tekmar 654 Snow Melting Control Installation - Manual (Page 29)

29 of 44 © 2013 654_D - 06/13
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 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
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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:
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 through-
out the winter and may result in high energy consumption.
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Additional Melting Time
Dry
Snow Ice Sensor
A Snow / Ice Sensor 090 or 094 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 addition melting time after the
sensor is dry.
Storm Operation
For many residential applications it is too costly to Idle the snow
melt system all winter. Storm combines the benefits of a fast
response time together with lower operating costs. The Storm
operation does this by allowing the user to manually pre-heat
the slab temporarily in preparation of a snow fall warning. 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 setup by setting the Storm temperature
and the Storm Run Time in the Set Temp menu. The Storm
operation can only be activated by a User Switch or Gateway.
To respond to a User Switch or Gateway, select the Storm
Group number to be 1 through 12. Then program the User
Switch or Gateway setpoint enable to be the same as the
Storm Group. Pressing the programmed User Switch button will
now activate the Storm operation on the snow melting control.
Melt
Away
Storm
Press
Storm
Likewise, sending the setpoint enable command through the
Gateway 482 will enable the Storm operation. On the Gateway
483, activating the storm group on the Scenes page in turn
enables the Storm operation.