The Snow Detector and Melting Control 664 is designed to control up to two zones in a snow melting system. The control automatically
adjusts the mixed supply water to the snow melting system by controlling up to two boilers and a single mixing device. For mixing, the
664 can use a variable speed injection pump, a fl oating action mixing valve or a 4-20 mA device. The snow melting system may be
started manually or automatically through the use of a Snow / Ice Sensor 090. The 664 control includes a large Liquid Crystal Display
(LCD) in order to view system status and operating information.
Additional features include:
• Temporary Idle
• Optional priority zoning operation
• Slab protection for the snow melting system
• Boiler protection
• Manual Override
• Cold Weather Cut Out (CWCO)
• Remote display and adjustment capabilities
• Test sequence to ensure proper component operation
• Pump and valve exercising
• CSA C US Certifi ed (approved to applicable UL standards)
• Adjustable Warm Weather Shut Down (WWSD)
Output
4-20 mA
device
Output
Variable
Speed
driven
Output
Mixing
Valve &
Actuating
Snow/Ice Sensor
090 installed with
Sensor Socket
OR
pump
OR
Motor
Input
091 Optional
or
Slab
Sensor
Optional
Input
Slab
Sensor
Optional
%
StartStop
Menu
Item
Snow Detector & Melting Control 664
Two Zone, Two Stage Boiler, Mixing
1 kΩ max
1+2–3
4-20 mA
Opn/
Var
4
5
Pwr
Cls6Red7Blk/
Mix
Com
8
Blu9Yel10Brn/
Do not apply power
11
Slab
Slab1
2
OR
Remote Display Module (RDM)
Remote Start / Stop Module
Input
or
Melt Demand
Idle Demand
WWSD
Minimum
Maximum
Water
Melting
12
Com13tN214Mix
15
16
Mix
Com17Boil18Out19Melt/Idle
Ret
Sup
Input
Universal
Sensor
Included
Idle Demand
Melt Demand
Made in Canada by
tekmar Control Systems Ltd.
tektra 900-01
Power 115 V
Relays 230 V (ac) 5 A 1/6 hp
Stage/Zn/P1 Relays 230 V (ac) 5 A 1/3 hp
Var. Pump 230 V (ac) 2.4 A max (FLA)
5 A max (LRA), fuse T2.5 A 250V
Demand 20 to 260 V (ac) 2 VA
Signal wiring must be rated at least 300 V.
20 21122 23224 25
Stage Stage
Demand
Input
Universal
Sensor
Included
Input
Universal
Sensor
Included
Zn
1
± 10%
50/60 Hz 600 VA
26
27
Com
Zn
Zn
2
Input
Outdoor
Sensor
Included
Tes t
28
Sys
P1
off
not testing
red
testing
red
testing paused
For maximum heat,
press and hold Test
button for 3 seconds.
This brochure is organized into four main sections. They are: 1) Sequence of Operation, 2) Installation, 3) Control Settings, and 4)
Troubleshooting. The Sequence of Operation section has 6 sub-sections. We recommend reading Section A: General of the Sequence
of Operation, as this contains important information on the overall operation of the control. Then read to the sub-sections that apply to
your installation.
The Control Settings section (starting at DIP Switch Settings) of this brochure describes the various items that are adjusted and
displayed by the control. The control functions of each adjustable item are described in the Sequence of Operation.
Table of Contents
User Interface ..................................................Pg 2
Description of Display Elements ..................Pg 3
Sequence of Operation ..................................Pg 4
The 664 uses a Liquid Crystal Display (LCD) as the method of supplying information. You use the LCD in order to setup and monitor
the operation of your system. The 664 has four push buttons (Menu, Item,
your control, record your settings in the ADJUST Menu table which is found in the second half of this brochure.
▲, ▼) for selecting and adjusting settings. As you program
Menu
All of the items displayed by the control are organized into various menus. These menus
are listed on the left hand side of the display (Menu Field). To select a menu, use the
Menu button. By pressing and releasing the Menu button, the display will advance to
the next available menu. Once a menu is selected, there will be a group of items that
can be viewed within the menu.
Item
The abbreviated name of the selected item will be displayed in the item field of the
display. To view the next available item, press and release the Item button. Once you
have reached the last available item in a menu, pressing and releasing the Item button
will return the display to the first item in the selected menu.
Adjust
To make an adjustment to a setting in the control, begin by selecting the appropriate
menu using the Menu button. Then select the desired item using the Item button. Finally,
use the
Additional information can be gained by observing the Status fi eld of the LCD. The status
fi eld will indicate which of the control’s outputs are currently active. Most symbols in the
status fi eld are only visible when the VIEW Menu is selected.
The following defined terms and symbols are used throughout this manual to bring attention to the presence of hazards of various risk
levels, or to important information concerning the life of the product.
- Warning Symbol: Indicates presence of hazards which can cause severe personal injury, death or
substantial property damage if ignored.
INSTALLATION
CATEGORY II
- Double insulated
- Local level, appliances
Sequence of Operation
Section A
General
Operation
Page 4 - 5
Section F
Idling
Operation
Page 14
Section B
Snow
Melting
Page 5 - 7
Section C
Boiler
Operation
Page 7 - 9
Section D
Melting Enable
/ Disable
Page 9 - 11
Section E
Melting
Operation
Page 12 - 13
Section A: General Operation
POWERING UP THE CONTROL
When the Snow Detector and Melting Control 664 is powered up, the control displays all LCD segments for 2 seconds, then the
control type number in the LCD for 2 seconds. Next, the software version is displayed for 2 seconds. Finally, the control enters into
the normal Operating mode and the LCD defaults to displaying the current outdoor air temperature.
MIXING DEVICE SELECTION (MIXING)
The 664 can supply a lower fluid temperature to the snow melting system by using a variable speed injection pump, a floating action
mixing valve or a modulating 4-20 mA device. The selection is made under the Mixing item in the ADJUST menu.
Variable Speed Injection (VAR)
A standard wet rotor circulator is connected to the 664 on the Pwr Mix
and Opn / Var terminals (4 and 3). The 664 increases or decreases the
power output to the circulator based on the system requirements. For
correct sizing and piping of the variable speed injection pump, refer to
Essay E 021. A visual indication of the current variable speed output is
displayed in the LCD in the form of a segmented bar graph.
Floating Action (FLOT)
A floating action motor is connected to the 664 on the Pwr Mix,
Opn / Var and Cls terminals (4, 3 and 5). The 664 pulses the actuator
motor open or close based on the system requirements. The mixing
valve that the actuator is connected to can be either a 2-way, 3-way or
4-way valve. A visual indication of the current position of the valve is
displayed in the LCD in the form of a segmented bar graph.
4-20 mA Output (4-20)
A 4-20 mA device is connected to the 664 on the 4-20 mA + and 4-20 mA – terminals (1 and 2). The 664 increases or decreases
the modulating output to the 4-20 mA device based on the system requirements. The 4-20 mA output can be used to operate a
variety of actuating motors for mixing valves and motor drives for larger pumps. A visual indication of the current output of the
4-20 mA device is displayed in the LCD in the form of a segmented bar graph.
The mixing target temperature is the supply fluid temperature calculated by the control. The control will operate the snow melt
system so that the mix supply temperature reaches the mixing target except while providing boiler return protection for the boiler.
MIXING MAXIMUM (MIX MAX)
The Mix Max sets the highest fluid temperature that the control is allowed to calculate as the mixing target temperature. If the control
does target the Mix Max setting, and the mix supply temperature is near the MIX MAX, the Maximum pointer is displayed in the LCD
while the MIX SUP temperature is being viewed.
BOILER PROTECTION (Boil MIN)
The 664 is capable of providing boiler protection from cold mixing system
Mixing
Sensor
Boiler Supply
Sensor
return fl uid temperatures. If the boiler sensor temperature is cooler than
the Boil Min setting while the boiler(s) is fi ring, the 664 reduces the output
from the mixing device. This limits the amount of cool return water to the
OR
boiler(s) and allows the boiler temperature to recover. This feature can
only be used if the Boil Sens item is set to Sup or Ret. The 664 can not
provide boiler protection if the Boil Sens item is set to None.
Boiler Return
Sensor
EXERCISING (EXERCISE)
The 664 has a built in pump and valve exercising function. The exercising period is adjustable and is factory set at 70 hours. If a
pump or valve output has not been operated at least once during every exercising period, the control turns on the output for 10
seconds. This minimizes the possibility of a pump or valve seizing during a long period of inactivity. In the case where a mixing valve is
being used as the mixing device, the 664 ensures that the valve operates over its entire range at least once each exercising period.
Note: The exercising function does not work if power to the control, valves or pumps is disconnected.
Section B: Snow Melting
Section B1
General
Snow Melting
Section B1: General Snow Melting
SLAB PROTECTION (∆T MAX)
The control can limit the rate at which heat is applied to the currently operating zone through
the ∆T Max setting. The ∆T (delta T) is the temperature difference between the snow melting
supply temperature and the snow melting return temperature. By limiting this temperature
difference, the rate at which heat is applied to the currently operating zone can be controlled
and thermal stresses in the slab can be minimized. When the control is operating at the
∆T MAX, the Maximum pointer can be seen when viewing the ∆T item in the VIEW menu.
The control provides slab protection differently based on boiler sensor placement.
Note: The ∆T MAX function is only available if the PRIORITY item is set to COND or FULL.
VISCOSITY COMPENSATION (EXCEEDING ∆T MAX)
At low temperatures, the glycol solutions used in 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 664 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 mixing return temperature is below 30°F (-1°C). When the control exceeds the ∆T Max setting, the Maximum pointer will
fl ash when viewing the ∆T item in the VIEW menu.
Note: This operation only occurs if the PRIORITY item is set to COND or FULL.
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 target mixed supply temperature. This feature helps reduce thermal stresses in the slab.
Note: This operation only occurs if the Boil SENS item is set to RET or NONE.
RUNNING TIME (RUN TIME)
The running time is the length of time that a zone operates once it has reached its slab target temperature. During the time that a
zone is approaching its slab target temperature, the Run Time does not decrease. Once a zone reaches its slab target temperature
the Run Time begins counting down. When the Run Time reaches 0:00 as displayed in the Status item of the appropriate zone in the
VIEW menu, the zone has fi nished melting.
Note: The running time is only applicable when a manual melting enable signal starts the snow melting system. Refer to Section D1
for a description of a manual melting enable.
WARM WEATHER SHUT DOWN (WWSD)
The control has a warm weather shut down for each zone that prevents the control from entering the Melt or Idle modes in order to
conserve energy. While a zone is in WWSD, the word WWSD is displayed in the STATUS 1 or STATUS 2 items in the VIEW menu.
When both zones enter WWSD, the 664 turns on the WWSD pointer in the display.
Automatic (Auto)
There is a warm weather shut down for each zone. When both the slab temperature of a
zone and the outdoor temperature exceed the zone’s Melt Tem perature setting by more
than 2°F (1°C), the zone enters into WWSD. While a zone is in WWSD, the word WWSD
Outdoor
Temperature
WWSD
Slab
Temperature
MELT
is displayed in the STATUS item of the appropriate zone in the VIEW menu. When both
zones enter WWSD, the 664 turns on the WWSD pointer in the display.
Control enters
Adjustable WWSD
Idle and waits
for Melt Enable
IDLE
When the WWSD is set to a temperature, the WWSD occurs when the outdoor air
temperature exceeds the WWSD setting by 1°F (0.5°C) and when the slab temperature of
a zone exceeds 34°F (1°C). The zone exits WWSD when the outdoor air temperature falls
1°F (0.5°C) below the WWSD setting or if the slab temperature of the zone falls below 34°F
CWCO
(1°C). This allows the Melting Temperature setting to be set higher than the WWSD. This is
useful where high slab temperatures are required to melt the snow or ice. A good example
of this is installations using paving bricks on top of sand and concrete layers.
COLD WEATHER CUT OUT (CWCO)
Maintaining the zone(s) at either the melting or idling temperature during extremely cold temperatures can be expensive or
impossible. The control turns the snow melting system off when the outdoor air temperature drops below the Cold Weather Cut
Out (CWCO) temperature. While the control is in CWCO, the word CWCO is displayed in the STATUS 1 and STATUS 2 item in the
VIEW menu. If a Snow / Ice Sensor 090 is used, the heater in the sensor is kept on during CWCO until the control detects moisture.
If water is detected, the heater is turned off but the control retains the moisture detected information. When the outdoor temperature
rises above the CWCO temperature, the control exits CWCO and if the Snow / Ice Sensor 090 detected moisture during CWCO, the
control initiates Melting mode. If the control has been started prior to the CWCO, it resumes the Melting mode once the outdoor air
temperature rises above the CWCO temperature.
STATUS 1 and 2 (STATUS)
While in the VIEW menu there are a number of items available to determine the current status of zone 1 and zone 2. To view the
current status of zone 1, select the STATUS 1 item in the VIEW menu. To view the current status of zone 2, select the STATUS 2 item
in the VIEW menu.
• STRT The word STRT is displayed after the snow melting system has been manually enabled. It is displayed until the
zone reaches its slab target temperature. If the zone is at its slab target 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 Melting mode.
• STOP The word STOP is displayed for fi ve seconds after the snow melting system has been manually disabled. The
word STOP is also displayed if either a Remote Start / Stop Module 039, Remote Display Module 040 or the Stop
on the control stops the snow melting system and an external melt demand is still present.
• IDLE The word IDLE is displayed as long as the zone is operating at its idling temperature.
• “IDLE” The word IDLE is fl ashed on the display as long as the zone is operating in temporary idle.
• EXT The word EXT is displayed when the RUN TIME has reached 0:00 and the control still has an external melt demand.
In this situation, the zone continues melting until the melt demand is removed or the control is stopped.
• DET The word DET is displayed after the snow melting system has been automatically enabled by the Snow / Ice
Sensor 090 and the zone is at its slab target temperature. DET is also displayed once the control is manually
enabled after automatic detection by the 090 and the running time has counted down to 0:00.
• 0:00 to 23:59 hr While the zone is up to temperature and melting, the remaining RUN TIME is displayed.
• INF If an infi nite RUN TIME is selected and the zone is melting, INF is displayed.
• WWSD When the zone is in Warm Weather Shut Down, WWSD is displayed.
• CWCO When the control is in Cold Weather Cut Out, CWCO is displayed.
BOILER PROTECTION
Refer to Section A for a description of boiler protection.
BOILER OPERATION
Refer to Section C for a description of boiler operation.
SNOW MELTING OVERRIDE
If the Away setting is selected in the SCHEDULE menu, the snow melting system is shut
down. Both the Melting and Idling temperatures are ignored as long as the control remains
in the Away mode.
SYSTEM PUMP OPERATION (Sys P1)
The System Pump (Sys P1) contact closes and remains closed as long as at least one of the zones is either in the Melting or Idling mode.
The System Pump contact shuts off if the control is in CWCO, if both zones are in WWSD, or if there is no call for Melting or Idling.
ZONE OUTPUTS (Zn 1 and Zn 2)
The Zone 1 (Zn 1) contact and the Zone 2 (Zn 2) contact operate based on the Melting and / or Idling operation. Refer to Melting
Section E and / or Idling Section F for a description of how the zone contact(s) operate. The Zone Pump contact(s) shuts off if the
control is in CWCO, if the corresponding zone(s) is in WWSD, or if there is no call for Melting or Idling.
PURGE
The system pump (Sys P1) and zoning device(s) (Zn 1 and Zn 2) continue to operate for up to 2 minutes after the last demand is
removed. This purges the residual heat from the boiler(s) into the snow melting slab. If the boiler temperature drops below the Boil Min
setting after 20 seconds, the purge is aborted and the system pump and zoning device(s) are turned off.
Section C: Boiler Operation
Section C1
Boiler Supply
Sensor
Section C2
Boiler Return
Sensor
Section C3
No Boiler
Sensor
Section C1: Boiler Supply Sensor
BOILER SENSOR ON THE SUPPLY (Boil SENS = SUP)
When operating a boiler or boiler plant that is dedicated to a snow melting system, the 664
is designed to operate the boiler(s) as effi ciently as possible. The boiler(s) are cycled based
on the mixing supply fl uid temperature. This is to provide longer and more effi cient boiler
cycles. This mode of operation only works if the Boil SENS item is set to SUP.
BOILER MINIMUM (Boil MIN)
The Boil MIN is the lowest water temperature that the control is allowed to use as a boiler target temperature. If the boiler(s) is
operating, and the boiler supply temperature is near the Boil Min setting, the Minimum pointer turns on in the LCD while the Boil SUP
temperature is being viewed. If the installed boiler(s) is designed for condensing or low temperature operation, set the Boil MIN
adjustment to OFF.
The 664 controls up to two stages in order to supply the required temperature. After the first stage is turned on in the firing
sequence, the control waits a minimum amount of time before turning on the next stage. After the minimum time delay between
stages has expired, the 664 examines the control error to determine when the next stage is to fi re. The control error is determined
using Proportional, Integral and Derivative (PID) logic.
Proportional – compares the actual temperature to the target temperature. The colder the temperature, the sooner the next stage
is turned on.
Integral – compares the actual temperature to the target temperature over a period of time.
Derivative – determines how fast or slow the actual temperature is changing. If the temperature is increasing slowly, the next
stage is turned on sooner. If the temperature is increasing quickly, the next stage is turned on later, if at all.
– Each stage has a minimum on time, and a minimum off time.
FIRE DELAY (FIRE DLY)
The FIRE DLY is the delay time that may occur between the time that the
664 closes a stage contact and the burner fi res for that stage. This delay
is usually the result of burner pre-purge or other forms of time delay built
into the burner’s safety circuits.
Boiler Contact Closes
Fire
Delay
Boiler Fires
Minimum
On Time
Minimum
Off Time
Time
Fire
Delay
Minimum
On Time
BOILER MASS (Boil MASS)
The Boil MASS setting allows the 664 to adjust to different types of heat sources depending on their thermal mass.
Light (LITE)
The LITE setting is selected if the boiler(s) that is used has a low thermal mass. This means that the boiler(s) has a very small
water content and has very little metal in the heat exchanger. A boiler that has a low thermal mass comes up to temperature quite
rapidly when fi red. This is typical of many copper fi n-tube boilers.
Medium (MED)
The MED setting is selected if the boiler(s) that is used has a medium thermal mass. This means that the boiler(s) either has
a large water content and a low metal content or a low water content and a high metal content. This is typical of many modern
residential cast iron boilers or steel tube boilers.
Heavy (HEVY)
The HEVY setting is selected if the boiler(s) that is used has a high thermal mass. This means that the boiler(s) has both a large
water content and a large metal content. A boiler that has a high thermal mass is relatively slow in coming up to temperature. This
is typical of many commercial cast iron and steel tube boilers.
DIFFERENTIAL (DIFF)
An on / off heat source such as a boiler must be operated with a differential in order to prevent short cycling. With the 664, either a
fi xed or an automatic differential may be selected.
Fixed Differential
The differential is centered around the target temperature. If the
temperature drops 1/2 the differential below the target temperature, the
664 closes the Boiler contact(s) to fi re the boiler(s). If the temperature
rises 1/2 of the differential above the target temperature, the 664 opens
the Boiler contact(s) to turn off the boiler(s).
Off
Differential
On
Auto Differential (AUTO)
If the AUTO Differential is selected, the 664 automatically adjusts
the Differential setting under the current load conditions to avoid
short cycling.
Time
STAGE 1 AND 2 (STAGE)
The Stage 1 and 2 setting may be selected to AUTO or OFF. When AUTO is selected, the stage is activated and the control
operates the appropriate boiler. When OFF is selected, the control does not fi re the stage.
The ROTATE item is an adjustable setting that is factory set at 48 hours. The firing order of the boiler changes whenever one stage’s
accumulated running time exceeds the other stage’s accumulated running time by more than the ROTATE setting. After each rotation,
the stage with the least running hours is the fi rst to fi re and the stage with the most running hours is the last to fi re. This function
ensures that both stages receive equal amounts of use. When this item is set to the OFF setting, Stage 1 is always the fi rst to fi re.
Section C2: Boiler Return Sensor
BOILER SENSOR ON THE RETURN (Boil SENS = RET)
The boiler sensor should be located on the boiler return if the 664 is one of many controls
that can call for boiler operation. When in the Return mode, the 664 provides a boiler
enable through the Stage 1 contact. The 664 no longer tries to control the boiler supply
water temperature directly, but allows the boiler to operate at its operating aquastat setting
when required. If this mode of operation is selected, the boiler pump should either operate
continuously, or be operated in parallel with the System Pump contact (Sys P1). When
the mixing device begins to ramp up, the Stage 1 contact closes on the 664. The Stage 1
contact remains closed until the mixing device no longer requires heat. With the sensor
on the boiler return, the 664 is still capable of providing boiler protection as described in
Section A.
Section C3: No Boiler Sensor
NO BOILER SENSOR (Boil SENS = NONE)
The 664 is capable of operating without a boiler sensor if desired. Without a boiler sensor,
the 664 is unable to provide boiler protection. In this mode of operation, the Stage 1 contact
is used to provide a boiler enable. When the mixing device begins to ramp up, the Stage 1
contact on the 664 closes. The Stage 1 contact remains closed until the mixing device no
longer requires heat. This type of application is typical if the 664 is drawing heat from a
source that already incorporates some form of boiler protection.
Section D: Melting Enable / Disable
Section D1
Snow Melting
Enable
Section D2
Snow Melting
Disable
Section D1: Snow Melting Enable
The snow melting system can be enabled manually or automatically. A melting enable signal applied to the control places both zones
into the Melting mode. If a melting enable signal is applied once the system is already in the Melting mode, the control responds to
the last command received.
MANUAL MELTING ENABLE
A manual melting enable signal requires the user to manually start the snow melting system and can be provided from the Start button
on the control, Remote Start / Stop Module 039, Remote Display Module 040, or an external melt demand.
Start Button on the Control
The snow melting system is enabled by pressing the Start button on the control while
in the VIEW menu. The control then displays the RUN TIME setting to allow the user to
adjust it. Once the snow melting system is enabled, the word STRT is displayed for at
least 5 seconds in the STATUS item of the appropriate zone while in the VIEW menu. If
the Start button on the control is pressed while the zone(s) is already melting and up to
temperature, the running time counter is reset to the RUN TIME setting.
The snow melting system is enabled by pressing the button on the front of the 039. While
the zone(s) is coming up to temperature, a green indicator light fl ashes on the front of
the 039. Once the zone(s) is up to temperature and the RUN TIME is counting down, the
green indicator light on the front of the 039 is on solid.
Remote Display Module 040
The snow melting system is enabled by pressing the ▲ button on the 040 while in the
VIEW menu. The 040 then displays the RUN TIME setting to allow the user to adjust
it. Once the snow melting system is enabled, the word STRT is displayed for at least 5
seconds in the Status item of the appropriate zone while in the VIEW menu.
External Melt Demand (DIP switch set to Melt Demand)
The snow melting system is enabled when a voltage between 24 and 240 V (ac) is applied
across the Melt / Idle Demand terminals (19 and 20). An external melt demand must be
present for at least 4 seconds in order to start the snow melting system. If the RUN TIME
reaches 0:00 and the external melt demand is still present, the control continues melting
until the external melt demand is removed or the system is otherwise stopped.
Note: This operation only occurs if the Idle Demand / Melt Demand DIP switch is set to
the Melt Demand position.
24 to 230 V (ac)
L
N
7
9
8
Start / Stop
19
Melt / Idle
Demand
StopStart
20
Idle Demand
Melt Demand
AUTOMATIC MELTING ENABLE (Snow / Ice Sensor 090)
The 664 can use the Snow / Ice Sensor 090 to provide an automatic melting enable signal
to start the snow melting system. The control continually monitors the 090 for the presence
of moisture. Once moisture is detected, the Water pointer is displayed in the LCD and the
snow melting system is enabled.
Note: In addition to the Snow / Ice Sensor 090 connected to the 664, the Zone 1 item in the
ADJUST menu must be set to AUTO in order for the automatic melting enable function to
work. Therefore, if zone 1 is turned off, the 090 can not provide a melting enable signal to
start the Melting mode for zone 2.
Water Detection Sensitivity (SENSTVTY)
The 664 has a Sensitivity setting which compensates for varying outdoor conditions which could affect how the moisture detector
in the 090 interprets the presence of moisture. This adjustable setting is available through the SENSTVTY item in the ADJUST
menu of the control. As snow becomes contaminated with dirt, and as the sensor itself becomes dirty, the control may incorrectly
indicate the presence of water. If this condition occurs, clean the surface of the sensor and / or turn down the SENSTVTY setting. If
the snow in your area is very clean, the SENSTVTY setting may need to be increased before snow is detected. If AUTO is selected,
the control automatically adjusts the sensitivity level used to detect moisture.
The snow melting system can be disabled manually or automatically. A melting disable signal applied to the control takes both zones
out of the Melting mode. Once the snow melting system is disabled, the zone(s) operates in the Idling mode. The Idling mode allows the
zone(s) to be either operated at a lower temperature or turned off.
MANUAL MELTING DISABLE
A manual melting disable signal requires the user to manually stop the snow melting system and can be provided from the Stop
button on the control, Remote Start / Stop Module 039, Remote Display Module 040, or an external idle demand.
Stop Button on the Control
The Stop button on the control can be used to stop the snow melting system. The snow melting system is disabled by pressing
the Stop button on the control while in the VIEW menu. Once the snow melting system is disabled, the word STOP is displayed for
5 seconds in the STATUS item of the appropriate zone while in the VIEW menu.
Remote Start / Stop Module 039
A Remote Start / Stop Module 039 can be used to stop the snow melting system. The snow melting system is disabled by
pressing the button on the face of the 039. When the system is stopped, a solid red indicator light is displayed on the face of the
039 for fi ve seconds. If the snow melting system is disabled while there is still an external melt demand for snow melting, the 039
displays a solid red indicator light until the external demand is removed.
Remote Display Module 040
A Remote Display Module 040 can be used to stop the snow melting system. The snow melting system is disabled by pressing
the
▼ button on the 040 while in the VIEW menu. Once the snow melting system is disabled, the word STOP is displayed for 5
seconds in the STATUS item of the appropriate zone while in the VIEW menu.
20
External Idle Demand (DIP switch set to Idle Demand)
The snow melting system is disabled when a voltage between 24 and 230 V (ac) is
applied across the Melt / Idle Demand terminals (19 and 20). An external idle demand
must be present for at least 4 seconds in order to stop the snow melting system.
Note: This operation only occurs if the Idle Demand / Melt Demand DIP switch is set to
the Idle Demand position.
24 to 230 V (ac)
L
N
19
Melt / Idle
Demand
If the snow melting system is placed into Idling mode by an external idle demand, then
a manual melting enable signal is applied, the idle demand is overridden until either the
running time has expired, a stop signal is given, or the external idle demand is removed
and reapplied.
Idle Demand
Melt Demand
AUTOMATIC MELTING DISABLE (Snow / Ice Sensor 090)
The Snow / Ice Sensor 090 can be used to automatically disable the snow melting system. Once the 090 is dry, the Water pointer
turns off in the LCD. The zone 1 slab temperature has to be at least the zone 1 slab target temperature for a minimum of thirty
minutes in order for zone 1 to turn off. If a manual melting disable signal is applied and the 090 is dry, the snow melting system
turns off immediately.