Combustion air shutoff system for a fuel-fired heating appliance

A fuel-fired heating appliance comprising:

• a combustion chamber thermally communicatable with a fluid to be heated;
• a fuel supply structure operative to deliver fuel from a source thereof into said combustion chamber for mixture with a quantity of combustion air from a source thereof;
• a wall structure defining a path through which the entire combustion air quantity may flow from the combustion air source into said combustion chamber for mixture and combustion with delivered fuel therein, said wall structure having a hollow cylindrical section with a side wall opening disposed therein and defining a portion of said path;
• and
• a combustion air shutoff system operative to sense a temperature indicative of an undesirably high operating temperature within said combustion chamber and responsively block essentially all of the combustion air flow through said path, said combustion air shutoff system including:
• linkage structure including a fusible link member exposed to heat generated by fuel/air combustion within said combustion chamber and being meltable at said temperature indicative of an undesirably high operating temperature within said combustion chamber, and
• a damper member held by said linkage structure in an open position permitting operative combustion air flow through said path, said damper member being urged toward a closed position in which said damper member blocks combustion air flow through said path, melting of said fusible link member being operative to permit movement of said damper member from said open position thereof to said closed position thereof,
• said damper member being a flexible band member wrapped around said hollow cylindrical section of said wall structure and supported for circumferential movement relative thereto between said closed position in which said band member covers and blocks said side wall opening, and said open position in which said band member uncovers and is outwardly spaced apart from said side wall opening.

A water heater comprising:

• a tank adapted to hold a quantity of water;
• a combustion chamber disposed beneath said tank and having a bottom side wall structure with a spaced series of air inlet openings therein;
• a fuel burner operative to receive fuel from a source thereof and deliver the received fuel into said combustion chamber;
• a hollow cylindrical skirt structure extending downwardly beyond said bottom side wall structure and having a vertical side wall portion with a spaced series of inlet openings formed therein for permitting a combustion air inflow therethrough into the interior of said hollow skirt structure for delivery therefrom into said combustion chamber, via said spaced series of combustion air inlet openings in said bottom side wall structure, for combustion with burner-delivered fuel therein;
• and
• a combustion air shutoff system operative to sense a temperature indicative of an undesirably high operating temperature within said combustion chamber and responsively shut off essentially all further combustion air inflow to said combustion chamber by blocking air flow through the interior of said skirt structure, said combustion air shutoff system including:
• linkage structure including a fusible link member disposed adjacent an exterior side portion of said bottom side wall structure, said fusible link member being meltable at said temperature indicative of an undesirably high operating temperature within said combustion chamber, and
• a damper member held by said linkage structure in an open position permitting operative combustion air flow through the interior of said skirt structure and into said combustion chamber via said air inlet openings in said bottom side wall structure, said damper member being urged toward a closed position in which said damper member blocks operative combustion air flow through the interior of said skirt structure, melting of said fusible link member being operative to permit movement of said damper member from said open position to said closed position,
• said damper member being a flexible band member horizontally extending exteriorly around said skirt structure and having a first end anchored to said skirt structure, and a second end circumferentially movable away from said first end to orient said band member in said open position in which said band member is spaced outwardly apart from and uncovers said inlet openings in said skirt structure, and circumferentially movable toward said first end to orient said band member in said closed position in which said band member overlies and blocks said inlet openings in said skirt structure.