Combination air induced and heat circulating log grate

In combination with a fireplace having a generally horizontal bottom with a supporting grate means thereon for supporting combustible material above the bottom, upwardly extending side and rear walls, an open front by which the combustible material may be placed in position on the grate means for burning and an upwardly extending exhaust chimney means for combustion products, a heat exchange assembly mounted on the grate means comprising a cold air inlet tube positioned along the bottom of the fireplace and under the grate means adjacent the center portion thereof and extending from the open front to a point adjacent the rear wall and under said grate means, a pair of hot air tubes paralleling said cold air inlet tube adjacent the sides of the grate means and positioned along the bottom of the fireplace and under the grate means, a header interconnecting the inner ends of said tubes and positioned along the inner edge of and below the grate means, each of said tubes having a plurality of apertures therein for discharging combustion supporting air under the grate means, means circulating air through the tubes, said means including a fan communicated with the cold air inlet tube adjacent a lower corner portion of the open front of the fireplace, said grate means being removable from the fireplace with the tubes and header, said hot air tubes terminating in open discharge forward ends to discharge heated air from the lower portion of the open front of the fireplace, each of said air tubes includes a control means thereon for controlling the combustion supporting air discharged under the grate means, said fan providing a positive pressure in the tubes to prevent entry of combustion products, and said means controlling the discharge of combustion supporting air including a plurality of longitudinally spaced apertures in each of said tubes, a sleeve rotatably mounted on each of said tubes and including a plurality of apertures therein for alignment with and misalignment with the apertures in the tubes, lock means mounted on each of said sleeves and engageable with a respective tube for locking the sleeve in adjusted position, said apertures in the tubes and sleeves being oriented along a plane passing through the horizontal centers of the sleeves and tubes when the apertures are aligned for discharging combustion supporting air laterally of the tubes and sleeves and in underlying relation to the grate means substantially throughout the entire area thereof, said fan including a pipe extending to and connected with the air inlet tube at the front end of the fireplace, and means enabling angular relative movement between the inlet tube and pipe extending from the fan to enable variation in the position of the fan in relation to the inlet tube when installing the tubes and header in a fireplace, said tubes and header being rigidly fixed to the grate means with the discharge ends of the outlet tubes being disposed inwardly of a fireplace screen covering the open front of the fireplace, the pair of air outlet tubes forming a volume greater than the inlet tube to provide for expansion of the air as it is being heated when passing through the tubes.