Instruction manual

52
Figure 33: Boiler Control & Option Panel Orientation
X. OPERATING
A. BOILER SEQUENCE OF OPERATION
1. The boiler's sequence of operation is shown in Table
10.
2. When there is a call for heat the boiler control starts the
system circulator and the thermal purge (circulator pre-
purge time) begins. If the time is completed or boiler
temperature is less than the Start Temperature (140 F
default) the start sequence continues by energizing the
oil primary to operate the following sequence: blower is
started and operates for pre-purge time; spark is energized
and fuel valve is opened for ignition trail time; burner
res until the thermostat is satised.
3. If the thermostat is not satised and the Operating Setpoint
(SP) is reached the system circulator will continue to
operate and the burner will stop. When the boiler water
temperature drops below the setpoint less the differential
setting the burner will restart.
4. After the thermostat is satised the burner and circulator
are stopped.
5. When an indirect water heater aquastat call for heat is
wired to the DHW input the control starts the Domestic
Hot Water circulator and when boiler temperature is less
than the operating setpoint energizes the oil primary to
turn on the burner without circulator pre-purge delay.
6. On water boilers equipped with a High Limit Option
Card, if boiler water temperature exceeds the high limit
setting, the system pump will continue to operate, and
the burner will stop. When the boiler water temperature
drops below the High Limit Card differential setting,
(15°F), the burner will restart.
7. On water boilers equipped with a LWCO Option Card,
if level probe senses a low water condition, the system
pump will continue to operate and the burner will stop.
When water level is replenished, the burner will restart.
Status Code Displayed in STA Mode
STA Status Description
1
Standby
(burner off,
circulator off)
No call for Heat Detected.
1
Standby
(burner off,
circulator on)
Either condition is true:
a. Call for heat detected and boiler
temperature higher than operating
setpoint.
b. Call for heat is detected and boiler
temperature higher than start tempera
ture (140°F default) and circulator pre-
purge time has not expired.
4** Pre-purge The blower is turned on for a valve-on delay.
6*
Trial For Ignition
(TFI)
The igniter is turned on and the fuel valve is
opened. A ame must be established within
the trial for ignition time.
7* Carryover
Once ame is established, the ignition remains
on for 10 seconds to ensure ame stability and
then turns off.
8 Running
The burner runs until the call for heat is satised.
The burner is then sent to burner motor-off
delay, as applicable, or it is shut down and
sent to standby.
9* Post-purge
The fuel valve is closed and the burner motor is
kept on for an off delay time before the control
returns the burner to standby.
10*
Retry / Recycle
Delay
If the ame is lost while the burner is ring,
the control shuts down the burner, enters a
recycle delay, and then repeats the ignition
steps outlined above. If the ame is lost three
times in a row, the control locks out to prevent
cycling with repetitious ame loss caused by
poor combustion.
14* Hard Lockout
If ame is not sensed by the end of the TFI, the
control shuts down on safety lockout and must
be manually reset. Press and hold reset button
for 30 seconds to reset the restricted lockout.
15*
Waiting for Limit to
Close
Heat request present and start sequence is
halted due to an open limit. Open limits include
high water temperature or low water detected
by IQ Option Cards.
16*
Flame Present Out
of Sequence
Flame signal is still present when expected to
be 0 (no ame).
17 Self Test Control internal checking.
TABLE 10: SEQUENCE OF OPERATION