Trane IntelliPak Installation, Operation And Maintenance Manual page 151

decrease the amount of air entering the combustion
chamber. Refer to Figure 123, p. 154
the combustion air damper.
8. Recheck the oxygen and carbon dioxide levels after
each adjustment. After completing the high-fire
checkout and adjustment procedure, the low-fire
setting may require adjusting.
Low-Fire Adjustment (500 MBH, 850 & 1,000
MBH only)
1. Use theTEST initiation procedures outlined in the
previous section to operate the furnace in the low-fire
state (1st Stage).
2. Use a carbon dioxide analyzer and measure the
percentage of carbon dioxide in the flue gas. Refer to
the illustration in Figure 119, p.
samples to assure that an accurate reading is obtained.
Refer to Figure 120, p. 151
dioxide levels. If the measured carbon dioxide level is
within the listed values, no adjustment is necessary. A
carbon dioxide level exceeding the listed range
indicates incomplete combustion due to inadequate
air or excessive gas.
3. Check the manifold gas pressure by using the manifold
pressure port on the gas valve. Refer to
the required manifold pressure during low-fire
operation. If it needs adjusting, remove the cap
covering the low-fire adjustment screw on the gas
valve. Refer to Figure 120
location.Turn the screw clockwise to increase the gas
pressure or counterclockwise to decrease the gas
pressure.
Note: Do not adjust the combustion air damper while the
furnace is operating at low-fire.
4. Check the carbon dioxide levels after each adjustment.
5. Press the STOP key at the Human Interface Module in
the unit control panel to stop the system operation.
Figure 120. Natural gas combustion curve (ratio of oxygen to carbon dioxide in percent)
18
17
16
15
14
13
12
11
10 A
9
8
7
6
5
4
3
2
1
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
RT-SVX36K-EN
for the location of
151.Take several
for the proper carbon
Figure 120
for the adjustment screw
Curve Fuel
A = 1,000 BTU per cu. ft.
of Natural Gas.
Percent Oxygen
Table 61. Recommended manifold pressures and CO
levels during furnace operation (see notes)
Furnace Stage MBH Firing Rate
High-Fire
Low-Fire
High-Fire
Low-Fire
High-Fire
Low-Fire
High-Fire
Low-Fire
High-Fire 1000
Low-Fire
Note:
1. Manifold pressures are given in inches w.c.
2. High fire manifold pressure is adjustable on all heaters.
3. Low fire manifold pressure is non-adjustable on 235 MBH and 350
MBH heaters.
Figure 119.Flue gas carbon dioxide and oxygen
measurements
for
Unit Start Up
Manifold
%CO
2
235 100% 8.5 - 9.5
117 50% 6.0 - 7.0
350 100% 8.5- 9.5
175 50% 6.0 - 7.0
500 100% 8.5 - 9.5
250 50% 6.0 - 7.0
850 100% 8.5 - 9.5
500 50% 6.0 - 7.0
100% 8.5 - 9.5
500 50% 6.0 - 7.0
2
Pressure
3.0 - 3.5
0.9
3.0 - 3.5
0.9
3.0 - 3.5
1.25
3.0 - 3.5
1.25
3.0 - 3.5
1.25
151