Weil-McLain 550 MBH Nstallation And Operation Manual page 100

®
SlimFit Series 3
Troubleshooting
Troubleshooting suggestions for SlimFit boilers
Control Fault Displays, Diagnostics and Suggested Corrective Actions
Display Condition
Nothing shown Control is not receiving 24V
on display power.
screen and boiler
will not respond
to call for heat
Nothing shown Control is not receiving 24V
on display power.
screen and boiler
will not respond
to call for heat
Nothing is Control is not receiving 120V
shown in display power.
screen and no
other boiler
components are
operating
Nothing is Occurs if the communication
shown on is lost from the control to the
display screen, display.
but boiler is
operating
Display contrast needs to be
adjusted.
TEMP RISE TOO Occurs if supply water
QUICKLY temperature in heat exchanger
rises faster than 2º F per
second during the first two
minutes the burner is on.
DISPLAY COMM Occurs if display
Fault communications out for 30
seconds.
100
COMMERCIAL CONDENSING GAS
(continued)
Diagnostics
Check wiring for short circuit or
incorrect wiring.
Check 3-amp low voltage fuse
on control shown on page 97.
Check transformer connection
to the control per wiring
diagram. Check for 24V output
of transformer.
Check wiring for short circuit or
incorrect wiring.
Check 3-amp low voltage fuse
on control shown on page 97.
Check transformer connection
to the control per wiring
diagram. Check for 24V output
of transformer.
Check service switch and/or
circuit breaker to boiler is turned
on.
Is there 120 VAC at the service
switch?
Check for 120 VAC at the line
voltage terminal block located
inside the top left electrical
compartment.
Inspect 12-amp fuse as shown
on page 97. Replace if necessary.
Check for loose connections
and proper pin alignment/
engagement on the control's
plug P9, Pump/Com board P6 +
J1, and the back of the display
circuit board.
Cycle power off and on using
boiler power switch and check
for operation.
or
Look at the screen from other
angles.
Automatically resets after 1
minute delay or using manual
reset on display.
Manual reset is necessary after 5
automatic resets have occurred
during the same Priority heat
demand. Reset using manual
reset screen on display.
Automatically resets when
communication is re-established.
-
FIRED WATER BOILER
(continued)
Corrective Action(s)
Correct wiring per wiring diagram including connection of transformer
to the control.
Replace fuse with proper part found in replacement part section of this
manual. If fuse blows again recheck wiring per diagram.
Replace transformer if it is receiving 120VAC, but not outputting 24VAC.
Correct wiring per wiring diagram including connection of transformer
to the control.
Replace fuse with proper part found in replacement part section of this
manual. If fuse blows again recheck wiring per diagram.
Replace transformer if it is receiving 120VAC, but not outputting 24VAC.
Turn on service switch to power boiler.
Troubleshoot and correct the power supply to the service switch.
Correct wiring inside the control pod using the wiring diagram in this
manual.
Replace the fuse with proper part found in the replacement part section
of this manual. If fuse blows again recheck wiring per diagram.
Check for continuity on the wire harness from the display to the control.
See repair parts section for proper replacement part.
Replace with new display module. See repair parts section for proper
replacement part.
Power cycle the boiler, wait about 45 seconds then Press and hold
the Enter button. While holding the Enter button, tap the up or down
buttons to adjust the contrast level. If this does not work replace display.
Verify water pipe is installed correctly per instructions in this manual.
Verify proper circulator and speed for boiler size and system
requirements.
See message displayed TEMPERATURE SENSOR and follow procedure for
loose connections.
Check for a loose connection at the molex plug on the control and
connection on the back of the display.
—
Boiler Manual
Part number 550-100-168/0516