LAARS NeoTherm NTV (Sizes 150–285 MBTU/h) - Service Manual - Manual (Page 66)

56 Service Manual NeoTherm 80 - NeoTherm 285
Combustion Adjustment Procedure -
Units with Current User Interface
WARNING
Improper adjustment of the high fire and low fire settings may lead
to poor combustion, increasing the amount of carbon monoxide
produced. Excessive carbon monoxide levels may lead to personal
injury or death.
Equipment required:
• Flue product analyzer
• 2 mm Allen wrench
Fig. C3-1 - High- and low-fire adjustments on gas
valve - NT 85 through NT 285
Procedure:
1. Start by measuring the CO
2
and O
2
in the flue prod-
ucts at high fire. The controller has a feature that
makes it easy to go directly to the high fire condition.
The unit will operate at high fire for 5 minutes, then
shut down automatically.
How to get there: From the “Home” screen, press
“I” to go to “Info/ Install.” Choose “Test,” then go to
“Forced Rate.” Select “Set High Fire,” then select
“Start Test.”
The CO
2
readings should be between the values
shown in Table C3-1. If the CO
2
is not within the cor-
rect range, adjust the high fire setting. See Fig. C3-1
to locate the high fire adjuster screw. Slowly make
adjustments (1/16 of a turn at a time) until the CO
2
is within the range shown in the table. For the high
fire adjustment, turning the screw counter-clockwise
(CCW) opens the adjustment and makes the mixture
richer.
Gas Type High Fire CO
2
Low Fire CO
2
Natural 8.5% to 9.0% 0.5% lower than high fire CO
2
Propane 9.8% to 10.0% 0.5% lower than high fire CO
2
Table C3-1 - CO
2
Range and Pressure Differential
Low fire
CO
2
adjustment
High fire
CO
2
adjustment
C3