A portable indirect fuel fired heater includes a burner assembly having a fuel burner to deliver fuel from a fuel supply to a combustion chamber of the heater and a combustion air blower to deliver combustion air to the combustion chamber with the fuel for combustion in the combustion chamber to produce exhaust gases. A heat exchanger receives air to be heated in heat exchanging relationship with at least a portion of the combustion chamber. A sensor senses an oxygen level as a partial pressure of oxygen in the exhaust gases. A controller operates an actuator operatively connected to the burner assembly to controllably vary the delivery rate of combustion air and thus vary the ratio of the air and fuel responsive to the oxygen level sensed by the combustion sensor so as to maintain the sensed oxygen level at a prescribed set point level stored on the controller.

A furnace for a heating, ventilation, and/or air conditioning (HVAC) system includes a heat exchanger tube including a tube inlet and a tube outlet, such that the heat exchanger tube is configured to receive combustion products via the tube inlet, circulate the combustion products through the heat exchanger tube, and discharge the combustion products via the tube outlet. Additionally, the furnace includes a collector box coupled to the heat exchanger tube and having a cavity configured to receive the combustion products via the tube outlet. The furnace includes a diverter plate disposed within the cavity, where the diverter plate overlaps the tube outlet to disperse the combustion products received via the tube outlet throughout the collector box.

A heat exchanger including a gas inlet through which a combustion gas flows in and a gas outlet through which the combustion gas flows out is provided. The heat exchanger includes a housing in which the gas outlet is formed, a partition member, and a plurality of heat transfer tubes accommodated in the housing. The partition member is mounted in the housing so that there is a portion in which a flow area of the combustion gas is smaller than that of the gas inlet between the gas inlet and the gas outlet.

A furnace for a heating, ventilation, and/or air conditioning (HVAC) system includes a heat exchanger tube including a tube inlet and a tube outlet, such that the heat exchanger tube is configured to receive combustion products via the tube inlet, circulate the combustion products through the heat exchanger tube, and discharge the combustion products via the tube outlet. Additionally, the furnace includes a collector box coupled to the heat exchanger tube and having a cavity configured to receive the combustion products via the tube outlet. The furnace includes a diverter plate disposed within the cavity, where the diverter plate overlaps the tube outlet to disperse the combustion products received via the tube outlet throughout the collector box.

A hookah device having a heating unit, a head for holding a cooking element, a pipe, and a base. The heating unit for use with the hookah device can be provided with optimally placed vents along a bottom wall, a sidewall, and a top wall to facilitate circulation of fresh air and heated air. An optional thermometer can be mounted to the housing for recording a temperature reading with a combustion chamber of the heating unit.

Apparatus and methods for a gas furnace are disclosed. The gas furnace includes a variable combustion control which monitors the temperature of the burner and modifies one of the amount of combustion air supplied and the amount of gas fuel supplied to the mixing chamber. The described systems can dynamically accommodate differences in air quality and gas fuel supply to provide an optimum BTU output irrespective of differences in geographic location of usage. The gas furnace can include a dynamic response unit which predicts an optimum rate of heating to maintain a target room temperature, thereby preventing unnecessary shut down and costly re-ignition sequences, and maintaining the gas furnace at an optimum BTU output level.

A heater is disclosed that is installed in a window opening in a room for heating the room. The heater has a cabinet having an inner and an outer cabinet with an air gap therebetween, with a heating chamber in the inner cabinet. A burner is provided that is located on an outside wall of the heater. The burner has an inlet and an outlet with a combustion nozzle therebetween, with the burner outlet in communication with a respective serpentine heat exchange tube within said heating chamber where the heat exchange tube receives the hot products of combustion from its burner and discharges the products of combustion to the atmosphere. The heater has a blower that draws air from within the room and forces the air over and around the heat exchange tube(s) within the heating chamber discharges the heated air back into the room.

A block heater is disclosed. The block heater may include a heating element configured to supply predetermined heat to a gas line and a heat transfer unit disposed between the gas line and the heating element to transfer heat to the gas line, wherein the heat transfer unit may include a convex portion or a concave portion formed on at least one side thereof in a longitudinal direction of the gas line.

A block heater is disclosed. The block heater may include a heating element configured to supply predetermined heat to a gas line and a heat transfer unit disposed between the gas line and the heating element to transfer heat to the gas line, wherein the heat transfer unit may include a convex portion or a concave portion formed on at least one side thereof in a longitudinal direction of the gas line.

A heating, ventilation, and air condition (HVAC) system is disclosed. The HVAC system includes mode-dependent, movable barriers that can open and close to increase the efficiency of the systems. The movable barriers can be positioned proximate either a gas furnace heat exchanger or air conditioning coils. In a closed configuration, the movable barriers constrict a portion of air flow through a cabinet or other air flow conduit. The movable barriers can be activated by several means including blower airflow, springs, motors, or other such motion devices. Redundancies are also described to ensure the movable barriers are in the proper position. The redundancies described include sensors that measure the condition of the air itself as well as sensors to directly detect the position of the movable barriers.