Cold Weather Operation; Inspection And Maintenance; Fan Section Icing Protection - BAC HXV Operation & Maintenance Manual

HXV HYBRID COOLER

Cold Weather Operation

Inspection & Maintenance
BAC products can be operated at subfreezing ambient temperatures provided proper
operating methods are established and diligently followed.
• Carry out frequent visual inspections and routine maintenance services during
operation in subfreezing weather.
• Ensure all controls for capacity and freeze protection are set properly and
functioning normally.
• Prevent excessively high water levels and possible overflow of the cold water basin due
to clogged strainers or make-up valve malfunction.
• Some unit icing can be expected in very cold weather. Usually this will not effect
the operation of the unit. Resolve any icing conditions that may damage the unit
or the supports, impair the system performance, or create a safety hazard.

Fan Section Icing Protection

There are three basic operational methods which can be used to provide the system's
required cooling: temperature setting, fan control, and dry operation. The method of
control employed on a given application depends upon the climatic extremes which are
expected, the variations in heat load that will be encountered, and the compatibility of the
control system with other portions of the installation.
In subfreezing ambient temperatures, effective icing control may require a combination of
these three methods. Operate each unit with the highest thermal load it can handle, rather
than evenly dividing the total heat load across all cells. During prolonged cold weather
periods, bypass the idle units and drain the basins.
Temperature Setting
Low leaving fluid temperatures promote ice formation. During operation in subfreezing
ambient temperatures, maintain the leaving fluid temperature as high as possible. Ensure
the unit operates with the maximum possible heat load. The minimum recommended
leaving fluid temperature is 50°F (10°C) for HXV units with water (non-glycol) as the heat
transfer liquid and 45°F (7.2°C) for HXV units with glycol as the heat transfer liquid. Coils
will freeze in ambient temperatures of 32°F or lower without a heat load. Use of glycol is
strongly recommended in applications where low ambient temperatures are possible.
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