Difference between 277 single phase and 277/480 3 phase unit?

The difference is the step down transformer that provides the power for the internal circuitry. On the 277 single phase the transformer is 277 VAC to 24 VAC and you will note that its primary winding is connected to the top and middle poles on the contactor.

On the 277/480 three phase unit the transformer is 480VAC to 24VAC and the primary winding is connected to the top and bottom poles on the contactor.

Consult a professional and or your electric provider to determine what configuration is needed.

APS single phase and three phase wiring


The APS-C series systems are designed to turn on and off, as the weather requires heat to deal with snow or icing conditions. Although a thermostatic dry contact switch can be used to override the system on for temperature only, is not recommended since it will reduce the efficiency of the system. Running the heaters on cold days that do not have snowfall will not hurt anything but your budget.

If you must do so choose a thermostat with dry contacts that close when the temperature is below 40F and connect it to the override-on terminals of the EMC section of the Class 2 terminal block.


APS Snow Sensor Overide for temperature only
External contactors used with the APS-4C?

No, using external contactors will cause the GFEP circuit on the APS-4C to detect the inductive load of the contactors coil as ground fault and alarm the system every time the contactor is turned on. In order to increase the size of the application, a SC-40C satellite control can be used with the APS-4C without triggering the ground fault protection.

The APS-3C is designed without an internal GREP circuit so it will work with external contactors or direct heater loads. In both of these applications you must provide a GFEP breaker to power the heater circuit.


Flashing supply light.

A flashing supply light indicates a missing or broken High-Temperature Limit sensor. This sensor is required to make the APS-C series controller to work. It is required on all of the APS-C series controllers.

The sensor is not polarized and must be connected to pins 10 and 11. Refer to figure 22 in the manual. If the Class two terminals are black with screw connections problems can occur when the screws are over tightened.

sensor connections for flashing supply light
Delay between SC-40C and APS-4C?

Why is there a delay between when the APS-4C turns on and when the SC-40C comes on?

This delay between the APS-4C and the SC-40C is programmed into the system in order to reduce surge current. When the heaters are turned on they will have a large inrush of current for a few seconds. If all the heater circuits came on at the same time the inrush current could be large enough to trip the main breaker in supplying panel. This 5-second delay is meant to reduce this problem.

APS-4C connected to SC-40C

Snow light on SC-40C stays on longer than APS-4C

The snow light stays on longer for the SC-40C than the APS-4C because the APS-4C gets its command from an actual snow sensor where the SC-40C’s get their command from the APS-4C.

When the snow sensor’s moisture grid dries out, it no longer sends a snow present command to the APS-4C so it’s snow light goes out. However, the APS-4C remains on for the duration of the hold on time set on the front panel dial. While the hold on time continues the APS-4C continues to send a snow signal to the SC-40C’s and hold them on as well. When the hold on time is complete all of the controllers will turn off.

APS-4C, SC-40C connection for snow light
Is a snow sensor required for a SC-40C?

No, the SC-40C does not use a snow sensor, it is completely controlled by the attached APS-4C. However, the SC-40C does require the High-Temperature sensor Thermistor to be connected (or bypassed with a 470K-ohm resistor) in order for the unit to operate. The SC-40C only acts to extend the load capabilities allowing you to energize a larger heater area off a APS-4C unit.

SC-40C, APS-4C and snow sensor digram
Temperature sensor was not installed

The high limit temperature sensor is intended for two purposes, either as a slab sensor when the APS-C series unit is used for heating sidewalks, patios or drives or for ambient air temperature when the unit is used for roof and gutter melt systems.In roof and gutter applications the sensor is run outside the building and placed in a location that is out of direct sunlight and away from other heat sources such as air conditioners or

In roof and gutter applications the sensor is run outside the building and placed in a location that is out of direct sunlight and away from other heat sources such as air conditioners or vents.

In slab applications, this sensor is usually installed in conduit. If this was not provided for when the slab was poured then the alternative is to either use it as an ambient air sensor or bypass this function all together.

The High Temperature limit can be bypassed by installing a 470K-ohm resistor in place of the sensor on pins 10 & 11 Refer to figure 23 in the manual.

Can I simulate a sensor call for heat?

Yes, you can simulate a sensor call for heat to test the system by putting a jumper between pins 1 and 2 of the class two terminal blocks, the system will respond as if the sensor were seeing snow conditions. The snow and heat indicators will come on and relay or contactor will be pulled in.

How to simulate a sensor call for heat
Snow sensor not detecting snow outside?

There can be several reasons for this. First, start by checking the snow sensor supply voltage between pins 2 and 3 of the class two terminal blocks. It should be close to 24 VDC (the label on some unit incorrectly say 24VAC). If there is no voltage then check the fuse on the board behind the terminals.

If you have already simulated a sensor’s call for heat and the controller is not suspect then examine the wiring to the sensor, damaged wires can cause loss of signal from the sensor or power to the sensor.

Lastly, the snow sensors must see both a temperature below 38F and moisture on the moisture grid. High wind conditions can keep snow from accumulating on the moisture grid so consider how the weather is affecting the snow sensor. High accumulations can bury the sensor and allow the moisture sensors to melt a cave in the snow, which will not allow snow to touch the grid. This igloo effect will render the sensor inoperative. This effect can be reduced by the use of a moisture cup on GIT sensors and by placing CIT and LCD sensors at a slight angle to allow gravity to help remove excess snow.

Snow sensor diagnostics

Why do I have a red GFEP light on?
The GFEP indicator will come on when a ground fault occurs in one of the heater circuits. The insulating resistance of the heater cable is breaking down or the cable has been damaged allowing current to pass to ground thru an incorrect pathway. Left un-repaired the cable could cause a fire if it continues to be powered.

When a ground fault is detected the controller will not allow power to be applied to the heater circuits until the problem is corrected. You can isolate the offending heater by removing all the heaters and reinstalling them one at a time to discover the heater with the fault. An alternative to this method is to use a Meg-ohm tester and test each heater leg per the manufactures specifications.

You will need to contact the heater manufacturer for instructions on how to locate the problem and fix it. Most heaters can be repaired with repair kits or splice kits but the manufacturer will be able to provide the details.

How do I connect my SC-40C to my APS-4C?

APS-4C to SC-40C connections are done on the Class 2 terminal blocks on both units as follows.

APS-4C Pin SC-40C Pin Next SC-40C Pin

Connection from APS-4C to SC-40C
Connection from SC-40C to SC-40C
Why is the GFEP light flashing on my APS-4C?

This indicates that there is a ground fault on one of the attached SC-40C satellite controllers. The SC-40C that has the ground fault will have a solid red GFEP light and will not allow the heaters to be powered. Isolating the heater leg that has the ground fault is done in the same way as on the Isolating a ground fault on the APS-4C. If the light is flashing but there is no indication of a ground fault on the APS-40C then review the wiring of the communication wiring between the APS-4C and the SC-40C.

What is the EMC light for?

EMC stands for Energy Management Computer, which can be used to remotely monitor and control the APS-C series ice melt controllers.

These connections are made to the Class 2 connection terminal block on pins 14 through 22. The following diagram will aid in making these connections.

The EMC can use the override on and override off to turn the systems on and off and provides internal dry contacts for monitoring and alarms. For a complete description of how the EMC works refer to the manual page 18.

Energy Management Computer (EMC) Interface
The APS “C” Series interfaces with an EMC via relays. Inputs from the EMC include Override On, which causes heater operation, and Override Off, which inhibits heater operation. These functions are independent of weather conditions and the status of the Hold-On Timer. The interface provides five system status contact closures for the EMC including Supply, Snow, Heater, Alarm, and Temperature Limit.
Absent signals from the EMC, the APS Control Panel controls the heaters based on environmental conditions. Automatic snow melting control is the default condition of the system.
High Temperature Limit dial not turning unit on?
Why doesn’t adjusting the High Temperature Limit dial turn the unit on?

The High Temperature limit dial is used to set the maximum temperature that the unit will work at. When the High Temperature limit sensor detects a temperature higher than what is selected on the dial it overrides the system and shuts it off. This function can be used to further regulate slab temperatures in pavement applications and as a warm weather override when the system is used for roof and gutter melting applications.

High Limit Thermostat
The calibrated 40°F to 90°F (4°C to 32°C) high limit thermostat prevents excessive temperatures when using constant wattage and MI heaters. It also permits safe testing at outdoor temperatures too high for continuous heater operation. The temperature sensor is included and must be connected to the system for proper operation.
There are two DIP switch configurable operation modes for the high limit thermostat. The factory default operation mode uses the high limit thermostat as a slab temperature regulator, preventing heater operation at temperatures above the High Temperature Limit setting. The optional operating mode uses the high limit thermostat as an ambient air sensor, preventing heater operation at temperatures above the High Temperature Limit setting until the temperature drops back to within the set limits.
The details of operation in each mode are as follows:

Slab Regulating Thermostat Mode
• High temperature causes unit to turn off heaters, if running, and to ignore any call for heater operation from the panel, RCU, or EMC
• High temperature continues any hold-on cycle that was initiated before the high temperature condition. If the slab temperature drops within limits during the hold-on time, the heater will be turned back on
• In a high temperature condition, an APS will still initiate operation of connected SC–40C contactor(s)
• The Heater Cycle functions normally

Ambient Temperature Thermostat Mode
• High temperature causes the unit to turn off heaters, if running, and to ignore any call for heater operation from the panel, RCU, or EMC
• High temperature cancels any Hold-On cycle that was initiated before the high temperature condition
• In a high temperature condition, an APS will not initiate operation of connected SC–40C contactor(s)
• If the Heater Cycle switch is operated in a high temperature condition, the heater(s) will be turned on for a maximum of 30 seconds. A new Heater Cycle cannot be initiated for another two minutes after that.

You’re Invited: ETI Fab Open House – Friday September 6th

Please join the ETI Fab team for our Grand Opening & Open House

RSVP with Robin Roberts at:

Friday, September 6th
12:00PM – 4:00PM
17055 Oak Ridge Road
Westfield, IN 46074

Stop by for Food Trucks, Plant Tours & much, much more



ETI Fab is a world-class metal fabrication facility based in the heart of the midwest in Westfield, Indiana, a suburb just north of Indianapolis.

Laser Cutting
CNC Machining

Welding – MIG & TIG


The eti snow owl


​ETI proudly introduces the ETI SNOW OWL Aerial Snow Sensor for surface snow and ice management systems.

The ETI SNOW OWL is designed to work with a controller or contactor, optimizing energy usage in heated snow/ice melting applications. The ETI SNOW OWL is also an excellent solution for building automation applications.

During dry or warm weather, the system’s heaters are turned off to save energy costs. The heaters are turned on only when snow and/ or ice is present​ and kept on only long enough to ensure complete melting and drying. Temperature and time parameters can be varied within the ETI SNOW OWL, enhancing system performance in a given environment and application.

To learn more or to order the ETI Snow Owl, contact the ETI Sales Team at: (800) 234-4239


ETI & ETI Fab Are Hiring


Positions Available

ETI & ETI FAB are equal opportunity employers. We offer competitive wages and great benefits.


  1. Purchasing Department
  2. Service & Administration Department

For more information, or to apply for these positions, please contact ETI & ETI Fab HR representatives, here:



  1. Accountant
  2. Machinist
  3. Quality Technician

For more information, or to apply for these positions, please contact ETI & ETI Fab HR representatives, here:





ETI proudly introduces the ETI SNOW OWL Aerial Snow Sensor for surface snow and ice management systems.

The ETI SNOW OWL is designed to work with a controller or contactor, optimizing energy usage in heated snow/ice melting applications. The ETI SNOW OWL is also an excellent solution for building automation applications.

During dry or warm weather, the system’s heaters are turned off to save energy costs. The heaters are turned on only when snow and/ or ice is present, and kept on only long enough to ensure complete melting and drying. Temperature and time parameters can be varied within the ETI SNOW OWL, enhancing system performance in a given environment and application.

  • Sleek design eliminates “igloo-ing” effect
  • Enhanced UV protection to ensure durability
  • Connects easily to 3/4″ PVC conduit
  • Handles up to 2 amps on a dry contact & can use AC, FWRAC, DC to serve wide range of electrical and hydronic applications


1850 N Sheridan St • South Bend, IN 46628 • (800) 234-4239
Media Contact: Tim Cramer •

June 19, 2019

(South Bend, IN) ETI, an OEM manufacturing company that for over 50 years specializes in designing and manufacturing products for effectively managing the environment, announced today that they have completed the acquisition of assets from a global manufacturing company headquartered in Indiana. The acquisition is a carve out of the metal fabrication and machining division located in Indianapolis, Indiana. ETI FAB, Inc is the newly formed entity and has completed the build out of a 30,000 square foot building and is completing the installation of the assets located in Westfield, IN. ETI FAB was able to retain the highly skilled employees and will remain as a leading contract manufacturer of metal and aluminum parts that will serve a variety of industries on a global scale. The facility will manufacture parts to customer designed drawings and produce parts for ETI improving speed in the support of its products. ETI FAB’s services include metal fabrication by laser cutting, forming, bending, stamping, welding and machining.

“Acquiring capability to metal fabricate allows the ETI network to be more insular. This acquisition is our first step in creating our future picture” stated Ben Crawford, President, and CEO of the ETI companies. Crawford further stated, “In working closely with the company that the assets were acquired from, we’re particularly excited about retaining employees that have been operating this equipment for many years. I’m truly grateful for the support and collaboration that has provided a smooth transition to ETI. Their guidance supporting employees and customers is very much admired”.

ETI FAB has begun fulfilling customer orders and will be in full production in June. “The team that has been assembled is a high-performing team that I’m thrilled to lead” stated “Jeff Frazee, Plant Manager of ETI FAB. Frazee further commented, “Our commitment to safety, quality, employees, and customers is our guiding precept”.

ETI, based out of South Bend Indiana, has been a world leader in sensors and controls for snow and ice melt systems, heat trace, and microwave waveguide dehydration for the past 50 years. ETI’s engineering and production teams work with their customers to design and manufacture solutions to their problems with a focus on energy efficiency and dependability. ETI was founded in 1968 and began producing the first Snow Switch® sensing and control products for commercial deicing in the industry. Having been awarded numerous patents for technologies used in snow and ice detection, condensate and humidity control, ground fault and arc detection, energy management, power distribution, and air pressurization systems, ETI has grown into a trusted name worldwide for environmental sensors and controls.

ETI FAB will be a one-stop shop for anything regarding metal fabrication. ETI FAB offers metal fabricated parts and machined components. Their state-of-the-art facility will offer laser cutting, bending, stamping, and welding capabilities in addition to grinding and assembly services. With over 80 years of combined experience, the team at ETI FAB will be able to take on any job no matter how large or small. ETI FAB’s mission is to not only provide the highest quality fabricated products but to follow in ETI’s footsteps and remain a stable employer of Hoosiers throughout the Midwest.

For Additional Information ETI FAB

Contact:  Robin Roberts
Business Development Representative
o: +1 574-999-1434
17055 Oak Ridge Rd
Westfield, IN 46074

We’re dedicated to our customers

We go above and beyond to help you with your projects.

Our Team  |  Sales Department 1-800-555-5555

We’re dedicated to our customers

We go above and beyond to help you with your projects.

Our Team  
Sales Department 1-800-555-5555

Meet the ETI Team at MCEE & Register to Win a FREE Yeti Cooler


The MCEE Show is where ground-breaking technology is unveiled, innovative solutions are displayed and game-changing trends are exposed. 

Prepare to explore aisle after aisle of limitless ideas and inspiration. Only here can you roll-up your sleeves and be hands-on with the products, services and people driving the future of our ever-changing industry. 

ETI invites you to contact us and schedule time to meet and have an in-depth discussion with our experts on how our cutting-edge solutions from the ETI SnowSwitch, Netcom & Tracon product lines can transform your operations.





DIRECT (574) 999-1273



DIRECT (574) 999-1226

ETI Partners with Optimum Viking Satcom at 27th Annual Convergence India Show

Team ETI has been on a whirlwind trip around the globe while spreading the benefits of the ETI product line. In late January, we attended the World of Concrete show in Las Vegas, Nevada. Less than a week later our team was headed off to the far east to attend the Convergence India trade show in New Delhi, India.

Chad Griffin, ETI Director of Sales & Marketing (right), along with Jeremy Crawford, ETI Business Development Representative assisted our strategic business partner’s, Optimum Viking Satcom, by explaining the value and benefits of adding the ETI product line to Southeast Asia telecom & SATCOM infrastructure.

Next, you’ll be able to catch up with the Team ETI at:

NAB ( National Association of Broadcasters )
April 8th – 11th
Las Vegas Convention Center
Las Vegas, NV

April 24th & 25th
Place Bonaventure
Montréal, Québec Canada

If you’re planning to attend either of these shows and would like more information about ETI, our line of environmental controls products and the added value they bring, our team would cherish the opportunity to meet with you and your team at either or both shows.

ETI Releases the New Snow Switch CIT-2 Model At World Of Concrete

For the last four days, the ETI Snow Switch Team has been showcasing the newest addition to the Snow Switch product line, the Snow Switch CIT-2, at the World of Concrete convention in Las Vegas, NV.

ETI Snow Switch CIT-2In addition to the revolutionary design of the CIT-2, what attendees of the World of Concrete were most impressed with is what the unit offers straight out of the box combined.

One of the best features of the Snow Switch CIT-2 is that for the first time in ETI’s 50 year history of engineering snow & ice melt solutions, this is the first unit to be designed specifically to work with the complete line of ETI Snow Switch controllers, as well as, any other comparable unit on the market, or even as a stand-alone unit.

That’s not just groundbreaking, it’s revolutionary.

Click the button below for more information about the Snow Switch CIT-2 Aerial Snow Sensor.

ETI Announces the Release of the Revolutionary CIT-2

ETI proudly introduces the SNOW SWITCH® CIT-2 Aerial Snow Sensor for surface snow and ice management systems.

The CIT-2 is designed to work with a controller or contactor, optimizing energy usage in heated snow/ice melting applications. The CIT-2 is also an excellent solution for building automation applications.

During dry or warm weather, the system’s heaters are turned off to save energy costs. The heaters are turned on only when snow and/ or ice is present, and kept on only long enough to ensure complete melting and drying. Temperature and time parameters can be varied within the CIT-2, enhancing system performance in a given environment and application.


  • Automatic snow sensor for reduced energy consumption in sidewalk, gutter/downspout snow and ice melting applications
  • Slim design minimizes visual impact
  • Mounts on 3⁄4” PVC conduit for easy installation
  • Operates on safe low voltage power
  • Simple four wire connections: 2 for power, 1 for signal output
  • Wire colors match commonly available cable for easier installation
  • Convenient power-on self-test to verify proper sensor
  • Made with UV-tolerant and corrosion-resistant materials for
    long life




24V AC 50/60Hz, 24V DC, or 24V full wave rectified AC/ pulsed DC 0.2A max


Relay contacts: 2A max, 30V.
Relay contacts close when the ambient temperature
is between min/max settings and precipitation is detected.

Relay contacts remain closed during pre-set delay after a snow event ends
Three wire connection (2 for power, 1 for relay)




Selectable -20°F, -15°F, -10°F or disabled for extremely coldconditions


Set 1 hour


33⁄4 inches tall, 13⁄4 inches diameter


Can be mounted 500 feet from the controller using 22ga cable or up to 1,000 ft. using 18ga cable (Depending on load requirements)

Acquisition Announcement

February 20th , 2018 (SOUTH BEND, INDIANA) — Ben and Kerri Crawford are excited to announce the acquisition of Environmental Technology Inc. (ETI) located in South Bend Indiana.  Born and raised in South Bend, Ben is excited to be back in the area and work in his hometown.  When asked, Mr. Crawford said,” It’s great to have a presence where I started my career in Manufacturing 24 years ago.  The team at ETI is strong and has an excellent reputation advancing engineered products for snow/ice management, heat tracing and telecommunications reliability and makes me proud to be a part of this industry.”

Ben Crawford has over twenty-four years of manufacturing experience as a C-Suite Executive of Industrial Operations.  Ben’s strengths include strategic planning and deployment, global business development, key metric management and continuous improvement objectives.

Kerri Crawford has over sixteen years of entrepreneur experience as the Founder, President and CEO of a successful Indiana based small business in the Commercial Lending Industry.  Kerri manages the daily operations and is heavily involved with the strategic vision of the company. Over twenty-two years of commercial lending experience and a dedicated employee focus have been the driving force behind her vision and the company’s success the past sixteen years.

When asked about the future of ETI the Crawford’s indicated, “We remain committed to our customers, vendors, and employees.”  “We are excited to assist in growing the business, expanding the product line and working closely with the management team.” They went on to say, “The Jones Family for the past fifty years have built a wonderful company and we are honored to be able to continue ETI’s legacy into the future.”

Launched in 1968, Environmental Technology, Inc. designs and manufactures products for effectively managing the environment. From energy efficient snow melting and deicing to pressurization systems for satellite and microwave transmission lines. ETI has fifty years of experience as an industry leader in developing and delivering effective environmental management systems. Environmental Technology, Inc. has the experience you can count on.

For more information on our products go to

For media inquiries, please contact:
Chad Griffin, Director-Marketing Environmental Technology Inc.



Snow and ice falling from buildings

How to avoid Snow and ice falling from buildings.

Sheets of snow and ice falling and being blown off buildings are a major hazard that can cause damage to the structure, equipment, and possibly injure someone. Winter conditions have been accounted for in the building design process for a long time, but mostly in a way that only accounts for the weight of the snow and ice acumination and how it will affect the building’s structure. New technologies, innovations, and design trends are requiring that more attention be paid to the dangers of snow and ice when designing and maintaining a building.

Before energy conservation was a big concern buildings were basically large boxes with inefficient insolation that would leak phenomenal amounts of heat that would melt most of the snow and ice almost immediately. Most older building also had simpler designs with smooth walls, and a flat roof with a tall parapet on top to contain snow and ice accumulation so it can be safely drained away. The only real concern back then was how much snow weight could the structure hold, and there were building codes and regulations to account for this.

With advancements in technology, materials, and engineering, buildings are vastly more energy efficient, retaining almost all their heat which creates a colder exterior for snow and ice to accumulate on. Some of these new materials create smooth surfaces snow and ice can slide down in an uncontrolled way causing hazards below. These new materials also allow for more complex building designs, which can create areas where snow and ice can accumulate in unforeseen dangerous ways. These advancements in technologies, materials, and building designs have immense benefits, but also create new problems and hazards which need to be addressed.

The most cost-effective way to address these hazards is in the design phase of the building. There are microclimate professionals that can take data such as local historic weather conditions, surrounding buildings, the building’s airflow patterns, shadow patterns, along with other factors and help identify any potential environmental problems with a building’s design before it is built. These microclimate professionals can also recreate designs in test conditions to see how they perform. It is highly recommended to consult a microclimate professional when designing a building to address potential hazards before the building is built and more expensive fix must be made.

Older buildings will still need to address this problem as they are constantly being upgraded to be more efficient and new buildings being built around them impacting their microclimate. This is where a snow and ice melt system should be installed for safety. Snow and ice acumination that forms in new ways on a building can cause unforeseen consequences. Water can freeze between and behind structures, expanding and causing structural damage. Drainage paths can be overwhelmed in some areas, causing refreezing and accumulation. New areas can become shaded by new buildings in the area causing accumulation where there wasn’t before that needs to be addressed and properly removed. A snow and ice melt system can increase the safety and protection of a building by minimizing the amount of accumulation and keeping drainage paths clear.

Preventing snow and ice buildup is important for the safety of a buildings structure, equipment, and the safety of people below. Whether it is in the design process, or after it is built a building needs to be able to manage snow and ice effectively. Any building’s microclimate should be periodically checked and analyzed to identify and address any problems, especially when they can impact the safety of the people below.

Click Here to view ETI’s Heat Trace and Snow and Ice Melt controls.

Heat Trace and Hoppers

Many industries that use hoppers utilize heat trace to aid in material flow. Hoppers are elevated storage containers that contain and dispense granular materials. Commonly used in agriculture hoppers are also used in industries such as plastics, chemical, pharmaceutical, energy, and construction. Despite being used to hold and dispense different types of materials they all function the same way and face the same issues.

The main issues with hoppers focus on the material flow. These issues include aspects related to material sticking together or accumulating on the walls of the hopper. This is commonly caused by the particle structure of the material or the presence of moisture. There are many ways moisture can enter the system, these can be caused by environmental conditions or by water or chemicals being applied to the material in the process before being placed in the hopper.

Major environmental factors that can introduce moisture into the hopper material are temperature and humidity. One way to mitigate this is to install a heat trace system onto the hopper. This controls the temperature of the hopper and material avoiding drastic temperature differences which could cause condensation to form on the inside of the hopper.

The application of water or chemicals to the material or the hopper for dust prevention, cleaning or as a step in the production process add moisture to the material. Moisture such as this should be accounted for in the design and selection of a hopper system to insure proper flow. However, despite accounting for this added moisture in the system variable conditions can still cause flow problems. One major problem for hoppers with chemicals or water added is freezing. Material freezing in a hopper can cause the material to clump together or freeze to the walls, causing a blockage or flow problems. This can cause production to be shut down until the material can be thawed or it is manually cleared out. The presence of a heat trace system in these cases will avoid the freezing and allow the material to flow in a predictable manner, avoiding costly shutdowns or disruptions.

There are many pieces of equipment that can be added to a hopper system to aid in the material’s flow such as augers and vibration units, but to combat the effects of variable environmental impacts a heat trace system should be included.

Click Here to check out ETI’s Tracon Heat Trace controls.

NAB 2018

Visit us at the 2018 NAB Show in Las Vegas, April 9th through the 12th. ETI will be presenting at the Viking Satcom booth #OE11045. Come out and see our ADH NETCOM and NETCOM NEMA on display and talk with ETI’s Dennis Sizemore and Chuck Gartland. Please contact your sales representative in advance to reserve a time to meet by
emailing, or calling (574) 233-1202.

Thank you and we look forward to seeing you there.

While at the NAB journey through 1,700 Exhibitors within the Las Vegas Convention Center. From established, global brands to up-and-coming innovators, this collection of ground-breaking tools and solutions are set to form the next generation of storytelling.

Stop by and enter to win a Yeti cooler from ETI and Viking Satcom.

Radiation Pattern Envelope

Satellite antennas radiate signal energy in distinct patterns that are reported as their radiation pattern envelope. These patterns consist of lobes which indicate the intensity of signal radiation radially on a horizontal plane emanating from the antenna. These patterns of signal strength are measured including both horizontal and vertical polarizations at three frequencies which represent the bottom, middle and top of the antenna’s band.

When the radiation signal strength is measured, a main lobe will indicate the main direction of the signal beam. This main lobe indicates the direction the signal will be effectively transmitted.  The size of the lobes representing the strength of the signal will decrease as they get further from the main beam. Side lobes appear as small surges in signal radiation adjacent to the main beam. These side lobes can result in unwanted signal noise which can also reduce the antenna’s carrier signal.

The signal capacity of an antenna can be determined by dividing its carrier signal strength by its signal noise. Better antennas produce a better signal by creating minimal side lobes which reduces signal noise and increases the signal capacity. Antennas of lesser quality which have larger side lobes which diminish the antenna’s signal capacity. There are however ways improve an antenna’s signal capacity.

There are two main approaches to increasing an antenna’s signal capacity, increasing the carrier signal strength by increasing the transmission power, or by decreasing the signal noise. Increasing an antenna’s transmission power seems like an obvious solution, but it comes with added energy costs, and might not be applicable due to increased interference, regulatory restraints, and infrastructure limitations. Another way to increase the signal strength is to install a larger antenna, but installing a larger antenna is expensive, requires more maintenance, power, and a larger infrastructure. When increasing signal strength is too costly or not applicable decreasing the signal noise is an option. Simply realigning the antenna creating a different link path can drastically improve an antenna’s signal capacity, this is a low-cost way to decrease signal noise. The best solution would be to purchase an antenna that produces small side lobes. These are higher quality antennas that produce less signal noise resulting in a more optimized signal capacity.

Consulting an antenna’s radiation pattern envelope is important for selecting the right antenna for an application and important in designing and installing a communications system. Antenna manufactures publish radiation pattern envelope information for their products and make them available for review. When selecting, designing, installing, optimizing or troubleshooting an antenna or communications system always consider the antenna’s signal capacity by reviewing its radiation pattern envelope.

Heat Trace with Plastic Pipes

Heat Trace with Plastic Pipes

Heat cable can be used on plastic pipes but the plastic’s durability and thermal properties must be considered. Plastic has approximately 125 times the thermal resistance than steel but is also more susceptible to damage from direct high temperatures. The key to heating plastic pipes is to use a lower temperature and distribute it as evenly as possible.

It is always a good idea to use a heat trace system with an automatic thermostat and control, but especially so when using heat trace on plastic pipe. An automatic heat trace control can monitor and maintain the system’s temperature, alarm for problems, and shut off the heat cable to prevent damage.

There is heat cable designed specifically for plastic pipes that is self-regulating and has limited wattage. Self-regulating heat cables have a conductive core between two bus wires that becomes more conductive when cold. This system increases the power to the cold spots and decreases it to the warmer areas, which provides a more even heat source.

The manufacture of the plastic pipe should be able to provide information as to the maximum temperature and how close heat cable can be spaced or wrapped on the pipe to avoid damage. Some applications may require heat cable to be applied to opposite sides of the pipe at a lower temperature to distribute the heat more evenly, avoiding one direct area of concentrates heat which may damage the pipe.

It is recommended to install a foil material between the pipe and the heat cable to avoid direct contact and help provide a more even heating. If doing this place the heat trace control thermostat directly onto the pipe with no foil over it or between it and the pipe to ensure a more accurate reading.

You can use heat cable on plastic pipes as long as you follow precautions, such as determining your pipe’s thermal capacities, selecting a self-regulating, low wattage heat cable and using an automatic heat trace control with safety functions. Following these guidelines will help prevent damage and increase the life of your heat trace system.

Click here to view ETI’s Heat Trace controls

Snow and Ice melt Environmental Impacts

Considering environmental impacts of snow and ice melt maintenance.

There are environmental costs involved with any snow and ice melt system, knowing and assessing these environmental costs can help you choose the snow and Ice maintenance system that will work best for your needs and environmental conditions.

Electric or hydronic snow and ice melt systems

Electric and hydronic snow and ice melt systems can be a large investment but offer a cleaner, complete, uniform melt that can be easily monitored and controlled automatically or manually. With electric and hydronic melt systems, the only environmental impact is from the energy used to heat the heater cables or fluid in the heating pipes. Modern snow and ice melt controls implement energy-saving technologies that can help reduce their operating cost and environmental impact.

Electric and hydronic melt systems also can consistently heat places where chemical snow and ice deicers would be damaging or impractical, such as on roofs and in gutters.

Chemical deicers

Chemical deicers are very common. They are versatile, require no initial setup or permanent installation and can easily be regulated and modified. However, there are several drawbacks to using chemical deicers. Chemical deicers can be corrosive and can impact the environment through runoff, absorption, and air transportation.

Chemical deicers are divided into three main types, chloride-based deicers, acetate-based deicers, and carbohydrates.

Chloride-based deicers

Chloride-based deicers, commonly known as salt deicers, are composed of Chloride (an anion) and either sodium, magnesium, or calcium (a cation). When chloride-based deicers dissolve, the anion and cation dissociate impacting the environment in different ways.

Chloride is corrosive, meaning it can deteriorate a material by chemical reactions. Chloride does not biodegrade or absorb into material easily, so it can accumulate changing the fertility and acidity of the soil, damage plant life, and enter ground and surface water.

Sodium, magnesium, and calcium effect soil and plant life differently. Sodium changes the structure of the soil, decreasing permeability, and infiltration. Sodium also increases the alkalinity of the soil, which reduces the magnesium, calcium, and other nutrients for plant life.  Magnesium and calcium can be good for the soil and plant life by adding nutrients. Sodium reduces the hardness of water, again reducing the magnesium, calcium, and other nutrients and metals. Magnesium and calcium increase water’s hardness (increases mineral content), they can also decrease the toxicity of heavy metals in the water.

Acetate-based deicers

Acetate-based deicers, sometimes referred to as pet-safe deicers are less corrosive and are not as toxic to plants and wildlife than chloride-based deicers and. The most common type of acetate deicer is calcium-magnesium acetate, otherwise known as CMA. The characteristics of CMA indicate that it is mostly absorbed by soil surface, minimizing the amount that would be carried away by runoff to surface water or enter ground-water.

Since most of the acetate-based deicer runoff is absorbed by soil only a limited amount enters the water system where it’s effects can be minimized by dilution, larger moving bodies of water will be affected less than small stagnant bodies of water. When it does enter a water system in large enough concentration it increases the biological oxygen demand on rivers and lakes, creating a potential threat to aquatic life.


Carbohydrate-based deicers do not melt snow and ice, they reduce the reduce the freezing point of ice further than Chloride-based deicers, and can help deicers better stick to the surface. Carbohydrate-based deicers are relatively safe for the environment, except they do pose a similar increase in biological oxygen in lakes and rivers as acetate-based deicers. Carbohydrate-based deicers can also be used with chloride-based deicers to mitigate their corrosive nature.

Desiccant vs Membrane Dehydration

Desiccant vs Membrane Dehydration. Two of the main types of dehydrators are used for waveguide dehydrators, desiccant dryers, and membrane dehydrators. Both effectively remove moisture from the air but do it in vastly different ways.

A waveguide is a tube-like structure that allows for the guided flow of electromagnetic waves with minimal energy loss. The waveguide must be clean and free of debris and humidity, because these can distort the wave, negatively impacting signal quality.

Waveguide dehydrators are commonly used to pump clean dry air into the waveguide to reduce the humidity. Two of the main types of dehydrators are used for waveguide dehydrators, desiccant dryers and membrane dehydrators. Both effectively remove moisture from the air, but do it in vastly different ways.


Desiccant dryers dry by passing the air through a container of a desiccant material. Dry air passes through the desiccant material while moisture adheres to the desiccant material. This process requires the desiccant to regenerate, which is the process of drying out the desiccant for further use. There are two ways the desiccant can be regenerated, with heat, and heatless. Regeneration with heat method uses an internal heating element to heat the desiccant material, which converts the moisture into steam that can be vented with pressurized dry air. Heatless regeneration uses purely the dry pressurized air to dry the desiccant.

Membrane dehydrators use a permeable membrane that will allow water to pass through, but not the larger oxygen and nitrogen molecules which is the prevalent molecule in air. The pressure would push the water molecules through the membrane while retaining the dry air.

Membrane dehydrators require less maintenance, but require higher pressure and cannot reach as low dew point as a desiccant system. A desiccant system can dry air to a lower dew point and requires less pressure, but needs to have it’s desiccant canisters replaced every 3 to 5 years, or more depending on use.

Both these methods of dehydration are applicable for waveguide dehydration system. It is important to assess your systems requirements and environmental conditions before selecting a proper dehydration unit. Please feel free to contact Environmental Technology or any of our partners here.

Leak rates and duty cycles of dehydrators

Understanding the leak rates and duty cycles of dehydrators

The overall purpose of the dehydrator is to eliminate moisture in the waveguide of the transmitter. Moisture will affect the reflected energy and increase the Standing Wave Ratio (SWR) of the system.

Dehydrators deal with moisture in waveguides differently than systems pressurized with inert gasses.

In pressurized systems, the system is sealed and moisture is kept out by the same seal that keeps the gas in. If the pressurized system develops a leak the inert gas leaks out and moisture can then accumulate in the system.  In most cases, these pressurized systems then need to be re-pressurized in order to find and repair the leak, then be evacuated with a vacuum pump and refilled with the inert gas. This can become a long and expensive process.

In comparison, a dehydrator supplied waveguide is constantly having the air in the waveguide replaced with desiccated air and its pressure is varying from the low set point to the target set point. This delta P is the operating pressure for the system.

The operating pressure (∆P) is determined by the wave guide’s manufacturer’s recommended max pressure and the lowest pressure the customer is comfortable with as a minimum to the system. The max pressure is generally dictated by the feed horn window material.

ADH Netcom dehydrators
In the NETCOM dehydrator it is possible to set the pressure parameters with four set points, these are:

  1. Low pressure alarm – this is the level at which the unit will present an alarm. This needs to be lower than the low limit pressure
  2. Low Limit Pressure – this is the level that will cause the dehydrator to start the compressor to pressurize the system. This must be at least .1 PSI lower than the High Limit Target Pressure
  3. High Limit Target Pressure – this is the level that the compressor will be turned off at.
  4. High pressure alarm – this is the level at which the unit will present an alarm. This needs to be higher than the High Limit Target Pressure
The difference between the Low Limit Pressure and the High Limit Target Pressure is the customer selected operating pressure (∆P).

Perfectly sealed systems are not only difficult to manufacture but impossible to maintain over time.  For this reason, ETI strives for perfect seals but accepts very small leaks in the system as normal.  Our maximum allowable leak rate on a new system is .04 psi per minute on a system pressurized at 7.5 PSI.  With a dehydrator’s outlet completely blocked off this would translate to a leak downtime of 2.5 hours or more if there is a ∆P of 6 PSI between the low limit pressure and the high limit target pressure.

It should be noted that the leak downtime is dependent on the ∆P.  For example, the same leak rate of .04 PSI will take 2.5 minutes when the ∆P is .1 PSI.

For this reason, it is important to understand the relationship between the ∆P, leak rate & duty cycle.  To do this also requires an understanding of how the duty cycle is calculated and what it means.

The duty cycle is calculated by averaging the time of two compression cycles using the time the compressor is on divided by total time (time compressor on and time off between cycles).  The on time is going to be affected by a number of variables but the two most important variables are the volume of the waveguide and the flow rate of the compressor.

There is no hard and fast rule as to what duty cycle you should have on your dehydrator; it is entirely up to the customer to determine what is best for their application.  In doing so it should be considered that once set, a change in the duty cycle indicates a change in the system/ waveguide.  Setting the duty cycle alarm to approximately two times the selected duty cycle will allow the system to give the customer an alarm indicating a problem with the system.

Setting the duty cycle is accomplished by changing the waveguide bleed (normally mounted on or near the feed horn) to allow a constant managed leak of the system.

Netcom compressors have a flow rate of 10 liters per min so for small systems (1l or less) you are looking at only a few seconds of compressor time for a complete fill and fractions of a second for satisfying the ∆P requirements for operating pressure.

For these reasons, it is possible to have a NETCOM pressurizing a small system with a very small ∆P that will run the compressor every 10 to 15 seconds for a period of a fraction of a second.  At first, this may appear to be an internal leak on the NETCOM but looking at the duty cycle and alarms you will be able to determine that the N     ETCOM is simply working normally at a 5% duty cycle.

It would be advisable to reduce the duty cycle to as low as 1% for small systems in order to increase the time between compression cycles. This will also allow the casual observer to feel the system is operating normally without internal leaks or issues.

Another way to accomplish this is, of course, to increase the ∆P on the system slightly if the system will allow it.  Again the limiting factor is the feed horn window max pressure limitations.

As an example:

If a system is initially set to a 1% duty cycle and the duty cycle alarm is set for 2% and after several months of operation the duty cycle alarm is indicated the operator has a number of options.  He can start looking for the leak, find and fix it immediately or determine that the leak is small enough to not warrant immediate action because there has been no effect on the SWR of the system.  The dehydrator has compensated for the leak with increased duty cycle.  At this point, the operator may bump the duty cycle alarm up to 3%, report the issue and put it on the agenda for future maintenance on a remote site.

Comparing the above example to an inert gas pressurized system the leak would leave the system open to atmosphere and SWR would be affected necessitating an immediate repair.


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Heat-Trace in Hot Water Maintenance

Heat-trace is used in many aspects of everyday modern life that mostly goes unnoticed. One main example of this is the ability to access hot water quickly from any faucet in a large building no matter how far from the water heater it is. This is a function of a building’s Hot Water Maintenance system. heat-trace is just part of a comprehensive Hot Water Maintenance system. Other components of a Hot Water Maintenance are the water heater, hot water storage tanks, a circulation loop and a pressure release.

Hot Water Maintenance is important for many reasons, one of the most important reasons is to sanitize. Hot water helps to prevent diseases, like Legionnaires Disease by killing the bacteria that causes it and preventing it from multiplying within the pipes. Water that is too hot can lead to injury. It is important to have the temperature set within a safe range. Keeping the water hot throughout the pipes will also reduce water and energy waste by not having to run the water before reaching the hot water.

Heat-Trace systems consist of a heat cable (heat tape) and control. There are two types of heat cable, self-regulating and constant wattage. Self-regulating cable does what it says, it regulates itself to an extent. It does this with a special conductive material core between two bus wires. The core’s conductive nature varies with temperature, the cooler it gets the more conductive it becomes which increases the heat the cable gives off, the warmer it gets the less conductive it becomes resulting in the cable giving off less heat. Constant wattage heat cable provides a uniform distribution of wattage, resulting in uniform heating along the whole cable. Self-regulating cable will save energy, where constant wattage cable will heat in a more uniform precise way. Both self-regulating and constant wattage heat cable require a heat-trace control unit to regulate the temperature and monitor and alarm for errors.

Hot Water Maintenance systems are a hardly noticed element of our everyday lives that make our modern lifestyle possible. Heat-trace is a critical component of these systems, keeping the water hot within the pipes. Next time you are in a building pay attention to the hot water and think about what makes that possible.


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