3. Ensure that no lock-out/tag-outs are present.
Check that all ventilation & combustion air
openings and louvers are clean and free of
Start-up Checks
debris.
Verify normal boiler water level.
Check that all stack dampers are open.
Examine the boiler furnace for foreign material
and loose/displaced refractory.
Ensure that fuel lines are not leaking gas
(distinctive smell) or oil (liquid accumulation).
Ensure the manual fuel valves are open.
Based on National Board of Boiler & Pressure Vessel
Inspection
4. Complete start-up checks first.
The Start-up sequence should be closely
Nexus Touchscreen
monitored to ensure proper mechanical
Start-up Overview
function.
Remain present until the boiler successfully
switches to modulation mode.
Note: You may experience a slight lag/delay
when pressing the touchscreen. Use slow
deliberate touches with the tip of your finger.
Review the start-up sequence on the following
pages:
5. The burner is held Burner Off/Standby
in this state until
all faults are
removed. To mute
an alarm, press
and release
"Mute." To reset a
fault after
troubleshooting,
press and HOLD
"Reset” for 3
seconds. Press
"Start" to initiate
automatic start-up
Sequence.
Nexus 6000 Start-up Screen Shots
6. The fuel and air Proving Closed
servos are driven
closed and must be
within +/- 5° to the
closed positions
stored in memory.
Variable Frequency
Drives (VFD) must
read zero.
Nexus 6000 Start-up Screen Shots
7. The burner control Proving Purge
recognizes a call
for heat. The
control verifies a
fuel/profile
selection.
Nexus 6000 Start-up Screen Shots
8. The controller Pre-Purge
confirms all
required drives are
at their purge
positions and gives
a "purge proved"
signal. The
controller remains
at this state until
the burner
controller signals
the end of pre-
purge, indicating
that all combustible
gases are safely
removed.
Nexus 6000 Start-up Screen Shots
9. The selected Moving to Ignition
motors are moved
to their ignition
positions. The
"purge proved"
signal is switched
off. When the
drives have all
stopped moving,
the control
advances to
ignition.
Nexus 6000 Start-up Screen Shots
10. The controller Pilot Trial for Ignition (PTFI)
confirms that a
pilot flame exists
for 10 seconds
before switching to
main ignition.
Nexus 6000 Start-up Screen Shots
11. The controller Main Trial for Ignition (MTFI)
confirms all
required drives are
at their ignition
positions, and
gives an "ignition
proved" signal. The
controller will hold
the drives at their
respective ignition
positions until the
signal to modulate
is received from
the burner
controller.
Nexus 6000 Start-up Screen Shots
12. Once the AUTO Moving to Low Fire
signal is received,
the fuel and air
motors are moved
from their ignition
positions to their
low fire positions.
These positions
may or may not be
the same as the
ignition positions.
Nexus 6000 Start-up Screen Shots
13. Once the fuel and Modulating (Online Operation)
air motors reach
their low fire
positions, they are
modulated
according to the
demand placed on
the burner.
Nexus 6000 Start-up Screen Shots
14. All servo motors Move to Post-Purge
are moved to low
fire position
(caused by a fault
or manual
shutdown). The air
damper is held in
position or moved
to low fire.
Nexus 6000 Start-up Screen Shots
15. The controller Post Purge
confirms all
required drives are
at their purge
positions and
gives a "purge
proved" signal. In
the event of a
shutdown or
lockout, the burner
will shutoff and
remain in standby.
Nexus 6000 Start-up Screen Shots
16. Familiarize yourself with the following faults.
Understand the cause of the fault before
restarting the boiler.
Common Faults
Review the start-up sequence to bring the
boiler back online.
Remain present until the boiler successfully
switches to modulation mode.
Follow proper reporting procedures.
Nexus 6000 Common Fault Screen Shots
17. This fault is the Low Water Cut Out (LWCO)
first low water
indicator
(McDonald-Miller).
Since it is not a
lock-out, the boiler
will reignite once
the water level is
resolved. Follow
proper reporting
procedures.
Nexus 6000 Start-up Screen Shots
18. This fault is the Low Water Probe
second low water
indicator (extra low
water). Since it is a
lock-out, you must
press and hold
“Reset” for 3
seconds to clear
the alarm AFTER
the water level is
resolved.
Nexus 6000 Start-up Screen Shots
19. The Variable Fan Fault (VFD)
Frequency Drive
(VFD) did not
properly start the
fan. Ensure the fan
has power and is
free from
obstructions.
Nexus 6000 Start-up Screen Shots
20. This fault indicates Air Flow
improper
combustion air.
Ensure the motor
is running and the
damper is properly
positioned and
free from
obstruction.
Nexus 6000 Start-up Screen Shots
21. Pilot gas pressure Low Pilot Gas
does not meet
minimal
requirements.
Check that manual
gas valves are
open. Note: pilot
gas valves are
upstream from
solenoid valves.
Nexus 6000 Start-up Screen Shots
22. This fault indicates Main High Gas
that the gas
pressure exceeds
set-points on the
regulator valves.
Verify that the set-
points are properly
calibrated.
Nexus 6000 Start-up Screen Shots
23. Ensure the boiler is in
low-fire operation before
blowing down.
Open the quick-opening
Bottom Blowdown
valve closest to the boiler
first.
Procedures
Steadily open the slow-
opening valve until you
see a ½” to 1” drop in the
sight glass.
Quickly close the slow-
opening valve, backing off
slightly from fully closed
to relieve pressure.
Close the valve nearest
the boiler.
Illustration from CleanBoiler.org
24. Ensure the boiler is in
low-fire operation before
Water Column Blowdown
blowing down water
columns.
Slowly open ONE hand
valve, taking care not to
Procedures
trip the boiler on low
water. Close the valve
after a healthy flush
occurs.
Repeat process for
remaining columns.
Blow down columns once
a shift to keep bowls
clean.
Illustration from Johnston Boiler Company
