IC-SA-1511 (02/2014)
V/LNV Series Manual
7-3
LNV Series FGR System
7.3 — FGR Shutoff Valve
The FGR shutoff valve is located as close to the stack as possible. A modutrol motor with a 90º stroke
opens and closes the FGR shutoff valve in 15 seconds. Proof of closure for the shutoff valve is provided by
an auxiliary switch in the modutrol motor. The modutrol motor has a maximum temperature rating of 150º F.
This valve should never be mounted with the motor shaft in a vertical position. Damage to the modutrol
motor will result. During pre-purge and post-purge, the FGR shutoff valve is closed to prevent any unused
gas fumes from returning to the combustion zone.
FIGURE 7-3.
FGR Shutoff Valve
7.4 — FGR Control Valve
The FGR control valve is mounted to the FGR damper on the burner. A burner mounted actuator with
linkage connections coordinates the air, fuel and NO
x
control devices to provide proper fuel/air/NO
x
ratios
through the firing range. The actuator must be able to complete its full travel range. Restrictions will
damage the motor and/or the linkage. The actuator transmits motion directly to the FGR control valve.
Before starting the boiler, make sure the control valve is closed. The boiler must never be operated if the control
valve is open. This will result in hot combustion gases flowing backwards in the system. This will damage the
system and can cause bodily harm.
!
Warning
1
2
3
1. MODUTRON MOTOR
2. F.G.R. SHUTOFF VALVE
3. COUPLER, ASSEMBLY
656-10219-000