Anticipating dual set-point bistable thermostat

• US 4,901,917 A
• Filed: 03/21/1989
• Issued: 02/20/1990
• Est. Priority Date: 03/21/1989
• Status: Expired due to Fees

• Current Assignee: Charles C. Littell III
• Original Assignee: Charles C. Littell III
• Inventors: Littell, Charles C. III
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US07/328,652
• Time in Patent Office: 336 Days
• Field of Search: 236/46 R, 236/47, 165/12, 364/557
• US Class Current: 236/46.00R
• CPC Class Codes: F23N 1/002 using electronic means F23N1/04 - F23N1/10 take precedence
• CPC Class Codes: F23N 2223/08 Microprocessor; Microcomputer
• CPC Class Codes: F23N 2225/12 room temperature
• CPC Class Codes: F23N 2227/10 Sequential burner running
• CPC Class Codes: F23N 2237/06 two predeterming temperatures, e.g. day-night
• CPC Class Codes: F23N 5/203 using electronic means
• CPC Class Codes: G05D 23/1904 variable in time

Abstract

Automatically adjusting the time when control is returned to the operational set-point, in compensation for changing load conditions, is accomplished by measuring the operation of a heating or cooling system controller in its standby mode, and using this measurement to calculate the advance time required to return the system to its operational temperature. The operational factor to be measured depends on the control system: with a bistable or on-off thermal source, such as a household furnace, measurement of the time required to heat the house the few degrees between the set-back on and off set-points will permit calculation of the time required to reheat the house to its operational temperature.

Claims

1. A method of predicting the time required to change the temperature of a zone from a setback temperature to a normal temperature, in a transition from a standby mode to a normal mode, used in a controller for a space conditioning system to modify the temperature of a zone within a structure wherein the system includes a thermal unit which is a bistable or on-off heat source, means for selectively transferring heat between the thermal unit and said zone with a normal mode and a setback mode, wherein the controller includes a system clock and a temperature sensor which measures the temperature in said zone, means providing system operating parameters comprising a normal temperature setting, a setback temperature setting, a clock normal setting and a clock setback setting, wherein during the normal mode the temperature of the zone is to be maintained in a range around the normal temperature at times beginning with the clock normal setting and ending with the clock setback setting, and wherein during the standby mode the temperature of the zone is to be maintained in a range around the setback temperature at times beginning with the clock setback setting and ending with the clock normal setting, with said ranges established by "temperature on" and "temperature off" set-points which control turning the thermal unit on and off, a clock normal offset being used as a time for changing operation to the normal mode in an attempt for the temperature of said zone to reach the normal temperature at the time designated by the clock normal setting;

said method comprising the steps;

measuring "clock dwell begin" and "clock dwell end" times indicated by the clock when the "temperature on" and "temperature off" setpoints respectively occur as determined by comparison to readings from said temperature sensor during the standby mode;

calculating a prediction of the amount of time required to adjust the temperature of the zone to the normal temperature using "clock dwell begin" and "clock dwell end" times as determined by said measuring step during the offset mode and using that prediction to set the clock normal offset time for the system to commence operation in the normal mode;

wherein calculating a prediction during the standby mode comprises, following each occurence of "clock dwell begin" followed by "clock dwell end", calculating clock dwell time by subtracting the "clock dwell end" time from the "clock dwell begin" time and using the resulting value to obtain a clock dwell factor which indicates the time required to heat the zone from the "temperature on" setpoint to the "temperature off" set-point, forming a temperature ratio as the range between the normal and setback temperatures divided by the range between the "temperature on" set-point to the "temperature off" set-point, forming a product of the temperature ratio multiplied by the clock dwell factor, subtracting that product from the clock normal setting, and using the result in the prediction to set the clock normal offset time.

2. A method according to claim 1, wherein the clock dwell factor is a clock dwell average (Cda) calculated by adding the N most recent clock dwell times and dividing by N, where N is any positive integer.

3. A method according to claim 2, wherein following entering the normal mode upon reaching the clock normal offset time, and then in response to reaching the normal temperature setting a clock normal reached time (Cnr) equal to the clock time (C), calculating an error ratio (Ef) by taking the difference between the clock normal reached time and the clock normal setting and dividing by the difference between the clock normal setting and the clock normal offset (Ef=(Cnr-Cn)/(Cn-Cno)), setting a first clock dwell average function (Cdf1) to the present clock dwell average (Cda) value, after setting a second clock dwell average function (Cdf2) to the first clock dwell average function from the most recent previous operation in the normal mode;

wherein calculating a prediction during the standby mode includes calculating an error compensation factor (F) with a first term equal to a previous value of the error compensation factor (F) multiplied by the ratio of the clock dwell average (Cda) and the second clock dwell average function (Cdf2), and a second term equal to one half of quantity of the error ratio (Ef) multiplied by the ratio of the clock dwell average divided by the first clock dwell average function (Cdf1), the first term and the second term being added to obtain a new value for the error compensation factor (F=(Fx(Cda/Cdf2))+(Efx((Cda/Cdf1)/2))), and calculating a corrected value for clock normal offset by adding to the previous value thereof a term equal to the error compensation factor (F) multiplied by the ratio of the range between normal and setback temperatures to the range between the "temperature on" and "temperature off" setpoints multiplied by the clock dwell average (Cda)

space="preserve" listing-type="equation">(Cno corrected=Cno+(Fx(Tns/Td)xCda));

wherein the means providing system operating parameters is a system console into which a user may enter the parameters comprising the normal temperature setting, the setback temperature setting, the clock normal setting and the clock setback setting, and entering any new value causes a reset flag to be set, wherein the method includes checking the reset flag at various points in the process during both the standby mode and the normal mode and if it is set going to a system reset mode to enter the current values of the parameters and setting the clock normal offset (Cno) to a default value;

wherein the system reset mode further includes setting the N most recent clock dwell times (Cd1, Cd2, Cd3), the clock dwell average (Cda), the first clock dwell average function (Cdf1) and the second clock dwell average function (Cdf2) all equal to the quantity of the clock normal setting minus the clock normal offset divided by the ratio of the range between the normal and setback temperatures to the range between the "temperature on" and "temperature off" values (=(Cn-Cno)/(Tns/Td)); and

setting the error compensation factor equal to "one" (F=1), and the error ratio equal to "zero" (Ef=0);

continuing with the standby mode processing if the system is in the standby mode or when it next enters the standby mode.

4. A method of predicting the time required to change the temperature of a zone from a setback temperature to a normal temperature, in a transition from a standby mode to a normal mode, used in a controller for a space conditioning system to modify the temperature of a zone within a structure wherein the system includes a thermal unit which is a bistable or on-off cooling unit, means for selectively transferring heat between the thermal unit and said zone with a normal mode and a setback mode, wherein the controller includes a system clock and a temperature sensor which measures the temperature in said zone, means providing system operating parameters comprising a normal temperature setting, a setback temperature setting, a clock normal setting and a clock setback setting, wherein during the normal mode the temperature of the zone is to be maintained in a range around the normal temperature at times beginning with the clock normal setting and ending with the clock setback setting, and wherein during the standby mode the temperature of the zone is to be maintained in a range around the setback temperature at times beginning with the clock setback setting and ending with the clock normal setting, with said ranges established by "temperature on" and "temperature off" set-points which control turning the thermal unit on and off, a clock normal offset being used as a time for changing operation to the normal mode in an attempt for the temperature of said zone to reach the normal temperature at the time designated by the clock normal setting;

said method comprising the steps;

measuring "clock dwell begin" and "clock dwell end" times indicated by the clock when the "temperature on" and "temperature off" setpoints respectively occur as determined by comparison to readings from said temperature sensor during the standby mode;

calculating a prediction of the amount of time required to adjust the temperature of the zone to the normal temperature using "clock dwell begin" and "clock dwell end" times as determined by said measuring step during the offset mode and using that prediction to set the clock normal offset time for the system to commence operation in the normal mode;

wherein calculating a prediction during the standby mode comprises, following each occurence of "clock dwell begin" followed by "clock dwell end", calculating clock dwell time by subtracting the "clock dwell end" time from the "clock dwell begin" time and using the resulting value to obtain a clock dwell factor which indicates the time required to cool the zone from the "temperature on" set-point to the "temperature off" setpoint, forming a temperature ratio as the range between the normal and setback temperatures divided by the range between the "temperature on" setpoint to the "temperature off" setpoint, forming a product of the temperature ratio multiplied by the clock dwell factor, subtracting that product from the clock normal setting, and using the result in the prediction to set the clock normal offset time.

5. A method according to claim 4, wherein the clock dwell factor is a clock dwell average (Cda) calculated by adding the N most recent clock dwell times and dividing by N, where N is any positive integer.

6. A controller for a space conditioning system to modify the temperature of a zone within a structure wherein the system includes a thermal unit which is a bistable or on-off heat source, means for selectively transferring heat between the thermal unit and said zone with a normal mode and a setback mode, wherein the controller includes a system clock and a temperature sensor which measures the temperature in said zone, means providing system operating parameters comprising a normal temperature setting, a setback temperature setting, a clock normal setting and a clock setback setting, wherein during the normal mode the temperature of the zone is to be maintained in a range around the normal temperature at times beginning with the clock normal setting and ending with the clock setback setting, and wherein during the standby mode the temperature of the zone is to be maintained in a range around the setback temperature at times beginning with the clock setback setting and ending with the clock normal setting, with said ranges established by "temperature on" and "temperature off" setpoints which control turning the thermal unit on and off, a clock normal offset being used as a time for changing operation to the normal mode in an attempt for the temperature of said zone to reach the normal temperature at the time designated by the clock normal setting;

means for predicting the time required to change the temperature of the zone from the setback temperature to the normal temperature, in a transition from the standby mode to the normal mode, comprising;

means for measuring "clock dwell begin" and "clock dwell end" times indicated by the clock when the "temperature on" and "temperature off" setpoints respectively occur as determined by comparison to readings from said temperature sensor during the standby mode;

means for calculating a prediction of the amount of time required to adjust the temperature of the zone to the normal temperature using "clock dwell begin" and "clock dwell end" times as determined by said measuring step during the offset mode and using that prediction to set the clock normal offset time for the system to commence operation in the normal mode;

wherein the means for calculating a prediction during the standby mode comprises means effective following each occurence of "clock dwell begin" followed by "clock dwell end" for calculating clock dwell time by subtracting the "clock dwell end" time from the "clock dwell begin" time and using the resulting value to obtain a clock dwell factor which indicates the time required to heat the zone from the "temperature on" set-point to the "temperature off" set-point, means for forming a temperature ratio as the range between the normal and setback temperatures divided by the range between the "temperature on" set-point to the "temperature off" setpoint, means for forming a product of the temperature ratio multiplied by the clock dwell factor, means for subtracting that product from the clock normal setting, and using the result in the prediction to set the clock normal offset time.

7. A controller according to claim 6, wherein the clock dwell factor is a clock dwell average (Cda) calculated by means for adding the N most recent clock dwell times and dividing by N, where N is any positive integer.

8. A controller for a space conditioning system to modify the temperature of a zone within a structure wherein the system includes a thermal unit which is a bistable or on-off cooling unit, means for selectively transferring heat between the thermal unit and said zone with a normal mode and a setback mode, wherein the controller includes a system clock and a temperature sensor which measures the temperature in said zone, means providing system operating parameters comprising a normal temperature setting, a setback temperature setting, a clock normal setting and a clock setback setting, wherein during the normal mode the temperature of the zone is to be maintained in a range around the normal temperature at times beginning with the clock normal setting and ending with the clock setback setting, and wherein during the standby mode the temperature of the zone is to be maintained in a range around the setback temperature at times beginning with the clock setback setting and ending with the clock normal setting, with said ranges established by "temperature on" and "temperature off" setpoints which control turning the thermal unit on and off, a clock normal offset being used as a time for changing operation to the normal mode in an attempt for the temperature of said zone to reach the normal temperature at the time designated by the clock normal setting;

means for predicting the time required to change the temperature of the zone from the setback temperature to the normal temperature, in a transition from the standby mode to the normal mode, comprising;

means for measuring "clock dwell begin" and "clock dwell end" times indicated by the clock when the "temperature on" and "temperature off" setpoints respectively occur as determined by comparison to readings from said temperature sensor during the standby mode;

means for calculating a prediction of the amount of time required to adjust the temperature of the zone to the normal temperature using "clock dwell begin" and "clock dwell end" times as determined by said measuring step during the offset mode and using that prediction to set the clock normal offset time for the system to commence operation in the normal mode;

wherein the means for calculating a prediction during the standby mode comprises means effective following each occurence of "clock dwell begin" followed by "clock dwell end" for calculating clock dwell time by subtracting the "clock dwell end" time from the "clock dwell begin" time and using the resulting value to obtain a clock dwell factor which indicates the time required to cool the zone from the "temperature on" set-point to the "temperature off" set-point, means for forming a temperature ratio as the range between the normal and setback temperatures divided by the range between the "temperature on" set-point to the "temperature off" set-point, means for forming a product of the temperature ratio multiplied by the clock dwell factor, means for subtracting that product from the clock normal setting, and using the result in the prediction to set the clock normal offset time.

9. A controller according to claim 8, wherein the clock dwell factor is a clock dwell average (Cda) calculated by means for adding the N most recent clock dwell times and dividing by N, where N is any positive integer.