Laars NeoThem NTH, Service Manual

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Service Manual - NeoTherm 500
2. Next, measure the CO
2
and O
2
in the flue products at low fire. The NeoTherm
can be forced to remain in low fire during the setup.
How to get there: From the “Home” screen, press “I” to go to “Info/ Install.”
Choose “Test,” then go to “Forced Rate.” Select “Set Low Fire,” then select
“Start Test.”
Again, the CO
2
readings should be between the values shown in Table C3-1.
See Fig. C3-1 to locate the low fire adjuster screw for your unit. For the low fire
adjustment, turning the screw clockwise (CW) makes the mixture richer.
3. You might have to go back and forth between high fire and low fire several
times before the CO
2
readings are correct in both cases. Repeat steps 2 and
3 and continue to adjust until the CO
2
readings are stable.
4. Check to see that the differential pressure is still within the correct range.
5. If any of the measurements cannot be adjusted to the specified ranges or the
CO levels are above 150ppm when adjusted, see Section C4, “Troubleshoot -
ing Combustion Problems.”
6. Remove the differential pressure gauge from the air and gas pressure taps.
Be sure to close all ports after you remove the gauge.
Combustion Adjustment Procedure -
Units with Current User Interface (continued)
C3
cont.