Tubular heat exchanger

Claim 1

In combination with a furnace of the type having a heat exchange zone through which air to be heated is circulated (26), said heat exchange zone being defined, in part, by a wall (22) which divides said zone from ambient atmosphere: a generally Ushaped heat exchange element (14) arranged in the path of said air to be heated and extending through said wall (22), said element having an inlet (16) and an outlet (18); a combustion chamber (12) at the inlet of said heat exchange element; an inshot-type burner assembly (10) spaced from said combustion chamber and disposed entirely within said ambient atmosphere, said burner assembly being arranged to direct a flame into said combustion chamber; a flue collector (38) cooperating with the outlet of said heat exchange element; a first blower (30) adapted to deliver a combustion supporting gas under pressure to said combustion chamber; means (48) for directing said gas tangentially to the axis of said inlet to produce a swirling path for products of combustion flowing through said heat exchange element; and a second blower (40) having its suction side connected to the outlet of said heat exchange element for indUcing flow from said heat exchange element toward said flue collector.