Abstract: A piggy back evaporator includes a drip pan having an oblique condensate drain sheet extending over the major length of the same. A steam hole within the condensate drain sheet allows steam to reach the lower surface of a bottom wall of a piggy back pan. The piggy back pan bottom wall is corrugated to define a series of laterally spaced troughs on its upper face and flues on its lower face. Maple sap is fed into the piggy back pan to a level covering the corrugations of the bottom wall. A hood overlies the piggy back pan and seals off the interior thereof. A high pressure air blower is mounted to the hood and feeds air under pressure into a plenum chamber and downwardly through the downpipes into individual horizontal sparging tubes which extend the length of the piggy back pan and are located within the bottoms of individual troughs defined by the corrugations.

Abstract: A piggy back evaporator is sealably coupled in open box form overlying a sugar maple sap evaporator and aligned with an upright flue pan of the conventional sugar maple sap evaporator which, when fired, boils off vaporizable constituents of the sap. The piggy back evaporator includes a drip pan sealably mounted to the flue pan. The drip pan includes an oblique condensate drain sheet extending over the major length of the same. A steam hole within the condensate drain sheet allows steam to reach the lower surface of a bottom wall of a piggy back pan. The piggy back pan bottom wall is corrugated to define a series of laterally spaced troughs on its upper face and flues on its lower face. A hood overlies the piggy back pan and seals off the interior thereof.