owners manual says soot can get into ducts!!!

Ricky248

I was reading my furnace owners manual and I came across this.  It says

for my upflow furnace, a Carrier, 34 y.o. oil burner (no boiler), model

58HV085:



"Upflow models are equipped with steel dustpan to hep prevent

distribution of soot and dirt particles through the duct system. "



I though if soot was coming through the ducts, it meant there was a hole

in the firewall.   If the fire is on the other side of the firewall, how

can soot be in the ducts?   And what kind of dirt particles are they

talking about?   They don't limit this to old furnaces with damaged firewalls.



Less important:  What would the "dustpan" look like or where would it

be?  I thought I knew all the parts by now.



It also says a few lines earlier, "No-drip nozzle adapter provides

positive fuel cutout to prevent fuel odor and soot problems in the

house."   No mention of ducts here, but still,  Are they only

referring to combustion gases escaping through the observation port or

the barometric damper?  Or do they have the ducts in mind?  If so, again,

how does soot get in the ducts?