Exhaust adapter, exhaust structure for water heater, and method for installing exhaust adapter

1. An exhaust structure for water heater connected to a water heater, comprising:

an exhaust tube which has one end and the other end and is connected to said water heater at said one end;

an exhaust pipe into which a part of said exhaust tube at the other end thereof is inserted; and

an exhaust adapter which is formed to have an annular shape enclosing a through hole, and is mounted on an outer peripheral surface of said exhaust tube by inserting said exhaust tube into said through hole and is mounted on an inner peripheral surface of said exhaust pipe,

when said exhaust adapter being fitted on said outer peripheral surface of said exhaust tube, an inner peripheral surface of said exhaust adapter pressing said outer peripheral surface of said exhaust tube, and when said exhaust adapter being fitted on said inner peripheral surface of said exhaust pipe, an outer peripheral surface of said exhaust adapter pressing said inner peripheral surface of said exhaust pipe, wherein

the exhaust adapter includes an annular member including one end surface and the other end surface facing each other and including said through hole penetrating across said one end surface and the other end surface, and an outer peripheral projection member having an annular shape and projecting from an outer peripheral surface of said annular member outward circumferentially,

the outer peripheral projection member includes a plurality of projections which are spaced apart from each other on the outer peripheral surface of the annular member,

the plurality of projections include a first projection and a second projection and the outer peripheral surface of the annular member between the first projection and the second projection extends in an axis direction of the annular member while maintaining an outer diameter of the annular member,

the annular member is mounted on said exhaust tube in such a way that one end surface of said annular member is positioned closer to the other end of said exhaust tube than the other end surface thereof,

the outer peripheral projection member is configured to press said inner peripheral surface of said exhaust pipe,

said exhaust tube is provided with a recess on said outer peripheral surface,

said exhaust adapter further includes an inner peripheral projection member having an annular shape and projecting from an inner peripheral surface of said annular member inward circumferentially so as to fit in said recess of said exhaust tube,

said exhaust tube is a flexible tube, and

a portion of said inner peripheral surface of said annular member other than said inner peripheral projection member extends in an axis direction of said annular member while maintaining an inner diameter of said annular member.

2. The exhaust structure for water heater according to claim 1 , wherein

each of the projections of the plurality of projections has an annular shape and projects from said outer peripheral surface of said annular member outward circumferentially, and

each of said plurality of projections is provided on said outer peripheral surface of said annular member at any position except an edge portion on the side of said one end surface of said annular member and an edge portion on the side of the other end surface thereof.

3. The exhaust structure for water heater according to claim 1 , wherein said inner peripheral projection member is disposed at either an edge portion on the side of said one end surface of said annular member or an edge portion on the side of the other end surface thereof.

4. The exhaust structure for water heater according to claim 1 , wherein said exhaust adapter further includes an abutting projection member disposed on said outer peripheral surface of said annular member closer to said one end surface of said annular member than said outer peripheral projection member thereof and projecting outward circumferentially from said annular member greater than said outer peripheral projection member for abutting against an upper end of said exhaust pipe.

5. The exhaust structure for water heater according to claim 1 , wherein said outer peripheral surface of said exhaust adapter has a tapered shape with the outer diameter of said exhaust adapter decreasing from one end toward the other end thereof.

6. The exhaust structure for water heater according to claim 1 , wherein

said water heater is a condensing type water heater, and

one surface of said exhaust adapter includes an inclined face with a descending slope in the direction from the outer periphery toward the inner periphery.

7. A method for installing exhaust adapter comprising the steps of:

preparing an exhaust adapter which is formed to have an annular shape enclosing a through hole, and is configured to have an inner diameter sized not greater than an outer diameter of an exhaust tube connected to a water heater and an outer diameter sized not smaller than an inner diameter of an exhaust pipe, and

fitting said exhaust adapter on an outer peripheral surface of said exhaust tube so that an inner peripheral surface of said exhaust adapter presses said outer peripheral surface of said exhaust tube and on an inner peripheral surface of said exhaust pipe so that an outer peripheral surface of said exhaust adapter presses said inner peripheral surface of said exhaust pipe, wherein

the exhaust adapter includes an annular member including one end surface and the other end surface facing each other and including said through hole penetrating across said one end surface and the other end surface, and an outer peripheral projection member having an annular shape and projecting from an outer peripheral surface of said annular member outward circumferentially,

the outer peripheral projection member includes a plurality of projections which are spaced apart from each other on the outer peripheral surface of the annular member,

the plurality of projections include a first projection and a second projection and the outer peripheral surface of the annular member between the first projection and the second projection extends in an axis direction of the annular member while maintaining an outer diameter of the annular member,

the outer peripheral projection member is configured to press said inner peripheral surface of said exhaust pipe,

said exhaust tube is provided with a recess on said outer peripheral surface,

said exhaust adapter further includes an inner peripheral projection member having an annular shape and projecting from an inner peripheral surface of said annular member inward circumferentially so as to fit in said recess of said exhaust tube,

said exhaust tube is a flexible tube, and

a portion of said inner peripheral surface of said annular member other than said inner peripheral projection member extends in an axis direction of said annular member while maintaining an inner diameter of said annular member.

8. The method for installing exhaust adapter according to claim 7 , further the step of

removing an exhaust terminal mounted to a top end of said exhaust pipe from said exhaust pipe before the step of fitting said exhaust adapter on said outer peripheral surface of said exhaust tube and on said inner peripheral surface of said exhaust pipe, and

mounting said exhaust terminal to said top end of said exhaust pipe after the step of fitting said exhaust adapter on said outer peripheral surface of said exhaust tube and on said inner peripheral surface of said exhaust pipe.