Air heating apparatus

1 . An air heating apparatus comprising:

an expansion tank configured to preserve water;

a water heater configured to receive heat from a combustion gas generated through a combustion reaction to heat the water;

a heating heat exchanger configured to receive the water heated by the water heater and exchange heat with air that is to be discharged for heating;

a fan configured to send the air to the heating heat exchanger;

a circulation supply passage configured to connect the expansion tank, the water heater, and the heating heat exchanger to guide the water in the expansion tank to the heating heat exchanger via the water heater;

a circulation recovery passage formed to connect the heating heat exchanger and the expansion tank to guide the water that exchanged heat with the air to the expansion tank; and

a hot water heating passage, one end of which is connected to a first point that is one point of the circulation supply passage, which is located on a downstream side of the water heater, an opposite end of which is connected to a second point that is one point of the circulation recovery passage, and through which the water in the circulation supply passage that passed through the water heater is introduced.

2 . The air heating apparatus of claim 1 , further comprising:

a valve part configured to open and close the hot water heating passage, and configured to open and close a downstream side of the first point.

3 . The air heating apparatus of claim 2 , wherein the valve part includes:

a first valve disposed in the hot water heating passage and configured to open and close the hot water heating passage; and

a second valve disposed between the first point of the circulation supply passage and the heating heat exchanger, and configured to open and close a downstream side of the first point.

4 . The air heating apparatus of claim 3 , wherein opening degrees of the first valve and the second valve are adjustable.

5 . The air heating apparatus of claim 3 , further comprising:

a circulation pump disposed in the circulation supply passage between a downstream side of the expansion tank and an upstream side of the water heater, and configured to pump the water in the circulation supply passage.

6 . The air heating apparatus of claim 5 , further comprising:

a first flow rate measuring part disposed in the circulation supply passage between a downstream side of the circulation pump and the upstream side of the water heater, and configured to measure a flow rate of the water that passes through the circulation supply passage; and

a second flow rate measuring part disposed in the circulation supply passage on the downstream side of the first point, and configured to measure a flow rate of the water that passes in the circulation supply passage on the downstream side of the first point.

7 . The air heating apparatus of claim 5 , further comprising:

a first temperature measuring part disposed in the circulation supply passage between a downstream side of the circulation pump and the upstream side of the water heater, and configured to measure a temperature of the water that passes through the circulation supply passage; and

a second temperature measuring part disposed in the circulation supply passage on the downstream side of the water heater and an upstream side of the first point, and configured to measure a temperature of the water that passes through the circulation supply passage.

8 . The air heating apparatus of claim 3 , further comprising:

a third temperature measuring part disposed in the circulation recovery passage, and configured to measure a temperature of the water that passes through the circulation recovery passage.

9 . The air heating apparatus of claim 4 , further comprising:

a controller electrically connected to the valve part, and configured to control an operation of the valve part.

10 . The air heating apparatus of claim 9 , wherein in a hot water mode, in which it is necessary to use hot water, the controller controls the first valve to open the hot water heating passage.

11 . The air heating apparatus of claim 10 , wherein when, in a heating mode for heating an interior, the heating mode and the hot water mode, in which it is necessary to use the hot water, are performed together, the controller controls the second valve to decrease a flow rate of the water that flows to the downstream side of the first point.

12 . The air heating apparatus of claim 11 , further comprising:

a hot water tank provided with a heating area of the hot water heating passage in an interior thereof, and in which the hot water is preserved; and

a hot water temperature measuring part coupled to the hot water tank and electrically connected to the controller, and configured to deliver acquired information on a temperature of the hot water in the hot water tank to the controller,

wherein the controller is configured to control the first valve and the second valve to control at least any one of an opening of the first valve or the second valve, based on a value obtained by comparing a temperature of the hot water, which is acquired by the hot water temperature measuring part, and a target hot water temperature.

13 . The air heating apparatus of claim 1 , further comprising:

a hot water tank, in which hot water is preserved,

wherein a heating area of the hot water heating passage is disposed in the hot water tank to heat the hot water in the hot water tank.

14 . The air heating apparatus of claim 13 , wherein the heating area is formed to have a spiral shape that extends downwards.

15 . The air heating apparatus of claim 13 , wherein an interior of the hot water tank and an interior of the hot water heating passage are not communicated with each other.