25
APPENDIX A - CONTROL MODULE
A.5 Operation
Module continuously monitors boiler water temperature and
fires 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 satisfied without firing
burners.
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 satisfied. .
3.
Burner is de-activated, ignition module completes
heating cycle, returns to idle and waits for temperature
to drop again.
4.
Circulator is turned on throughout “Call for Heat.”
Table 6 - Vent Damper Models Operation State Codes
1. State code sequence through a normal heat cycle
Order
State
Code
Number
Definition
Explanation
a
1
Idle
There is no call for heat and or:
b
1
Circulator
Thermostat has call for heat. Control has activated system circulator pump and is
waiting to see if there is enough heat to satisfy the thermostat without firing the
burners. This may last as long as 2 minutes, but will typically be much less.
c
17
Diagnostics
Pilot valve diagnostics/current leakage detection. Typically a few seconds.
d
18
Wait for damper to
open
Vent damper should be closed while boiler is off to conserve energy. Now, the vent
damper must open before burner can safely be lit. The vent damper must confirm it is
open (a switch closes to do this). The control is waiting for this to occur. This may last
up to one minute. If the vent damper switch has not closed after one minute, ERR 55
will be displayed.
e
17
Diagnostics
Another diagnostic check. The control will also check the safety switches (rollout and
vent) are closed. This will be so quick the control may move on before the STA code is
flashed. Should the safety switches be detected open, the control will show STA15 for
as long as the switches are open.
f
6
Spark
Spark for ignition. There should be an audible sparking (buzzing ) noise. This will
last until the control detects a pilot flame, but not more than 30 seconds (90 for
S9361A2095). (If no flame is detected after the trial period, sparking will cease, and
a 5 minute delay will occur before the control tries again. STA10 will be displayed
during this period).
g
7
Flame stabilization
The pilot flame must be strong enough(1
µA
) for the control to release the main
burners. This will last up to 10 seconds. (If the flame is still not strong enough after
10 seconds, the control will shut off the pilot, wait 5 minutes, then try again. STA10
will be displayed during the 5 minute period).
h
8
Running
Main burners are providing heat. This will continue as long as the thermostat requires.
During this period, the control will monitor the pilot signal, boiler temperature,
damper, and limit switches to assure safe operation.
g
1
Post operation
The damper will close again to conserve heat, and the circulator pumps will continue
for a short time to deliver stored heat to the house before it has a chance to escape
during the upcoming off period.
