Two Stage Gas Furnace - Trane INTELLIPAK Installation Operation & Maintenance

The volume of air supplied by the combustion blower de-
termines the amount of oxygen available for combustion,
while the manifold gas pressure establishes fuel input. By
measuring the percentage of carbon dioxide produced as
a by-product of combustion, the operator can estimate the
amount of oxygen used and modify the air volume or the
gas pressure to obtain the proper air/fuel ratio.
Arriving at the correct air/fuel mixture for a furnace results in
rated burner output, limited production of carbon monoxide,
and a steady flame that minimizes nuisance shutdowns.
WARNING
Hazardous Gases and Flammable Vapors!
Exposure to hazardous gases from fuel substances
have been shown to cause cancer, birth defects or
other reproductive harm. Improper installation, adjust-
ment, alteration, service or use of this product could
cause flammable mixtures. To avoid hazardous gases
and flammable vapors follow proper installation and set
up of this product and all warnings as provided in this
manual. Failure to follow all instructions could result in
death or serious injury.
When using dry nitrogen cylinders for pressurizing
units for leak testing, always provide a pressure regula-
tor on the cylinder to prevent excessively high unit
pressures. Never pressurize unit above the maximum
recommended unit test pressure as specified in appli-
cable unit literature. Failure to properly regulate pres-
sure could result in a violent explosion, which could re-
sult in death or serious injury or equipment or prop-
erty-only-damage.

Two Stage Gas Furnace

High-Fire Adjustment
1. Use Table 4-1 to program the following system compo-
nents for operation by scrolling through the Human In-
terface displays;
Gas Heat
Supply Fan (On)
Inlet Guide Vanes (100% Open, if applicable)
Variable Frequency Drive (100% Output, if
applicable)
RTM Occ/Unocc Output (Unoccupied)
Heat Stages 1 & 2 (On)
Turn the 115 volt control circuit switch 4S24
located in the heater control panel to the "On"
position.
Open the manual gas valve, located in the gas
heat section.
2. Once the configuration for the appropriate heating sys-
tem is complete, press the NEXT key until the LCD dis-
plays the "Start test in __Sec." screen. Press the + key
to designate the delay before the test is to start. This
service test will begin after the TEST START key is
pressed and the delay designated in this step has
elapsed. Press the ENTER key to confirm this choice.
3. Press the TEST START key to start the test. Remember
that the delay designated in step 2 must elapse before
the system will begin to operate.
4. Once the system has started, check the appearance of
the flame through the sight glass provided on the front
Unit Start-Up (Continued)
of the heat exchanger. In appearance, a normal flame
has a clearly defined shape, and is primarily (75%)
blue in color with an orange tip.
5. Check the manifold gas pressure by using the manifold
pressure port on the gas valve. Refer to Table 4-7 for
the required manifold pressure for high-fire operation. If
it needs adjusting, remove the cap covering the high-
fire adjustment screw on the gas valve. Refer to Figure
4-8 for the adjustment screw location. Turn the screw
clockwise to increase the gas pressure or counterclock-
wise to decrease the gas pressure.
6. Use a carbon dioxide analyzer and measure the per-
centage of carbon dioxide in the flue gas. Refer to the il-
lustration in Figure 4-7. Take several samples to assure
that an accurate reading is obtained. Refer to Table 4-7
for the proper carbon dioxide levels. A carbon dioxide
level exceeding the listed range indicates incomplete
combustion due to inadequate air or excessive gas.
Combustion Air Adjustment (O
7. Use an oxygen analyzer and measure the percentage
of oxygen in the flue gas. Take several samples to as-
sure an accurate reading. Compare the measured oxy-
gen level to the combustion curve in Table 4-8. The oxy-
gen content of the flue gas should be 4% to 5%. If the
oxygen level is outside this range, adjust the combus-
tion air damper to increase or decrease the amount of
air entering the combustion chamber. Refer to Figure 4-
10 for the location of the combustion air damper .
8. Recheck the oxygen and carbon dioxide levels after
each adjustment. After completing the high-fire check-
out and adjustment procedure, the low-fire setting may
require adjusting.
Low-Fire Adjustment
(500 MBH, 850 & 1,000 MBH only)
1. Use the TEST initiation procedures outlined in the pre-
vious section to operate the furnace in the low-fire state
(1st Stage).
2. Use a carbon dioxide analyzer and measure the per-
centage of carbon dioxide in the flue gas. Refer to the il-
lustration in Figure 4-7, Inset A. Take several samples to
assure that an accurate reading is obtained. Refer to
Table 4-8 for the proper carbon dioxide levels. If the
measured carbon dioxide level is within the listed val-
ues, no adjustment is necessary. A carbon dioxide level
exceeding the listed range indicates incomplete com-
bustion 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 Table 4-8 for
the required manifold pressure during low-fire opera-
tion. If it needs adjusting, remove the cap covering the
low-fire adjustment screw on the gas valve. Refer to
Figure 4-8 for the adjustment screw location. Turn the
screw clockwise to increase the gas pressure or coun-
terclockwise 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.
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