12
443 06 4002 00
Specifications subject to change without notice.
making this conversion are required. Specify that unit is
now converted for use with natural gas.
2. Place ALL unused parts, adjusting key, and these
Installation Instructions in adhesive pouch attached to
outside of main furnace door or accessible side of
furnace.
3. Reinstall main furnace door.
CHECKOUT
1. Observe unit operation through two complete heating
cycles.
2. See Sequence of Operation in furnace Installation,
Start
−
Up, and Operating Instructions.
3. Set room thermostat to desired temperature.
SECTION III: CONVERSION FROM
PROPANE TO NATURAL GAS
INSTALLATION
1. Set room thermostat to lowest setting or “OFF”.
2. Disconnect power at external disconnect, fuse or circuit
breaker.
3. Turn off gas at external shut
−
off or gas meter.
4. Remove outer doors and set aside.
5. Turn electric switch on gas valve to OFF.
MANIFOLD/ORIFICE/BURNER REMOVAL
!
CAUTION
UNIT OPERATION HAZARD
Failure to follow this caution may result in unit damage or
improper operation.
Label all wires prior to disconnection when servicing controls.
!
PRUDENCE
D’EQUIPEMENT D’OPERATION
Toute erreur de câblage peut être une source de danger et
de panne.
Lors des opérations d’entretien des commandes, étiqueter
tous les fils avant de les déconnecter.
NOTE
: Use a back
−
up wrench on the gas valve to prevent the
valve from rotating on the manifold or damaging the mounting
to the burner box.
1. Disconnect the gas pipe from gas valve and remove pipe
from the furnace casing.
2. Disconnect the connector harness from gas valve.
3. Disconnect wires from Hot Surface Igniter (HSI) and
Flame Sensor. (See
Figure 9
)
4. Remove the orange wires connected to the Low Gas
Pressure Switch.
5. Support the manifold and remove the four (4) screws that
secure the manifold assembly to the burner box and set
aside. (See
Figure 3
)
6. Note the location of the green/yellow wire ground wire for
re
−
assembly later.
7. Slide one
−
piece burner assembly out of slots on sides of
burner box.
8. Remove the flame sensor from the burner assembly.
9. Remove the orifices from the manifold and discard.
ORIFICE SELECTION/DERATE
GAS INPUT RATE INFORMATION
The gas input rate for natural is the same as for propane gas.
See furnace rating plate for input rate. (See
Figure 12
) The
input rate for propane is determined by manifold pressure and
orifice size.
Furnace gas input rate on rating plate is for installations at
altitudes up to 2000 ft. (610 M).
In the U.S.A., the input rating for altitudes above 2000 ft.
(610M) must be reduced by 2 percent for each 1000 ft. (305 M)
above sea level.
In Canada, the input rating must be derated by 5 percent for
altitudes of 2000 ft. (610 M) to 4500 ft. (1372 M) above sea
level.
Furnace input rate must be /
−
2 percent of input on
furnace rating plate adjusted for altitude.
1. Determine natural gas orifice size and manifold pressure
for correct input.
a. Obtain average yearly heat value (at installed
altitude) from local gas supplier.
b. Obtain average yearly specific gravity from local gas
supplier.
c. Find installation altitude in
Table 3
.
NOTE
: For Canada altitudes of 2000 to 4500 ft., (610 to 1372
M) use USA. altitudes of 2001 to 3000 ft. (610 to 914 M) in
Table 3
.
d. Find closest natural gas heat value and specific
gravity on
Table 3
.
e. Follow heat value and specific gravity lines to point of
intersection to find orifice size and manifold pressure
settings for proper operation.
2. Check and verify burner orifice size in furnace. NEVER
ASSUME ORIFICE SIZE; ALWAYS CHECK AND
VERIFY.
NOTE
: If orifice hole appears damaged or it is suspected to
have been redrilled, check orifice hole with a numbered drill bit
of correct size. Never redrill an orifice. A burr
−
free and squarely
aligned orifice hole is essential for proper flame characteristics.
EXAMPLE
: 0
−
2000 ft. (0
−
609.6M) altitude
Heating value = 1050 Btu/cu ft.
Specific gravity = 0.62
Therefore: Orifice No. 44
Manifold pressure: 3.4
−
in. w.c.
* Furnace is shipped with No. 44 orifices. In this example,
all main burner orifices are the correct size and do not need
to be changed to obtain proper input rate.
INSTALL ORIFICES
1. Locate natural gas orifices in loose parts bag attached to
furnace casing. Verify orifices selected are correct
orifices for natural gas.
2. Install main burner orifices. Do not use Teflon tape.
Finger
−
tighten orifices at least one full turn to prevent
cross
−
threading, then tighten with wrench. (See
Figure 3
)
3. There are enough orifices in each kit for largest furnace.
Discard extra orifices.
NOTE
: DO NOT reinstall the manifold at this time.
REMOVE MIXER SCREWS
1. Locate the mixer screw on each burner venturi tube.
2. Remove each screw and discard.
3. It is not necessary to plug or seal the screw hole in the
burner venturi.
REINSTALL BURNER ASSEMBLY
To reinstall burner assembly:
1. Attach flame sensor to burner assembly.
