LNE Series FGR System
8-4
750-297
Profire E/LNE Series Manual
8.4 — Air/FGR Damper Assembly
The Air/FGR damper regulates the volume of combustion air. Position of the rotary damper blade is controlled by a
modutrol motor.
The damper blade in the low fire position is normally approximately 1" open at low fire. The Air/FGR damper and
FGR control valve blades open as the modutrol motor drives toward the high fire position where flue gas is pulled into
the regulated combustion air flow above the damper blade as controlled by the FGR control valve. Combustion air
mixed with flue gas is passed on through the blast tube to the combustion zone.
8.5 — Stack Temperature Interlock
An optional stack temperature interlock device monitors flue gas temperature in the stack. The stack temperature
interlock is used as a low fire hold device. The stack temperature interlock is set at 25 degrees F below the minimum
stack temperature at low fire (nominal 200º F). After the stack temperature rises above the set point, the interlock
closes and allows the burner to modulate.
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