An air heating apparatus includes a burner configured to cause combustion reaction, a heat exchange part configured to receive heat from a combustion gas generated by the combustion reaction so as to heat water, a heating heat exchanger configured to receive the water heated by the heat exchange part so as to be heat-exchanged with air to be discharged for heating, a fan configured to blow the air to the heating heat exchanger, a condensed water receiver configured to collect and discharge condensed water generated in the heat exchange part, a case in which the burner, the heat exchange part, the heating heat exchanger, the fan, and the condensed water receiver are embedded, and a condensed water trap disposed outside the case and configured to receive the condensed water transferred from the condensed water receiver so as to provide a trap configured to block leakage of the combustion gas.

A hot air gun includes a gun body, the gun body including a handle and a hand guard disposed at a front side of the handle, the gun body being provided with a hot air assembly and a temperature sensing arrangement, the hot air assembly including a heat generating assembly for generating hot air and a hot air tube for blowing the hot air towards a work area, the temperature sensing arrangement being configured to sense temperature of the work area, where the temperature sensing arrangement is rotatably connected to the hand guard, the hand guard is provided with a tuning element for tuning a sensing angle of the temperature sensing arrangement, and the tuning element extends towards the handle relative to the hand guard. The disclosure is mainly used to tune the temperature sensing arrangement via a single hand.

To substantially reduce inequality in hot combustion flow rates through first and second heat exchanger tubes from a fuel-fired heating appliance burner box connected thereto and internally combusting a fuel/air mixture received therein from a source thereof to create the hot combustion gas, a perforated diffuser member having a non-uniform perforation pattern is provided. The fuel/air mixture is flowed through the perforated diffuser member into the interior of the burner box. The non-uniform perforation pattern of the diffuser member functions to alter relative combustion gas flow rates through the first and second heat exchanger tubes in a manner reducing an undesirable operating temperature differential therebetween.

To substantially reduce inequality in hot combustion flow rates through first and second heat exchanger tubes from a fuel-fired heating appliance burner box connected thereto and internally combusting a fuel/air mixture received therein from a source thereof to create the hot combustion gas, a perforated diffuser member having a non-uniform perforation pattern is provided. The fuel/air mixture is flowed through the perforated diffuser member into the interior of the burner box. The non-uniform perforation pattern of the diffuser member functions to alter relative combustion gas flow rates through the first and second heat exchanger tubes in a manner reducing an undesirable operating temperature differential therebetween.

A fuel-fired furnace incorporates specially designed fuel/air mixing and combustion structures. The fuel/air mixing structure is of a mixing sound-attenuating design and comprises a venturi having a perforated sidewall portion and being surrounded by a noise-damping housing chamber communicating with the interior of the venturi via its sidewall perforations. During use of the mixing structure, air is flowed through the venturi in a swirling pattern while fuel is transversely injected internally against the swirling air. The combustion structure comprises a burner box housing into which the fuel/air mixture is flowed, combusted, and then discharged as hot combustion gas into and through the heat exchanger tubes. The fuel/air mixture entering the burner box housing initially passes through a non-uniformly perforated diffuser plate functioning to substantially alter in a predetermined manner the relative combustion gas flow rates through the heat exchanger tubes.

A self-locking switch assembly and heat gun, which relates to power tools; switch assembly includes switch, trigger, holder, self-locking structure, and first elastic member, self-locking structure including toggle button deflectably disposed on trigger and abutment block disposed on holder, toggle button having lock position wherein toggle button abuts against abutment block to prevent trigger from sliding towards switch and unlock position wherein toggle button is detached from abutment block so the trigger may be stressed to slide towards trigger, first elastic member being configured to be stressed and deformed when toggle button is deflected from lock position to unlock position and to drive toggle button to be deflected from unlock position to lock position when toggle button is released, holder being provided with stop portion for preventing toggle button at unlock position from rotating back towards lock position, toggle button at unlock position being fitted with stop portion.

A breakdown cabinet for a furnace filter, the cabinet being made up of a frame support member, a base plate, vertical side and end panels joined together to define a generally rectangular housing having a frame support member, one of the end panels having a door way and an upper door panel mounted in the door way and hinged along its lower edge with spring loaded hinges and pivotal side clip members between the door and sides of the door frame or side panels to securely retain the door in a closed position.

A fuel-fired furnace incorporates specially designed fuel/air mixing and combustion structures. The fuel/air mixing structure is of a mixing sound-attenuating design and includes a venturi having a perforated sidewall portion and being surrounded by a noise-damping housing chamber communicating with the interior of the venturi via its sidewall perforations. During use of the mixing structure, air is flowed through the venturi in a swirling pattern while fuel is transversely injected internally against the swirling air. The combustion structure includes a burner box housing into which the fuel/air mixture is flowed, combusted, and then discharged as hot combustion gas into and through the heat exchanger tubes. The fuel/air mixture entering the burner box housing initially passes through a non-uniformly perforated diffuser plate functioning to substantially alter in a predetermined manner the relative combustion gas flow rates through the heat exchanger tubes.

A waste-heat recirculating system enables waste-heat to be transferred from flue gas to air. The air can be used to heat an enclosed space. The system comprises a housing body, a heat exchanger and a control means. The housing body has a flue-gas flow path and an air flow path. The heat exchanger is positionable or positioned within the housing body for providing a boundary between the flue-gas flow path and the air flow path. The fluid-circulating means enables transfer of waste-heat from the flue gas to the air via the heat exchanger by circulating the flue gas along the flue-gas flow path and/or the air along the air flow path; and a control means for controlling the waste-heat recirculating system, wherein the control means includes at least one of: a sensor, a logic processor module, an alarm module, a memory module, a communication module, and a user-interface module.