44 JANUARY 2016 | FUEL OIL NEWS | www.fueloilnews.com
HVAC/ HYDRONICS
T
his is a second update on the fifth article I ever wrote
back in January of 1992 and updated again in 2000.
We missed a 10-year update in 2010, so here goes.
One of the things that all of us have heard is that they
don't build ignition transformers like they used too. In the past
it was not unusual to see a 30- or 40-year-old oilburner with
the original ignition transformer, and now it seems they just
don't last. Is it the fault of the manufacturers or have there been
changes in our servicing policy over the years?
Let's take a look at that old gun type burner. First of all, the
design is not that of a flame retention head. The fire may have
little or no distinctive shape or patterns. Flame control was poor
or totally nonexistent. Not a lot of efficiency here, Figure 1, and
yet these burners were mostly run on intermittent ignition or
what we now call interrupted. First generation oilburners were
pretty crude by today's standards. One of the biggest problems
with these burners was keeping the flame stable, and in many
cases a good cure-all was to put the burner on intermittent (for-
merly constant) ignition.
The next design to come along was the Shellhead® and its
clones. Those of you who have serviced these burners know
that this burner had a flame shape (sunflower) that was quite
defined and controlled and that the preferred ignition operation
was interrupted. Every OEM I ever saw demanded intermittent
back then (today's interrupted) because if the flame and draft
were not stable you needed to adjust them.
The motor on most of our older burners was low speed (1725
rpm). The air coming down the air tube is really not moving with
a lot of velocity as it does with today's high velocity burners. Not
much chance of blowing the spark out, right? Oh, sure, but first
you have to get it to light. And oh yes, finally look at this if you
will, the burner is operated by a stack-mounted protector relay,
what most of us call a stack switch, Figure 2. Now before you
think that I'm crazy in bringing all this up remember that this
is not high tech, this is low tech, but it works. Many of the old
Ignition Systems, One More Time
BY GEORGE LANTHIER
Figure 1
Figure 2
