7
3. NORMAL OPERATION (summary)
When a signal is received from the thermostat supplying 24 volts to the
W terminal
of the HSI
module, the control will reset, perform a self check routine, flash the diagnostic L.E.D. for up
to four (4) seconds and a pre-purge delay begins. Following the inter-purge period, the Hot
Surface Ignitor is activated and the Gas Valve is energized for the trial for ignition period.
When a flame is detected during the trial for ignition, the Hot Surface Ignitor is deactivated
and the Gas Valve remains energized. The thermostat and main burner flame are constantly
monitored to assure the system continues to operate properly. When the thermostat/micro
processor controller (computer) is satisfied and the demand for heat ends, the Gas Valve is
de-energized immediately.
Should the main burner fail to light, or a flame
is not
detected during the first trial for
ignition period, the Gas Valve is de-energized and the HSI Module (controller) goes through
an inter-purge delay before another ignition cycle is attempted. The HSI Module will
attempt two (2) additional ignition trials before going into LOCKOUT and the Gas Valve
relay will be de-energized immediately.
Recovery from LOCKOUT requires a manual reset by either resetting the thermostat or
removing the 24 volts for a period of five (5) seconds.
If the computer is still calling for heat after one (1) hour the HSI Module (controller) will
automatically reset and attempt to ignite the burner again.
D . TROUBLESHOOTING
The troubleshooting information provided in this manual is intended for use only by
QUALIFIED SERVICE TECHNICIANS. Observe
ALL
safety precautions displayed on the
equipment or specified in the Installation/Operator’s Manual included with the dryer.
IMPORTANT: UNDER
NO
CIRCUMSTANCES
SHOULD
ANY
SAFETY
OR
HEAT
CIRCUIT
DEVICE
EVER
BE
DISABLED.
The following troubleshooting guide
provides systematic procedures for
isolating equipment problems, and again,
is intended for use by a QUALIFIED
SERVICE TECHNICIAN.