Air heating apparatus

Abstract

An air heating apparatus includes an expansion tank that stores water, a water heating device that receives heat from combustion gas generated by a combustion reaction and heats the water, a heating heat exchanger that receives the water heated by the water heating device and conducts heat exchange between air to be released for heating and the water, a fan that supplies the air to the heating heat exchanger, a case in which the water heating device, the expansion tank, the heating heat exchanger, and the fan are disposed, a main passage that connects the expansion tank, the water heating device, and the heating heat exchanger, and an overpressure prevention passage that branches off from the main passage and has one end portion disposed on one side of the case.

What is claimed is: 
     
         1 . An air heating apparatus comprising:
 an expansion tank configured to store water;   a water heating device configured to receive heat from combustion gas generated by a combustion reaction and heat the water;   a heating heat exchanger configured to receive the water heated by the water heating device and conduct heat exchange between air to be released for heating and the water;   a fan configured to supply the air to the heating heat exchanger;   a case in which the water heating device, the expansion tank, the heating heat exchanger, and the fan are disposed;   a main passage configured to connect the expansion tank, the water heating device, and the heating heat exchanger; and   an overpressure prevention passage configured to branch off from the main passage, the overpressure prevention passage having one end portion disposed on one side of the case.   
     
     
         2 . The air heating apparatus of  claim 1 , wherein the main passage includes a connecting part configured to connect the water heating device and the heating heat exchanger, and
 wherein the overpressure prevention passage branches off from the connecting part.   
     
     
         3 . The air heating apparatus of  claim 2 , wherein the overpressure prevention passage includes:
 a first passage part configured to extend from the connecting part in a first direction crossing an up-down direction; and   a second passage part configured to extend upward from an end portion of the first passage part configured to face in the first direction.   
     
     
         4 . The air heating apparatus of  claim 3 , wherein a connection point between the first passage part and the second passage part is formed to be rounded. 
     
     
         5 . The air heating apparatus of  claim 3 , wherein the connecting part includes:
 a first connecting region configured to extend downward from the water heating device;   a second connecting region configured to extend from a lower end portion of the first connecting region in a direction crossing the up-down direction; and   a third connecting region configured to extend upward from an end portion of the second connecting region configured to face in an extension direction of the second connecting region, the third connecting region being connected with the heating heat exchanger, and   wherein the overpressure prevention passage branches off from one of the first to third connecting regions.   
     
     
         6 . The air heating apparatus of  claim 5 , wherein the first connecting region includes:
 a connecting adaptor having one end portion connected to the water heating device, the connecting adaptor including a first outlet and a second outlet open in a direction different from a direction in which the first outlet is open; and   a first passage member connected to the first outlet of the connecting adaptor and configured to constitute a portion of the main passage, and   wherein the overpressure prevention passage is connected to the second outlet.   
     
     
         7 . The air heating apparatus of  claim 1 , further comprising:
 an overpressure prevention valve connected to the one end portion of the overpressure prevention passage and configured to selectively open and close the overpressure prevention passage.   
     
     
         8 . The air heating apparatus of  claim 7 , further comprising:
 a through-adaptor configured to penetrate an upper surface of the case and connect the one end portion of the overpressure prevention passage and a lower end portion of the overpressure prevention valve.   
     
     
         9 . The air heating apparatus of  claim 7 , wherein the overpressure prevention valve is a pressure relief valve. 
     
     
         10 . The air heating apparatus of  claim 1 , wherein the one end portion of the overpressure prevention passage is disposed on an upper side of the case.