Patent ID: 8567387

Claim:
An unvented gas fireplace comprising: a substantially closed combustion chamber; a plenum for circulating air outside of and around said combustion chamber, said plenum having an ambient air intake to receive air from a room in which the fireplace is located and an air outlet to exhaust air into said room; a fan for drawing air from said room and for pressurizing said plenum; said combustion chamber comprising an air inlet from said plenum into said combustion chamber, said air inlet downstream from said fan, and an air outlet from said combustion chamber into said plenum; said plenum comprising a restriction located between said combustion chamber air inlet and said combustion air outlet, said fan and said restriction cooperating to cause a positive air pressure differential between said plenum and said combustion chamber, upstream of said restriction and at said combustion chamber air inlet, whereby to force a portion of the air in said plenum to enter said air inlet from said plenum to said combustion chamber while allowing the balance of the air in said plenum to proceed to said air outlet; and wherein heated air is exhausted from said combustion chamber into said plenum through said combustion air outlet between said restriction and said air outlet.