Wall thimble with outside air inlet
View Patent ↗An improved wall thimble is useful as part of a venting apparatus for a direct vent heating appliance. Dual functionality is provided in a single wall thimble device by having a vent path for exhausting combustion by-products, and a separate air inlet path to draw in outside combustion air for use by the heating appliance. The wall thimble is formed as a two-part housing such that a first cylindrical portion can be inserted into a second cylindrical portion. When a smaller diameter exhaust pipe is routed through the cylindrical portions, an annular region is formed between the exhaust pipe and the cylindrical portions. A first air vent is formed in the first cylindrical portion to draw combustion air into the annular region from outside. A second air vent is formed in the second cylindrical portion to route the combustion air from the annular region to an opening in the housing where a combustion air inlet pipe is connected.
1. A wall thimble for use in a wall opening of a building as part of a venting apparatus for a heating appliance located inside of the building, said heating appliance having an exhaust outlet and a combustion air inlet, wherein an exhaust pipe is coupled to the exhaust outlet and a pipe is coupled to the combustion air inlet, comprising:
a pair of mounting plates each adapted to be affixed on opposite sides of the wall opening, namely an inside mounting plate and an outside mounting plate, each mounting plate having a corresponding first opening therein aligned with the wall opening;
a hollow structure coupled to the mounting plates, said hollow structure comprising a surface enclosing an area and having opposing ends that are open, said surface being sized in correspondence with the first openings in the mounting plates; and
a pair of cover plates affixed to the opposing ends of the surface, each cover plate having a corresponding second opening therein which is smaller than the first opening and sized to receive the exhaust pipe therethrough such that a first passageway is defined within the exhaust pipe and a second passageway is defined between the exhaust pipe and the surface of the hollow structure;
wherein one end of the hollow structure is an outside end and extends beyond the outside mounting plate to the outside of the building, and the other end of the hollow structure is an inside end;
wherein outside vent openings are formed on the surface of the hollow structure proximate to the outside end, and wherein inside vent openings are formed on the surface of the hollow structure proximate to the inside end; and
wherein the inside mounting plate includes a third opening proximate to the inside vent openings and a coupling adapted to receive the pipe.
2. The wall thimble of claim 1 , wherein the hollow structure is a cylinder.
3. The wall thimble of claim 2 , wherein the cylinder is formed in two parts that mate with each other.
4. The wall thimble of claim 2 , wherein the cylinder is formed in two parts that rotate with respect to each other.
5. The wall thimble of claim 3 , wherein the two cylinder parts comprise an inner portion insertable into an outer portion.
6. The wall thimble of claim 5 , wherein said outside air vent is formed on the inner portion and said inside air vent is formed on the outer portion.