Mike Gordon on tue 21 dec 04
my guess is:
you have too much primary air moving into the
tube, and, the gas pressure is too low.
so the flame jumps back to the orifice and burns there.
I fire an old Alpine 20 cu. updraft with the original burner system and
I sometimes get a back burning in the reduction burners, 4 separate
burners from the 4 primary burners. It sounds like a hollow sound, not
the quiet normal sound they usually make. I just turn the valve up more
than I would want them to be and the extra pressure forces the flame
out of the burner tube and it becomes quiet and normal again. Then I
turn the pressure back to low or where ever I wanted it to be
originally. After this, it fires without a problem. I have always
thought that it was caused by 1) pressure inside the kiln forced the
flame to ignite down by the orifice or 2) as Mel said not enough gas
pressure to begin with. It also only happens on one or two burners so I
will check to see if they are clogged in any way, spiders, you know.