A heating device includes a heating chamber, a heating element for heating air in the heating chamber, and a condensing counter-flow heat exchanger including a first flow path that receives outgoing air from the heating chamber and a second flow path for providing incoming air to the heating chamber. The first flow path and the second flow path are configured in a counter-flow heat exchange relationship such that the outgoing air flows in a direction opposite the incoming air and the latent heat of evaporated water in the outgoing air is transferred to the incoming air thereby condensing liquid water from the outgoing air.