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APPENDIX A - CONTROL MODULE
A.5 Operation
Module continuously monitors boiler water temperature and
fi res or shuts off burner based on this temperature data.
1.
When “Call for Heat” occurs, control enables circulator
and monitors boiler water temperature to determine
whether thermostat can be satisfi ed without fi ring
burners.
Table 1 - Operation State Codes
State
Code
Number
Defi nition Explanation
1
Idle Standby - no call for heat
Circulator
Heat request present. Boiler temperature suffi ciently high to run circulator pump
only.
2
Wait for pressure switch
to open
Inducer is off. Control waits for pressure switch to open.
Checked at beginning of heat cycle before turning on inducer.
If pressure switch does not open in 60 seconds, control goes to State 11.
3
Wait for pressure switch
to close
Inducer is turned on. Control waits for pressure switch to close.
Checked at beginning of heat cycle after turning on inducer.
If pressure switch does not close in 60 seconds, control goes to State 12
4
Pre-purge System is purging before ignition trial; includes Pilot Valve circuit diagnostics.
6
Spark System sparking. Flame is not present
7
Flame stabilization
Flame signal is being established. Variation in signal is allowed during this state,
fl ame must be stable at end of period
8
Running System is running. Flame signal must be present.
9
Post-Purge System is purging at end of call for heat
10
Retry delay Successful ignition was not detected, and delay is called before retry.
Recycle delay Flame signal was lost, and delay is called before retry
11
Wait for pressure switch
to open - failed to close
Inducer is still off. Pressure switch has not opened at beginning of heat cycle.
Alarm is sent, but no lockout occurs
12
Wait for pressure switch
to close - failed to open
Inducer is on. Pressure switch has not closed at beginning of heat cycle.
Alarm message is sent but no lockout occurs.
13
Soft lock-out Soft lockout duration is one hour, may override with manual reset.
14
Hard lock-out Manual reset is required for hard lockout
15
Wait for limit to close Possible thermostat call for heat; limit switch is open.
16
Flame out of sequence
Flame signal sensed before trial for ignition. Appropriate alarm is sent.
OR
Flame signal sensed during post purge. Appropriate alarm is sent.
OR
Flame signal present when not expected. Appropriate alarm is sent.
17
Pilot valve diagnostics Pilot valve circuitry diagnostics during pre-purge.
Current leakage detection
Self check performed at start up, again at beginning of heat cycle, and during
“Wait for Recovery “ State.
Wait for recovery
Self check performed at start up, again at beginning of heat cycle, and during
“Wait for Recovery “ State
2.
Control determines burner operation is required,
module proceeds to start burner (see state codes list)
and heats water in boiler until setpoint temperature is
achieved or thermostat is satisfi ed. .
3.
Burner is de-activated, ignition module completes heat-
ing cycle, returns to idle and waits for temperature to
drop again.
4.
Circulator is turned on throughout “Call for Heat.”