Foil heaters for bulk containers

A foil heater to heat a material in a bulk container, comprising:

• a lower backing layer of a metallic foil having substantially the same plan area as the underside of the bulk container to be heated;
• a heating cable laid out on an upper facing surface of the lower backing layer to form a heating circuit to deliver thermal energy when connected to an external source of electricity, the heating cable equally spaced over the upper facing surface;
• a first thermostat, which interrupts electricity to the heating cable when the first thermostat detects a temperature of the material above a first set temperature, and which re-connects electricity to the heating cable when the first thermostat detects the temperature is below the first set temperature, the first thermostat located away from the heating cable to not directly sense the thermal energy from the heating cable;
• a second thermostat in series connection with the first thermostat, which interrupts electricity to the heating cable when the temperature detected is above a second set temperature;
• a non-resetting thermal fuse in series connection with the first and second thermostat, which interrupts electricity to the heating cable when the temperature detected is above a third set temperature;
• an upper backing layer of a metallic foil having substantially the same plan area as the underside of the bulk container to be heated, the lower backing layer and upper backing layer encapsulating the heating cable, first thermostat, second thermostat and non-resetting thermal fuse, and forming an interior between the upper backing layer and lower backing layer;
• an electrical connection for the heating cable, after the first and second thermostat, to the external source of electricity, the electrical connection including an earth connection from any conductive material of the foil heater;
• at least one cold region, the cold region defined by having no heating cable, first thermostat or second thermostat present;
• and
• at least one region of high thermal resistance between the first thermostat and the at least one cold region to prevent thermal energy from reaching the cold region until at least the first thermostat can reach the first set temperature.