HeatStation™ CONDENSING WATER BOILER
45
34-1161 05/17
5. Heat-Up
- Following the pre-purge delay, the hot surface igniter will be energized:
a. The flame control will send 120V to the hot surface igniter for approximately 20 seconds.
b. The HSI Element proving current is verified.
c. The heat-up delay takes place to allow the hot surface element to reach ignition temperature.
6. Ignition
- When the 20 second heat-up time is completed a 4-second Trial for Ignition (TFI) period is initiated:
a. The Gas Safety Valves are energized.
b. The hot surface element is de-energized during the last second of the TFI period, to allow detection of flame.
c. The flame control will monitor the flame using flame rectification through the hot surface igniter.
d. If the flame control senses the presence of flame before the end of the TFI period, the flame control will
continue to monitor the flame, through the igniter, until the call for heat condition ends.
7. Heating
a. The flame status, fan speed, LWCO switch, high/low gas switches, and other safety switches are continually
monitored for proper state. The blocked flue is only monitored during pre-purge.
b. The High Limit sensor is confirmed to read below the High Limit setpoint.
c. The temperature of the controlling sensor is compared to the temperature control set point to determine when
to begin firing in heating mode.
d. The boiler remains in heating mode and, with extended operation, condensation begins to fill the
condensation trap and drain line. The boiler attempts to match the temperature control target by modulating
the firing rate around the target temperature.
e. The gas valve(s) are immediately disabled.
f.
A Blower Post-purge is completed and the control proceeds to Standby mode.
8. Flame Failure / Flame Loss
a. If the igniter fails to sense flame during an attempt to light the burner (Ignition Trail Fail), the ignition control
will end the ignition sequence and the gas valve will be closed. Immediately following the end of the first failed
ignition cycle, the HeatStation will enter a hard lockout state. The standard configuration of the HeatStation
boiler allows for only one ignition failure before lockout and requires manual reset to meet CSD-1
requirements.
b. If the burner successfully lights and operates but the flame is lost, the gas valve will be closed and the blower
will continue to operate in order to purge any remaining combustion products from the boiler. This flame loss
will result in a lockout and requires manual reset to attempt operation again. The standard configuration of
the HeatStation boiler allows for only one (Main Flame Loss) occurrence before lockout.