Fuel-fired heating appliance with combustion air shutoff system having frangible temperature sensing structure

A method of operating a fuel-fired heating apparatus having a combustion chamber, a burner structure operative to create hot combustion products in said combustion chamber, and a flow path external to said combustion chamber and operative to deliver combustion air into said combustion chamber, said method comprising the steps of:

• sensing an undesirable temperature increase in said combustion chamber caused by a reduction in air flow through said flow path into said combustion chamber which increases the level of carbon monoxide created in said combustion chamber during firing of said burner structure;
• said sensing step being performed using a temperature sensing structure projecting into said combustion chamber and supporting within said combustion chamber a heat-frangible element shatterable at a set point temperature;
• and
• responsively terminating combustion air flow through said flow path in a manner terminating burner combustion prior to the concentration level of carbon monoxide in said combustion chamber reaching a predetermined magnitude.

Fuel-fired heating apparatus comprising:

• a combustion chamber thermally communicatable with a fluid to be heated, said combustion chamber having an outer wall defined by an arrestor plate having a perforated portion defined by flame quenching openings formed in said arrestor plate;
• a burner structure disposed in said combustion chamber and operative to receive fuel from a source thereof;
• a wall structure defining a flow path external to said combustion chamber and through which combustion air may flow into said combustion chamber for mixture and combustion with fuel received by said burner structure to create hot combustion products within said combustion chamber;
• a damper structure disposed externally of said combustion chamber and being resiliently biased toward a closed position in which it terminates air flow through said flow path;
• and
• a temperature sensing structure projecting into said combustion chamber and supporting a heat-frangible element within the interior of said combustion chamber, said temperature sensing structure releasably blocking said damper structure in an open position in which it permits combustion air to flow through said flow path into said combustion chamber, and being operative to unblock said damper structure, and permit it to be driven to its closed position, in response to the shattering of said heat-frangible element caused by the presence of a predetermined, undesirably high temperature in said combustion chamber during firing of said burner structure.

Combustion air shutoff apparatus for a fuel-fired heating appliance, comprising:

• a frame structure having spaced apart opposing first and second wall portions and a passage extending through said first wall portion;
• a heat-frangible element bearing against said second wall portion;
• and
• a spring member releasably interposed between said first wall portion and said heat-frangible element, resiliently holding said heat-frangible element against said second wall portion, and overlying and blocking said passage.

Combustion air shutoff apparatus for a fuel-fired heating appliance, comprising:

• a first frame member having spaced apart opposing first and second wall portions and a first passage extending through said first wall portion;
• a heat-frangible element releasably carried by said first frame member and bearing against said second wall portion;
• a spring member releasably interposed between said first wall portion and said heat-frangible element, resiliently holding said heat-frangible element against said second wall portion, and overlying and blocking said passage;
• and
• a second frame member having a base wall with a second passage extending therethrough;
• said first frame member being releasably securable to said second frame member in a manner positioning said first wall portion in an overlying relationship with said base wall, with said first and second passages being aligned with one another.