US PATENT SUBCLASS 454 / 43
.~ Having flue heater

Current as of: June, 1999
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454 /   HD   VENTILATION

1  DF  CHIMNEY OR STACK {6}
43.~ Having flue heater

DEFINITION

Classification: 454/43

Having flue heater:

(under subclass 1) Subject matter comprising means to heat the air or products of combustion to increase their flow rate through the vertical conduit section.