Instruction manual

107
Insufficient pressure differential. Ensure that the sample piping is tapped into
the discharge side of the circulation pump, and
flows to either atmospheric pressure (the
cooling tower sump) or the suction side of the
circulation pump.
Insufficient prebleed prior to biocide If the biocide addition and subsequent lockout
addition and bleed lockout. of the bleed will cause the conductivity to rise
to the high alarm limit, then the prebleed
needs to be extended to drop the conductivity
further before starting the biocide addition. Go
to the Biocide 1 or Biocide 2 Output Page
(whichever one has caused the problem). If the
prebleed is not used, then click on the radio
button to prebleed either by time or by
conductivity. If the prebleed is already used,
increase the amount of time, or decrease the
conductivity value.
Control direction is set incorrectly. The normal control direction for an open
recirculation loop cooling tower is “Force
Lower”. Go to the Bleed Output Page and
check the setting for the control direction.
Faulty bleed solenoid. Repair or replace the bleed solenoid.
Fuse blown. Replace fuse (F3).
Faulty bleed solenoid wiring. Correct wiring.
Faulty bleed relay. Replace the relay interface board.
System Conductivity Low Alarm
This error message indicates the conductivity reading is below the user-programmed minimum
allowable value.
Possible Causes Corrective Actions
Dirty conductivity electrode. Clean and calibrate the conductivity sensor as
described in Section 7.2 above. If calibration
fails, see troubleshooting for Conductivity
Calibration Failure above.
Faulty conductivity electrode wiring. Correct wiring.
Faulty conductivity electrode. Replace sensor.
Prebleed time set too high, prebleed If the low alarm happens after a biocide
conductivity set too low. addition, go to that Biocide Output Page, and
reduce the prebleed time, or increase the
prebleed conductivity.