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P/N HN-IOM-1 82-0331 Copyright 2009 Mestek, Inc.
Finned copper tube gas boilers & water heaters – Control manual
Line #4 log entries
Table 10
Troubleshooting
(continued)
9
Line #4 entry
Explanation
SETBACK#1 IS ACTIVE
SETBACK#2 IS ACTIVE
SETBACK#3 IS ACTIVE
SETBACK#4 IS ACTIVE
SETBACK#1 IS EXPIRED
SETBACK#2 IS EXPIRED
SETBACK#3 IS EXPIRED
SETBACK#4 IS EXPIRED
If one or more of the setbacks is enabled, these entries will occur when the setback is started or
ended.
NO LOCAL SYSTEM FLOW
NO SYSTEM FLOW
This indicates failure of flow proving (switches wired to J11A and J11B).
COMBUSTION AIR FAIL
Logs if the combustion air damper is used and does not prove across J10B DAMPER or J12B
DAMPER
SYSTEM RESET -- ---
Records the type of reset the control board experienced —
O: stack overflow; U: stack underflow; (both of these are software faults)
R: reset instruction (firmware or default load)
W: Watchdog (firmware code ran erroneous code and rebooted)
P: Power-ON (Power switch toggled)
B: Brown-out (Microcontroller saw a voltagle less than 4.5 VDC)
OUTDOOR RESET
This message indicates that warm weather shutdown is in effect.
HIGH DELTA TEMP
This message occurs when the temperature across the heat exchanger is greater than 40 °F.
LOW RETURN TEMP
If the return temperature is less than 130 °F, condensation may occur.
SHUTDOWN UV TEST
After 24 hours of continuous operation, the ignition control module must check its UV detector. The boiler
will shutdown and restart, allowing the self-check to occur on start-up. This message indicates this sequence
has occurred.
HIGH LIMIT EXCEEDED
This indicates the limit control has exceeded it limit.
IGNITION CTRL ALARM
This indicates the ignition control module faulted while performing an ignition sequence or while monitor-
ing during flame operation.
IRI ALARM
This indicates the gas valve proving circuit detected a gas pressure problem.
DOMESTIC HOT WATER
This indicates the occurrence of a DHW call for heat from a DHW sensor or external DHW aquastat.
LOW WATER CUT-OFF
VAR FREQ DRIVE
GAS PRESSURE
SPARE 4
OP LIMIT MECH
These are faults due to interlocks connected to 24VAC interlock inputs on J11A and J11B.
OP LIMIT REMOTE
This indicates the software operating temperature limit was exceeded.
