This manual refers to the Snow Switch®
Model PD Pro control panel manufactured
after October 31, 2013, which uses a
universal (100 – 277 VAC; 50/60 Hz) power
supply.
Older units use a voltage-specific power
supply and have different wiring
configurations.
table of conents
2
4
5
6
6
6
7
8
9
13
15
18
19
24
25
26
SECTION
SAFETY INFORMATION & WARNINGS
PRODUCT TESTING RECORD
UNPACKING THE UNIT
INVENTORY
PRODUCT DESCRIPTION
SELECTING THE PROPER SENSOR
AVAILABLE OPTIONAL COMPONENTS
INSTALLING THE CONTROL
PREPARATION & SYSTEM SET-UP
SYSTEM SCHEMATIC DIAGRAMS
POST-INSTALLATION TESTING
OPERATION
MAINTENANCE
TROUBLESHOOTING
HEATER CONNECTION
SPECIFICATIONS
ORDERING INFORMATION
PAGE
9
WarmlyYours
Be Connected.
Be Warm. Be Radiant.
Advanced Snow & Ice Melt Control
SCA-DUAL
2INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
SAFETY INFORMATION AND WARNING SUMMARY
Read and become familiar with the safety
information below.
Abnormal Odor or Smoke
In the event of smoke or a burning or abnormal odor,
immediately interrupt power to the unit by turning off
the circuit breaker protecting the unit.
Odeur ou fumée anormale
En cas de fumée ou de brûlure ou d'odeur anormale,
coupez immédiatement l'alimentation de l'unité en
fermant le disjoncteur protégeant l'unité.
ELECTRICAL SHOCK / FIRE HAZARD
Even when the heat cables are disconnected, if the
circuit breaker is on and power is running to the unit,
voltage is still being applied to the yellow heat cable
leads. Therefore, never touch the ends of the yellow
leads or let the two leads touch each other. Do not let
the two yellow heat cable leads contact any component
inside the unit.
Any installation involving electric heater wiring must be
grounded to earth to protect against shock and fire
hazard. Suitable ground fault detection and
interrupting systems must always be in use to reduce
shock and fire hazard and to protect equipment.
Electric wiring to heating elements must be installed in
accordance with National Electrical Code (NEC)
requirements and all other local and applicable
electrical codes and any third-party standards. Follow
the installation instructions contained herein and those
provided by the heater manufacturer.
Use a GFEP (Ground Fault Equipment Protection) circuit
breaker on each branch circuit connected to the ice
melting system. Clearly label each circuit breaker with
its function. This is vitally important when there is more
than a single point of disconnect.
Size the circuit breaker in accordance with the size of
the expected load. The maximum current load for the
PD Pro is 30 Amp resistive. The PD Pro often serves as a
pilot duty relay for operating high current single- or
three-phase contactors in residential or light
commercial applications. This product is intended for
use in residential or light commercial applications. For
larger or more critical installations, the “CMC” Series of
control panels from Environmental Technology, Inc.,
provides a cost-effective solution offering enhanced
system design and performance features.
Make certain that the heater shield is properly
grounded. Failure to do so may result in damage to the
equipment or fire.
Following installation, and prior to beginning system
operation, refer to and perform the Post-Installation
Tests described in this manual.
DANGER D'ÉLECTROCUTION / D'INCENDIE
Même lorsque les câbles chauffants sont déconnectés,
si le disjoncteur est activé et que l'alimentation est
l'appareil, une tension est toujours appliquée aux fils
jaunes du câble chauffant. Par conséquent, ne touchez
jamais les extrémités des fils jaunes et ne laissez pas les
deux fils se toucher. Ne laissez pas les deux fils jaunes
du câble chauffant entrer en contact avec un
composant à l'intérieur de l'appareil.
Toute installation impliquant un câblage de chauffage
électrique doit être mise à la terre pour se protéger
contre les chocs et les risques d'incendie. Des
systèmes appropriés de détection et d'interruption des
défauts à la terre doivent toujours être utilisés pour
réduire les risques de choc et d'incendie et protéger
l'équipement.
Le câblage électrique des éléments chauffants doit
être installé conformément aux exigences du National
Electrical Code (NEC) et à tous les autres codes
électriques locaux et applicables et à toute norme
tierce. Suivez les instructions d'installation contenues
dans le présent document et celles fournies par le
fabricant de l'appareil de chauffage.
Utilisez un disjoncteur GFEP (Ground Fault Equipment
Protection) sur chaque circuit de dérivation connecté
3INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
au système de fonte des glaces. Étiquetez clairement
chaque disjoncteur avec sa fonction. Ceci est d'une
importance vitale lorsqu'il existe plusieurs points de
déconnexion.
Dimensionnez le disjoncteur en fonction de la taille de
la charge attendue. La charge de courant maximale
pour le PD Pro est résistive de 30 ampères. Le PD Pro
sert souvent de relais de service pilote pour le
fonctionnement de contacteurs monophasés ou
triphasés à courant élevé dans des applications
résidentielles ou commerciales légères. Ce produit est
destiné à être utilisé dans des applications
résidentielles ou commerciales légères. Pour les
installations plus grandes ou plus critiques, la série de
panneaux de commande «CMC» de Environmental
Technology, Inc., offre une solution rentable offrant
une conception de système et des fonctionnalités de
performance améliorées.
Assurez-vous que le blindage du radiateur est
correctement mis à la terre. Ne pas le faire peut
endommager l'équipement ou provoquer un incendie.
Après l'installation et avant de commencer à utiliser le
système, reportez-vous à et effectuez Tests
post-installation décrits dans ce manuel.
WARNING:
Even when the heat tapes are disconnected, if the
circuit breaker is on and power is running to the unit,
voltage is still being applied to the yellow heat tape
leads. Therefore, never touch the ends of the yellow
leads or let the two leads touch each other. Do not let
the two yellow heat tape leads contact any component
inside the unit.
Risque de choc électrique / d'incendie
Même lorsque les rubans chauffants sont déconnectés,
si le disjoncteur est sous tension et que l'unité est sous
tension, la tension est toujours appliquée aux fils jaunes
du ruban chauffant. Par conséquent, ne touchez jamais
les extrémités des fils jaunes et ne laissez pas les deux
fils se toucher. Ne laissez pas les deux fils jaunes du
ruban chauffant entrer en contact avec un composant à
l'intérieur de l'unité.
4INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
PRODUCT TESTING RECORD
Use this page to record the results of the testing procedures in this manual. Specifically, these are a mega-ohm test
following installation of the heat cable, a post-installation test of the control box, and a post-installation test of the system
sensor(s). This record will be a useful resource throughout the life of the product.
MEGA-OHM TESTING
(Follow heat cable manufacturer’s recommendations or, if not available, use a 500 VDC mega-ohm meter on the heat
cable.)
TEST DATE AMBIENT TEMP
READING
(Target: 20 MΩ or greater; Check heat cable manufacturer’s documentation.)
TEST DATE AMBIENT TEMP
SUPPLY VOLTAGE (VOLTS)
If heat cable is disconnected. (Use voltmeter.)
(Target: faceplate voltage)
SYSTEM CURRENT (AMPS)
If heat cable is not disconnected. (Use amp
meter.) (Target: should be based on heat
cable used,
consult heat cable supplier; reading must
be less than faceplate amps and system
breaker sizing)
POST-INSTALLATION CONTROL TESTING
(Use a voltmeter or clamp-on amp meter on either yellow control lead.)
5INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
TEST DATE AMBIENT TEMP
SENSOR SUPPLY VOLTAGE (VOLTS)
RED TO BLACK
(Target: 23 – 28 VDC)
POST-INSTALLATION SENSOR TESTING
(Use a voltmeter on the leads indicated.)
SENSOR CONTROL VOLTAGE
WHITE TO BLACK
Warm & Dry (Target:
22 – 28 VDC)
Cold & Wet (Target:
less than 2 VDC)
Immediately upon receipt, inspect the container and
packing material for any noticeable damage. Unpack
the unit, taking care not to damage the packing
materials. Save the shipping container and related
materials until normal operation has been established.
If the unit must be returned, take care to ensure that it is
repackaged as it was received.
As soon as the unit arrives at your facility, inspect it for
mechanical damage. If any of the following problems is
found, contact Environmental Technology, Inc.,
Customer Service immediately:
• contents incomplete or incorrect;
• internal or external mechanical damage; or
• defective operation
ETI Customer Service is available between 8:00 a.m.
and 5:00 p.m. Eastern Time at (574) 233- 1202 or (800)
234-4239. In the event of shipping damage, keep the
packing materials for inspection by the carrier.
Equipment cannot be returned for credit once it has
been installed. ETI will repair or replace faulty
equipment under warranty. Prior to removal of
equipment for warranty return, please contact ETI
Technical Support at (800) 234-4239 for
troubleshooting assistance.
Before returning a unit to Environmental Technology,
Inc., obtain a Return Merchandise Authorization from
our Customer Service Department, available between
8:00 a.m. and 5:00 p.m. Eastern Time at (574) 233-1202
or (800) 234-4239. If possible, use the original container
and packing materials when packing the unit for
shipment. It is important to mark the Return
Merchandise Authorization clearly on the outside of the
shipping container so that it may be correctly processed
upon receipt at Environmental Technology.
For more information about replacement parts or for a
replacement Data Sheet or Manual, please visit
http://www.networketi.com/.
UNPACKING THE UNIT RETURNS AND REPLACEMENT PART PURCHASES
6INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
Using the information below, verify that the shipping
package contains all of the parts listed. Notify
Environmental Technology, Inc., Customer Service
immediately if there are any discrepancies.
Environmental Technology, Inc. Customer Service is
available between the hours of 8:00 a.m. and 5:00 p.m.
Eastern Time at (574) 233-1202 or (800) 234-4239.
FEATURES AND BENEFITS
Compatible with standard Snow Owl, GIT–1, and
SIT–6E sensors
Two sensor input to allow for application specific
sensor combination such as:
Snow Owl
aerial
sensor
and
a
GIT–1gutter
sensor
for
roof
and
gutter
deicing
aerialSnow Owl sensor
and
SIT–6
Epavement- mounted
sensor
for
snow
melting
Adjustable
0
–
8
hour
hold-on
time
Compatible
with
the
RCU–3
remote
control
Durable
IP66,
NEMA
4X
enclosure
UL
Listed
to
UL
873
Temperature-Indicating
and
Regulating
Equipment
Depending on the specifics of your order, there will also
be up to two sensors included with the system, as well.
These will be either the Snow Owl aerial -mount
sensor , the GIT –1 gutter ice sensor , or the SIT –6E
pavement-mount sensor.
INVENTORY
The Snow Switch model PD Pro snow and ice control is
designed for use with up to two compatible sensors.
Compatible sensors include the Snow Owl (aerial ),
GIT–1 (gutter) and SIT–6E (pavement ) snow and ice
sensors . These sensors provide the snow
management industry ’s most versatile and cost
effective snow melting control when used with
Environmental Technology control panels . Sensors
should be selected to best suit the intended
application.
The Snow Owl , GIT–1, and SIT–6E snow and ice
melting sensors combine to reliably detect snow
and ice in gutter and pavement applications . The
Snow Owl sensor may be paired with either the GIT–
1 sensor for gutter applications or the SIT –6E
sensor for pavement applications. These sensors
detect precipitation as snow at temperatures
below 38°F (3.3°C). Control panels are signaled
only if moisture occurs below this temperature ,
saving energy and ensuring reliable melting.
SELECTING THE PROPER SENSOR
The Snow Switch model PD Pro snow and ice control,
when used with up to two compatible sensors,
automatically controls snow and ice melting heaters for
minimal energy costs. Applications include pavement,
sidewalk, loading dock, roof, gutter, and down spout
snow/ice melting in commercial and residential
environments. The PD Pro control is powered from
operating voltages of from 100 to 277 VAC and is rated
for 7 amps inductive load. The PD Pro is rated for 30
amps resistive load.
The PD Pro control is housed in an
environmentally-sheltered IP 66, NEMA 4X
weather-resistant enclosure to provide several
installation options.
PRODUCT DESCRIPTION
ITEM NUMBER
1
2
3
PD PRO/ PART #23736
ACCESSORY KIT/ PART #23731
PD PRO INSTALLATION SHEET/ PART #23735
DESCRIPTION & PART NUMBER
7INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
Table 1 below presents the recommended sensor
combinations for use with the PD Pro snow and ice
control.
TABLE 1.
RECOMMENDED SENSOR COMBINATIONS
For more complete information regarding the sensors
and their individual capabilities, refer to the Products
link on the ETI website, http://www.networketi.com.
equidistant between runs (see diagram, page 12). This
optional temperature sensor assembly or thermistor is a
high-temperature shut-off: it regulates the power to the
heat cable by automatically suspending an active
heating cycle if, at any time during that cycle, the
temperature at the sensor end rises to above 45°F.
Then, if, during the Hold-On Time period, the
temperature drops to below 44°F, the heating cycle will
resume automatically and continue until the end of the
Hold-On Time period as set on the face of the unit. This
lowers system operating costs while protecting the heat
cable from overheating*. The HEAT light will flash to
indicate the unit is regulating system temperature.
Regulation can occur any time the HEAT light is on.
As the placement of the RCU–3 remote control unit is a
key factor in the overall configuration of, as well as
customer satisfaction with, the PD Pro system, it is
important that it be installed as part of the system
initially. Similarly, as the temperature sensor assembly
monitors the temperature at the point of the cable end
to keep the heat cable from overheating*, so it is
necessary, for best results, to lay the temperature sensor
at the same time as the heat cable to ensure proper
placement and routing. It is not recommended to try
and retrofit either of these optional assemblies once the
system is already installed and operational.
To ensure proper installation and to facilitate
placement, wiring, routing, and function of either or
both the RCU–3 or the temperature sensor, it is strongly
advised and suggested that these assemblies, whether
together or individually, be installed with the system
initially rather than retrofitted afterwards. Use the
information below to order either or both of these
important optional components.
Prior to installation and set-up, consider two important
optional components available for the PD Pro system.
Either or both of these optional components must be
ordered separately and installed along with the system
which facilitates installation and optimizes performance.
The first is the Remote Control Unit, RCU–3 (Part
Number 21357), for the convenient operation of the
system away from the control box. Remote operation is
especially useful if the PD Pro is installed in a location
not easily or readily accessible by personnel who may
be better situated to assess the need to melt ice or snow
from walkways or parking areas.
Using the RCU–3, the operator is able to access the full
range of system functions and controls from a
secondary location: manually set the Cycle Time,
equivalent to the Hold-On Time setting on the face of
the unit itself, or manually initiate or terminate a heating
cycle.
The second optional component for the PD Pro system
is the Temperature Sensor Assembly (Part Number
19272). This temperature sensor assembly detects the
temperature at the cable end and regulates the
Hold-On Time period once precipitation has ended and
the call for heat has passed. The sensor is installed with
the sensor end (white cap) placed near the heat cable,
AVAILABLE OPTIONAL COMPONENTS
ONE (1) OR TWO (2) SNOW OWL SENSORS
ONE (1) GIT–1 SENSOR
ONE (1) GIT–1 AND ONE (1) CIT–1 SENSOR
ONE (1) SIT–6E SENSOR AND ONE (1) SNOW OWL SENSOR
ORDER NUMBER
21357
DESCRIPTION
Optional Remote Control Unit RCU–3
To order either or both of these optional components
for your system, contact the Environmental Technology
Sales Department between the hours of 8:00 a.m. and
5:00 p.m. Eastern Time at (574) 233-1202 or (800)
234-4239.
8INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
*For cables other than self-regulating (SR) heat cable
products.
Install this unit in compliance with National Electrical
Code (NEC) and Canadian Electrical Code (CEC)
standards, as well as all other local and applicable
electrical codes for your area. Prior to beginning
installation, make sure that the facility has properly sized
electric service and breaker. For additional information
regarding electrical ratings and facility power
requirements, refer to the Specifications section of this
manual.
This unit is intended for wall mount installation only. The
wall used for the installation should be capable of
supporting four times the weight of the unit, or about 20
pounds. Install the unit directly to a solid, stable surface.
The IP 66, NEMA 4X weather-resistant enclosure can be
installed either inside or outside.
Internal connections for any optional remote control
unit or system sensor(s) will be made in the next section.
The dimensions shown in the Top View of Figure 1
below are for the mounting hole location footprint and
run from centerline to centerline of the four slotted
mounting holes. The dimension shown in the Right Side
View of Figure 1 is from the bottom of the enclosure to
the top of the clear plastic lid and shows the distance
that the unit will protrude from the mounting surface.
INSTALLING THE CONTROL
CONTROL BOX INSTALLATION
Figure 1: PD Pro Mounting Hole Footprint
During installation, leave all mounting hardware loose
enough to allow for slight adjustments to component
placement. Once all components and the front panel
and clear plastic cover have been installed, then, as the
final step in installation, fully tighten all mounting
hardware and weather-tight fittings. Make sure all
connections and fittings are snug, air-tight, and
water-tight.
Use the box as a template to determine the
mounting hole footprint pattern. Hold the unit up
against the wall onto which it will be mounted, with
the mounting blocks against the wall, then mark the
wall at the locations of the slotted mounting holes
to determine the location of the mounting holes on
the wall.
As desired, to hold the box in place during the
installation process, you may loosely install one or
both of the top mounting bolts as the remaining
holes are marked. To ensure accurate and level
installation, however, do not fully tighten any of the
mounting hardware until all hardware has been
started.
Once the four mounting holes have been located
and marked, install the box to the wall using
properly sized mounting hardware. Be sure to use
mounting hardware appropriate for the job,
heavy-duty and long enough to fasten the unit
securely to the mounting surface. Make sure to use
all four mounting holes. Because conduit will also
be installed to protect the cables running from the
control box, install the box, but leave the mounting
hardware loose enough to work the conduit into
place. The conduit will be installed later in this
process, at which time all mounting hardware will
be securely tightened.
1
2
3
9INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
Install the conduit, system sensor(s) and sensor cables,
heater cables, and power cable. Refer to Figures 2 and
3, as well as Table 2. Remove the clear plastic unit cover
and face plate to access the inside of the unit. These will
be replaced at the end of the installation process. A
post- installation test will be performed in the next
section to verify proper function.
NOTE: During installation, leave all mounting hardware
loose enough to allow for slight adjustments to
component placement. Once all components and the
front panel and clear plastic cover have been installed,
then, as the final step in installation, fully tighten all
mounting hardware and weather-tight fittings. Make
sure all connections and fittings are snug, air-tight, and
water-tight.
INSTALLING THE SENSOR(S)
Refer to the enclosed Installation Sheet(s) and
Instruction Manual(s) for sensor installation and
operating instructions.
INSTALLING THE SENSOR CABLES
Route the sensor cables through the weather-tight
connection ports on the right side of the unit, then
connect the red, black, and white leads to the front
panel PC board terminal block J1 terminals. If using two
sensors in the system, even if they are of the same type,
it does not matter which one is wired into which set of
terminal blocks, upper or lower. After connecting the
red, black, and white leads, push a little more of the
cable into the connection port to create a little more
slack to relieve some of the tension from the wires at the
point of the terminal strip, then fully tighten the
weather-tight connection to secure the cable in place. If
installing an extension onto the sensor cable(s), a
junction box is required in accordance with applicable
code.
INSTALLING THE HEATER CABLES
Lay-out, configure, and install the system heater cables
in accordance with National Electrical Code (NEC) or
Canadian Electrical Code (CEC) and manufacturers’
requirements, as well as all other local and applicable
building and electrical codes. Make sure to properly
seal and waterproof all cable runs. If using a SIT–6E
pavement-mount sensor, position the heater cabling so
it does not interfere with the sensor wiring.
Upon conclusion of heater cable installation, perform a
mega-Ohm or “megger” test on the heater cables as
directed by the heater cable manufacturer. Record the
results on page 2 of this manual and retain for future
reference.
INSTALLING THE OPTIONAL COMPONENTS
Route the remote control (RCU–3) cables through the
conduit then into the enclosure. Connect the remote
cables to the front panel PC board terminal block J1
terminals labeled REMOTE.
Route the optional temperature sensor assembly wiring
through the same conduit as the RCU–3 cable then into
the enclosure. Connect the temperature sensor
assembly cables to the front panel PC board terminal
block J1 terminals labeled AUX.
INSTALLING THE POWER CABLE
With the circuit breaker off, install the power cable. As
shown in the wiring charts, the power cable is provided
by the customer. Size the cable for a 30 Amp maximum
load. Run the cable through conduit and connect the
leads to the control box wiring. The line is black, neutral
is white, and ground is green. The unit has no power
switch so remember that power is running to the system
as soon as power is applied.
This manual refers to the Snow Switch® Model PD Pro
control panel manufactured since October 31, 2013,
which uses a universal (100 – 277 VAC; 50/60 Hz) power
supply. Older units use a voltage-specific power supply
and have different wiring configurations.
Figure 2 is a schematic diagram of an entire PD Pro
system, including the available optional components.
PREPARATION AND SYSTEM SET-UP
SYSTEM SCHEMATIC DIAGRAMS
10 INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
FIGURE 2. Representative PD-Pro System Schematic
TABLE 2. Cable Ratings & Connections
TO HEATER CABLE
Heater Load 1/Yellow
INPUT POWER
Line/Black
Neutral/White
Ground/Green
RCU–3 &
Optional Temp.
Sensor
GIT-1 SENSOR
SNOW OWL SENSOR
100 – 277 VAC
50/60 Hz
30 Amp Max.
(Input Power & Ground)
Heater Load 2/Yellow
Heater Ground
(Shield)/Green
POWER Cable (provided by customer)
INPUT Power
(provided by customer)
OUTPUT To Heater
(provided by customer)
SENSOR Wiring
Line 1
Line 2 / Neutral
Ground
Heater Load 1
Heater Load 2
Heater Ground (Shield)
Black
White
Green
Yellow
Yellow
Green
HEATER Cable (provided by customer)
REMOTE Wiring
WIRE LEAD CONNECT TO
TEMPERATURE SENSOR ASSEMBLY Wiring
Size for 30 Amp maximum load
#18 AWG jacketed, 3-conductor
Size to system load
#22 AWG jacketed, 2-conductor
#22 AWG jacketed, 2-conductor
INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
11
FIGURE 3. Representative SIT-6E Pavement Installation
A representative schematic diagram of an SIT–6E pavement sensor installation is shown below
in Figure 3. Note how the heat cable and other components do not cross.
Heat Cable
SIT-6E Sensor
Optional
Temperature
Sensor
Cablels Inside
Conduit
INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
12
Cable Connector
Receptacle
(Note the notch
to ensure proper
orientation)
Terminal Block
U1 with Terminals
Labeled for
System Cables
and Wiring
Optional
Temperature
Sensor Wiring
Optional Remote
Control
(RCL-3 Wiring)
Fuse LED
Sensor Cables
(It doesn’t matter
which of the
sensors is wired
into which set of
terminals)
1 Amp Fuse
FIGURE 4. The PD Pro Front Panel PC Board
Refer to Figure 4 for useful information regarding the front panel PC board.
INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
13
Installation errors cause the majority of system
problems. Therefore, thoroughly check the system
before placing it into service. Simple electrical tests and
visual inspection can identify any wiring errors, as well
as improper waterproofing. Visually inspect for proper
wiring and waterproofing, making sure that all box
joints are sealed and that all wiring is properly
terminated.
In performing the post-installation test procedure as
described below, the heat cable will activate, even if
only for a brief time, so that system performance can be
accurately simulated and measured. For that reason,
and depending specifically on the ambient temperature
or general conditions in which the system is being
installed, it is recommended to continuously and
carefully monitor the system and its components during
the entire testing process. High temperatures can cause
damage to asphalt and similar paving materials. Never
leave the site during testing. Never leave the system
unattended during testing. If fire or smoke or an
abnormal odor is observed during testing, shut off
power to the system and suspend the test.
To most accurately simulate and measure system
performance, leave the heat cable connected to the
control during testing and use a clamp-on amp meter as
directed in this procedure. Using the clamp-on amp
meter clamped around the wires prevents the operator
from having to touch bare or exposed metal or wiring
and also keeps the operator from having to break the
circuit, all while still allowing the accurate simulation
and testing of the system, including the Ground Fault
Equipment Protection circuitry, if your system is so
equipped.
It is the responsibility of the on-site installer to assess
the overall safety concerns at the site and to disconnect
the heat cable, as necessary or desired, whether before
or during this test, as well as to re-establish those wiring
connections at the conclusion of this procedure.
Even when the heat cables are disconnected, as long as
the circuit breaker is on and power is running to the unit,
voltage is still being applied to the yellow heat cable
leads. Therefore, never touch the ends of the yellow
leads or let the two leads touch each other. Do not let
the two yellow heat cable leads contact any component
inside the unit.
This procedure requires a clamp-on amp meter or
voltmeter. Make sure the gutter and downspout are
both dry before testing the GIT–1 sensor. Record test
results in the appropriate section on page 2 of this
manual for future reference.
CONTROL TESTING
Remove system power. There may be two or more
points of disconnect.
Open the clear plastic cover and remove faceplate
from the unit. Retain all parts and mounting
hardware. If the heaters have been disconnected for
testing, using a voltmeter, measure the voltage
across the two yellow leads. If the heaters have not
been removed tor testing, using a clamp-on amp
meter, measure the current through the yellow lead.
Restore power to the unit. After a brief initialization
routine, the SUPPLY LED should be on, but no other
LEDs. Once initialization is complete, the amp meter
or voltmeter should read 0.
With power still running to the unit, turn up the
Hold-On Time dial to a setting higher than 0, then
press the Heater Cycle button. The HEAT LED should
come on and the amp meter should show a reading
of less than the maximum system load as shown on
the faceplate. The voltage across the yellow leads
will match the system voltage.
Do not touch the yellow lead ends.
Press the Heater Cycle button again. The HEAT LED
will go off and the amp meter reading should drop
back to 0 or the voltage will drop to 0. Record results
on page 2 of this manual.
POST-INSTALLATION TESTING WARNING
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INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
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Remove the amp meter or voltmeter. Do not yet
re-install the unit front plastic cover or faceplate.
Proceed to sensor testing on the following page.
SNOW OWL AND GIT–1 SENSOR TESTING
The SNOW OWL and GIT –1 sensors have two
interrelated systems : the temperature sensing
system and the moisture detection system .
Complete testing of the sensor involves
manipulation of both . The tools needed for this
procedure are a voltmeter and an aerosol circuit cooler
(“Freeze Spray ” is preferred ) or cup of ice water . The
Freeze Spray is available at most electric supply
stores.
Ensure that the moisture sensing grid on the sensor is
clean and dry.
Follow the steps below to perform the SNOW OWL
and GIT–1 sensor post-installation test procedure.
Connect the voltmeter across the black and red
leads from the sensor (low-voltage wiring terminals
at the control). Connect the black test lead to the
black wire. You should obtain a reading of 23 to 28
VDC. Now, check the reading across the black and
white sensor leads. You should read 22 to 28 VDC
with a warm (above 38°F) and dry sensor. Both the
SNOW LED and HEAT LED should remain off.
Cool the temperature probe of the sensor with the
Freeze Spray. You should see frost form on the
temperature probe. Alternately, place the
temperature probe in ice water. The SNOW LED and
HEAT LED should remain off.
Using a moist finger, touch the moisture sensing grid
on top of the sensor. Both the SNOW LED and HEAT
LED should come on and the voltage between the
white and black sensor leads should be less than 2
VDC.
With the unit cold and the sensing grid moist, allow
the unit to warm up to above 38°F. The SNOW LED
should turn off and the HEAT LED should stay on and
the voltage should return to 22 – 28 VDC. Record
results on page 2 of this manual.
If testing a SIT–6E sensor, proceed to the next
section now. If testing is complete, with unit
powered off, restore all wiring connections and re-
install the face plate and clear plastic cover. Set the
Hold-On Time control dial to the desired setting.
SIT–6E SENSOR TESTING
If paving material or other residue adheres to the
sensing elements, clean the surface with a ScotchTM
Brite Pad. Avoid using metallic or coarse abrasives or
detergents.
Regardless of weather conditions, the functional
operation of an installed SIT–6E sensor can be
determined using a digital voltmeter (DVM) and a
10-pound (4.54kg) bag of crushed ice as described
below.
With the DVM set to the 100 VDC range, verify the
sensor supply voltage by connecting the negative (–)
test lead to the sensor black wire and the positive (+)
test lead to the sensor red wire. A DVM reading
between 23 and 28 VDC is acceptable.
With the negative (–) test lead remaining in place,
reconnect the positive (+) test lead to the sensor
white wire and confirm there is 22 to 28 VDC
present. Both the HEAT LED and the SNOW LED
should be off.
Place the entire contents of the bag of crushed ice
on top of the sensor and allow a time lapse in excess
of 20 minutes before observing that less than 2 VDC
is indicated by the DVM. Depending on ambient
conditions, however, this might take only a few
minutes, in which case, that is not a problem. (A
nominal temperature below 38°F or 3.3°C must be
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SUPPLY
HEAT
SNOW
detected before the sensor’s normally-open contact
is closed. If the sensor surface temperature was
excessive prior to beginning this procedure, it will
be necessary to extend the cool-down time interval
by as much as an additional 20 minutes.) Most
importantly, make sure both the HEAT LED and the
SNOW LED come on. Record results on page 2 of
this manual.
With satisfactory results, control and sensor
pre-operational testing is now complete. Disconnect
and remove all testing devices from the system.
Once all post-installation testing is complete and
with unit power off, restore all wiring connections.
Re-install the face plate and clear plastic cover onto
the control. Set the Hold-On Time control dial to the
desired setting.
OPERATION
This section presents operating instructions for the unit
and begins with a picture of the front panel. Refer to
Figure 5. Note the system information on the left side of
the panel, as well as the operator controls and
indicators located on the right side of the panel. The
controls and indicators are explained in this section.
Note that because the unit has no ON/OFF power
switch, power runs to the unit as soon as facility power is
connected to it. For as long as power is running to the
unit, the green SUPPLY LED will always be lit. The unit
initiates a heating cycle when the system sensor(s)
detect snow or ice at or below 38°F (3.3°C).
Upon initial Start-Up, all of the LEDs will come on for 2.5
seconds, and then shut off for 2.5 seconds. After this,
the device goes into normal operation.
OPERATOR CONTROLS & INDICATORS
Operator controls and indicators are explained below.
Refer to Figure 6 on the following page.
The SUPPLY LED lights up and stays lit as
long as power is running to the unit,
whether it is currently in a heating cycle or
not.
When the HEAT LED is lit, the unit is
currently engaging power to the heater
outputs in response to sensor input. The
HEAT LED stays on for the duration of the
heating cycle. As desired, press the Heater
Cycle button to stop a current heating
cycle, unless the SNOW LED is lit.
The SNOW LED lights up when any of the
sensors detect snow or ice at or below
38°F (3.3°C) and stays on until the sensors
no longer detect snow or ice or the
temperature surpasses 38°F (3.3°C). Note
that the Heater Cycle button cannot be
used to cancel a current heating cycle if
the SNOW LED is lit.
Operator Controls
& Indicators
Note the information
presented here
FIGURE 5. The PD Pro Front Panel
INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
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FIGURE 5. The PD Pro Front Panel
System sensors currently
detect precipitation.to the
system
When the Hold-On Time is set
at 0, the unit will produce heat
only while the system sensor(s)
detect moisture at or below
38°F (3.3°C) and for no longer.
For best results, it is
recommended to set the
Hold- On Time to
approximately 2 to 6 hours so
all moisture completely melts
and evaporates.
Power is running to the
system
Heating Cycle is currently in
progress
Press to start or cancel a
heating cycle
In this view, the Hold-On
Time is currently set at 0.
Rotate the control knob to
the right to increase the
setting or to the left to
decrease the setting.
INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
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SETTING THE HOLD-ON TIME
Heating action begins a few seconds after the sensor
detects moisture at or below 38°F (3.3°C). However,
heating action continues even after the sensor no
longer detects moisture based on the Hold-On Time
setting. The Hold-On Time control knob allows you to
set the length of time the unit will continue heating even
after the sensor no longer detects moisture. This is
beneficial because it typically takes longer for ice to
melt than it took to form initially and also because it
keeps moisture from re-freezing before it has fully evap-
orated. As indicated on the front panel, the Hold-On
Time can be set for anywhere from 0 to 8 hours as
indicated by the arrow on the control knob. Note that if
the Hold-On Time control knob is set at 0 (as shown in
Figure 5), the unit will produce heat only for as long as
the sensor detects moisture but for no longer. For that
reason and to ensure more effective heating, it is recom-
mended that the Hold-On Time be set up closer to the
mid-way point, corresponding to about 2 to 6 hours.
Set or increase the Hold-On Time as desired by rotating
the control knob to the right or clockwise. Decrease the
Hold-On Time setting by rotating the control knob to
the left or counterclockwise. Again, remember that if the
Hold-On Time control knob is set at 0, the unit will
produce heat only for as long as the system sensor(s)
detect moisture and no longer.
USING THE HEATER CYCLE BUTTON
The Heater Cycle control button allows you to manually
initiate a heating cycle regardless of weather condi-
tions, whether or not the sensor currently detects mois-
ture, and regardless of the temperature. The Heater
Cycle control button also allows the operator to cancel
a heating cycle currently in progress, regardless of the
Hold-On Time setting, unless the SNOW LED is on,
indicating the sensor currently detects moisture at or
below 38°F (3.3°C). Remember, if you manually initiate a
heating cycle by pressing the Heater Cycle button, that
heating cycle will last for the duration of the current
Hold-On Time setting, unless manually cancelled by
pressing the Heater Cycle a second time.
It is not necessary for the Hold-On Time setting on the
control box and the Hold-On Time setting on the RCU to
be identical. Note, however, that if a heating cycle is
manually started by pressing the Heater Cycle button
on the control box, that the resulting heating cycle will
last as long as the Hold-On Time setting on the control
box. Similarly, if a heating cycle is initiated using the
RCU, the resulting heating cycle will last as long as the
Hold-On Time setting on the RCU.
OPTIONAL REMOTE CONTROL OPERATION
The PD Pro can be operated either “locally” on the face
of the unit itself or by using the optional remote control
unit, RCU–3. Refer to Figure 7.
When LED is lit,
a heating cycle
is in progress
When LED is lit,
power is running
to the system
Press button to
initiate or cancel
a heating cycle
Rotate dial to
select desired
Cycle time
duration
FIGURE 7. Remote Control Unit RCU-3
INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
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The RCU Cycle Time control dial moves in discrete
increments rather than in a continuous motion as on the
control box. Cycle Time on the RCU applies only to a
manual heating cycle initiated at the RCU, not the Cycle
Time setting on the control box. The RCU cannot be
used to manually cancel a heating cycle which was man-
ually set on the control box.
To manually start a heating cycle, press the RCU Heater
Cycle control button. The RCU HEAT LED light will come
on. This will start a heating cycle which will last as long
as the RCU Cycle Time setting. To manually cancel a
current heating cycle which was manually set at the
RCU, press the RCU Heater Cycle button. The RCU HEAT
LED light will go out. To use the RCU to change the
duration of a heating cycle, rotate the RCU CYCLE TIME
control dial to the desired setting, either higher or
lower.
MAINTENANCE
To ensure the best function and results, it is recom-
mended to always keep the area around the sensors
clean from debris and general obstructions to maximize
the ability of the sensor to do its job. Clean the sensor
using a cleansing pad and water. Keep the gutters clean
and the area around the sensor free of leaves or other
debris which could limit the ability of the sensor to
detect the conditions necessary for optimum system
performance. Finally, once monthly, visually inspect the
fuse LED located on the front panel circuit board to
make sure it’s on. If the fuse LED is not on, change the
fuse.
INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
19
TROUBLESHOOTING
FLOWCHART 1
Snow Switch® Model PD Pro
Instruction Manual
23735
Rev. C
01/15
(800) 234-4239
http: www.networketi.com
Environmental Technology, Inc.
24 of 30
TROUBLESHOOTING FLOWCHART 2
INSTALLATION GUIDE & OPERATION MANUAL | PART NO. 23735 REV E
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TROUBLESHOOTING FLOWCHART 2
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