Closed passage heat holding apparatus

In holding apparatus for food and the like, the combination comprising:

• (a) an inner heat-holding compartment having walls made of a heat-conductive material for confining a relatively still volume of air about a food and the like and having at least one door for closing said compartment;
• (b) an outer jacket means arranged about said compartment defining a closed passage arranged along two sets of perpendicular axes about the external surface of the compartment and about a major portion of the external surface area of the compartment, said outer jacket means having thermally insulated walls arranged entirely about the closed passage to provide substantially uniform heating of the body of gas in said compartment and thereby the food and the like therein by conduction and convection without significant heated air flow in contact with the food;
• (c) a controllable heat source for heating air in said passage in a selected heat range;
• (d) a controllable pressure source for recirculating the heated air in said passage for maintaining heated recirculating air about said volume of air;
• and
• (e) a controllable source of moisture in open communication with the heated volume of air in the compartment to introduce controlled quantities of moisture thereinto.

In holding apparatus for holding food and the like at desirable heat and moisture levels the combination comprising:

• (a) an inner compartment having top, bottom, opposed side walls and a rear wall, each wall being made of an imperforate sheet metal leaving the front open for access, for confining a still volume of air;
• (b) an outer jacket having a top section, a bottom section, opposed side sections and a back section with at least one closure door for the compartment adapted to swing between open and closed positions, said outer jacket being of a double-wall sandwich construction with heat insulation between two outer sheet metal panels, said outer jacket forming a closed flow passage about said inner compartment along said top, bottom and opposed sides thereof to maintain a flow of heated recirculating air about said compartment;
• (c) an electric heating element in the passage in said top section;
• (d) a blower having a blade in an aperture in a partition in said top section adapted to blow air over said heating element and through said passage;
• (e) a water pan containing water located in said compartment in open communication with said volume of air, said pan having a lid adjustable to expose a selected surface area of the water;
• and
• (f) a control circuit including control devices on a control panel on said top section for selectively regulating electric power from a power supply to said heating element and said blower.