Method for efficient fan control for electric or gas furnaces and heat pumps in heating mode
First Claim
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1. A method for controlling a heating system ventilation fan, the method comprising:
- controlling a fan relay signal from a thermostat to a fan relay, the fan relay normally controlled by a thermostat G terminal to control the ventilation fan to circulate air through a heating system;
monitoring a heating system operating time defined from when the thermostat is initiating a call for heating until when the thermostat is terminating the call for heating;
after the thermostat initiates the call for heating, performing at least one action selected from the group consisting of;
turning on the ventilation fan after an initial delay to circulate air through the heating system,energizing the fan relay normally controlled by the thermostat G terminal to circulate air through the heating system, andwaiting while the heating system is turning on the ventilation fan to circulate air through the heating system and waiting a first period of time P1 with the ventilation fan operating, and after the period of time P1, energizing the fan relay normally controlled by the thermostat G terminal to circulate air through the heating system;
continuing to circulate air through the heating system and the thermostat continuing calling for heating until a selected thermostat set point temperature is satisfied;
the thermostat terminating the call for heating when the thermostat set point temperature is satisfied thereby turning off the heating system;
setting a heating system operation time P3 to the length of time from when the thermostat is initiating a call for heating until when the thermostat is terminating the call for heating;
computing an extended fan-off delay period of time P2 as a function of the heating system operation time P3 and energizing the fan relay signal for the entire fan-off delay period of time P2, and de-energizing the fan relay signal at the end of the fan-off delay period of time P2.
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Abstract
A method for controlling heater ventilation fan operation increases fan speed from low to high after a short delay after turn-on, and continues fan operation for a period of time based on duration of operation, after turn-off. The higher fan speed improves heat transfer and efficiency while the heating system is operating. Continuing fan operation after turn-off maximizes recovery of additional heat from the heat exchanger. Known methods do not provide sufficient air flow to efficiently transfer heat from the heat exchanger to the air, and leave high temperature air (i.e., 110 to 200° F.) in the heat exchanger after turn-off.
48 Citations
37 Claims
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1. A method for controlling a heating system ventilation fan, the method comprising:
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controlling a fan relay signal from a thermostat to a fan relay, the fan relay normally controlled by a thermostat G terminal to control the ventilation fan to circulate air through a heating system; monitoring a heating system operating time defined from when the thermostat is initiating a call for heating until when the thermostat is terminating the call for heating; after the thermostat initiates the call for heating, performing at least one action selected from the group consisting of; turning on the ventilation fan after an initial delay to circulate air through the heating system, energizing the fan relay normally controlled by the thermostat G terminal to circulate air through the heating system, and waiting while the heating system is turning on the ventilation fan to circulate air through the heating system and waiting a first period of time P1 with the ventilation fan operating, and after the period of time P1, energizing the fan relay normally controlled by the thermostat G terminal to circulate air through the heating system; continuing to circulate air through the heating system and the thermostat continuing calling for heating until a selected thermostat set point temperature is satisfied; the thermostat terminating the call for heating when the thermostat set point temperature is satisfied thereby turning off the heating system; setting a heating system operation time P3 to the length of time from when the thermostat is initiating a call for heating until when the thermostat is terminating the call for heating; computing an extended fan-off delay period of time P2 as a function of the heating system operation time P3 and energizing the fan relay signal for the entire fan-off delay period of time P2, and de-energizing the fan relay signal at the end of the fan-off delay period of time P2. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for efficiently controlling a ventilation fan, the method comprising:
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turning on a heating system when a thermostat is initiating a call for heating; turning on the ventilation fan by at least one control device selected from the group consisting of; the thermostat, the heating system, and a fan controller; continuing the call for heating by the thermostat and continuing to circulate air through the heating system by the ventilation fan until a selected thermostat set point temperature is satisfied; terminating the call for heating by the thermostat when the thermostat set point temperature is satisfied defining the end of the heating system operation time P3, thereby turning off the heating system; setting the heating system operation time P3 to the length of time from when the thermostat is initiating a call for heating until when the thermostat is terminating the call for heating; determining a ventilation fan-off delay period of time P2 as function of the heating system operation time P3 and energizing a ventilation fan relay for the entire fan-off delay period of time P2, and de-energizing the ventilation fan relay controlled by a thermostat G terminal after the fan-off delay period of time P2. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A method for controlling a ventilation fan by a fan controller, the method comprising:
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interrupting a direct electrical connection between a thermostat G terminal to a fan relay normally controlled by the thermostat G terminal, the fan relay providing power to the ventilation fan; after the thermostat initiates the call for heating and energizes the thermostat W terminal, performing at least one action selected from the group consisting of; turning on the ventilation fan after an initial delay to circulate air through a heating system, energizing the fan relay normally controlled by the thermostat G terminal to circulate air through the heating system, and waiting while the heating system is turning on the ventilation fan to circulate air through the heating system and waiting a first period of time P1 with the ventilation fan operating, and after the period of time P1, energizing the fan relay normally controlled by the thermostat G terminal to circulate air through the heating system; continuing the thermostat call for heating and energizing the thermostat W control terminal and continuing energizing the fan relay to circulate air through the heating system for the entire heating system operation time P3 until a selected thermostat set point temperature is satisfied; setting the heating system operation time P3 to the duration of the signal present on the thermostat W terminal based on the length of time from when the thermostat is initiating a call for heating until when the thermostat is terminating the call for heating; determining a fan-off delay period of time P2 as a function of the heating system operation time P3 and continuing to circulate air through the heating system for the entire fan-off delay period of time P2 and de-energizing the fan relay and turning off the ventilation fan at the end of the fan-off delay period of time P2. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29)
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30. A method for efficiently controlling a ventilation fan, the method comprising:
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turning on a heating system when a thermostat initiates a call for heating; turning on the ventilation fan by at least one control device selected from the group consisting of; the thermostat, the heating system, and a fan controller; monitoring a thermostat call for heating; determining a heating system operation time P3 as the length of time from when the thermostat is initiating the call for heating until when the thermostat is terminating the call for heating; determining a ventilation fan-off delay time P2 as function of the heating system operation time P3 based on the heating system operation time P3, and continuing energizing the ventilation fan for the entire fan-off delay time P2, and de-energizing the ventilation fan after the fan-off delay time P2. - View Dependent Claims (31, 32)
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33. A method for efficiently controlling a heating system ventilation fan, the method comprising:
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monitoring a duration of a thermostat call for heating time P3 defined from when the thermostat is initiating a call for heating until when the thermostat is terminating the call for heating; and continuing the heating system ventilation fan operation for a variable period of time P2 after the thermostat call for heating has ended based on the duration of the thermostat call for heating time P3. - View Dependent Claims (34, 35, 36)
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37. A method for connecting a fan controller (211) to an existing heating system including a fan, and controlling the fan by the fan controller (211), the method comprising:
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disconnecting a first electrical connection between a thermostat G terminal (204) on thermostat or equipment control terminals (201) and a fan relay terminal (205) used to control the fan (206); connecting a second electrical connection between the thermostat G terminal (204) on thermostat or equipment control terminals (201) to a first fan controller terminal (214) on a fan controller (211); connecting a second fan controller terminal (212) on the fan controller (211) to the fan relay (205) used to control the fan (206); connecting a thermostat W terminal (208) to a third fan controller input (216) of a fan controller (211) used to monitor a heating system operating time P3 defined from when the thermostat is initiating a call for heating until when the thermostat is terminating the call for heating; determining an amount of time a heater ventilation fan operation time P2 is extended after the heating cycle based on the duration of a heating system operating time P3 defined from when the thermostat is initiating a call for heating until when the thermostat is terminating the call for heating; and the fan controller (211) continuing the heater ventilation fan operation time P2 based on the heating system operation time P3.
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Specification