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on access, inspection, evaluation and replacement if
needed.
11. Work in reverse order to replace parts once the gas
-
ket cement has dried on the upper fireback assem-
bly. Be sure to install the spacer on the left end of
the damper rod before installing the upper fireback
assembly.
12. Install the upper fireback assembly, left end first;
pass the damper rod through he hole in the left side
of the stove, then lift the right end of the assembly
into place. Loosely install all four bolts before you
tighten any of them. These bolts should be snug but
not tight, to allow some expansion and movement
under heat.
13. Test the damper operation and the gasket’s snug
-
ness, as described at the start of this section.
Continue after you are sure the damper operates
properly.
14. Install the lower fireback. Note that there are two
notches in the bottom edge; these must align behind
two mating nubs on the firebox floor.
15. Stand the five firebricks on end in front of the lower
fireback. Note that these stand behind a raised rib
on the firebox floor. (Fig. 7) Join the firebricks by
slipping the steel clip onto their top ends. The clip’s
longer edge should go behind the firebricks, for
easier installation.
16. Replace the left and right wedges. Note that their
rear vertical edges bear against the outermost left
and right edges of the lower fireback. Gently tap the
wedges downward with a rubber mallet or a ham-
mer and a block of wood to cushion the impact. The
wedges should be snug but not overly tight.
17. Replace the baffle by placing its ends on the sup
-
port brackets which are part of the lower fireback.
The baffle shields the catalytic combustor from direct
flame impingement and must be in place during
operation.
Testing the Gasket Seals
After the cement has had several hours to dry, test the
new door seal by closing and latching the door on slips
of paper placed at approximately 6” intervals along the
top and bottom of the door opening. Be sure to include
the area where the right front door overlaps the left
door. It should not be possible to slide the papers, and
they should be pulled straight out only with consider-
able resistance. If the paper pulls out easily, readjust
the doors as needed till the doors hold the paper tightly.
Do not apply this test to the glass gasketing - it is not
accessible and does not get the repeated impacts that
other seals receive.
8. From inside the firebox, pull the right-hand end of the
upper fireback toward yourself. Carefully maneu
-
ver the left end of the fireback assembly to let the
damper rod clear its hole in the left side of the stove.
Be sure to capture the spacer on the left end of the
damper rod. Remove the assembly from the stove
and set it on a shielded working surface.
St557
inspect
catalytic ele
3
11/00
Lower Fire-
back
ST557
Fig. 8 Remove the lower fireback.
KT318
Upperfireback
gasket
8/02 djt
Gasket
KT318
Fig. 9 Back view of upper fireback (damper and rod re-
moved).
9. Pull the damper rod out of the upper fireback.
Release the bolts holding the steel tabs in place,
and remove the damper. Pull off the old gasket
and clean off the old cement. Thoroughly clean the
damper plate and around the damper opening in
the upper fireback. Cut a piece of the 5/16” gas-
ket material to length, allowing a one inch excess.
Place a continuous 1/8” bead of gasket cement in
the damper gasket channel. Press the new gasket
in place, trimming off the excess length. (Fig. 9)
Remove any excess cement. Replace the damper,
the steel tabs and bolts, and the damper rod. Close
and lock the damper to seat the gasket. Use waxed
paper between the damper and the upper fireback to
keep the cement from traveling through the gasket
and sticking to the fireback.
10. This is a fine opportunity to inspect the catalyst.
Follow the directions in the Defiant Owner’s Manual
MHSC
149 Cleveland Drive • Paris, Kentucky 40361
www.mhsc.com