5
PART NO.
24861
REV
A.0
INSTALLATION AND OPERATION MANUAL |
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)
.
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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.
ALARMS
When the LCD-8 operates normally, its green LED is lit
continuously. Under an alarm condition, this LED will flash
rapidly—on and off twice a second. The alarm may or may not
inhibit operation, depending on circumstances.
Three possible conditions exist which initiate an alarm:
GREEN LED PULSE PATTERN
Prior to learning how to change the configuration of the LCD–8,
it is first nec- essary to understand how the device
communicates with the user; see Table 1. As there is no display
on the unit, the only means of communicating with the device is
to carefully observe the pulse pattern of the green LED.
The bad thermistor alarms will clear if the thermistor repairs
itself. The cor- rupted configuration alarm will clear if the unit is
reconfigured: in that case the user is advised to cycle power,
confirming reconfiguration.
SPECIAL CASE: HOLD-ON TIME IS 0
For the special case that only occurs with a manual swipe when
the hold-on time is set to zero (0), the heater operates for at
least one hour, even if there is a snow condition. In terms of a
strict state description in this one case, a snow condi- tion does
not cause the system to enter the snow state, but rather to stay
in the hold-on state. If the snow remains after the one hour, the
heater remains energized.
In the “enabled” Lockout state, the heater is not on. When snow
is detected, the system enters the Snow state if the ambient air
temperature is above 17°F, but it enters the Lockout state
instead if the temperature is below 17°F. Additionally, this
Lockout state is entered if the temperature falls below 17°F
during an automatic hold-on cycle. If the temperature rises
above 17°F in the Lockout state but with no moisture detected
(not snowing), the hold-on timer is restarted. In the Lockout
state, the heater is not on.
If in the Idle state and the temperature is below 17°F when a
magnet swipes the magnetic switch, the system initiates its
manual cycle as usual. If the tempera- ture falls below 17°F
during the cycle, it is ignored. If the unit is in the Lockout state
and the user swipes the magnetic switch, the temperature
reading is ignored. This will be maintained until the end of the
snow event (that is, until a return to the Idle state).
The override ends when the heaters turn off. However, if a
manual cycle is initiated while when the environment is frigid,
and then snow starts, the heaters remain energized until the
snow stops and for the hold-on time thereafter.
Note: Avoid selecting both low-temperature lockout and a
hold-on time of zero (0) hours, as the heaters may not energize.
BAD CUP THERMISTOR:
If the cup thermistor is bad, the unit will not do automatic
snow melting. The rationale is that we can’t turn on the cup
heater without risking damage to the unit; and if snow or
freezing rain falls with the cup cold, it may stay there for
weeks, and the unit would never shut off. The manual
hold-on cycle will work.
BAD AMBIENT THERMISTOR:
If the ambient thermistor is bad, the unit will operate
normally if it is configured as a precipitation sensor; if it is
configured as a snow sensor, it will not do automatic snow
melting. The manual hold-on cycle will work.
CORRUPTED CONFIGURATION.
If the configuration is corrupted, the unit will operate under
its default configuration.
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•
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*When the Temperature Set-Point feature is configured to be in the “OFF” setting, the LCD–8 senses moisture
only and activates the heaters regardless of temperature.
Hold-On Time
(in hours)
0 Hours
(1 Pulse)
1 Hour
(2 Pulses)
3 Hours
(3 Pulses)
5 Hours
(4 Pulses)
Temperature
Set Point (in °F)
OFF*
(1 Pulse)
36°F (2.22°C)
(2 Pulses)
38°F (3.33°C)
(3 Pulses)
40°F (4.44°C)
(4 Pulses)
Low Temperature
Lock-Out
OFF
(1 Pulse)
ON
(2 Pulses)
TABLE 1
LCD–8 CONFIGURATION OPTIONS AND GREEN
LED PULSE PATTERN