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forced air/reduction -- fan damper

updated sat 27 jul 02


Dave Finkelnburg on thu 25 jul 02

You are absolutely right, when you start to close the air shutter at the
inlet of the blower, the blower motor is not working as hard. Think of a
fan as an air mover. The less air it moves, the less work the motor has to
I set the rheostats on my forced-air burner blowers at high speed early
in the firing, with the fan inlet dampers completely closed. Each time I
turn up the fuel I open the dampers a little more, as needed, to keep the
air and fuel in balance for the atmosphere I want. The oxyprobe is a great
help to see the result of the adjustments. I adjust the kiln stack damper
to maintain back-pressure in the kiln.
Good firing,
Dave Finkelnburg, enjoying a cool after-rain-shower evening in Idaho

----- Original Message -----
From: "vince pitelka"
> Our forced-air downdraft at the Craft Center has those hokey, unreliable,
> imprecise blower rheostats, as did the Alpines when I was at
> I always set them on medium, and I do not touch them for the entire
> All adjustments are done with the swinging air shutter over the blower
> intake.
> Some people hesitate to use an air shutter because they assume that the
> blower motor is working harder when you partially cover the air intake,
> that does not seem to be the case at all. If anything, it actually seems
> be easier on the blower motor when the intake is partially covered. Just
> listen to the motor. When you partially cover the intake, it speeds up
> rather than slows down. If it was placing a greater load on the motor,
> motor would slow down.