OPERATION
TYPICAL FURNACE INSTALLATION
In a typical application the 50D50-842 is designed to generate sparks and energize the gas valve and monitor the flame
sensor. It is a 100% shut off design that locks out the gas valve if the burner does not light within the trial for ignition period.
The ignition sequence begins with a call for heat from the room thermostat. The thermostat applies power to the control.
After pre-purge interval, the valve is energized and sparks are generated for the selected trial for ignition time. If the burner
lights within the allowed period the gas valve will remain open until the call for heat is satisfied. If the burner does not light,
the control will either go into lockout or make two more ignition retries depending on the options selected. The control can be
reset from lockout by cycling the thermostat to remove power for a minimum of 10 seconds. It includes a system analysis/
troubleshooting LED that indicates normal operation, lockout, or control fault.
TROUBLESHOOTING
For proper control operation, the control must be electrically connected to the gas valve and all the ignition wiring connectors
plugged in. Gas valves with an electric "ON/OFF" switch must have the switch set to "ON".
The light on the control provides a self-diagnosis indication. If the red light on the module is off continuously, the fault is likely
to be internal to the module. To make sure, interrupt the line or 24 volt thermostat power for 10 seconds, check program key
installation and then restore. If the internal fault is indicated again, and flame sensor is not shorted to ground, replace the
control. A flashing light indicates a problem, most likely in the external components or wiring (see chart below). Proceed as
follows:
Visual checks
1)
After the pre-purge delay (if applicable) the valve opens and the ignition (sparks) starts
2)
The burner flame will light
3)
The ignition (sparks) stops
Troubleshooting the system consists of checking for these visual indications. The chart on the next page defines the proper
action if any of these indications does not occur.
4
LED
Solid On
One Flash
Two Flashes
Three Flashes
Four Flashes
Five Flashes
OFF
No Power / Internal Fault
Condition
Normal - Control ON
False flame signal
No Flame Detected
Safety Drive Fault
N/A
MV Drive Fault
