Thermolator TW Series UGH025-0504
6-22 TROUBLESHOOTING
IMPORTANT: Always
refer to the wiring dia-
grams that came with
your Thermolator to
locate specific electrical
components. Illustrations
in the User Guide are
intended to be represen-
tative only.
REPLACING THE
HEATER
CONTACTOR
Thermolators use mercury displacement heater contactors. The
heater contactors should be replaced if you have checked:
l the amp draw on each of the three-phase legs and discov-
ered a voltage imbalance greater than 10%.
l the continuity and found that ohms at the coil equal zero.
To replace the heater contactor:
Disconnect and lockout the main power.
Open the electrical enclosure door.
Turn the screw on the front panel counterclockwise to
open.
Disconnect the wires from the heater contactor
Make sure you label the wires to ensure you can connect
them correctly to the new contactor.
Remove the contactor
by removing the screws that
hold it in place.
Discard old contactor
using the proper disposal
procedure. See Material
Safety Data Sheet.
Reverse this proce-
dure
to install the new contactor.
Make sure the wires are
connected correctly.
1
2
3
4
5
WARNING: Hazardous Substance
Thermolators use mercury displacement contactors.
Mercury is considered a hazardous substance and must
be dealt with accordingly. See the Material Safety Data
for information on the how to avoid the potential haz-
ards and how to clean up and dispose of mercury if it
spills.
WARNING: Electrical Shock Hazard
Only qualified service personnel who have been
trained on electrical testing and the procedures for
avoiding the hazards should diagnose or correct prob-
lems that require opening the unit with power on.
6
Heater contactor
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