External Thermostat Fan Controller

A method for efficiently controlling a heater ventilation fan, the method comprising:

• electrically connecting an external thermostat fan controller, including a trial as a switching device, to existing thermostat leads of an existing HVAC system, comprising the steps of:
• positioning the external thermostat fan controller;
• disconnecting a fan relay lead originally connecting a thermostat fan terminal to a fan relay controlling a fan, from the thermostat fan terminal;
• reconnecting the fan relay lead to a fan activation switch terminal of the external thermostat fan controller;
• connecting the thermostat fan terminal to a fan terminal on the external thermostat fan controller;
• 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;
• turning on a heat source in a heater;
• turning on the heater ventilation fan to low speed;
• waiting a first period of time P1 of about four minutes;
• switching the heater ventilation fan to high speed after the period of time P1;
• running the heater for a period of time P3 until a selected temperature is reached;
• turning off the heat source in the heater;
• waiting a second period of time P2, wherein P2 is:
• zero minutes if P3 is less than four minutes;
• linearly increase from zero minutes to four minutes as P3 increases from four minutes to eight minutes;
• and
• four minutes if P3 is greater than eight minutes;
• and
• turning the heater ventilation fan off after the period of time P2.

A method for efficiently controlling a heater ventilation fan, the method comprising:

• electrically connecting an external thermostat fan controller to existing thermostat leads of an existing HVAC system, wherein all of the power requirements of the external thermostat fan controller are provided though the existing thermostat leads;
• turning on a heat source in a heater;
• turning on the heater ventilation fan to low speed;
• waiting a first period of time P1 of about four minutes;
• switching the heater ventilation fan to high speed after the period of time P1;
• running the heater for a period of time P3 until a selected temperature is reached;
• turning off the heat source in the heater;
• waiting a second period of time P2, wherein P2 is:
• zero minutes if P3 is less than four minutes;
• two minutes if P3 is between four and five minutes;
• two and one half minutes if P3 is between five and six minutes;
• three minutes if P3 is between six and seven minutes;
• three and one half minutes if P3 is between seven and eight minutes;
• and
• four minutes if P3 is greater than eight minutes;
• and
• turning the heater ventilation fan off after the period of time P2.