Installation

13 of 36 © 2001 D 364 - 07/01
RUNNING TIME (RUN TIME)
The run time is the length of time the snow melting system operates once the slab has reached the melting temperature. During the
time that the slab is approaching the melting temperature, the run time does not decrease. Once the slab has reached the melting
temperature, the run time begins counting down. When the run time reaches 0:00 as displayed by the SNOWMELT item in the View
menu, the 364 has finished melting.
Note: If a slab sensor is not used, the run time begins counting down as soon as the melting mode is enabled.
COLD WEATHER CUT OUT (CWCO)
Maintaining the slab at either the melting or idling temperature during extremely cold temperatures can be expensive or impossible.
The control shuts off the snow melting system once the outdoor air temperature drops below the Cold Weather Cut Out (CWCO)
setting. While the control is in CWCO, the word CWCO is displayed in the SNOWMELT item in the View menu. If the control had
been started prior to the CWCO, it resumes the melting mode once the outdoor air temperature rises above the CWCO setting.
BOILER OPERATION
Refer to Section F for a description of the boiler operation.
BOILER PROTECTION
The 364 ensures that the boiler water temperature remains above the Boil MIN setting. If the boiler water temperature begins to drop
due to slab return temperature, the mixing device is throttled back to allow the boiler to recover. This minimizes the time that the boiler
operates below its condensing temperature and prolongs the life expectancy of the boiler. The 364 can only provide boiler protection
if the Boil SENS item is set to SUP or RET. The 364 can not provide boiler protection if the Boil SENS item is set to NONE.
MIXING SYSTEM PUMP (P3) OPERATION
The mixing system pump (Mix Sys Pmp P3) contact closes and remains closed as long as the control is either in the melting or idling
mode. The mixing system pump contact shuts off if the control is in WWSD, CWCO or there is no call for melting or idling.
SLAB OUTDOOR RESET
When using a slab sensor, the control assumes that the sensor is approximately 1 inch below the surface of the snow melting
slab. Since this point is closer to the source of the heat, this point is
warmer than the surface of the slab. Therefore, the sensor must be
maintained at a higher temperature in order to ensure that the surface
of the slab is maintained at the correct temperature. The amount of the
temperature difference between the surface of the slab and the slab
sensor changes with the outdoor air temperature. Therefore, the slab
core temperature is increased as the outdoor air temperature drops.
The temperature displayed as the slab temperature is the temperature
of the slab sensor. This sensor temperature is higher than the surface
temperature of the slab.
MELTING MODE (MELTING)
The Universal Reset Control 364 is a manual snow melting control.
In order for the snow melting system to be started, one of the three
methods described in section E4 must be used. When the control is in
the melting mode, the Melting pointer is visible in the View menu and
either EXT, INF or a running time can be read when viewing the SNOWMELT item in the View menu. The MELTING setting in the
Adjust menu sets the slab surface temperature that is maintained while the control is in the melting mode.
IDLING MODE (IDLING)
When the snow melting system starts from a cold temperature, the time required for the slab to reach the “Melting” temperature may
be excessive. To decrease the start up time, the slab can be maintained at an “Idling” temperature. The Idle feature is also useful
for preventing frost and light ice formation. When the control is in idling mode, the word IDLE can be read when looking at the
SNOWMELT item in the View menu. The IDLING setting in the Adjust menu sets the slab surface temperature that is maintained
while the control is in the idling mode.
WARM WEATHER SHUT DOWN (WWSD)
When both the slab temperature and the outdoor temperature exceed
the MELTING temperature by more than 1.5°F (1°C), the control
enters into WWSD. In WWSD, the snow melting system is shut down
in order to conserve energy.
Section E2: With Slab Sensor
Surface temperature = 35˚F
Decreasing Air Temperature
Increasing Slab Core Temperature
Slab Surface Temperature is Constant
Slab Outdoor
Reset
Slab Outdoor
Reset
Core (sensor)
is warmer