3
Troubleshooting
(continued)
Service Manual
Table 3-4 Troubleshooting Chart - Fault Messages Displayed on Boiler Interface
FAULT
DESCRIPTION
CORRECTIVE ACTION
Gas Pressure SW
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
SMART SYSTEM
display
to reset.)
The gas pressure switch contacts on the
Low Voltage Connection Board are open.
• Check for a loose or misplaced jumper on the Low
Voltage Connection Board.
• Check for the addition of a device wired across the gas
pressure switch terminals on the Low Voltage
Connection Board.
Flow Switch/
LWCO
(will require a manual
reset once condition has
been corrected. Press
the RESET button on the
SMART SYSTEM display
to reset.)
Either the optional flow switch or the optional
low water cutoff is not making.
• Check boiler pump operation on a call for heat.
• Check for closed valves or obstructions in the boiler
piping.
• Verify system is full of water and all air has been
purged from the system.
• Check for loose or misplaced jumpers if flow switch or
LWCO is not installed on the L o w Voltage
Connection Board.
Blown fuse.
• Replace fuse F3 on the control board, see page 33
of this manual.
Blocked Drain SW
(will require a manual
reset once condition has
been corrected. Press
the RESET button on the
SMART SYSTEM display
to reset.)
The blocked drain jumper has been removed
from the wire harness.
• Check wire harness and replace jumper if necessary.
• Check for loose wiring connection at wire harness
plugs.
Air Pressure SW
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
SMART SYSTEM
display
to reset.)
Air pressure switch contacts are open.
• Check the wiring connections to switch. Wires should
be connected to the common and normally closed
terminals.
• Air intake lengths exceed the maximum allowed
lengths. Refer to Section 3 - General Venting of the
Knight Wall Mount Installation and Operation Manual
for proper lengths.
•
Check for obstruction or blockage in the air
intake pipes or at terminations.
• Check reference hoses connected to the air pressure
switch for blockage or obstruction.
• Inspect the burner. Reference page 31 of this manual
for removal and cleaning procedures. Replace if
necessary.
• Inspect the heat exchanger. Reference page 32 of
this manual for removal and cleaning procedures.
Replace if necessary.
• Faulty air pressure switch. Replace switch.
Anti-cycling
The main control board has received a call
for heat too quickly after the previous call
for heat has ended.
• The control board will release the call for heat after a
set time period.
• The control board will release the call for heat if the
inlet temperature drops too quickly.
37
Summary of Contents for WH 399
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