A
G-TRAC2
IOM-25
34 of 42
Mar 99 R7
White
Sleeve
Shaft
Connection
Blue shaft that you
adjust if needed
Combustion Set Up
Pot Position Fine Tuning (Low Fire Rate, Low Fire Air)
Adjusting the trim pots may, at times seem to have no effect, but turning the pot just a little more will move the operator a
large step. For some applications this step may be too large. If this happens there is a method to get the G-TRAC2 to
recognize small or partial step movements. This is done by placing the G-TRAC2 into service mode and attaching a DC meter
between the position feedback terminal
(PG gas or PA air)
and the PL terminal and record the voltages. Make a very slight
adjustment to the required pot. Next, rotate the manual service pot up or down enough to get the operators to move about
5 to 10 degrees, then rotate the service pot back to its original position. The operator(s) should now stop in a slightly
different position
(part step)
. In most instances the only indication of a slightly different stopping position will be a slight
change of the position feedback voltage
(terminal PG and PA)
.
NOTE:
Making a large trim pot adjustment may slightly affect the setting of the other pots. If a large adjustment
is made recheck the settings of the other combustion related pots.
NOTE
:
The following set up steps, 1 through 5, have already been done in the factory. They should not need to be
repeated unless damage occurred. A field check to ensure proper combustion would be advised, but only
make adjustments if combustion were not correct. If changing an operator or G-TRAC2, consult
information later in this manual.
NOTE:
The current gas actuator model TT005 does not have a stem to adjust the resistance. Step “2” below only
applies to the older model #TTB3005A gas actuators.
NOTE:
When using model TT005 gas actuator and BT405 air actuator, change the resistance value in step “3”
below to 100
.
Place the probe of the combustion analyzer directly into the heat exchanger outlet, not to the flue. If the probe is not
inserted far enough, flue gas may be diluted by air entering into drain holes in flue, etc.
1.
Select the correct burner and gas valve curve
(dipswitch on Block B)
. Setting the dipswitches located next to the
set-point knob makes the selection. If the unit is in the field there should be a label noting the factory settings. If
not, a description of the switch settings is near the beginning of this manual or contact the factory.
2.
With the power off, install and adjust the gas valve operator onto the ball valve so that the operator travels the full
90º stroke
(full closed to full open by the clutch)
. The “PG” terminal is the gas actuator’s positional feedback
connection. With the G-TRAC2 off and the valve in the fully closed position, the resistance of the gas operator’s
feedback pot is less then 50-ohms with the wires disconnected from terminals “PL and PG”. The pot shaft in the
operator is friction fit. To obtain 50
leave
in the
closed
position. Adjust pot with needle-nose pliers if needed.
3.
With the power off, install and adjust the air operator onto the air damper so that with the operator in the closed
position, the combustion air damper
is just slightly cracked
(4 to 8 degrees
open)
. With the G-TRAC2 off and the
air operator in the fully closed
position, the resistance of the air
operator’s feedback pot is less then
50-ohms with the wires disconnected
from terminals “PA and PL”. Adjust
the pot with needle nose pliers (if
needed) to obtain 50
.
Leave
in the
closed
position.
