Instruction manual
4. Remove 2 screws from blower access door and remove blower
access door.
5. Disconnect blower leads from furnace control. Record wire
color and location for reassembly. All other factory wires can
be left connected, but field thermostat connections may need
to be disconnected depending on their length and routing.
6. Remove 2 screws holding control box to blower shelf.
7. Hang control box from front of furnace casing and away from
blower compartment.
8. Remove 2 screws holding blower assembly to blower deck
and slide blower assembly out of furnace.
9. Clean blower wheel and motor using a vacuum with soft brush
attachment. Blower wheel blades may be cleaned with a small
paint or flux brush. Do not remove or disturb balance weights
(clips) on blower wheel blades.
10. Vacuum any loose dust from blower housing, wheel and
motor.
Table 12—Orifice Size* And Manifold Pressure For Gas Input Rate (Continued)
(Tabulated Data Based On 22,000 Btuh Per Burner, Derated 4 Percent For Each 1000 Ft Above Sea Level)
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
AT ALTITUDE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.58 0.60 0.62 0.64
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
U.S.A. Only
5001
to
6000
725 43 3.4 43 3.5 43 3.6 43 3.7
750 43 3.2 43 3.3 43 3.4 43 3.5
775 43 3.0 43 3.1 43 3.2 43 3.3
800 43 2.8 43 2.9 43 3.0 43 3.1
825 43 2.6 43 2.7 43 2.8 43 2.9
850 43 2.5 43 2.5 43 2.6 43 2.7
875 43 2.3 43 2.4 43 2.5 43 2.6
900 43 2.2 43 2.3 43 2.3 43 2.4
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
AT ALTITUDE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.58 0.60 0.62 0.64
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
U.S.A. Only
6001
to
7000
675 43 3.4 43 3.5 43 3.6 43 3.7
700 43 3.1 43 3.3 43 3.4 43 3.5
725 43 2.9 43 3.0 43 3.1 43 3.2
750 43 2.7 43 2.8 43 2.9 43 3.0
775 43 2.6 43 2.7 43 2.7 43 2.8
800 43 2.4 43 2.5 43 2.6 43 2.7
825 43 2.3 43 2.3 43 2.4 43 2.5
850 43 2.1 43 2.2 43 2.3 43 2.4
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
AT ALTITUDE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.58 0.60 0.62 0.64
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
U.S.A. Only
7001
to
8000
650 43 3.1 43 3.2 43 3.4 43 3.5
675 43 2.9 43 3.0 43 3.1 43 3.2
700 43 2.7 43 2.8 43 2.9 43 3.0
725 43 2.5 43 2.6 43 2.7 43 2.8
750 43 2.4 43 2.4 43 2.5 43 2.6
775 43 2.2 43 2.3 43 2.4 43 2.4
800 43 2.1 43 2.1 43 2.2 43 2.3
825 48 3.7 43 2.0 43 2.1 43 2.2
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
AT ALTITUDE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.58 0.60 0.62 0.64
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
U.S.A. Only
8001
to
9000
625 43 2.9 43 3.0 43 3.1 43 3.2
650 43 2.7 43 2.8 43 2.9 43 3.0
675 43 2.5 43 2.6 43 2.7 43 2.8
700 43 2.3 43 2.4 43 2.5 43 2.6
725 43 2.2 43 2.2 43 2.3 43 2.4
750 43 2.0 43 2.1 43 2.2 43 2.2
775 48 3.6 48 3.7 43 2.0 43 2.1
* Orifice numbers 43 are factory installed
39