A
G-TRAC2
IOM-25
36 of 42
Mar 99 R7
Properly adjusting the low fire air is the most difficult step in the set up process.
The low fire air is meant to be set by an initial mechanical adjustment followed by fine-tuning on the
low fire air
pot.
For the initial factory adjustment, place the low fire air pot to mid-scale. Mechanically adjust the damper blade until
the O
2
is between 15 and 18% then use the pot to fine tune the O
2
readings. Record the DC volts across terminal PA (+)
and PL.
NOTE
:
At no time should the air damper operator be in the fully closed position. This is evident, by examining the
damper operator mechanical stops or by reading the PA to PL voltage. It should never read below .3 volts.
This is to ensure the operator is always in its control range.
7.
Adjust the unit to about
firing rate
(about 2.5 VDC across terminals “PG and PL”)
. Check the O
2
. The reading
should be between 13 and 17.5 %. If it is closer to 13%, there is an increased chance of condensation. Closer to
17% reduces condensation.
For factory set up, if proper O
2
readings cannot be attained, a new air and/or fuel ratio curve must be selected.
Do not
change setting while in the field. Contact the factory.
Once a different curve is selected you must repeat the factory
set up procedures.
NOTE:
Do not change air or fuel curves without contacting the factory. If the air or fuel curves are changed both
the high and low fire must be rechecked and the voltages recorded on a new label.
8.
Turn off the service mode dipswitch A-5 and ensure you have recorded the set up voltages on the unit. Record the
dipswitch settings, selected pot settings, low fire air, high fire air, and low gas voltage. This will enable faster and
easier change-out of parts in future, as noted in section XXII.
NOTE:
If large low fire gas or air adjustments are made with their respective pots, the high fire settings should be
rechecked. After set up is complete ensure dipswitch A-5 is turned off.
O
2
SETTINGS FOR COMBUSTION SETUP
TURNDOWN
HIGH FIRE
LOW FIRE
20 : 1
3.5 – 4.2%
13 – 17.5%
10 : 1
3.5 – 4.2%
10.5 – 11.5%
5 : 1
3.5 – 4.2%
8.5 – 9.5%
NOTE:
Use the above settings for high and low fire during combustion setup procedure. Refer to the specified
turndown of the unit. Do not change air or fuel curves without contacting the factory.
