A glass melting tank comprising at least one front part for introducing the charge material, and at least one charging device. To reduce atmospheric heat losses and reduce dust transport into the upper furnace of the tank, and nevertheless to intensify the heating of the charge material, the front part has a length “LV” of at least 2,250 mm in the direction of the melting tank, and a length “LG” of at least 1,200 mm is provided with an insulating roof. An end wall near the charging device, together with the roof, encloses a gas chamber open toward the melting tank. A characteristic value “K” of 3.50 tonnes (t) per hour and per square meter of surface is not exceeded. The characteristic value is calculated from P/F, where P is the throughput per hour in tonnes (t) and F is the inner surface of the front part in m.