RT-SVX073A-EN
161
2-stage and Modulating Burner Setup
Important: It is necessary to measure gas pressure at the
following points listed below. Install the
necessary fittings prior to starting the burner in
the Manual Override.
• Inlet Pressure (see Figure 109, p. 163)
• Main Gas Regulator outlet pressure (see
Figure 109, p. 163)
• Load Line Pressure (see Figure 108, p.
162)
• Manifold Pressure (see Figure 110, p.
163)
Important: Flue readings should be taken from center of
the flue and at least 4 inches down from the
outlet. See Figure 112, p. 164.
1. Program the following system components for
operation by scrolling through the user interface
displays:
a. Open the manual gas valve, located in the gas heat
section.
b. Set toggle switch located on heater control box to
ON.
c. Press Stop button on user interface.
d. Navigate to the Gas Heat Manual override screen.
See Figure 106, p. 162 for 2–stage and Figure
107, p. 162 for modulating. Set the modulating
percentage to 1% and/or enable the 1
st
stage.
Touch the Auto button in the top right corner of the
screen.
e. Turn the Supply Fan ON by the navigating to the
Manual Override Screen. Set the Fan speed to
100%.
Low Fire Adjustment
2. After the initial purge sequence and once the burner
has started, run the burner at low fire for 10 minutes to
allow the burner to stabilize.
3. Use a flue analyzer to measure the oxygen (O
2
),
carbon dioxide (CO
2
), and carbon monoxide (CO)
levels in the flue gas. Take several readings to ensure
burner operation is stable.
If the measured O
2
level is between 17.0%-19.0% and
the CO
2
level is no more than 400ppm (corrected to 3%
O
2
), no adjustment is necessary. If an adjustment is
needed, turn the adjustment screw on the ratio
regulator. CCW to increase O2, CW to decrease O2.
See Figure 108, p. 162.
Note: Ratio regulator turns affects amount of gas flow.
The number of turns on the ratio regulator is
preset at the factory. Only small adjustments
should be made for fine tuning combustion.
High Fire Adjustment
4. Adjust the user interface to operate the furnace at max
firing rate (100%) or 2
nd
Stage. Allow the system to
operate for 10 minutes to stabilize the burner.
Note: The burner capacity is controlled by the
combustion fan speed. This has been preset at
the factory and normally does not need field
adjustment.
5. Check the inlet pressure at the tap upstream of the pilot
regulator. Refer to the illustration in Figure 109, p. 163.
The inlet pressure should between 7.0" to 14.0" w.c.
6. Check the outlet pressure of the main gas regulator at
tap on the upstream solenoid valve. Refer to the
illustration in Figure 109, p. 163. The outlet pressure
from the main gas regulator should be 6.0" w.c.
7. Check manifold pressure at tap closest to where the
valve train attaches to the burner. Refer to the
illustration in Figure 110, p. 163. Verify the manifold
pressure is within range shown in Chart B (Table 63, p.
162). If manifold pressure is not within the specified
range, contact Large Commercial Technical Support for
information on how to adjust maximum fan speed (FHi).
8. Use a flue analyzer to measure the oxygen (O
2
),
carbon dioxide (CO
2
), and carbon monoxide (CO)
levels in the flue gas. If the measured oxygen level is
between 3.0 to 5.0% and the carbon dioxide level is
between 8.5 to 10% and the CO is less than 100 PPM,
no adjustment is necessary. If an adjustment is needed,
check the inlet gas pressure or the air damper on the
burner (closing will increase the CO
2
level). See Figure
111, p. 163.
For 2–stage, proceed to Step 12. For modulating,
continue to Step 9.
Mid Fire Adjustment (for modulating burners only)
9. Adjust the user interface to operate the furnace at mid
firing rate (approx. 38%).
10. Check the load line pressure on the ratio regulator.
Using the Modulating Gas Heat Actuator screen adjust
the % value until load line pressure is at 2" w.c.
11. Check manifold pressure at tap closest to where valve
train attaches to the burner. Refer to the illustration in
Figure 110, p. 163. Verify the manifold pressure is 0.8 -
0.9" w.c. If adjustment is necessary, turn the adjustment
screw on the ratio regulator. Refer to illustration in for
the adjustment screw location.
12. Program the burner for low fire operation (1%) or 1st
stage and recheck O
2
(or CO
2
) and CO values.
13. Press the STOP key on the user interface screen and
remove manual overrides to stop the system operation.
Unit Startup
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