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point of a water-sensing thermostat in the evaporator (typically about 50°F or 10
C), energy
saver cooling becomes available.
Systems with an Energy Saver Coil should have at least one fluid-sensing thermostat on the
fluid cooler set lower to take advantage of colder ambient temperatures. The desired fluid
temperature for energy saver cooling is 45°F (7.2
C). Field adjustment of fluid-sensing
thermostats is not unusual.
It is desirable to use the energy saver mode as much as possible. However, fluid temperature
that is too cold can cause excessive dehumidification and coil sweating. Fluid temperature that
is too high can also cause the indoor space temperature to rise. This could cause the
evaporator’s microprocessor control to lock out the energy saver mode for one hour while it
reverts to compressor (mechanical) cooling. Adjust the set points of the thermostats to allow the
maximum free cooling time. Over cooling or under cooling the fluid should be avoided. Every
application will have a different ambient temperature and indoor heat load/air distribution profile.
Therefore it is not possible to dictate the exact water-sensing thermostat set points. Field
adjustments are typical to allow fi ne-tuning to specific conditions.
With an Energy Saver coil, the condenser 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 set points which are typically staggered to
maintain water temperature in the 85° to 105°F (29.4° to 40.6°C) range. This is generally the
desired range for glycol cooled systems.
A surge tank is standard on all fluid coolers. This is enough on most applications; however, an
expansion tank should be installed at the highest point in the system and the point of least
pressure.
8.
CONTROLS
Refer to dap4 User Manual for operating instruction, parameter setting and control logic.