Technical Instructions LMV Series
Document No. LV3-1000
Section 4 Page 20 SCC Inc.
2. A free excel spreadsheet is available to assist in creating smooth fuel-to-air ratio curves and to
record commissioning data for reference. This spreadsheet, called the LMVx Curves
spreadsheet, can be found at www.scccombustion.com. The spreadsheet uses fuel flow to
accurately lay out the fuel-to-air ratio curves. If fuel flow is not available, burner head pressure
can be used as a last resort.
The next page shows how the LMVx Curves spreadsheet can be used to set up a steam boiler
with a fuel actuator, air actuator, and a VSD. This is an example to illustrate what a typical setup
might look like, and is not intended to be copied verbatim to an LMV3 in the field.
3. Press the + button to go to Point 1 (P1). Point 1 is automatically set to ignition position values.
NOTE: The text “P1” will be solid when the actuators / VSD are moving to the displayed
position. The text “P1” will begin flashing when the indicated positions are reached.
4. If the low fire point is not known (maximum burner turndown), adjust the Point 1 actuator / VSD
positions until maximum safe burner turndown is achieved. Once the desired low fire actuator /
VSD positions have been achieved, record the Point 1 actuator / VSD positions and burner
turndown in the LMVx Curves spreadsheet.
NOTE: While commissioning the Ratio Control Curves, it is the responsibility of the technician
to ensure that safe fuel-to-air ratios are being maintained. If an AZL23 + or - button is held
down when adjusting an actuator position, the position will be changed at a progressively
faster rate.
5. Press the + button eight times until P9 (high fire) is displayed. Now increase the effective firing
rate of the burner by increasing the actuator / VSD positions in a way that maintains a safe fuel-
to-air ratio. This is typically accomplished by increasing air, fuel, and VSD positions in a stepwise
rotation. Keep increasing the firing rate in this manner until high fire positions of the actuators /
VSD are reached.
NOTE: Typically, the gas pressure regulator immediately upstream of the firing rate control
valve will need to be adjusted on a new installation. Adjust the regulator such that the firing
rate control valve is between 60-80° open at high fire.
6. Once high fire actuator / VSD positions and gas pressure regulator(s) are set, record the Point 9
actuator / VSD positions, burner head pressure at high fire, and burner output at high fire in the
LMVx Curves spreadsheet.
Now that P1 (low fire) and P9 (high fire) have been set, and all of the appropriate information
has been entered into the LMVx Curves spreadsheet, the fuel flow (or burner head pressure) at
the remaining points on the fuel-to-air ratio curves are displayed in the spreadsheet.
NOTE: Exactly nine curve points (P1-P9), plus ignition position P0, are required to be entered.
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