36 of 48
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. The display shows "System is Idling" 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
A Snow-Free Area Ratio of 0 is defined as a system that
allows snow accumulation. These systems operate the snow
melting system from a cold start resulting in the lowest energy
consumption costs and the longest times to start melting snow.
In this case set the Idle to off. This is recommended for most
residential applications such as:
• Flat residential driveways
• Patios
• Residential sidewalks
Some systems are designed for keeping a slab surface free of
ice rather than free of snow. The most common applications
include:
• Car wash bays and aprons
• Aircraft hanger aprons
• Turf conditioning on golf course greens
These systems require the use of Idling at or near freezing
throughout the winter and may result in high energy consumption.
Storm Operation
The Storm operation combines the benefits of a fast response
time together with lower operating costs. Typically the storm
temperature is set below freezing to maximize energy savings.
In the event that snow falls and is detected by a Snow/Ice
Sensor or a Snow Sensor or the system is manually started, the
snow melt system heats the slab up to the melting temperature
and completes a melting cycle.
Should no snow fall during the storm time period, the control
exits Storm operation and returns to Off.
The Storm operation is set up by setting the Storm temperature
and the Storm Run Time in the Temperatures menu.
Auto Storm
--------------------------------------
--------------------------------------
The control automatically checks an Internet weather service
to determine the snowfall forecast for a region based upon the
US ZIP or Canadian postal code. When the Storm feature is
on and snowfall is predicted, the control automatically heats
the slab to the storm setting.
When connected using tekmarNet, a 670 can automatically
start the storm operation on a Snow Melting Control 654. To
do this set the 670 and the 654 to use the same Storm Group
number.
Auto Storm (Weather Predictive)
User Switch Button
Gateway Storm Enable
Storm Run Time Elapses
Away scene
User Switch Button
Gateway Storm Disable
WWSD
CWCO
Storm
Off
If
Then
forecast
Manual Storm
-----------------------------------
-----------------------------------
The storm operation can be manually started by a User Switch
480 or 481 or a Gateway 482 or 485. The manual storm uses
the Storm Group number in the tekmarNet menu.
Setup Procedure
Step 1: Set the 670 Storm Group number from 1 to 12. The
default is 12.
Step 2: Set the User Switch or the Gateway to use the corre-
sponding Storm Group number.
When the User Switch button is pressed, the 670 will enter
the Storm Operation. Likewise, activating the Storm Group
on the Gateway cause the 670 to enter the Storm Operation.
