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SYSTEM LOCKOUT FEATURES
When system lockout occurs, the gas valve is de-ener-
gized, the circulator blower is energized at heat speed,
and, if flame is sensed, the inducer blower is energized for
5 seconds. The diagnostic indicator light will flash or glow
continuously to indicate system status. (System lockout
will never override the precautionary features de-
scribed above.)
To reset the control after system lockout, do one of the
following:
1. Interrupt the call for heat at the thermostat for at least
one second (if flame is sensed with the gas valve de-
energized, interrupting the call for heat at the thermo-
stat will not reset the control).
2. Interrupt the 24 VAC power at the control for at least
one second. You may also need to reset the flame
rollout sensor switch.
3. After one hour in lockout, the control will automatically
reset itself.
DIAGNOSTIC FEATURES
The 50A62-820 control continuously monitors its own
operation and the operation of the system. If a failure
occurs, the DIAG 1 and DIAG 2 LEDs will indicate a failure
code as shown below.
MANUAL FAN ON MODE
If the thermostat fan switch is moved to the ON position,
the circulator fan (fan speed) and optional electronic air
cleaner are energized. When the fan switch is returned to
the AUTO position, the circulator fan and electronic air
cleaner (optional) are de-energized.
PRECAUTIONARY, SYSTEM
LOCKOUT, AND DIAGNOSTIC
FEATURES
PRECAUTIONARY FEATURES
The following precautionary features are built into the
50A62 control.
1. If, at any time, the flame rollout sensor opens, the gas
valve and ignitor are de-energized.
2. If, at any time, flame is sensed when the gas valve is
de-energized, the heat circulator blower and inducer
fan are energized and the ignition sequence will go
into system lock out. The heat circulator and inducer
will remain on as long as flame is detected. If flame
is no longer detected, the inducer will turn off in 5
seconds and the circulator will turn off using the
maximum heat off delay.
3. If, at any time, the flame rollout switch opens, the heat
circulator blower and inducer fan are energized and
the ignition sequence will go into system lock out. The
inducer will remain energized for 5 seconds. The
circulator will remain on as long as the flame rollout
switch is detected open, then use the maximum heat
off delay.
4. If at any time the main valve sense input does not
correspond to the program’s requested gas valve
state, the inducer is de-energized and the ignition
sequence will go into system lock out. The heat
circulator blower will be energized using the maxi-
mum heat off delay, provided a heat off delay is
already in progress.
SAFETY CIRCUIT
DIAG 1 DIAG 2
Limit Control Slow Flash On
Pressure Switch Off Slow Flash
Watch Guard - Burners Alternate Alternate
Failed to Ignite Slow Flash Slow Flash
Flame Sensed Without
Slow Flash Off
Valve Energized
Roll Out Open or 9-Pin
On Slow Flash
Connector Disconnected
Bad Board On On
Power On
Simultaneous Simultaneous
Slow Flash Slow Flash
Low Flame Slow Flash Slow Flash
Reverse Polarity Fast Flash Slow Flash
Low Voltage or Alternate Alternate
Ignitor Disconnected Fast Flash Fast Flash
Heat Demand
Simultaneous Simultaneous
Fast Flash Fast Flash