The Snow Detector & Melting Control 667 is a microprocessor-based control which operates a snow melting system. The control can
operate automatically when a Snow / Ice Sensor 090 is installed or the user can manually enable and / or disable the system. The
667 controls a variable speed injection pump to provide both boiler and slab protection. When the control is not in the Melting mode,
the system can either be shut down or it can be maintained at an idle temperature for faster response and improved safety. The 667
control includes a large Liquid Crystal Display (LCD) in order to view system status and operating information.
Additional features include:
• Temporary Idle
• Slab protection for the snow melting system
• Boiler protection
• Manual Override
• Adjustable Warm Weather Shut Down (WWSD)
• Remote display and adjustment capabilities
• Test sequence to ensure proper component operation
• Pump exercising
• Viscosity compensation
• CSA C US Certifi ed (approved to applicable UL standards)
• Cold Weather Cut Out (CWCO)
Output
Variable Speed
Injection Pump
Snow/Ice Sensor
090 installed with
Input
Sensor Socket
091 Optional
or
Start
Stop
Menu Item
Snow Detector & Melting Control 667
Variable Speed Injection
Do not apply power
1
Var2Pwr
3
Red4Blk5Blu6Yel7Brn/
Do not apply power
8
Boil9Com10tN211Mix12Mix13Com14Out
SlabMixRet Sup
Melt Demand
Idle Demand
WWSD
Minimum
Maximum
Water
Melting
Idle Demand
Melt Demand
Made in Canada by
tekmar Control Systems Ltd.
tektra 900-04
Power 115 V
Relays 230 V (ac) 5 A 1/3 hp
Var. Pump 230 V (ac) 2.4 A (FLA), 5A (LRA)
fuse T2.5 A 250V
Demand 20 to 260 V (ac) 2 VA
Signal wiring must be rated at least 300 V
15
16 17
1821
Melt/Idle
Demand Pmp 2
19 20
System Boiler
± 10%
Tes t
50/60 Hz 600 VA
22 2325
Melting
off
red
red
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 7 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
Testing The Wiring .................................Pg 17
User Interface
The 667 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 667 has four push buttons (Menu, Item, ▲, ▼) for selecting and adjusting settings. As you program
your control, record your settings in the ADJUST Menu table which is found in the second half of this brochure.
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 ▲ and / or ▼ button to make the adjustment.
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.
Displays the
current status
of the control's
inputs, outputs
and operation
Number Field
Displays the current value of the selected item
Melt Demand
Idle Demand
WWSD
Minimum
Maximum
Water
Melting
Buttons
Selects Menus, Items
and adjust settings
Symbol Description
Mixing Device Output Scale
Shows output of injection pump. Arrows
show whether the output is increasing or
decreasing.
Pump
Displays when the system pumps are
operating.
Override
Displays when the control is in override mode.
Warning
Displays when an error exists or when a limit
has been reached.
Lock / Unlock
Displays when the access levels are
locked or unlocked.
Burner
Displays when the Boiler relay is
turned on.
Pointer
Displays the control operation as
indicated by the text.
°F, °C, min, hr, sec
Units of measurement.
Definitions
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.
When the Snow Detector & Melting Control 667 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
Variable Speed Injection Pump
A standard wet rotor circulator is connected to the 667 on the Var and
Com terminals (1 and 2). The 667 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.
MIXING TARGET (MIX TRG)
The mix 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 SUP 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 667 is capable of providing boiler protection from cold mixing system
return fluid temperatures. If the boiler sensor temperature is cooler than
the Boil Min setting while the boiler is firing, the 667 reduces the output
from the mixing device. This limits the amount of cool return water to the
boiler 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 667 can not provide
boiler protection if the Boil Sens item is set to None.
Mixing
Sensor
Boiler Supply
Sensor
OR
Boiler Return
Sensor
EXERCISING (EXERCISE)
The 667 has a built-in pump and valve exercising function. The exercising period is adjustable and is factory set at 70 hours. If a
pump 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 seizing during a long period of inactivity.
Note: The exercising function does not work if power to the control or pumps is disconnected.
The control can limit the rate at which heat is applied to the zone through the ΔT Max setting.
The ΔT (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 zone can be controlled and thermal stresses in the slab can
be minimized. When the control is operating at the ΔT MAX, the Maximum pointer can be
seen when viewing the ΔT item in the VIEW menu. The control provides slab protection
differently based on boiler sensor placement.
VISCOSITY COMPENSATION (EXCEEDING ΔT 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 667 is allowed to exceed the ΔT 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 ΔT Max setting, the Maximum pointer
will flash when viewing the ΔT item in the VIEW menu.
tensile stresses
SOFT START
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 the system operates once it has reached its slab target temperature. During the time that
the system is approaching its slab target temperature, the RUN TIME does not decrease. Once the system reaches its slab target
temperature, the RUN TIME begins counting down. When the RUN TIME reaches 0:00 as displayed in the Status item in the VIEW
menu, the system has finished 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 that prevents the control from entering the Melt or Idle modes in order to conserve
energy. While in WWSD, the word WWSD is displayed in the Status item in the VIEW menu and the WWSD pointer is on the display.
The WWSD can be either set to Automatic or it can be set to a temperature.
Automatic (Auto)
When the WWSD is set to AUTO, the WWSD occurs when the slab temperature and the
outdoor temperature exceed the Melting setting by 2°F (1°C). The control exits the WWSD
when the slab or outdoor temperature falls to the Melting setting temperature.
Adjustable WWSD
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
exceeds 34°F (1°C). The control exits WWSD when the outdoor air temperature falls
1°F (0.5°C) below the WWSD setting or if the slab temperature falls below 34°F (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.
Maintaining the system 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 item in the VIEW menu. 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 (STATUS)
While in the VIEW menu there are a number of items available to determine the current status of zone 1. To view the current status
of zone 1, select the Status 1 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 fi ve
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.
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 and System Pmp 2)
The system pump contacts close and remain closed as long as the system is either in
the Melting or Idling mode. The system pump contacts shut off if the control is in CWCO,
WWSD, or if there is no call for Melting or Idling.
MELTING CONTACT OPERATION
The Melting contact (terminals 21 and 22) closes and remains closed as long as the system is in Melting mode. This contact can be
used as an external signal to indicate that the system is currently in Melting mode. This contact can also be used as a means of
prioritizing or enabling multiple snow melting controls.
PURGE
The system pumps continue to operate for up to 2 minutes after the last demand is removed. This purges the residual heat from the
boiler 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 pumps are turned off.
When operating a boiler that is dedicated to a snow melting system, the 667 is designed
to operate the boiler as efficiently as possible. The boiler is cycled based on the mixing
supply fluid temperature. This is to provide longer and more efficient 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 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 is designed for condensing or low temperature operation, set the Boil MIN
adjustment to OFF.
FIRE DELAY (FIRE DLY)
The FIRE DLY is the delay time that may occur between the time that
the 667 closes the Boiler contact and when the burner fires. 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
Fire
Delay
Minimum
On Time
Time
BOILER MASS (Boil MASS)
The Boil Mass setting allows the 667 to adjust to different types of heat sources depending on their thermal mass.
Light (LITE)
The Lite setting is selected if the boiler that is used has a low thermal mass. This means that the boiler 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 fired. This is typical of many copper fin-tube boilers.
Medium (MED)
The Med setting is selected if the boiler that is used has a medium thermal mass. This means that the boiler 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 that is used has a high thermal mass. This means that the boiler 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 667, either a
fixed 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 667 closes the Boiler contact to fire the boiler. If the temperature rises 1/2 of the differential above the target temperature, the
667 opens the Boiler contact to turn off the boiler.
If the AUTO differential is selected, the 667 automatically adjusts
the Differential setting under the current load conditions to avoid
short cycling.
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 667 is one of many controls
that can call for boiler operation. When in the return mode, the 667 provides a boiler
enable through the Boiler contact. The 667 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 Boiler contact closes on the 667. The Boiler contact
remains closed until the mixing device no longer requires heat. With the sensor on the
boiler return, the 667 is still capable of providing boiler protection as described in section
A.
Off
Differential
On
Snowmelting Load
Time
Section C3: No Boiler Sensor
NO BOILER SENSOR (Boil SENS = NONE)
The 667 is capable of operating without a boiler sensor if desired. Without a boiler sensor,
the 667 is unable to provide boiler protection. In this mode of operation, the Boiler contact
is used to provide a boiler enable. When the mixing device begins to ramp up, the Boiler
contact on the 667 closes. The Boiler contact remains closed until the mixing device no
longer requires heat. This type of application is typical if the 667 is drawing heat from a
source that already incorporates some form of boiler protection.
The snow melting system can be enabled manually or automatically. A melting enable signal applied to the control places the system
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 while in the VIEW menu. If the Start button on the control
is pressed while the system is already melting and up to temperature, the running time
counter is reset to the Run Time setting.
Remote Start / Stop Module 039
The snow melting system is enabled by pressing the button on the front of the 039. While
the zone is coming up to temperature, a green indicator light flashes on the front of the
039. Once the zone 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 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 (15 and 16). 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.
AUTOMATIC MELTING ENABLE (Snow / Ice Sensor 090)
The 667 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.
Water Detection Sensitivity (SENSTVTY)
The 667 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.
24 to 230 V (ac)
L
N
16
15
Melt / Idle
Demand
Idle Demand
Melt Demand
Section D2: Snow Melting Disable
The snow melting system can be disabled manually or automatically. A melting disable signal applied to the control takes the zone
out of the Melting mode. Once the snow melting system is disabled, the zone operates in the Idling mode. The Idling mode allows the
zone to be operated either 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 while in the VIEW menu.
Remote Start / Stop Module 039
A Remote Start / Stop Module 039 can be used to stop the snow melting. 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 five
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 while in the VIEW menu.