WARM WEATHER SHUT DOWN (WWSD)
(See fig. o)
The control enters into WWSD when:
• Slab and outdoor temperatures exceed MELTING
temperature by more than 1.5°F (1°C)
• In WWSD, the snow melting system is shut down to
conserve energy
In cases where a slab sensor has not been or cannot be
installed in snow melting slab, it is still possible for the
SYSTEMpro 311 to operate the snow melting system. In this
mode the control supplies a calculated mixed supply water
temperature to the slab.
NOTE: This mode of operation is generally not
recommended since the control can no longer
regulate slab temperature. As a result, it can cause
the slab to operate at surface temperatures that
are higher or lower than required. A higher surface
temperature can lead to excessive energy usage
and fuel costs. A lower surface temperature can
cause the slab to freeze over.
WARM WEATHER SHUT DOWN (WWSD)
(See fig. p)
When a slab sensor is not in use:
• The Warm Weather Shut Down is determined only from the
outdoor temperature
• If outdoor temperature rises above MELTING setting by
more than 2°F (1°C), control goes into WWSD and ignores
any demand for melting or idling
MELTING MODE (MELTING) (See fig. q)
The SYSTEMpro 311 is a manual snow melting control:
• For the snow melting system to be started, one of four
methods described in section E4 must be used
• When the control is in melting mode, the Melting pointer is
visible in View Menu
• Either EXT, INF or a running time can be read when viewing
STATUS item in View Menu
• The MELTING setting in Adjust Menu sets the theoretical
slab surface temperature that is maintained while control is
in melting mode
Section E3: Slab Without Slab Sensor
77
CONTROL FUNCTION
OVERVIEW
CONTROL FUNCTION OVERVIEW - Section E - Snow Melting
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