OPERATION
CHILLER-IOM-2004-E
37
3.7.
Fan control pressure switch and thermostat
The function of these devices is to ensure a level of head pressure compatible with proper unit operation.
An increase in outdoor air temperature increases head pressure, and this is maintained at its required value by fan operation.
3.8.
Antifreeze function
This function only exists on units designed for glycolated water or glycol/water chilling for which the freezing
temperature depends on the concentration of the solution.
Whatever type of device is used (see case 1 and 2), cut-out by the antifreeze function causes immediate unit stoppage.
CASE 1: Antifreeze thermostat:
This device monitor chilled liquid temperature at the evaporator outlet. It triggers when the temperature goes below the
minimum value (+ 4°C for water).
CASE 2: Antifreeze pressure switch:
This monitors evaporating pressure of the refrigerant. It triggers when the temperature goes below the preset minimum
value. Note: On units fitted with CLIMATIC control, see the appropriate user manual for more specific details.
4.
UNIT OPERATION: ELECTRICAL AND CONTROL FEATURES
See the specific «Basic CLIMATIC controller» manual
4.1.
Fan over current protection
Circuit breaker designed to stop the fan motors in the event of phase over current in relation to the permitted value.
4.2.
Compressor motor over current protection
Circuit breaker designed to protect each motor winding against accidental over current.
4.3.
Flow switch for the chilled liquid (standard)
This control device initiates unconditional unit stoppage as soon as the flow of chilled liquid (water, glycolated water, etc...) ensured by the
pump becomes insufficient, since this could cause rapid evaporator freeze up. When the contact opens due to a lack of flow the unit stops
immediately.
If the purchaser installs a flow switch himself, electrical connections should be made to a dry contact of Climatic.
SPECIAL CASE OF HYDROLEAN
This control device is supplied loose as standard on all HYDROLEAN and initiates unconditional unit shut down as soon as the flow of
chilled liquid (water, glycolated water, etc...) is too low.
On HYDROLEAN units a cable is provided to connect the external flow switch to the control panel.
If the user installs a flow switch himself, electrical connections should be made to the two remote interlock terminals (dry contact).
The type of connection can vary depending on the size of the unit
EVAPORATOR
Electrical connection to main
electrical cabinet
