Adjustments
4-14
IC-SA-1511 (02/2014)
V/LNV Series Manual
4.5.5 — High Gas Pressure Switch
Turn the adjusting screw until the indicator moves to a pressure setting slightly above the maximum
operating gas pressure. The control will break a circuit if pressure exceeds this value. The control should be
adjusted to prevent operation with excessive gas pressure, but not at a pressure so close to normal
operating pressure that unnecessary shutdowns occur. This switch must be manually reset after tripping.
To reset, allow gas pressure to drop and press the manual reset button.
4.5.6 — Gas Combustion Adjustment
After operating for a sufficient period of time to assure a warm boiler, make adjustments for most efficient
combustion.The butterfly gas valve directly controls the rate of flow. The low-fire light-off setting should be
regarded as preliminary until proper gas pressure for high-fire operation is established.
Determine the actual gas flow from a meter reading at high-fire. With the butterfly valve open and with
regulated gas pressure set, the actual flow rate should be quite close to the required input. If corrections
are necessary, increase or decrease the gas pressure by adjusting the gas pressure regulator, following
manufacturer's directions for regulator adjustment.
When proper gas flow is obtained, take a flue gas analysis reading.
With the high-fire air-fuel ratio established, the gas pressure regulator needs no further adjusting.
Recheck low-fire and adjust if necessary.
Proper setting of the air-fuel ratios at all rates must be determined by combustion analysis. See Section 4.2
of this chapter for additional information.
4.5.7 — On-Off Gas Burner Adjustment
On-Off gas burners are typically equipped with a pressure regulator and a solenoid operated diaphragm
gas valve to control the on-off operation of the burner. Adjustments are made by matching the correct fuel-
air ratios.
1.
Open the manual gas shutoff cocks.
2.
Check the gas pressure at the inlet of the regulator and the pressure downstream of the regulator. Make
sure they are in accordance with the regulator specifications. The gas pressure required at the manifold
is the pressure that is required to fire the burner at its rated capacity. To adjust the regulator, unscrew the
cap located on top and turn the adjustment screw clockwise to increase pressure, or counterclockwise
to decrease pressure.
3.
Turn the burner switch to the “ON” position.
4.
Adjust the burner for a smooth ignition of the main flame. The bleed valve adjustment controls the
opening of the V48 valve. When the controller is not calling for heat, the coil is de-energized. The plunger
in the 3-way actuator is in the “DOWN” position so the bleed port is closed and the supply port is open.
Gas flows into the top part of the valve. The gas pressure on top of the diaphragm, the weight, and the
NOTE:
Check for CO through the entire firing range.
NOTE:
Maximum valve inlet pressure for the V4944 is 0.5 psi. If line pressure is greater, an over pressure device
is to be installed downstream of the main gas regulator. (CSD-1-CF160)