INSTALLATION AND OPERATION INSTRUCTIONS
5-6
SL 20-115 MODULATING GAS BOILER
SYMPTOM
DIAGNOSIS
REMEDY
MAxIMUM IGNITION TRIALS
ERROR
LCD Screen Message
:
Error – Ignition Failure after 3
tries
Boiler has failed to ignite on 3
successive attempts. Boiler in
lockout for 1 hour, then repeats
3-try seq. Consult service
technician if error recurs.
No spark when igniting.
Igniter probe/flame
sensor disconnected.
Check that igniter lead is secure at the control
module and at the probe.
Manual gas shutoff is
closed or gas line not
fully purged.
Check for gas flow. Open manual gas shutoff
and reset boiler.
Gap between igniter
probe rods is too large
or too small.
adjust ignitor probe rod gap as follows:
With Capable Controls ignition module – 3/16”
(5mm)
With Fenwal module – between 1/8th and
3/16th (3.2-4.7mm)
Spark, but no ignition.
Check spark module is sending power to gas valve
– close gas supply, then disconnect (black) electric
housing from face of gas valve, gently spread
plastic tabs to open, and look for 24vac voltage
between blue and brown wires during an ignition
cycle. replace module if no current detected
Boiler ignites, but shuts
off at the end of the
ignition trial. Improperly
grounded pressure
vessel/burner or
unserviceable ignition
lead or spark module.
• Ensure pressure vessel is grounded.
• Check the igniter probe/flame sensor is
electrically isolated from the vessel, and its
ceramic insulator is intact.
• Replace ignition lead
• Replace spark module
HI LIMIT ERROR
On boilers equipped with both
Water high limit AND factory
installed LWCO
LCD Screen Message:
Error – Water High-Limit/LWCO
Water temperature exceeds hi-
limit or water level is low. Boiler
in hard lockout. Will reset in 1
hour. Consult service technician.
Check for illuminated
red light on LWCO
Control Module if
boiler is equipped
with factory installed
LWCO option.
If equipped with
Factory installed
Water high limit only:
a) Check for any
evidence of actual
excess temperature
b) Check temperature
sensors
c) Check for flow
problems
d) Push reset button
(cycle power off and
back on after pushing
reset button)
Red light on
Water level oK - check manual reset water high
limit:
a) Check for any evidence of actual excess
temperature
b) Check temperature sensors
c) Check for flow problems
d) Push reset button (cycle power off and back
on after pushing reset button)
Red light off
Water level low:
a) Check air vent at top of boiler to ensure it is
working and boiler is not air locked
b) Check tridicator for correct water pressure
c) Open water feed point (boiler fill valve or
boiler pressurization unit) to make sure system
is filled to operating pressure.
If boiler is filled but red light does not come on,
check for power at LWCO control module (24
Vac between terminals 1 (yellow) and 3 (blue).
Replace LWCO control module as required.