Section 3 – SR-2 Software Description
FreshSet Floor Limit
Micro Rev
All
HMI Rev
All
Choices
1.0°F (0.5°C) to 6.0°F (3.5°C)
Factory Set
2.5°F (1.4°C)
Exceptions Only appears if Controlling Sensor =
Return.
Description This feature allows the minimum
discharge air temperature during return air
modulation to be programmed. When the discharge
air temperature reaches this number of degrees
below setpoint, control is switched to the discharge
air sensor. The discharge air temperature is limited
to the programmed limit to provide additional
protection from freezing for sensitive loads. Control
will switch back to the return air sensor when the
return air temperature reaches setpoint.
For example, with a 35°F (1.7°C) setpoint and a
2.5°F (1.4°C) Floor Limit, the discharge air
temperature is limited to 32.5°F (0.3°C).
The minimum discharge air temperature is controlled
to 29°F (-1.5°C) regardless of the programmed floor
limit with setpoints of 30°F
(-1.1°C) and higher.
FreshSet Freeze Protection
Revision
All
Revision
All
Choices
Off or On
Factory Set
Off
Exceptions Only appears if Controlling Sensor =
Return.
Description Freeze protection controls the
discharge air temperature to 35°F (2°C), minus the
limit determined by the setting of FreshSet Floor
Limit.
Freeze Protection is a subset of return air
modulation control. The mode is designed to allow
the unit to pull the return air temperature to setpoint
while preventing freeze damage. It is designed for
use with medium to high setpoints and high
refrigeration loads or lightly insulated trailers. This
feature is active for setpoints above 35°F (1.7°C).
Example: Setpoint is 49°F (9°C). Floor Limit is 4°F
(3.3°C). The minimum discharge air temperature
with Freeze Protection on is 31°F, determined by
(35°F-4°F). In Celsius the minimum discharge air
temperature is -0.5°C, determined by
(1.7°C – 1.2°C).
Freeze Protection is not available for OptiSet ranges
where the maximum setpoint temperature is less
than 35°F (1.7°C).
3-38
31 January 2005
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