[justplumducky]

Spider nest in gas valve can cause sooting on single burner mobile home furnace

Never mind, already realized that it can...

 

[yuri]

Usually it is in the burner orifice.

FYI a partly plugged intake can also starve the burner(s) for air and cause soot.

Old school burners used to have adjustable Primary air shutters on the intake and if the burner tube got dirty from years of sucking in dirty air then it can burn dirty.

If those shutters were set too much closed you get a dirty flame. Conversion burners also have them and you may see them on upshot burners for mobile homes.

Newer burners have diffuser rings at the end of them to mix the gas and air and even they can eventually get dirty.

 

[justplumducky]

Usually it is in the burner orifice.

FYI a partly plugged intake can also starve the burner(s) for air and cause soot.

Old school burners used to have adjustable Primary air shutters on the intake and if the burner tube got dirty from years of sucking in dirty air then it can burn dirty.

If those shutters were set too much closed you get a dirty flame. Conversion burners also have them and you may see them on upshot burners for mobile homes.

Newer burners have diffuser rings at the end of them to mix the gas and air and even they can eventually get dirty.

The only orifices I've seen on these old mobile home single burner units are located on the regulated side of the gas valve, so that the orifice inserts into the hole in the spud plate, see pic. However, I know that you know where the orifice goes:biggrin2:

Is the single mobile home burner pic below what you are calling an old school burner, or did old school residential burners used to have primary air shutters also?

Regarding the end of the burner tube (pic) where does the flame begin?

Gonna start another thread about fan blade height in a shroud (cowling). In this case an old (antique) AC only package unit.

 

[justplumducky]

I know the flame begins near the pilot light in this case, but wondered if its point of ignition might reach back into the end of burner tube a little, but since my understanding it that those diffuser rings are supposed to help mix air/fuel, I suppose the flame ignition point would be immediately after the end of the b-tube.