adapted to receive a flue connector 49 as illustrated in fig1 or may receive conventional flue pipe directly turret 46 also forms a sight glass platform 50 defining a surface spaced above aperture 34 platform 50 is pierced directly above aperture 34 by a sight glass opening 51 which opening is covered by a sight glass 52 resting on a sight glass gasket 53 and protected and held in place by a frame 54 and guard 55 thus sight glass opening 51 is in registration with aperture 34 and combustor 35 in the embodiment of the present invention illustrated in fig1 and 3 a secondary air tube 15 communicates between the outside and inside of the firebox 10 and an area of combustion chamber 67 near combustor 35 by registering with a secondary air opening 56 in the bottom 7 of stove 1 secondary air tube 15 may be constructed by welding a u shaped metal channel to the inside surface of front wall 3 of the stove in registration with air opening 56 secondary air opening 56 is variably obstructed by a secondary air adjustment slide 57 which may be constructed of relatively springy sheet metal air adjustment slide 57 pivots as is indicated by arrow 58 in fig1 on a screw 59 or other.