Single-zone snow melt control installation and operation manual | 25
Additional melting time
A Pavement Snow and Ice Sensor
(A3040090) automatically shuts off the snow
melting system when the water sensor is
dry. Due to the construction of the slab and
the layout of the heating pipe or electrical
cable, there may be areas that do not
melt completely. The Additional Melt
Time setting in the Set Temp menu allows
the installer to set additional melting time
after the sensor is dry.
Idle operation
When the snow melting system starts
from a cold temperature, there may be a
long time delay before the slab is warm
enough to melt snow. This time delay allows
snow to accumulate on the slab which is
not acceptable in some commercial and
institutional applications. To decrease the
start-up time, the slab can be pre-heated to
maintain a minimum temperature.
This is known as the Idle temperature.
Idling requires large energy consumption
and is generally recommended for
institutional and/or commercial installations
where safety concerns are paramount.
Idle is shown on the display when the
control is in idle operation.
When designing a snow melting system, an
engineer may specify the amount of allowed
snow accumulation as the Snow-free Area
Ratio. There are three different levels. A
Snow-free Area Ratio of 1 is defined as a
system that melts all snow as it falls with
no allowed accumulation. This requires
that the Idle temperature be set just below
freezing. Examples of these types
of applications include:
• Hospital emergency areas
• Helicopter landing pads
• Parking garage ramps
A Snow-free Area Ratio of 0.5 is defined
as a system with partial snow accumulation
on the slab but not in all areas.
These types of systems may also use idling
but usually set at a temperature several
degrees below freezing to reduce energy
consumption. Applications may include:
• Steep residential driveways
• Commercial sidewalks
• Loading docks
When moisture is detected and both
the slab and outdoor temperatures
are below the Melting setting, the
control automatically starts the snow
melting system. The snow melting
system operates to heat the slab
to the slab target temperature and
continues to operate until the time set
by the Manual Melt Run Time in the
Set Temp menu elapses.
Pavement snow
and ice sensor
Dry
WWSD
Touch STOP key
Aerial Snow Sensor and slab dry
and MELT time elapses
Aerial Snow Sensor detects water
Touch MELT key
CWCO
Timed
melt
Idle
or
off