A.O. Smith 12 40GPC T 100 - Manual (Page 48)

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Removing Old Burner Orifice :
11. Burner may be hot, wait until burner has cooled
off. After noting the position of the condensation
drain hole on the top of the burner. Turn the inner
door/manifold/burner assembly upside. Using a
phillips head screwdriver remove the 2 screws
attaching the burner to the manifold pipe (saving
screws for reinstallation later) (Figure 108).
12. Using a ratchet with 1/2” socket, remove the
burner’s old orifice (Note: the burner orifices have
different threads dependent upon the gas type.
Right handed treads for natural gas (Figure 109).
Installing New Burner Orifice :
13. Using a ratchet with 1/2” socket, install the
new burner orifice (Note: the burner orifices
have different threads dependent upon the gas
type. Right handed treads for natural gas (turn
clockwise to install) and Left handed threads for
propane gas (turn counterclockwise to install)
(Figure 109).
14. Care MUST be taken to ensure the burner is
installed correctly on the inner door/manifold
assembly. Position the new burner upside down
with the orientation of the burner’s condensation
drain as shown in illustration (Figure 108).
15. Align the screw holes on the inner door/manifold
assembly. Using the two screws removed in step
11, installed the new burner to the inner door/
manifold assembly (rotate the assembly to visually
check the top portion of the burner assembly and
confirm the orientation of the condensation drain
hole on the top of the burner is toward the back as
shown in the illustration) (Figure 108).
Installation Caution Must Be Taken:
16. Prior to installing the new inner door/manifold/
burner assembly, look inside the burner chamber
to fully understand the correct positioning of the
burner assembly and burner manifold tab (Figure
107). It may be necessary to use a flashlight
to ensure correct placement. Care must be
taken so as to not damage any electrical wiring,
components or the air pressure tubing as you
are installing the new inner door/manifold/burner
assembly.
Extra caution should be taken to ensure
that electrical wiring, air hose, fiberglass
insulation nor any other object is between
door gasket and combustion chamber shield.
ORIFICE
SCREWS
BURNER
Figure 109.
Figure 106.
1/4” HEX
HEAD SCREW
Figure 107.
INNER DOOR/
MANIFOLD/BURNER
ASSEMBLY
SLOT
BURNER’S
TIP END
TAB
INST
ALL
REMOVE
Figure 108.
BURNER’S
CONDENSATION DRAIN
TWO SCREWS
TOP VIEW
BOTTOM VIEW
ORIENTATION OF SCOOP
TO BE ON THE SAME SIDE
AS THE VIEW PORT
VIEW PORT
BURNER’S
CONDENSATION DRAIN