Replacing Main Chamber Elements - Gilson HM-378 Operating Manual

Gilson Company, Inc.
Program the controller for the element to heat at the
full rate. When the elements glow dull red, turn the
controller's main power switch to the OFF position,
disconnect and lockout the power supply.
b. With a pair of long-nosed pliers, shrink the bulging
portion of the element by pressing the individual
turns in the coils together slightly. Take a little
from each turn so that no two turns are pressed
tightly enough to touch.
c. As the element shrinks, work it back toward the
groove and into place. Work rapidly, and at the
first sign of stiffness in the coils, STOP bending
and reheat the furnace. The elements do not have
to be red to be bent safely, as the stiffening can
be felt through the pliers.
d. To lengthen the element to fit into the corners,
reverse the above procedure and expand the
distance between coils by using snap-ring pliers.
Use caution, as the warranty covers only elements
that fail in service under normal use and not from
being broken while cold.
e. When you have the coils positioned above the
dropped recess in the grooves, reheat the furnace,
disconnect and lockout the power supply, and
run a blunt object around the elements to seat
them into grooves and to make sure they fit all
the way back into each corner.

10.2.2 Replacing Main Chamber Elements

The replacement elements for the furnace are made
to fit. However, a little stretching or compressing may
be necessary for a perfect fit.
NOTE: It is safe to bend and stretch new elements
before they have been fired, but once fired and
allowed to cool, elements become brittle and will
break if bent.
WARNING!
Disconnect and lockout electrical supply before
proceeding.
a. Allow the furnace to cool to room temperature.
b. Remove the screws on each side of switch box
and place the box to the side being careful not
to stress the wiring.
c. Remove the screws in the element connectors
that hold the element lead wires to the element
you are replacing.
d. On the same connectors, loosen the screws that
hold the element and throw old connectors away.
NOTE: ALWAYS use the new connectors furnished
with the new element.
e. Remove and save the porcelain insulators that
were under the element connectors.
f. Using long-nose pliers, remove the staples that
hold the elements in place. Save the staples and
mark the locations of the holes for later installa-
tion.
g. Remove the old element carefully to prevent
breaking the lip of the element grooves. If the old
element burned out due to contact with foreign
materials, there will probably be a melted, glazed
spot in the element groove. Glazed spots left in
the grooves may ruin the new elements, so dig
out any of these spots. A small mirror is helpful
in locating these spots in the grooves. The small
hole left in the groove will not affect the new ele-
ment. Pieces of firebrick in the grooves should be
removed with a dry paint type brush or vacuum
cleaner.
h. Protect the new element from accidentally com-
ing in contact with foreign materials by placing
newspaper on the furnace floor.
i. Reach inside the furnace and push one end of
the new element into one of the element holes.
The element end will appear at the other side of
the hole outside the case. Begin threading the
element into the groove.
j. The element must fit all the way into the back of
each corner. Making a bend in the element at the
corner will help hold the element in place during
firing. Start by pushing the element into the first
corner with a screwdriver. Make sure the element
is pushed as far into the corner as it will go. Hold
the element against the back of the corner with
the screwdriver. Then gently pull the free end of
the element towards you. The element will bend
where the screwdriver presses against it.
NOTE: If you do not push the element fully to the
back of each corner, the element will NOT stay in
the grooves when fired!
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Gilson Binder Ignition System: HM-378