US Patent 10981079 Fog machine

A fog machine supplies air to a fog liquid reservoir to force the fog liquid into a heater, wherein the fog liquid vaporizes to produce fog. The fog liquid supply to the heater can be halted, and the air supply can then be used to purge the heater of residual fog liquid. Within the heater, the fog liquid travels from outer passages further from the heating element(s) to inner passages closer to the heating element(s), whereby the fog liquid is preheated prior to vaporization, resulting in a higher degree of vaporization and “drier” fog with finer vapor particles. The fog machine may draw fog liquid from an “offboard” fog liquid reservoir, such as an off-the-shelf jug of liquid, and is preferably remote-controllable via a user's smartphone.