External thermostat fan controller

Abstract

A programmable controller circuit that can be connected directly to the fan switch of any thermostat with a forced air heating and/or cooling system that includes a blower fan for circulating air throughout the home. The controller can be installed with minimal modifications to the existing wiring. The present invention increases the efficiency of the cooling system by evaporating condensate and extracting residual coolness from the thermal mass of the evaporator coils. The present invention can be programmed with a single button. A method of adapting additional fan run time based on compressor run time an AC compressor off time and an AC compressor on time.

I claim: 
     
       1. A method for connecting an external fan controller ( 211 ) to an existing Air Conditioning (AC) system including a system fan ( 206 ), and controlling the fan by the external fan controller, the method comprising:
 positioning the external fan controller; 
 disconnecting a fan relay lead ( 217 ) originally connecting a thermostat fan “G” terminal ( 204 ) to a fan relay ( 205 ) controlling the fan, from the thermostat fan “G” terminal ( 204 ); 
 reconnecting the fan relay lead to a fan activation switch output terminal ( 212 ) of the external fan controller; 
 connecting the thermostat fan “G” terminal to a fan terminal input ( 214 ) on the external fan controller; 
 connecting an A/C compressor terminal (207) of the thermostat to an AC compressor input (215) of the external fan controller (211);  
 leaving an original AC compressor lead in place between an AC compressor terminal of the thermostat and an AC compressor; and 
 leaving a power signal lead in place between a transformer and the thermostat; 
 connecting a power signal lead from a system transformer ( 210 ) to a low-voltage input ( 213 ) of the fan controller ( 211 ); and 
 the external fan controller controlling a run time of the fan, comprising the steps of: 
 monitoring a duration of each AC compressor cycle; 
 determining a variable amount of time a fan operation is extended after each cooling cycle based on the duration of each AC compressor cycle; and 
 extending the fan operation after the end of each cooling cycle for the variable amount of time based on the duration of each AC compressor cycle. 
 
     
     
       2. The method of  claim 1 , wherein the external fan controller does not include a user interface. 
     
     
       3. The method of  claim 1 , further including a step of connecting a sole power signal for the external fan controller in parallel with a hot contact terminal of the thermostat. 
     
     
       4. The method of  claim 1 , further including the external fan controller extending a run time of the fan for a factory programmable fixed duration after an end of a cooling cycle. 
     
     
       5. The method of  claim 1 , wherein the controller extends the fan run time for a user programmable fixed amount after a cooling cycle. 
     
     
       6. A method for connecting an external fan controller to an existing Air Conditioning (AC) system including a fan, and controlling the fan by the external fan controller, the method comprising:
 positioning the external fan controller; 
 disconnecting a fan relay lead originally connecting a thermostat fan terminal to a fan relay controlling the fan, from the thermostat fan terminal; 
 reconnecting the fan relay lead to a fan activation switch terminal of the external fan controller; 
 connecting the thermostat fan terminal to a fan terminal on the external fan controller; 
 leaving an original AC compressor lead in place between an AC compressor terminal of the thermostat and an AC compressor; 
 connecting an A/C compressor terminal of the thermostat to an AC compressor input of the external fan controller;  
 leaving a power signal lead in place between a transformer and the thermostat; and 
 the external fan controller controlling a fan run time of the fan, comprising the steps of:
 monitoring a duration of each AC compressor cycle; and 
 determining a variable amount of time a fan operation is extended after each cooling cycle based on each duration. 
 
 
     
     
       7. The method of  claim 1 , further including:
 monitoring the duration of the air conditioner compressor cycle; and   determining an amount of time the fan operation extension based on user selected values after the cooling cycle.   
     
     
       8. The method of  claim 1 , wherein the external fan controller includes a user interface comprising an LCD display and keypad. 
     
     
       9. The method of  claim 1 , wherein the external fan controller includes a user interface comprising at least one LED and one switch. 
     
     
       10. The method of  claim 1 , further including programming the external fan controller using a single button. 
     
     
       11. The method of  claim 1 , further including the external fan controller determining whether it is operating in fixed delay mode or adaptable delay mode, wherein both the fixed and adaptable mode can be programmed with a single button. 
     
     
       12. The method of  claim 1 , wherein the external fan controller includes a triac, and including a step of switching the fan relay on and off by the triac. 
     
     
       13. The method of  claim 1 , wherein the external fan controller includes an electro-mechanical switch, a microprocessor controlling the external fan controller, and a battery to power the microprocessor when the electro-mechanical switch is closed, and including a step of switching the fan relay on and off by the electro-mechanical switch. 
     
     
       14. A method for connecting an external fan controller to an existing Air Conditioning (AC) system including a fan, and controlling the fan by the external fan controller, the method comprising:
 positioning the external fan controller; 
 disconnecting a fan relay lead originally connecting a thermostat fan terminal to a fan relay controlling a fan, from the fan relay; 
 reconnecting the fan relay lead to a thermostat fan activation switch terminal of the external fan controller; 
 connecting a second fan relay lead from a fan relay terminal on the external fan controller to the fan relay; 
 leaving an original AC compressor lead in place between an AC compressor terminal of the thermostat and an AC compressor; 
 connecting an A/C compressor terminal of the thermostat to an AC compressor input of the external fan controller;  
 leaving a power signal lead in place between a transformer and the thermostat; and  
 wherein the external fan controller performs the following actions:
 monitoring a duration of each AC compressor cycle; 
 determining a variable amount of time a fan operation is extended after each cooling cycle based on the duration of each AC compressor cycle; and 
 
 the external fan controller controlling a fan run time of the fan for the variable amount of time for each AC compressor cycle. 
 
     
     
       15. A method for connecting an external fan controller to an existing Air Conditioning (AC) system including a fan, and controlling the fan by the external fan controller, the method comprising:
 positioning the external fan controller; disconnecting a fan relay lead originally connecting a thermostat fan terminal to a fan relay controlling a fan, from the fan relay; 
 reconnecting the fan relay lead to a thermostat fan activation switch input terminal of the external fan controller; 
 connecting a second fan relay lead from a fan relay output terminal on the external fan controller to the fan relay; 
 leaving an original AC compressor lead in place between an AC compressor terminal of the thermostat and an AC compressor; 
 connecting an A/C compressor terminal of the thermostat to an AC compressor input of the external fan controller;  
 leaving a power signal lead in place between a system transformer and the thermostat; 
 connecting a sole power signal for the external fan controller in parallel with the power signal lead of the thermostat; and 
 the external fan controller controlling a fan run time of the fan, comprising the steps of:
 monitoring a duration of each AC compressor run time; 
 determining a variable amount of time a fan operation is extended after each AC compressor AC compressor run time based on the duration of each AC compressor run time. 
 
 
     
     
       16. The method of  claim 1 , wherein duration of the AC compressor cycle is at least one duration selected from the group consisting of: an AC on time, and an AC off time. 
     
     
       17. The method of  claim 6 , wherein duration of each AC compressor cycle is at least one duration selected from the group consisting of: an AC compressor on time, and an AC compressor off time. 
     
     
       18. The method of  claim 14 , wherein duration of each air conditioner compressor cycle is at least one duration selected from the group consisting of: an AC on time, and an AC off time. 
     
     
       19. The method of  claim 1 , wherein duration of each AC compressor cycle is an AC compressor on time. 
     
     
       20. The method of  claim 6 , wherein duration of each AC compressor cycle is an AC compressor on time. 
     
     
       21. The method of  claim 14 , wherein duration of each AC compressor cycle is an AC compressor on time. 
     
     
       22. The method of  claim 1 , wherein monitoring the duration of each AC compressor cycle is based on whether or not the fan or AC compressor are activated by the thermostat based on the presence or absence of at least one signal selected from the group consisting of: a fan signal, and an AC compressor signal. 
     
     
       23. The method of  claim 6 , wherein monitoring the duration of each AC compressor cycle is based on whether or not the fan or AC compressor are activated by the thermostat based on the presence or absence of at least one signal selected from the group consisting of: a fan signal, and an AC compressor signal. 
     
     
       24. The method of  claim 14 , wherein monitoring the duration of each AC compressor cycle is based on whether or not the fan or AC compressor are activated by the thermostat based on the presence or absence of at least one signal selected from the group consisting of: a fan signal, and an AC compressor signal. 
     
     
       25. The method of  claim 1 , wherein monitoring the duration of each AC compressor cycle is based on whether or not the fan or AC compressor are activated by the thermostat based on the presence or absence of a thermostat call for cooling. 
     
     
       26. The method of  claim 6 , wherein monitoring the duration of each AC compressor cycle is based on whether or not the fan or AC compressor are activated by the thermostat based on the presence or absence of a thermostat call for cooling. 
     
     
       27. The method of  claim 14 , wherein monitoring the duration of each AC compressor cycle is based on whether or not the fan or AC compressor are activated by the thermostat based on the presence or absence of a thermostat call for cooling.