Patent ID: 7607408

Claim:
Fuel-fired heating apparatus comprising: a combustion chamber; a first fuel burner structure disposed in said combustion chamber, said first fuel burner structure including a hollow body with an interior communicating with the interior of an air inlet plenum box projecting outwardly from said hollow body, said air inlet plenum box being disposed entirely within said combustion chamber and, during firing of said first fuel burner structure, receiving unpressurized combustion air from a source thereof; a second fuel burner structure disposed in said combustion chamber, said second fuel burner structure having a combustion air inlet tube sequentially extending outwardly therefrom, through the interior of said combustion chamber, and then into the interior of said air inlet plenum box, said combustion air inlet tube having an open inlet end disposed within the interior of said air inlet plenum box and covered with a perforate cloggable structure, said first and second fuel burner structures being cloggable by particulate matter in combustion air being delivered thereto during firing thereof, and a shutdown system operative to limit the maximum amount of clogging of said first fuel burner structure by sensing the attainment of a predetermined degree of clogging of said second fuel burner structure and responsively disabling further operation of said first fuel burner structure.