Reznor DV Operation Manual (for units built before August 2003) - Manual (Page 10)

Form O-DV/RDF/ADF, P/N 148385, Page 9
9. Limit Safety
Controls
Each unit has an automatic temperature activated limit control, a manual reset
temperature activated limit control, and an electrical activated energy cutoff
device.
• Automatic Reset Limit Control
Function: If the temperature of the discharge air reaches the setpoint, the limit
will open the circuit to the burner system and close all burner and pilot valves.
The limit control will be activated if total airflow is reduced or if gas pressure
surges at the burner causing excessive discharge air temperature. The system
will restart when the discharge air temperature decreases below the setpoint.
Service: Failure of this limit requires replacement of the control.
FIGURE 11 - Automatic
Reset Limit Controls
Model P/N Setting
RDF 86979 135°F
ADF 122856 130°F
ADFH 57953 170°F
DV None
• Manual Reset Limit Control
Function: The manual reset limit has a higher setting than the automatic limit
and requires manual resetting to restart the system. If for any reason the auto-
matic limit should fail to protect against overheating, the manual limit will
shutdown the system. Should the manual reset limit activate, check the entire
system to determine the cause. Make any necessary changes or adjustments
before restarting the burner system. Restart of the unit can be done only after
the limit has been cooled and the reset button depressed
CAUTION: If the manual reset limit activates, find and correct
the cause before restarting the system.
Service: Failure of this limit requires replacement of the control.
Service: Replacing burned out bulbs is the only service required. If a bulb is
not lit, check the bulb by switching it with a bulb that is lit.
FIGURE 13 - ECO Limit
Control
Setting
305°F,
P/N 82414
FIGURE 12 - Manual Reset
Limit Controls
Model DV - Manual Reset
Limit with Capillary, Size
109-122 Setting 190°F, P/N
161437; Size 125, 205°F,
P/N 161433
Model RDF -
Setting 150°F,
P/N 82610
Model ADF - Setting
135°F, P/N 122858;
Model ADFH - Setting
170°F, P/N 57953
Reset
Button
• Emergency Cut Off Limit Control
Function: The emergency cut off is a fusible link high temperature limit which
provides onetime redundant protection against overheating. If the temperature
sensitive limit controls malfunction, the electrically activated emergency cut-
off will shutdown the system.
Service: If this limit activates, the manual limit control has failed and must be
replaced. The cause for activating the emergency cut off limit control must be
found and corrected before re-starting the system.