Dual mode thermal actuator

A method of actuating an actuator, the method comprising:

• providing a first cup having a resistance heater and defining a first chamber filled with thermally-responsive wax;
• providing a second cup exposed to an ambient heat source and defining a second chamber filled with thermally-responsive wax;
• providing a piston positioned intermediate the first and second cups;
• wherein the first and second cups receive corresponding first and second guides, wherein the first guide surrounds a first end of the piston, wherein the second guide surrounds an opposite second end of the piston, and wherein the first guide surrounds a portion of the second guide;
• wherein, an increase in temperature of the resistance heater causes the thermally-responsive wax in the first chamber to expand and the actuator to go from a retracted position to an extended position, and
• wherein, an increase in temperature of the ambient heat source causes the thermally-responsive wax in the second chamber to expand and the actuator to go from the retracted position to the extended position.

An actuator for use in a fluid flow system comprising:

• a first cup defining a first chamber filled with thermally-responsive wax, the first cup having an open end and a closed end;
• a second cup defining a second chamber filled with thermally-responsive wax, the second cup having an open end and a closed end;
• a piston disposed between the first cup and the second cup, wherein the piston comprises a first end and an opposite second end, the piston including a radial flange extending outwardly;
• a first guide received in the open end of the first cup, the first guide surrounding the first end of the piston and extending axially away from the first cup, the first guide including an annular seat;
• and
• a second guide received in the open end of the second cup and extending axially away from the second cup, the second guide surrounding the opposite second end of the piston and including an annular end;
• wherein one of expansion of the wax in the first chamber or expansion of the wax in the second chamber causes the actuator to go from a retracted position to an extended position or expansion of the wax in the first chamber and expansion of the wax in the second chamber causes the actuator to go from the retracted position to the extended position, and
• wherein in the retracted position the flange is sandwiched between and abuts the annular seat and the annular end.