Abstract: A low profile, high efficiency, fireplace boiler wherein a burner tray supports a number of gas fired burners and artificial logs within a hearth area of the firebox and about which logs the gas and flames are distributed. Combustion air is drawn from a conduit that surrounds an exhaust conduit at a chimney and circulated via a distributing manifold to the space beneath the burner tray, where it mixes with the fuel. Additional secondary air is directed from ports at intersecting levels of the tray to create flickering. Heated exhaust gasses are directed by a baffle to contact exposed walls of a liquid filled heat exchanger formed into the top and rear walls of the firebox and to pass through the bottoms of a number of vertical plenums mounted within the heat exchanger behind the baffle. A spring biased explosion door is provided beneath the burner tray. Liquid is circulated through the heat exchanger to distribution conduits arrayed about the premises.