Abstract: An apparatus and process for drying lumber under vacuum conditions using a drying vessel operationally connected to a sump which collects the extracted moisture. Vaccum conditions are maintained in the vessel and in the sump within the range of 10,000 to 15,000 microns, which reduces the boiling point of water to less than 80.degree. F. The temperature within the vessel is raised to approximately 105.degree. F. by a heating source and this combination of reduced pressure and elevated temperature causes the moisture in the lumber to boil off as vapor. This vapor is condensed inside the vessel by refrigeration coils cooled to a temperature between 36.degree. F. and 42.degree. F., and the liquid condensed on the coils is carried to the sump through a drain pipe where it is pumped to waste disposal through a flow meter.