S-Series Technical Manual
63
Cambridge Air Solutions
OPERATING INSTRUCTIONS
OPERATING SEQUENCE
POWER ON
1. Control transformer energized.
2. Operator must select ”SUMMER
VENTILATION” or ”HEATING” mode.
SUMMER VENTILATION MODE
1. Mode switch in ”SUMMER VENTILATION”
position.
2. Optional TSS Controller schedule calls for
ventilation.
3. Optional motorized damper opens.
4. Blower motor starts.
5. Unit continues to run until turned off.
HEATING MODE
1. Mode switch in ”HEATING” position.
2. Thermostat or interlock calls for heat.
3. Optional motorized damper opens.
4. Blower motor starts.
5. Airflow switch closes.
6. Entering air thermostat closes when inlet
temperature is below setpoint after the prepurge
delay.
7. Igniter warm up timing.
8. Gas valve opens.
9. Burner lights.
10. Igniter is de-energized.
11. Low Fire Start is de-energized after 15 seconds.
12. Unit runs and modulates until operating
thermostat and/or interlock opens (heater shuts
off).
13. Steps (2) through (12) repeat themselves
automatically as necessary.
