This is part of an user manual i used to give for cooling controllers – app007.pdf
The Logic of cooling in temperature control is inverted, Activating the relay powers a compressor which cools the system. A small modification at the output stage, makes any heating controller into a cooling controller. It can also be done with external relay logic, but make sure on power failure (control power line) the compressor ( 3 ph power) shuts down. In all heating and cooling control, when a broken or disconnected sensor is detected, the controller should turn off all outputs and indicate a fault condition.
Before you use a Controller to Cool a Chamber to Say +5 Deg C.
Do not Connect the Controller. Directly Connect the Cooling Device e. g. : Compressor. to the system and check the maximum cooling it can produce. In case temperature goes to 0 deg or -10 deg then by using a STC1000 you can control at +5 deg.
But if directly you get cooling of only upto +10 deg then it is impossible for any controller to produce extra cooling, in such a case as this use a better compressor or more insulation.
Connect Sensor properly and replace when broken keep sensor close to the source of cooling.
Deadband (DB) at minimum is 1 Deg this is the best setting, maximum setting of deadband may increase compressor life and also save power but will produce a huge variation in temperature.
If large Variation of temperature is present and you need accurate control Reduce deadband to min.
Unit is factory set db at 1 deg, remove seal tape before dead band adjustment.