An improved gas-fired burner for a fireplace. The gas-fired burner includes a substantially sealed enclosure. This enclosure, or “heat tank,” may be of any desired shape, but is preferably of a rectangular, box-like shape. The enclosure includes an inlet port for the ingestion of relatively cold air into the enclosure, and two exit ports, for the exhaust of relatively warm air. The enclosure has a front and a back end, and both the inlet and exit ports may be secured to the back end of the enclosure.