Data Aire DAFC-11 Manual de usuario descargar pdf (Pagina 10)

Fan Motor Controls

Fluid cooler fan motors are cycled on and off by individual water-sensing thermostats

strapped to the leaving water header. The ﬁ rst fan motor will only have a thermostat if the

unit has an energy saver coil. Without the optional energy saver coil, the ﬁ rst fan motor runs

whenever there is a call for cooling via an auxiliary signal sent by the indoor evaporator.

The water-sensing thermostats have adjustable setpoints which are typically staggered

to maintain water temperature in the 85° to 105° F range. This is generally the desired range

for glycol cooled systems. These set points are factory set but may require ﬁ eld adjustment

based on local conditions and application.

Energy Saver Cooling

In colder climates, the evaporator will often be equipped with an additional free cooling

coil to take advantage of the colder ambient temperatures. When incoming ﬂ uid falls below

the setpoint of a water-sensing thermostat in the evaporator (typically about 50° F), energy

saver cooling becomes available.

Systems with an energy saver coil should have at least one ﬂ uid-sensing thermostat on

the ﬂ uid cooler set lower to take advantage of colder ambient temperatures. The desired ﬂ uid

temperature for energy saver cooling is 45° F. Field adjustment of ﬂ uid-sensing thermostats

is not unusual.

It is desirable to use the energy saver mode as much as possible. However, ﬂ uid

temperature that is too cold can cause excessive dehumidiﬁ cation and coil sweating. Fluid

temperature that is too high can cause the indoor space temperature to rise. This can cause

the indoor microprocessor controls to lock out the energy saver mode for one hour while it

reverts back to compressorized cooling. Adjust the setpoints of the thermostats to allow the

maximum free cooling time. Overcooling or undercooling the ﬂ uid should be avoided.

Every application will have a different ambient temperature and indoor heat load/air

distribution proﬁ le. Therefore it is not possible to dictate the exact water-sensing thermostat

setpoints. Field adjustments are typical to allow ﬁ ne-tuning to speciﬁ c conditions.

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Data Aire DAFC-11 Manual de usuario Pagina 10