al section of the enclosure, per se, of FIGS. 1 and 2.FIG. 6 is a vertical section of a valved water filled cup associated with the enclosure and heat-exchanger unit of FIGS. 1 and 2.FIG. 7 is a section taken on line 7--7 of FIG. 3.Referring to FIGS. 1-3 and 5, and in accordance with the present invention there is provided a novel and improved fireplace enclosure and heat-exchanger unit combinatio