Installation
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The Universal Reset Control 364 is capable of controlling a single zone snow melting system. In order to provide the best control of
the snow melting system, the 364 should be equipped with an optional tekmar Slab Sensor and an optional Universal Sensor 071
that measures the slab return temperature. These can be purchased separately or as part of the Snow Melt Enable Kit 092. With both
additional sensors installed, the 364 is capable of providing the features listed in the following section. Also described in this section
are the different methods of starting and stopping the snow melting system.
Note: When operating in the snow melting mode, the Snow Melting / Mixing Reset DIP switch must be set to the Snow Melting position.
SLAB PROTECTION (∆T MAX)
A mixing device is installed between the snow melting slab and the boiler(s) in order to
control the rate at which heat is transferred to the snow melting system and to protect
the slab from damage due to thermal stresses. The control limits the rate at which heat
is applied to the slab through the ∆T MAX setting. The ∆T (delta T) is the temperature
difference between the slab supply temperature and the slab return temperature. By
limiting this temperature difference, the rate at which heat is applied to the slab can be
controlled and thermal stresses in the slab can be minimized. When the slab is operat-
ing, the control ensures that the slab supply temperature does not exceed the slab return
temperature by more than the ∆T MAX setting. When the control is operating and the
actual ∆T is near the ∆T MAX, the Maximum pointer can be seen when viewing the MIX
∆T item in the View menu.
VISCOSITY COMPENSATION (EXCEEDING ∆T MAX)
At low temperatures, the glycol solutions used in the snow melting systems become very viscous and difficult to pump. In order to
overcome this condition during a cold start of a snow melting system, the 364 is allowed to exceed the ∆T MAX setting for a period
of time in order to warm the glycol solution. This allows the control to compensate for the high viscosity of the glycol solution and
is used when the return temperature is below 30°F (-1°C). When the control exceeds the ∆T MAX setting, the Min / Max pointer will
flash when viewing the MIX ∆T item in the View menu.
RAMPING OF THE ∆T
When the control starts applying heat to the slab, the supply temperature to the snow melting system is ramped up over a period
of time until it reaches the maximum allowed ∆T.
OPERATING STATUS (SNOWMELT)
While in the snow melting mode, an additional item is available in the View menu called SNOWMELT. This item displays the current
operating status of the snow melting system.
• STRT The word STRT is displayed after the snow melting system has
been enabled. It is displayed until the slab reaches the melting
temperature. If the slab is at the melting temperature, STRT is
displayed for five seconds after the snow melting system has started
operation. This is to verify that the control has entered into the snow
melting mode.
• STOP The word STOP is displayed for five seconds after the snow melting
system has stopped. The word STOP is also displayed if either a
Remote Start / Stop Module 039 has stopped the snow melting
system or an external demand is still present.
• IDLE The word IDLE is displayed as long as the control is operating the slab at the idling temperature.
• EXT The word EXT is displayed when the RUN TIME has reached 0:00 and the control still has an external demand
for melting. In this situation, the control continues melting until the snow melting demand is removed or the
control is stopped.
• 0:00 to 17:00 hr While the slab is up to temperature, and the control is melting, the remaining RUN TIME is displayed.
• INF If an infinite run time is selected and the control is melting, INF is displayed.
• WWSD When the control is in a Warm Weather Shut Down, WWSD is displayed.
• CWCO When the control is in a Cold Weather Cut Out, CWCO is displayed.
Section E
General
Section E1: General
Section E2
With Slab
Sensor
Section E: Snow Melting
tensile stresses
Section E3
Without Slab
Sensor
Section E4
Snow Melting
Enable