Thermobox

A thermobox is essentially a large heat battery that can store a large amount of heat energy. Periodically it will attempt to provide heat from its storage to a machine at its front, indicated by the orange arrows/side. The other blue sides accept heat from heaters, HEAT rays, and even other thermoboxes' output sides into its storage.

To rotate a thermobox to the correct orientation, you can use a standard Minetest screwdriver and right-click it to rotate it. Hold SHIFT to prevent the GUI from appearing while clicking with the screwdriver to successfully rotate it.

As all machines retain their heat when broken and picked up, you can also use a thermobox as a simple way to transport a large amount of heat from one area to another.

A less expensive and similar machine is the Thermal Distributor which takes one input and distributes it evenly to several outputs.