Hongso Magnetic Temperature Switch on Magnetic Bracket / Magnetic Thermostat Switch for fireplace fan / fireplace blower kit. Temperature switch closes (turn on) at approximately 120°F and opens (shut off) at approximately 90°F (+/- 5°F tolerance). Strong magnet! Easy and simple to place! Perfect for fireplace blower and fan kit applications. NOTE:Blower will not start until thermodisc is heated to approximately 120° F.