WarmlyYours SCV-DUAL - Manual (Page 9)

Snow Switch ® Model LCD–8 Aerial Snow Controller, 100 – 240 VAC
24782 Rev. A 03/13 (800) 234-4239 http://www.networketi.com 8 of 14 Environmental Technology, Inc.
Operation
Initialization Sequence
Upon power up, the LCD-8 performs an initialization sequence, allowing a user
or technician to verify its operation.
First, the external relay energizes for ten seconds. Next, the relay powers off
and the cup heaters energize for ten seconds. Finally, both are off for another ten
seconds. During this time, the green LED blinks slowly—one (1) second on, one (1)
second off. Normal operation follows.
When energized, the controller’s green LED is on continuously. During an
alarm condition, the green LED blinks quickly, alternating between on and off twice a
second. Exceptions are when the green LED conveys information during the configu-
ration process or when the unit is in an automated testing device.
When the system detects moisture and the ambient temperature is below the
operating temperature, if there is one, this defines a “snow” event. For a precipita-
tion sensor (operating temperature off), moisture is detected at any temperature:
this could be snow or rain.
Four States of LCD-8 Controlled System
The system can be in one of four states, three with lockout disabled or one in
lockout enabled:
• Idle: the LCD-8 monitors during conditions lacking moisture and/or cold
air temperature
• Call for Heat: the LCD-8’s sensors recognize snow or ice as moisture
• Holding: the LCD-8 continues system operation for hold-on duration un-
less snow begins again; when hold-on time is over or parameter is set to
zero (0), systems returns to Idle state
• Lockout enabled: low-temperature lockout, where temperature is too
cold for system to operate effectively and energy is conserved
The heater is on during a snow event or within its holding state.
Initiating Hold-On State
The user can also swipe the magnet to start a hold-on cycle or to terminate
a hold-on cycle. If a manual cycle is started, it operates for the normal hold-on
duration (note: if the hold-on time is set to 0, operation lasts one hour). However,
if the ambient temperature is above 50°F when the cycle starts, the cycle duration
is ten (10 ) minutes. If the temperature rises above 50°F during the cycle, operation
truncates to 10 minutes. This 10-minute constraint is only for manually-triggered
hold-on cycles; a cycle resulting from snow proceeds for the full duration. Note: this
does not apply to a precipitation sensor.