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W W W . B A L T I M O R E A I R C O I L . E U
COLD WEATHER OPERATIONS
About cold weather operation
BAC cooling equipment can be operated in sub freezing ambient conditions provided the proper measures are
taken. Listed below are general guidelines which should be followed to minimize the possibility of coil freeze-up.
As these guidelines may not include all aspects of the anticipated operation scheme, system designer and
operator must thoroughly review the system, location of the equipment, controls and accessories to ensure reliable
operation at all times.
Protection against sump water freezing
Units exposed to below freezing ambient temperatures, require protection to prevent freezing of the water in the
wet sump. During dry operation all water will drain into the wet sump, that is shielded from the air stream. Heaters
in the wet sump are sufficiently sized to prevent freezing at temperatures as low as -18°C at full speed of the fan
system.
CAUTION
Switch off heaters when the sump is drained.
Capacity control
In addition to protecting the sump water, all exposed water piping, in particular make-up water lines should be heat
traced and insulated.
Spray pumps also need to be heat traced and insulated from pump suction to the overflow level, if they can be
exposed to sub-freezing ambient conditions.
It is necessary to prevent the recirculating water from approaching freezing conditions when the system is
operating under load. The most « critical » situation occurs, if operation at subfreezing conditions coincides with
light load conditions. The key to protecting the recirculating water is capacity control by adjustment of air flow to
maintain the temperature of the recirculating water minimal above freezing point. As a rule of thumb this minimum
temperature is 5°C, but there are applications, where even lower temperatures can be accepted. (Contact your
local BAC Balticare representative for advice.)
The desired method to match the cooling capacity to load and weather conditions is to adjust the air flow by the
use of modulating controls (variable speed drives).
Alternatively, multi speed fan motors or fan cycling can be applied, but fans operating on a common heat exchange
section should always be operated simultaneously.
It is not recommended to cycle the spray pump as a means of controlling the unit capacity.
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HFL
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4 Cold Weather Operations
4 Cold Weather Operations