LAARS NeoTherm NTV (Sizes 399-850 MBTU/h) - Service Manual - Manual (Page 71)

61 Service Manual - NeoTherm 500
2. Once you have completed the high fire combustion test, measure the CO
2
/
O
2
in the flue products at Low Fire.
How to get there: Use the Down arrow to set the “Rate” to “20%.” The NT
unit is now forced to low fire for 5 minutes.
The CO
2
readings should be between the values shown in Table C2-1. If
the CO
2
is not within the range shown, adjustments may be made. To adjust
the low fire CO
2
, locate the low fire adjuster screw as shown in Fig. C2-1.
Slowly make adjustments in 1/16 of a revolution increments until the CO
2
is within the range identified. For the low fire adjustment, turning the screw
clockwise (CW) makes the mixture richer.
3. Repeat steps 2 and 3 to confirm that the CO
2
readings are within the re-
quired ranges. Adjust each setting again if necessary.
4. Confirm that the differential pressure is still within the appropriate range.
5. If any of the measurements cannot be adjusted to the specified ranges or
the CO levels are above 150 ppm when adjusted, see Section C4, “Trouble-
shooting Combustion Problems.”
6. Remove the differential pressure gauge from the air and gas pressure taps
making sure to close all ports after the gauge has been removed.
Combustion Adjustment Procedure -
Units with Original (White) User Interface - continued
C2
cont.