Sterlco Micro Series Water Temperature Control Unit - Manual (Page 40)

Page 40 MICRO Series Water Temperature Control Units
Chapter 7: Troubleshooting
Condition Possible cause Solution
No power.
Check main disconnect, fuses,
wiring, and power lead to unit.
Wrong voltage supplied to unit.
Voltage must be within plus or
minus 10% of nameplate rating.
Defective on/off switch. Replace.
Control circuit fuse blown. Replace.
Unit does not turn on.
Defective control transformer. Check transformer.
Broken or loose wire in pump motor
control circuit.
Locate and repair.
Pump motor contactor holding coil is
open.
Repair or replace.
Low water pressure light on.
Check for at least 16 psig
(110.32 kPa/1.1 bars) water
pressure on
WATER IN or CITY
WATER MAKEUP .
Water supply to unit is turned off. Open water supply.
Unit does not run.
Pump overload light on.
Reset and test each leg for
balanced amp draws.
Pump running in reverse.
Verify proper rotation. If not
clockwise, reverse any two
incoming power leads.
Foreign matter in the system. Clean the system. Low pump pressure.
System has minimal back pressure, and
is operating at the far end of the pump
curve. As long as there is satisfactory
process temperature control
there is no problem.
Foreign matter obstructing system. Clean the system.
Restricted water flow.
Check for closed valves etc. Be
sure all lines are properly sized.
High pump pressure.
System has high back pressure, and is
operating at the near end of the pump
curve; a low flow condition. As long as there is satisfactory
process temperature control
there is no problem.
Insufficient cooling or makeup water
pressure.
Check for 25 psig (172.38
kPa/1.72 bars) water pressure
on WATER IN or CITY WATER
MAKEUP.
Pressure switch circuit is
open.
Switch is broken.
Jump power across switch and
see if unit starts. Replace switch
if needed.