3
RATING PLATE NOT SHOWN
(LOCATED ON BLOWER DOOR)
GAS VALVE
MAIN LIMIT SWITCH
(BEHIND GAS VALVE)
REPRESENTATIVE DRAWING ONLY, SOME MODELS MAY VARY IN APPEARANCE.
ELECTRICAL JUNCTION
BOX (IF REQUIRED,
LOCATION MAY VARY)
MEDIA CABINET
OPERATING INSTRUCTIONS
NOT SHOWN (LOCATED ON
MAIN FURNACE DOOR, SEE
OPERATING INSTRUCTIONS
INSIDE DOOR FIGURE).
FURNACE
CONTROL
BOARD
MANUAL RESET
ROLLOUT SWITCH
FLAME
SENSOR
MANUAL RESET
ROLLOUT SWITCH
GAS BURNER
HOT SURFACE
IGNITER
INDUCER MOTOR
ASSEMBLY
BLOWER AND
MOTOR
CAPACITOR/
POWER CHOKE
BLOWER DOOR
SAFETY SWITCH
A11408
Fig. 1 -- Component Location
Orifice
Connect Green/Yellow
ground wire here
Manifold
Gas Valve
Gas valve must be installed on
manifold with minimum engagement of
6 threads. Cross threading is not
acceptable.
CL
Gas valve is parallel to manifold
or - 3˚
Indicated surfaces
to be 90 ˚+ or -2˚
A11486
Fig. 2 -- Modulating Gas Valve with Orifices
FLAME SENSOR
(BELOW BURNER)
FLAME ROLLOUT
SWITCH
BRACKET, IGNITER
IGNITER
BURNER SUPT. ASSY
BURNER ASSY
A11403
Fig. 3 -- Burner Assembly
ORIFICE SELECTION/DERATE
UNIT DAMAGE HAZARD
Failure to follow this caution may result in unit damage.
DO NOT re--drill burner orifices. Improper drilling may
result in burrs, out--of--round holes, etc. Obtain new orifices
if orifice size must be changed. (See Fig. 4.)
CAUTION
!
BURNER
ORIFICE
BURNER
ORIFICE
A96249
Fig. 4 -- Burner Orifice
Determine natural gas orifice size and manifold pressures for
correct input at installed altitude by using Table 3 (for 20,000
Btuh/Max--Heat/8000 Btuh Min--Heat per Burner) or Table 4
(For 20,200 Btuh Max Heat/8,000 Btuh Min--Heat per Burner).
1. Obtain yearly heat--value average (at installed altitude) for
local gas supply.
2. Obtain yearly specific--gravity average for local gas sup-
ply.
3. Find installation altitude in Table 3 or Table 4, depending
on furnace gas input rate.
NOTE
: For Canada altitudes of 2000 to 4500 ft. (610 to 1372
M), use U.S.A. Altitudes of 2001 to 3000 ft. (610 to 914 M) in
Table 3 or Table 4, depending on furnace gas input rate.
4. Find closest natural gas heat value and specific gravity in
Table 3 or Table 4, depending on furnace gas input rate.
5. Follow heat--value line and specific--gravity line to point
of intersection to find orifice size and maximum and min-
imum manifold pressure settings.