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SAGINAW CONTROL & ENGINEERING • A/C USER MANUAL
4. Technical Information
Concise Unit Description
Heat Exchangers are used where the heat generated by energy losses in control cabinets must be conducted away to
protect temperature-sensitive components. The characteristics graph shown in the “Performance Characteristics” section
applies to external (ambient) air as the coolant
In Air-to-Air Heat Exchangers, the internal temperature of the control cabinet cannot be cooler than the ambient temperature.
There are natural limits to the cooling performance, dependent on the air supply temperature and the requirement for a
temperature difference of at least 9
°
F. Unlike systems in which the heat generated is allowed to escape by air convection
through ventilation slots, with the Heat Exchanger, the clean air inside the control cabinet is prevented from mixing with the
air outside, which may well be unclean.
5. Functional Principle
Functional Principle
The Heat Exchanger is a cooling device that creates a heat-transfer through a large area of thin aluminum sheet metal
folded up in the Heat Exchanger core by means of forced convection. Used within an enclosure, it uses the ambient air as
the cooling medium, thus avoiding the utilization of refrigerant.
The cooling performance of the Heat Exchanger is dependant on the ambient (external) air temperature. The internal fan
is set to be always on. The external fan is controlled via a controller. When the cabinet temperature increases beyond the
pre-set thermostat temperature, the external fan is switched on and the Heat Exchanger starts cooling. Cooling stops when
the cabinet temperature cools below the pre-set temperature. Switching difference is 5.4
°
F.
