Unvented gas fireplace

Abstract

An unvented gas fireplace in which air flow through a dosed combustion chamber is controlled by means of a restriction in the air flow path through an outer plenum chamber surrounding the combustion chamber, causing a pressure differential between the plenum and combustion chamber, forcing air from the plenum into the combustion chamber, where it is combusted and mixed with the cool air that has passed the restriction in the plenum, before the air mixture is exhausted into the surrounding room or area. A diverter selects between exhausting the heated air in the same or the opposite side as the air intake. The unit may be used as an outdoor stand-alone fireplace.

1 . An unvented gas fireplace comprising:
 a substantially dosed combustion chamber;   a plenum outside of said combustion chamber, said plenum having an ambient air intake to receive air from a room in which said fireplace is located, and an ambient air outlet to exhaust air into said room;   said plenum comprising a restriction, said restriction adapted to cause a positive air pressure differential between said plenum and said combustion chamber, upstream of said restriction;   wherein said positive air pressure differential forces air into said combustion chamber through a combustion air intake between said combustion chamber and said plenum; and   heated air is exhausted from said combustion chamber into said plenum through a combustion air outlet between said restriction and said ambient air outlet.   
     
     
         2 . The gas fireplace of  claim 1  further comprising at least one blower to pull air into said ambient inlet. 
     
     
         3 . The gas fireplace of  claim 2  further comprising ducting between said ambient inlet and said blower. 
     
     
         4 . The gas fireplace of  claim 1  wherein said heated air is mixed in said plenum with air that has not passed through said combustion chamber, before exhausting the mixed air from said fireplace. 
     
     
         5 . A method of heating a room with an unvented gas fireplace having a plenum outside of a closed combustion chamber, comprising the steps of:
 receiving a flow of ambient air from said room into said plenum;   restricting said flow of ambient air at a restriction in said plenum to create a positive air pressure differential between said plenum and said combustion chamber upstream of said restriction, whereby force air from said plenum into said combustion chamber through a combustion air intake;   exhausting heated air from said combustion chamber to said plenum downstream of said restriction;   mixing said heated air with air that has not passed through said combustion chamber within said plenum to form warm air; and   exhausting said warm air to said room.   
     
     
         6 . The method of  claim 5  further comprising the step of blowing ambient air from said room into said plenum through an ambient air intake. 
     
     
         7 . An unvented gas fireplace comprising:
 a substantially closed combustion chamber;   a plenum outside of said combustion chamber for carrying air from an ambient air intake to an ambient air outlet;   said plenum comprising a restriction, said restriction adapted to cause a positive air pressure differential between said plenum and said combustion chamber, upstream of said restriction;   wherein said positive air pressure differential forces air into said combustion chamber through a combustion air intake between said combustion chamber and said plenum; and   wherein heated air is exhausted from said combustion chamber into said plenum through a combustion air outlet between said restriction and said ambient air outlet.   
     
     
         8 . The gas fireplace of  claim 1  or  7  further comprising a diverter selectively positionable between first and second positions, said first position directing said heated air to a first side of said fireplace and said second position directing said heated air to a second side of said fireplace. 
     
     
         9 . The gas fireplace of  claim 1 ,  7  or  8  wherein a first portion of said plenum comprises two spaced transparent panels allowing the viewing from a first side of said fireplace into said combustion chamber and a second portion of said plenum comprises two spaced transparent panels allowing the viewing from a second side of said fireplace into said combustion chamber, said first side and second sides being opposed sides of said fireplace. 
     
     
         10 . The gas fireplace of  claim 7  further comprising a diverter selectively positionable between first and second positions, said first position directing said heated air to a first side of said fireplace and said second position directing said heated air to a second side of said fireplace opposite from said first side and said fireplace being an outdoor stand-alone unit.