Greenheck IG / IGX (464104 IOM) (Pre-2009) - Manual (Page 37)

37
Start-Up - 8:1 Staged Control
Step 1 Send the Unit to High Fire
For the furnace to light, the heat switch must be
closed or jumpered out. Reference the unit ladder
diagram for proper terminals to jumper.
To send the unit to high fire, press and hold the up,
down and enter keys. “HIF” will flash on the screen
when the unit is forced to high fire.
The unit will remain at high fire until the escape key is
pressed (“HIF” will stop flashing).
WARNING!
Once the unit is forced to high fire, it will remain at high fire until the escape key is pressed.
NOTE!
A second high limit with manual reset is located in the control center of the unit.
NOTE!
Forcing the unit to high fire during warm or hot weather conditions may cause the high limit switch to
trip. If the switch trips, it will reset once the discharge air temperature has reached a safe level.
Start-Up
IMPORTANT!
8:1 staged furnaces use two manifolds and two staged gas valves per furnace. The high and low fire
manifold pressure must be checked and properly set on each manifold.
IMPORTANT!
Confirm that the discharge air sensor is installed in the duct, at least three duct diameters
downstream of the furnace
Step 2 Check the High Fire Manifold Pressure
Using a manometer, measure the high fire burner manifold pressure for each furnace at the pressure test port.
Refer to the gas train layout in the reference section for the test port location.
The recommended high fire manifold pressure is 3 1 ⁄
2
inch wc for natural gas and 10 inch wc for LP Gas.
If needed, adjust the high fire screws on each staged gas valve to set both high fire manifold pressures.
Counterclockwise rotation will decrease the gas pressure and clockwise rotation will increase the gas pressure.
Eight Stage Manifold
Pressure (inches wc)
Natural Gas LP
Low Fire 7 ⁄
8
2 1 ⁄
2
High Fire 3 1 ⁄
2
10
High Fire
Adjustment
Escape
Down Enter
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