NTI FTG 600 - Page 35

FTG │Installation & Operation Manual
35
Figure 9-2 Gas Valve Offset Check/Adjustment (FTG 2000-2400)
The Gas Valve Offset Pressure is factory set for Natural Gas; only applications
operating with Propane need to have the Gas Valve Offset Pressure field adjusted.
Improperly adjusted Gas Valve Offset Pressure will result in unpredictable burner
operating characteristics, which may lead to burner malfunction causing property
damage, serious injury or death.
Offset Adjustment Screw – used
to set offset and combustion at min.
modulation rate; see Figure 9-1(b)
Differential Pressure
Manometer – min. graduation
of 0.01 in. w.c (1 Pa)
Offset Adjustment Procedure:
1) Differential Pressure Manometer –
obtain a meter capable of measuring
differential pressure (“+” and “-“ ports)
with a minimum graduation of 0.01
inches w.c. (or 1 Pa).
2) Installation – with the burner off,
remove the caps from the pressure
tappings. Connect the Feedback
Pressure Tapping to the Positive (+) port
of the manometer; connect the Manifold
Pressure Tapping to the Negative (-)
port of the manometer. Verify that the
manometer is reading zero – zero the
meter if necessary.
3) Calibrate Combustion – operate burner
to maximum modulation rate (seeTable
9-2), ensuring gas line pressure is
maintained above 4 inches w.c.; set
combustion according to Table 9-1 using
the Throttle Screw – record CO
2
value.
4) Set Offset – operate burner to minimum
modulation rate (see Table 9-2); set
offset pressure according to Table 9-1
using the Offset Adjustment Screw.
NOTICE: Since the Manifold Pressure
Tapping is connected to the Negative (-)
port of the manometer, a negative Offset
Pressure will read positive; e.g., to
achieve an offset pressure of -0.03,
manometer will read +0.03.
5) Verify Combustion – with the burner
remaining in operation at the minimum
modulation rate, measure combustion
and compare to readings obtained
during maximum modulation – CO
2
must
be 0.5 to 1.0% lower at minimum
modulation. If readings are out of
tolerance – CONTACT NTI FOR
ASSISTANCE.
6) Complete Test – shutdown the burner,
remove the manometer tubing and
reinstall the factory caps on Offset
Pressure Tappings.
Positive (+)
Negative (-)
Feedback
Pressure
Manifold
Pressure
Throttle Adjustment Screw –
used to calibrate combustion at max.
modulation rate; see Figure 9-1(b)