Troubleshooting
5-2
750-136
Model WB Electric Boiler Manual
Low water alarm pilot light on.
• Float-type LWCO: Water below
cutoff line on float cage.
• Float-type LWCO: Float stuck/
switch mechanism jammed.
• Probe-type LWCO: Probe circuit
open/water below cutoff level.
• Probe-type LWCO: Probe or relay
faulty.
• Assure unit has proper water
level. Check that LWCO line is at
proper level.
• Check that float blocking plug
has been removed. Perform blow-
down of float cage. Assure switch
plate operates freely.
• Check for loose connections/
improper wiring. Assure unit has
proper water level.
• Replace probe or relay.
Control power pilot light on, alarm
pilot lights off, contactors not ener-
gized.
• Alarm pilot light(s) burned out.
• Step control fuse blown.
• Pressure/temperature control
improperly wired to step control.
• Replace pilot light(s).
• Replace fuse.
• Check that wiring is per control
literature and per unit wiring dia-
gram.
Steps do not all energize.
• Step control faulty.
• Contactor coil inoperative.
• Step control relay(s) faulty.
• Replace step control.
• Check for loose coil connection.
Replace contactor.
• Check that relay is tight in socket.
Replace relay.
Steps do not draw rated current
• Branch circuit fuse(s) blown.
• Element bussing improper.
• Check element(s) for proper ohms
and resistance to ground then
replace fuse(s).
• Check that element bussing is per
wiring diagram.
Contactors noisy (chatter).
• Element(s) open.
• Contactors damp/dirty.
• Replace faulty element(s).
• Blow out contactors with com-
pressed air. Remove contactor,
disassemble and clean, and
replace contactor.
Problem Possible Cause Action
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