have a converted garage attatched to house so it is now a family room, purchased a ventless propane fireplace to use as a supplement heat source on cold winter days or for ambience when in room, room currently is heated by hydronic baseboard 2 walls, room dimensions are 20x12 with vaulted cieling of 15', no door on room open to entrance area and leads into kitchen and living room and dining room , no doors open layout . figuring approx 2880 cf of space in family room, approx 7880 cf total with combined rooms ( small cape w/ bedroom upstairs approx 1700 sf living space), heat home with pellet stove located in living room. is the size of the vented gas fireplace of 26,000 btu sufficient or overkill ?