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ST7997 OIL BURNER MOUNTED ELECTRIC FAN TIMER
HEAT OFF DELAY TIME
1
2
1
2
60
90
(SHADED AREA IS SWITCH HANDLE POSITION.)
1
FOR SELECTED MODELS ONLY.
Fig. 6. ST7997 Fan Timer location and settings for
Heat Fan-Off and Heat Fan-On delay switches.
69-1204
HEAT ON DELAY TIME
1
2
1
2
3
120
150
45
CHECKOUT
Verify system operation by running the system through
one complete heating and cooling cycle, if applicable.
Troubleshoot by checking for appropriate voltages at the
ST7997 terminals controlling the burner motor and heat
and cool circulating fan. The ST7997 schematic (Fig. 3)
shows internal switching to clarify operation and assist in
troubleshooting. Table 2 provides the ST7997 operating
sequence.
Use the green diagnostic LED to assist in troubleshooting:
a.
Off when system is on and thermostat is satisfied.
b.
On continuously when ST7997 recognizes a valid call
for cool or fan from the thermostat and/or a valid call
for heat from the R7997.
c.
Blinks rapidly on and off when limits are opened.
3
60
1
M12918
6
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