to power supply 33
`by line 27, which is connected to a 24-volt transformer
`in HVAC 14. Power supply 33 provides power through 45
`line 46 to operate microprocessor 36, as well as other
`components in control unit 15.
`OPERATION
`
`Control unit 15 is connected to the components of 50
`HVAC 14 and to room thermostat 16 and temperature
`sensors 21 and 22 in supply duct 12 and return duct 22
`as shown in the drawings. EPROM memory chip 39 is
`programmed to establish optimal operation (i.e., cy-
`cling) of HVAC 14 to substantially increase efficiency 55
`in all types of weather conditions.
`Initially, in a calibration mode, control unit 15 oper-
`ates HVAC 14 in an uncycled or uncontrolled standard
`mode based on demand indicated by room thermostat
`16 while monitoring information and recording it in 60
`RAM chip 38. In this mode it notes various perfor-
`mance data during normal operation of the HVAC 14.
`This includes temperature variation between the supply
`duct 12 and return duct 13 during normal operation of
`the system. Using information gathered and the pro- 65
`gram in EPROM memory chip 39, it creates its own
`program variables, based upon collected data, and cal-
`culations. Thus, utilizing the program in EPROM chip
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`4,607,787
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`4
`39, it adjusts the equipment’s operation to match the
`building, equipment used, occupants, temperature set-
`tings desired, type of fuel used and exterior weather
`conditions to provide the most fuel-efficient and eco-
`nomical mode of operation.
`Data monitored and recorded include return duct
`temperature, supply duct
`temperature,
`temperature
`differential between supply and return ducts; demand
`time, total time during which fuel is consumed, energy—
`used coefficient (to determine savings), and rise maxi-
`mum during a preset period.
`Monitoring is automatically performed during the
`calibration mode when no data are present in RAM
`chip 38. This occurs at the time of installation, any time
`power is interrupted, or whenever recalibration to
`maintain efficiency is desired (normally weekly).
`When monitoring is complete, one of two program-
`s—for either heating or cooling—will be used to maxi-
`mize efficiency.
`For heating, the program cycles the HVAC’s burner
`“on” until the temperature differential between supply
`and return ducts reaches a first percentage (e.g., 85%)
`of the rise in a preset period of time (e.g., 5 minutes) as
`recorded previously during monitoring, and “off" until
`the temperature differential between supply and return
`ducts reaches a second percentage (e.g., 60%), lower
`than the aforementioned first percentage of the rise.
`This cycling continues until room thermostat 16 indi-
`cates the demand has been satisfied. To further enhance
`efficiency, the fan is held “on” until demand indicated
`by room thermostat 16 is satisfied and the supply duct
`temperature drops below a preset temperature (e.g., 100
`degrees Fahrenheit).
`With the system in the cooling mode, for purposes of
`calibration the program of control unit 15 activates the
`air conditioner and continues operation until the de-
`mand indicated by room thermostat 16 is satisfied. Data
`are monitored as previously noted and logged into
`memory. When demand is again indicated by room
`thermostat 16, the program cycles the air conditioner
`compressor on and off for preset segments of calibrated
`time periods; for example, on for one-fifth of the time
`required to satisfy the demand indicated by room ther-
`mostat 16 in the calibration mode and off for a minimum
`of three minutes or a sufficient time to allow the com-
`pressor head pressure to equalize. The program contin-
`ues to operate the fan during each “off" period until a
`preset
`temperature (e. g., 66 degrees Fahrenheit) is
`reached in the supply duct, at which point, if sufficient
`time has elapsed to allow the compressor head pressure
`to equalize, it reactivates the compressor. Control unit
`15 continues to cycle the air conditioner compressor on
`and off until the demand indicated by the room thermo-
`stat 16 is satisfied. When. the demand is satisfied, the
`compressor is deactivated and the program holds the
`fan on until the air in the supply duct reaches a preset
`temperature (e.g., 68 degrees Fahrenheit). Efficiency is
`gained partly as a result of clearing the ducts of cooler
`air, and also through the evaporation of moisture on the
`cooling coils which occurs during the “coasting” per-
`iod.
`
`The program utilized also provides for displaying the
`calculated percentage of savings. This figure is deter-
`mined with calculations performed on the basis of effi-
`ciency realized during the calibration period versus
`efficiency realized during operation utilizing the tech-
`niques taught herein. This calculation, which is per-
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`5
`formed by the control unit 15, is based on the following
`formulae:
`
`4,607,787
`
`6
`between said outlet and said inlet reaches a first
`percentage of said temperature rise which oc-
`curred during normal operation of said heating
`systen and off until the temperature differential
`between said outlet and said inlet reaches a second
`percentage of said temperature rise which oc-
`curred during normal operation and continuing
`said cycling until said room reaches said second
`temperature reached during normal operation.
`2. The method of claim 1, wherein said heating sys-
`tem includes a fan for circulating air through said heat-
`ing system and wherein said fan is held on until said
`room reaches said second temperature.
`3. The method of claim 2, wherein said fan is held on
`after cycling until said outlet reaches a third tempera-
`ture.
`
`4. The method of claim 1, including disconnecting
`said control, positioning a microcomputer having a
`room temperature sensor in its place and programming
`said microcomputer to monitor room temperature, said
`first and second temperature sensing means and said
`heating system, and to operate said heating system ac-
`cordingly.
`5. The method of claim 4, including programming
`said microcomputer to compute the increase in effi-
`ciency due to said microcomputer on the basis of the
`following formulae:
`
`100 X
`
`_ _ normal output
`controlled output
`normal input
`controlled input
`controlled output
`controlled input
`
`=
`
`% savings,
`
`and displaying said percentage savings.
`*
`It
`*
`t
`13
`
`standard output _
`standard input
`— % efficnency With standard operation
`
`output using control unit _
`input using control unit — % efficnency usmg control unit
`
`% efficiency using control unit —
`° % savings displayed
`100 X % efficiency without control unit _
`% efficiency using control unit
`
`While the foregoing description of the invention has
`shown a preferred embodiment using specific terms,
`such description is presented for illustrative purposes
`only. It is applicant’s intention that changes and varia-
`tions may be made without departure from the spirit or
`scope of the following claims, and this disclosure is not
`intended to limit applicant’s protection in any way.
`What is claimed is:
`
`1. A method of increasing efficiency of a heating
`system having a burner, a control to turn said burner on
`and off and an inlet whereby cool air enters said heating
`system and an outlet whereby warm air exits said heat-
`ing system, comprising:
`positioning a first temperature sensing means in said
`inlet;
`positioning a second temperature sensing means in
`said outlet;
`measuring temperature rise between said inlet and
`said outlet occurring during normal operation of
`said heating system in heating a room from a first
`temperature to a second temperature;
`cycling said burner on when said room reaches said
`first temperature until the temperature differential
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