A damper assembly for minimizing heat loss through an exhaust stack includes a housing mountable within the stack and an umbrella received within the housing. The umbrella is selectively movable between a first position in which the umbrella is received within the housing, and second position in which the umbrella is extended from the housing such that a peripheral edge of the umbrella is in close association with an interior sidewall of the exhaust stack to minimize a flow of fluid past the umbrella and out of the stack.

A damper assembly for minimizing heat loss through an exhaust stack includes a housing mountable within the stack and an umbrella received within the housing. The umbrella is selectively movable between a first position in which the umbrella is received within the housing, and second position in which the umbrella is extended from the housing such that a peripheral edge of the umbrella is in close association with an interior sidewall of the exhaust stack to minimize a flow of fluid past the umbrella and out of the stack.

Nozzles for delivering air into a combustion system of a boiler utilizing an interchangeable divided nozzle barrel along with a variable vane. The vane can be rotated to different divisions in the nozzle to change the size of the outlet flow area and subsequently the flow velocity of the air into the combustion system to optimize performance and adjust for changes in load and fuel.

A furnace inducer choke and a gas furnace employing the furnace inducer choke. In one embodiment, the furnace inducer choke includes: (1) a choke body configured to engage a furnace inducer blower, the choke body having an opening extending entirely therethrough to limit an amount of combustion air entering a furnace that the furnace inducer blower is attached, and (2) a tab protruding from the choke body a distance sufficient to identify the opening when the choke body and furnace inducer blower are installed in the furnace.

A furnace inducer choke and a gas furnace employing the furnace inducer choke. In one embodiment, the furnace inducer choke includes: (1) a choke body configured to engage a furnace inducer blower, the choke body having an opening extending entirely therethrough to limit an amount of combustion air entering a furnace that the furnace inducer blower is attached, and (2) a tab protruding from the choke body a distance sufficient to identify the opening when the choke body and furnace inducer blower are installed in the furnace.

A combustion apparatus having: an upstream-side air supply chamber and a downstream-side mixing passage, both being respectively interposed between a fan and a burner; and a zero governor which is interposed in a gas supply passage and which adjusts a secondary gas pressure to a pressure equivalent to an internal pressure in the air supply chamber, thereby enabling to maximize a turndown ratio to the extent possible. The combustion apparatus has: first and second, totally two, mixing passages; a first gas outlet which is in communication with a narrowed part of the first mixing passage; a second gas outlet which is in communication with a narrowed part of the second mixing passage; a first air valve which varies an opening degree of an air inlet of the first mixing passage; a second air valve which varies an opening degree of an air inlet of the second mixing passage; and a gas valve.

A combustion apparatus having: an upstream-side air supply chamber and a downstream-side mixing passage, both being respectively interposed between a fan and a burner; and a zero governor which is interposed in a gas supply passage and which adjusts a secondary gas pressure to a pressure equivalent to an internal pressure in the air supply chamber, thereby enabling to maximize a turndown ratio to the extent possible. The combustion apparatus has: first and second, totally two, mixing passages; a first gas outlet which is in communication with a narrowed part of the first mixing passage; a second gas outlet which is in communication with a narrowed part of the second mixing passage; a first air valve which varies an opening degree of an air inlet of the first mixing passage; a second air valve which varies an opening degree of an air inlet of the second mixing passage; and a gas valve.

A water heater includes a vessel (20) provided with a burner (3) having a downward combustion surface, a fan casing (10) accommodating a fan (10a) for supplying a mixture gas of primary combustion air and fuel gas to the burner, an annular packing connecting a first connection end surface at a downstream end of a first passage forming a downstream-side passage of the fan casing with a second connection end surface at an upstream end of a second passage forming an upstream-side passage of the vessel in airtight state, and a check valve (5) disposed near the upstream end in the second passage (2).

A damper opening/closing mechanism includes: a damper which swings about a shaft to open and close a flow passage; an actuating lever which swings so as to swing the damper about the shaft; a reciprocating part which moves reciprocatively; and elastic members which are attached to the reciprocating part and positioned on forward-and-backward both sides in a swinging direction of the actuating lever and moreover which elastically bias the actuating lever along with reciprocative motions of the reciprocating part.

A damper opening/closing mechanism includes: a damper which swings about a shaft to open and close a flow passage; an actuating lever which swings so as to swing the damper about the shaft; a reciprocating part which moves reciprocatively; and elastic members which are attached to the reciprocating part and positioned on forward-and-backward both sides in a swinging direction of the actuating lever and moreover which elastically bias the actuating lever along with reciprocative motions of the reciprocating part.