Sequence Of Operations - Harsco Industrial SC-1500 Owner's Manual

3. Perform combustion check (Refer to
high fire & low fire if the O
Installation and service must be performed by a qualified installer or service
agency that has been trained on the Harsco Industrial, Patterson-Kelley boiler.
If any "Manual Reset" limit
device trips, DO NOT reset
without determining and
correcting the cause. Manual
Reset Limits include: Flame
safeguard, high or low gas
pressure, high temperature
limit, stack temperature, low
water level. Attempting to
operate a boiler without
diagnosing the cause of failure
can result in unsafe operation,
increasing the risk of injury.
Never attempt to bypass a
safety limit device.
N !
OTICE
Once the boiler begins the
ignition sequence, the firing
sequence will continue until main
flame is reached regardless of
heat request. The sequence can
be interrupted by turning the
power switch off.
7. The NURO Control modulates the firing rate between low and high fire to maintain the desired outlet
water temperature.
8. The burner will continue firing until the outlet water temperature exceeds "CH SETPOINT" plus "CH
DIFFERENTIAL OFF". At this temperature, the gas valves are closed combustion air fan continues to
run until the "POST PURGE TIME" timer has expired.
9. When the outlet water temperature is reduced by the load on the system, a heat request is generated.
The operating sequence will recycle to Step 3.
Section 3.11.2
% or CO % are out of range.
2 2
NOTE

5.5 Sequence of Operations

1. When the Boiler On/Off switch is turned on, power is provided
through over-current protection (fuse and/or circuit breaker) to the
boiler control and the combustion blower.
2. When the outlet water temperature drops below "CH SETPOINT"
minus "CH DIFFERENTIAL ON", a heat request is generated.
3. Provided all interlocks are made and the remote enable signal (if
installed) is active, the boiler will attempt to start.
4. The NURO control checks to make sure air pressure switch is
open indicating there is no airflow through the boiler. The
combustion blower is then driven towards the pre-start fan speed.
When the air pressure switch closes, the "PRE PURGE TIME"
timer is started. Once the "PRE PURGE TIME" timer expires, the
blower is driven to the ignition speed.
5. A trial for ignition begins and the sequence of events is illustrated
graphically on the next page. A valid flame signal must be
detected within 4 seconds after the gas valves open (elapsed
time 7 seconds).
6. After a successful ignition, the fan is driven to low fire and the
"CH LOW FIRE HOLD TIME" timer is started. Once the "LOW
FIRE HOLD TIME" timer expires, the boiler is released to
modulation.
P-K SONIC
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and Section 3.11.3) and adjust air/gas mixture at
TM
Gas Fired Boiler