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5.6
T
ROUBLESHOOTING
and correcting the cause. (Manual Reset Limits include: Flame safeguard, high or low gas pressure,
high temperature limit, stack temperature, low water level.)
Loss of Power
In the event of a power failure the "Power" indicator is not illuminated and the entire system is de-
energized, closing all automatic valves and halting all boiler operations. When power is restored the
sequence of operation will resume at Step 5, provided that all the limits are satisfied.
Loss of Water Flow
When the "Water Flow" indicator is illuminated, there is insufficient water flow to close the switch, and
burner operation is interrupted. When water flow is re-established, the sequence returns to Step 5,
provided that the other limits are satisfied.
Low or High Gas Pressure
When the "Gas Press" indicator is illuminated, there is (or has been) too little or too great gas pressure
available for safe and proper operation of the boiler, and power to the programmer is interrupted. If a
gas-supply shut-off valve is closed for any reason, a low gas condition will result.
When gas pressure is restored, the "Gas Press" indicator will remain on and the boiler will remain locked
out until the low gas pressure switch is manually reset.
On boilers equipped with a High Gas pressure switch, the "Gas Press" indicator may also be illuminated
to indicate high gas pressure. This is also a manual reset condition.
Once the switch is reset, the sequence returns to Step 5, provided that the other limits are satisfied.
High Water Temperature
When the boiler water has exceeded both the operating and high-limit temperature; power to the
programmer is interrupted. When the water temperature falls below the high-limit temperature, the boiler
will remain locked out until the switch is manually reset. Once the switch is reset, the sequence returns
to Step 5 to await heat demand below the operating temperature, provided that the other limits are
satisfied.
Low Air
If the "Low Air" indicator remains on for longer than 10 seconds, there is insufficient airflow through the
burner. Check that the burner is clean (see Section 5.2 "Cleaning the Burner") before adjusting the air
inlet damper (see Section 3.10.3). A low air indication does not necessarily mean that the low air switch
is defective.
Ignition Failure
In the event the pilot flame is not detected by the UV scanner during the 10 second trial-for-ignition
period (Step 8), the pilot gas valve and spark ignition are de-energized. At this time a safety lockout
occurs which de-energizes all outputs from the programmer except Terminal A, which is connected to the
"Flame Failure" indicator. A manual reset of the programmer (located inside the control panel) is
required when a safety lockout occurs.
Flame Failure
In the event of a flame failure during a firing period, the main fuel valves are de-energized and the
programmer immediately goes into a "lockout" mode. If flame failure occurs during a trail-for-ignition, a
safety lock-out occurs (see Ignition Failure). If flame failure occurs and the indicator is illuminated, the
programmer must be manually reset.
If any "Manual Reset" limit device trips, DO NOT reset without determining
P-K THERMIFIC
50
®
Gas-Fired Boiler
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