Replacing Afterburner Elements - Gilson HM-378 Operating Manual

Gilson Company, Inc.
k. To hold elements in grooves, reinstall staples at
marked locations by pressing them in using a
pair of long nose pliers.
If the element is slightly too long when you reach
the second firebrick hole, insert element end into
the firebrick hole and let the curved groove take up
the extra length. You can compress the element
with long nose pliers if necessary. If the element
is several inches too long, it was not pushed all
the way to the back of each corner and should be
re-threaded. If the element is too short to reach
the second firebrick hole, unthread some of it.
Gently stretch it in your hands. Avoid stretching
only a short portion of the element. It is better to
distribute the stretch over a longer section.
Press the element down into the lower part
of the groove with a plastic comb or wooden
tongue depressor. Reinstall the porcelain insula-
tors. Push them flush against the furnace case.
They protect the element from contact with the
case, so they must not work their way out after
the element connector is tightened into place.
Sandpaper the eyelet of the element lead wires
if insulation on old ones is brittle. Use the brass
screw to connect lead wire eyelets to the new
element connectors.
Before tightening the screw, adjust eyelet to
where it will be tilted away from furnace case
when connector is attached to element. Then
hold the connector with pliers and tighten brass
screw securely with nut driver. Pull the end of the
element tight and install new element connectors
even against porcelain insulators to prevent in-
sulator from slopping away from brick wall. Use
stainless screw in the element connector to hold
the element. The brass screw holds the lead wire
eyelet.
Hold connector with pliers as you tighten the
screw. Tighten the screw until it squeaks, and
then tighten some more. Cut off twisted end of
element even with side of element connectors.
NOTE: Leaving the excess element sticking out past
element connector could ruin your new element!
The element can short against something in the
switch box.
As you move the switch box back into place,
check to see that no wire touches an element
connector. Wires and wire nuts must also not
touch the furnace case inside the switch box.
Wires and wire nuts will burn if they touch the
case or element connectors. Replace screws in
switch box and tighten into place.

10.2.3 Replacing Afterburner 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. Disconnect the power and conduit from the fan
by removing the access plate at the motor with
two screws. Remove the wire nuts and separate
the wires. Loosen the conduit clamp screws and
pull the conduit with wires from the fan.
g. Remove the 12 sheet metal screws holding the
fan and shroud to the top plate of the furnace.
Remove the fan assembly from the furnace.
h. Remove the ten screws holding the top metal
plate to the top of the furnace and remove the
top plate.
Page 13
Gilson Binder Ignition System: HM-378