48
Sequence of Operation
1. Upon initial application of 24VAC power, the PIM™
resets with all outputs in the “OFF” state.
2. The PIM™ and VERSA IC
®
Control perform a
processor and memory self-test to ensure proper
operation.
3. The PIM™ confirms the presence of a valid ID
Card which matches the configuration stored in
memory at the factory. If a valid ID Card is NOT
present, the PIM™ generates a diagnostic fault
and will shut down waiting for this fault to be
addressed.
4. The PIM™ reads the DIP switch settings and con-
figures itself for the desired operation.
5. The PIM™ scans the Ft_bus communications for
the VERSA IC
®
Control and if found, system oper-
ation is controlled by the VERSA IC
®
Control.
6. Non-volatile memory is checked for any active
lockout conditions. If any exist, they must be
addressed before the PIM™ will allow a new trial
for ignition to start.
7. The PIM™ continually monitors the flame status to
ensure that no flame is present during Standby. If
an erroneous flame is detected, the PIM™ gener-
ates a False Flame error fault.
8. The PIM™ verifies that the vent sensor (some
models) is below the vent limit temperature before
burner operation. If the vent temperature is
exceeded, the PIM™ performs a Post-purge and
proceeds to a hard lockout.
9. A Call-for-heat is initiated by the presence of any
one or more of the 4 sources below:
a. A heat demand (contact closure) on the TH
field wiring terminals
b. A voltage greater than 0.5 VDC on the analog
0-10 VDC EMS signal input
c. A heat demand present on the DHW field
wiring terminals
d. A heat demand from the VERSA IC
®
control
based on the DHW sensor temperature
10. The PIM™ initiates a trial for ignition counter to the
programmed number of trials for ignition (1 or mul-
tiple) and proceeds to Pump Purge mode.
firing rate for as long as desired and the display will
flash “HOLD” at 1-second intervals during this period
of time. Any CFH received from the system during this
User Test will be ignored until the test is completed.
For Cascade configurations, the USER TEST item is
only available though the master unit. To perform a
user test at each individual follower go to each Boiler
menu from the Master user interface, and enable only
the boiler to be tested.
When CWP is enabled (VERSA
®
DIP#3) VALV
becomes available for USER TEST.
Commission Test Mode
When the PIM™ DIP switch #8 is turned to the ON
position, a Commission Test Mode is activated. The
PIM™ lights the amber Alarm/Test LED. This mode
activates certain functions to assist initial commission
testing of the system. The configured high limit tem-
perature is overridden to match the setpoint
potentiometer position. The high limit can then be
adjusted by the potentiometer to assist commission
testing and verification. The operating setpoint is auto-
matically set to 20°F above the high limit (stand-alone
mode), or it can be controlled by the VERSA IC
®
Control.
Max Heat Function
This function sets the target temperature equal to
Boiler Maximum value whenever any demand is pres-
ent. In addition, the DHW priority is disabled and
WWSD is disabled. The Max Heat function will be
aborted if 24 hours has elapsed since it was initiated
or if the user sets MAX HEAT = OFF in the
TOOLBOX
menu.
Max Delta T Protection
The VERSA IC
®
system is capable of controlling the
operation of the heaters so that a maximum value of
Delta T is not exceeded in an attempt to protect the
heaters from flashing to steam or damaging the heat
exchanger due to scale which can form at high tem-
peratures.
If the Maximum Delta T value is exceeded, the heater
will shutdown (pumps will continue to operate), the
alarm light will turn on and the display will show
“DELTA T ERR”. Once the Delta T drops below half
the maximum value, as defined by the unit type, the
alarm light will turn off and the heater will return to
IDLE state until a CFH is present.
Summary of Contents for 5000.72A
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