Instruction manual

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(For special order units with the following controller.)
Operation of the Watlow 945 High Limit Instrument
This is intended as a quick reference guide and should not be substituted for reading
the product manual! The purpose of this sheet is to get the furnace up and running quickly
and simplify operation in the beginning.
Your new furnace was tested at the factory prior to shipping and the instrument(s) were
tuned for optimum performance. There should be no need for further adjustment in the field. It is
also locked out on several levels to prevent unauthorized changes. If you have any problems,
CALL MIFCO FIRST!
NOTE: This lockout is installed for your protection. If you feel the need to change the
factory parameters, call MIFCO first! We will discuss your needs and help you through the
process. If you change the parameters on your own and run into problems, you will be
charged a fee of $20.00 to troubleshoot the problem over the phone. Troubleshooting for
unauthorized tampering will not begin until we have a VISA or MASTERCARD number.
OPERATION
The 945 High Limit Instrument is relatively simple to operate. It comes preconfigured with
maximum high limit setpoints in place and these operate automatically when the furnace is run.
The purpose of the High Limit system is to protect the furnace in the event the main control
fails and the furnace attempts to “run away”. In high temperature furnaces and the upper chamber
of dual chamber units, this value is pre-set by MIFCO at 2250°F; in low temperature ovens and the
lower chamber of dual chamber units, this value is pre-set at 1225°F. The only reason to adjust the
setpoint would be to protect a particular process from overheating (at some temperature below the
maximum temperature of the furnace or oven). If adjustments are required, set the high limit setpoint
at a value of approximately 30 degrees greater than the main controller’s setpoint. Please call the
factory for details on this procedure.