52 Rev. 2
SYSTEM OPERATION
HEATING TIMING CHART FOR WHITE-RODGERS 50A52 (RADIANT SENSE) OPERATION
ON
OFF
ON
OFF
ON
OFF
OPEN
CLOSED
OPEN
CLOSED
POWERED
NOT POWERED
AIR CIRCULATION
BLOWER
GAS
VALVE
IGNITOR
PRESSURE
SWITCH
INDUCED DRAFT
BLOWER
"W" OF ROOM
THERMOSTAT
0T T+1 T+45 0 90
T = 17 SECONDS (MINIMUM) - 90 SECONDS (MAXIMUM)
NORMAL OPERATION, T = 17 SECONDS OR SLIGHTLY LONGER
SEQUENCE OF OPERATION
(Models with White-Rodgers 50A52 Radiant Sense Igni-
tion Control)
NORMAL SEQUENCE OF OPERATION
1. The thermostat calls for heat, and the induced draft blower
is energized.
2. The pressure switch closes.
3. The ignitor is energized. It will heat for at least 17 sec-
onds, and will continue to heat until the radiant sensor
determines the ignitor is hot enough (i.e., until a heat
signal is produced.)
4. The gas valve is opened. Combustion begins.
5. One second after the gas valve opens, the ignitor is de-
energized.
6. The radiant sensor monitors the flame. As long as flame
is present and the call for heat continues, the gas valve
will remain open. Either a hot ignitor or a flame can pro-
duce a heat signal.
7. 45 seconds after the gas valve opens, the control turns
on the air circulation blower.
8. Sometime later, the thermostat is satisfied. The call for
heat ends. The gas valve closes, and the induced draft
blower is de-energized.
9. 90 seconds after the gas valve closes, the control turns
off the air circulation blower.
Seconds 0 5 0 45
On
Off
On
Off
On
Off
Indoor Fan
Outdoor Fan
And
Compressor
Thermostat
COOLING TIMING CHART FOR WHITE-RODGERS 50A52 (RADIANT SENSE) OPERATION
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