Abstract: A ground thawing apparatus has a housing containing a fire tube for generating high heat conditions within the housing. The housing is thermally insulated to prevent excessive heat loss. In one embodiment, the roof of the housing is peaked and carries a steam vent along the underside of its ridges. The steam vent is a V-shaped baffle with inlet slots along the side edges, where it meets the roof, and outlet or drain openings in opposite ends of the housing, at the base of the V. In another embodiment, a steam vent is a tube leading from the interior of the housing to the interior of the flue for the fire tube. The steam vent allows the escape of excessive amounts of moisture vapor from the housing without undue heat loss.