Technical information

A G-TRAC2 MANUAL
General Manual Revised: 03/15/99
Page
30
B. (Initial Operator Wiring Pre-Check) With power to the FS terminal "off", but power to the actuators "on":
• Jumper “OG to G” (open gas) – the gas actuator should move towards open. The DC volts across
terminals PG to PL should be increasing as the operator moves.
• Jumper “CG and G” (close gas) – the gas actuator should move back to the closed position. (Only if
required, interchanging wires “OG and CG” can reverse the above rotation.)
• Jumper “OA to A” (open air) – the operator should return to the open position. As the operator moves
the DC volts across PA, and PL should be increasing.
• Jumper “CA to A” (close air) – the air operator should begin to close.
C. Power the “FS” terminal. Set the manual service pot to high fire – full clockwise (CW). Set the “high air” pot
to maximum. Set the low fire and low air pots to mid position.
• If the combustion air switch is open and there is a valid discharge sensor, the combustion air blower will
start. This will close the combustion air switch.
• If required, the combustion air damper will open to the purge position and the G-TRAC will start the pre-
purge cycle (85 seconds).
• Once pre-purge is done both operators will move to the light off position. Once both operators are at the
correct position the flame relay will be energized. In the service mode the G-TRAC will not lock out on
flame failure.
D. After the flame starts the unit will go to high fire. Adjust the unit gas pressure regulator to obtain the correct
clocked high fire rate. This has been factory pre-set and should not require field adjustment.
E. Adjust the high fire air pot until the high fire O
2
reading is between 3.5 and 4.2%. The high fire air pot
controls the opening of the air damper motor by changing the voltage to it. When combustion is set use a 0-10
VAC meter to measure the air damper position voltage across terminals PA (+) and PL. Record the DC
voltage reading.
5. Low Fire Gas Flow Rate
PG (hot) to PL (neutral)
At the factory, the low fire gas flow rate was clocked. As the manifold pressures are too low to measure in
the field, check low fire gas flow by the following:
Set the manual service pot to low fire (full CCW). After both operators have stopped moving, check that
the PG to PL DC voltage matches the low fire data recorded on the G-TRAC2 configuration label. (Use
the low fire pot, only if adjustment is needed. To make a partial (small) step, rotate the low fire pot the desired
direction a very small amount. The control will not have moved if you are making a very small step, however if you
now rotate the service pot CW for 3-4 seconds, then return it to low fire CCW, the gas operator should have stopped
at a slightly different position)
6. Low Fire Combustion Air
PA (hot) to PL (neutral)
Adjust the low fire air pot to trim (set) the correct low fire oxygen content. (Eng. Air HT burner = [15.5 to
18.0% for field set up] 15-18% factory set up.)
Properly adjusting the low fire air is the most difficult step in the set up process.