Table 5-1. Troubleshooting - Continued
2. Low fire switch closed, burner
does not ignite - Continued
n. Electrode cracked.
n. Remove burner and cycle low fire
start switch. Observe spark, if spark
is weak remove and inspect elec-
trodes. Replace cracked electrodes.
o. Air in fuel line.
o. Burner cycles, oil pressure gage
fluctuates (see malfunction 2, step
f. Allow burner to recycle until oil
displaces air and ignites.
p. Time delay contact block
p. Observe block to see if cocked on
guides. Free block to work freely on
2A. High fire switch closed, burner
does not ignite.
a. Fuel valve or lines restricted or
a. See malfunction 2, step e.
b. Fuel valve solenoid coil loose or
b. See malfunction 2, step f.
c. Burner nozzle is plugged.
c. Remove burner and inspect nozzles.
Remove nozzle and clean orifice,
nozzle strainer and supply pipe.
d. Flame safeguard contacts dirty.
d. See malfunction 2, step h.
e. Wire loose or broken.
e. Check conductors of control circuits
5 and 6 from control terminal board
to high fire switch for tightness and
continuity. Check conductor of
circuit 5 from terminal board to
flame safeguard for tightness and
continuity. Tighten, repair or replace
conductors as necessary.
f. Air in fuel lines, occurring when unit
is restarted after fuel lines
f. With high fire switch turned on, oil
supply pressure will drop causing
low fire burner to trip out. Restart
low and high fire until all air is
displaced by oil.
g. Defective high fire start switch.
g. See malfunction 1, step h.
3. Air pressure switch contacts open,
inadequate air. (Switch closes at 0.15
a. Blower inlet obstructed.
b. Air sensing static tube plugged.
b. Remove ¼-inch copper tubing from
air flow switch and connect water
tube manometer to tubing. Start fan,
if manometer does not read at least
0.15-inch the switch will not close.
Clear static tubing by blowing air
through tube from switch side.
c. Static tube not aligned.
c. Same as malfunction 3, step b.
Remove burner and align opening of
tube to face toward the blower end of
air duct. Assure tube is centered in
duct. Rest air sensing is toward
blower and slightly downward.
d. Switch setting incorrect.
d. Switch will not shut down burner
when obstruction is placed in front of
blower housing. Increase set point
by turning adjustment clockwise.
Check the trip point by covering
blower inlet. When setting switch by
this method, hold cover over inlet for
only a few seconds or until black
smoke emits from exhaust. If switch
is set properly burner will trip in-
stantly. Switch will not allow
burner to ignite because setting is