Operating instructions

72
1.4 Sequence of Operation
Operational State User Interface Display Explanation
If ame detected before Gas Valve
opens during ignition boiler will
lockout.
Please refer to troubleshooting
guide.
Gas Valve energized to deliver air/
fuel to burner.
If ame undetected after 3 sec-
onds boiler will de-energize Gas
Valve and enter post purge mode
for 30 seconds.
Ignition attempted 5 times before
lockout.
Boiler will run provided all op-
erational and safety devices are
within limits
Refer to for more information.
Control module adjusts ring rate
according to heating demand.
When Boiler detects demand met,
will enter post purge mode then
standby mode.
If simultaneous demand for
Central Heat and DHW, boiler will
enter DHW Priority Mode.
Priority mode limits amount of
time boiler can run in DHW mode
to meet CH demand.
Max DHW Priority Time setting
determines maximum time
allowed for DHW heating mode.
Please refer to section Appendix A
section 1.5 for more information.
Flame
Detected?
Gas Valve
Energized
Flame
Detected?
Heat Demand
Met?
DHW
Priority
Mode
Simultaneous
DHW + CH
Demand?
No
Yes
No
Yes
See Max DHW
Priority Time
Setting
No
After 2 seconds
After 3 seconds
No
30 second
post purge
Yes
Yes
Lockout
Error A21
Note:
5 Ignition
trials,
then
Lockout A01
APPENDIX A - CONTROL MODULE