User Guide

56
Service Manual NeoTherm 80 - NeoTherm 285
Combustion Adjustment Procedure -
Units with Current User Interface
WARNING
Improper adjustment of the high re and low re 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-re adjustments on gas
valve - NT 85 through NT 285
Procedure:
1. Start by measuring the CO
2
and O
2
in the ue prod-
ucts at high re. The controller has a feature that
makes it easy to go directly to the high re condition.
The unit will operate at high re 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 re setting. See Fig. C3-1
to locate the high re 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
re 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 re CO
2
Propane 9.8% to 10.0% 0.5% lower than high re CO
2
Table C3-1 - CO
2
Range and Pressure Differential
Low re
CO
2
adjustment
High re
CO
2
adjustment
C3