A furnace for heat treatment of glass containers may include: a thermally insulated structure; and a conveyor unit. The conveyor unit may include pallets configured to feed the glass containers to a loading area, heating area, cooling area, and unloading area of the furnace. The conveyor unit may define a pallet flow path along an upper conveying branch, lowering branch, lower return branch, and raising branch. Shaped rods, extending from opposite sides of the pallets, may connect to one or more drive units external to the thermally insulated structure. The shaped rods may pass through slits in the thermally insulated structure. At least one of the one or more drive units may include a drive element selectively connected to the pallets along the pallet flow path. The raising branch may include an ascent elevator and the lowering branch may include a descent elevator at opposite ends of the heating area.