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IMPORTANT
For safety, shut unit off and remove manometer as
soon as an accurate reading has been obtained.
Take care to replace pressure tap plug.
F- Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking com
bustion. Take combustion sample beyond the flue outlet.
Table 29 shows acceptable combustions.
TABLE 29
SL297
Model
CO
2
%
For Nat
CO
2
%
For LP
Low Fire
High Fire
Low Fire
High Fire
040
6.3 - 7.8
6.3 - 7.8
N/A
N/A
060
6.5 - 8.2
6.5 - 8.2
9.3 - 10.0 9.3 - 10.0
080
7.2 - 8.4
7.2 - 8.4
9.5 - 10.2 9.5 - 10.2
The maximum carbon monoxide reading should not exceed 100ppm.
G- High Altitude
Units are
NOT
approved for installations over 4500 ft
H- Proper Ground and Voltage
A poorly grounded furnace can contribute to premature ig
nitor failure. Use the following procedure to check for
ground and voltage to the integrated control.
1 - Measure the AC voltage between Line Neutral (spade
terminals) and “C” terminal (low voltage terminal
block) on the integrated control. See figure 50. A wide
variation in the voltage between Line Neutral and “C”
as a function of load indicates a poor or partial ground.
Compare the readings to the table below. If the read
ings exceed the maximum shown in table 1, make re
pairs before operating the furnace.
2 - In addition, measure the AC voltage from Line Hot to
Line Neutral (spade terminals) on the integrated con
trol. See figure 50. This voltage should be in the range
of 97 to 132 Vac
TABLE 30
Furnace Status
Measurement VAC
Expected
Maximum
Power On Furnace Idle
0.3
2
CAI / Ignitor Energized
0.75
5
Indoor Blower Energized
Less than 2
10
CHECK VOLTAGE BETWEEN LINE
NEUTRAL AND LOW VOLTAGE “C”
TERMINAL
CHECK VOLTAGE BETWEEN
LINE HOT AND LINE NEUTRAL
FIGURE 50
W
1
W
2
G Y
2
Y
1
C C R D
H
L O D
S
W
1
W
2
G Y
2
Y
1
C C R D
H
L O D
S
