I know it’s the start of summer and you’re thinking, “who is thinking snow and cold temps?” But it could be the best time to ramp up your snowmelt game for the upcoming winter season. Once upon a time, commercial snowmelt systems lived independently, with little concern about the larger mechanical environment they were often a part of. Typically, a boiler provided heat and a smart tubing layout, properly circulated, offered thermal distribution.
Voila! As if by magic, tropical warmth gently melted away midwinter precipitation from parking lots, walkways, ramps and driveways.
All good things change, and occasionally for the better. As for modern snowmelt systems, their renaissance has come in the way of—you probably guessed it— improved and more sophisticated controls. Now, snowmelt systems can integrate with BAS (building automation systems).
It only makes sense that snowmelt systems would eventually cross that bridge. Getting there, however, wasn’t without challenge.
BAS networks, by design, are largely “inclusive.” That is, their purpose in life is to integrate, control and monitor as many of a building’s key functions as possible, including heating, cooling, ventilation, lighting and other important operations.
Yet, because snowmelt systems operate outside a building, and are exposed to ambient conditions outside the envelope—with conditions that change quickly, often requiring far more than simple on/off function—BAS systems are challenged by their limitations. The key frustration expressed by design engineers, installers and building owners alike is that the ever-changing nature of outside, ambient conditions defies the constraints of most automated controls.
For this reason, anyone attempting to tie commercial snowmelt function with a BAS confronted a giant hurdle.
Fortunately, those impediments may now be things of the past.
The nature of the beast
For the longest time, achieving proper connection to and communication between snowmelt controls and a BAS was the seemingly impossible task. The two key parts of that puzzle were a.) sensors didn’t want to communicate digitally with the BAS, and b.) controls were mostly incapable of anything more than on-off operation. Maintaining idle operation, controlling gradual increases in temperature, or especially measured deactivation—these became the key challenges.
After all, if snowmelt system deactivation happens too soon, winter accumulations may pile up, or snow may melt prematurely, turning into treacherous ice. Or, if a system demands too much heat, or stays on too long, it punishes the building owner with unexpected operational costs.
For many years, there were many reverse-engineered attempts to connect snow and ice sensors with building automation systems. However, more recently, new technology has been developed to meet this challenge.
This new technology helps connect these two previously disconnected functions by receiving input data and sending information from sophisticated sensors directly to the building automation system, which ultimately tells the snow melting system to turn on or off.
A snow and ice sensor interface communicates directly with a BAS controller through BACnet MS/TP protocol, letting the BAS know to engage the on and off function of a snowmelt system when the outside sensors detect snow or ice. This unique piece of technology has quickly turned a traditionally inefficient process into a smart and truly automated system.
Having the ability to interface snow and ice sensors directly with any BACnet controller is not only creating more efficient snow melting systems for facility and building owners, it’s making it easier for contractors to have a simple, standard solution that can be easily applied to any snowmelt job—without custom coding or complex installation.
Despite its simplicity, connecting a snow and ice sensor interface to a BAS should incorporate many functions, also known as objects (see bullets below). The device itself is designed to be installed in a mechanical room, or at any remote location on site—perhaps in a service room closer to the snow melting area.
The list of data objects shared with the BAS controller should ideally include:
- Snow or ice has been detected
- Snow or ice has not been detected
- Outdoor air temperature
- Slab temperature
- Slab target temperature
- Snow/ice sensor sensitivity
- Warm weather shut down (WWSD)
- Cold weather cut off (CWCO)
- Error codes
As is often the case—and especially when new technology is introduced—questions arise. Here are some common questions from professionals in the field:
What happens if ambient conditions are too cold, or too warm?
Interface features such as warm weather shut down (WWSD) and cold weather cut off (CWCO) are particularly useful in ensuring the snow melting system is only running when needed. For instance, with CWCO, when outdoor air temperature is too cold (below CWCO setting), the BAS heat source is not able to increase the slab temperature to melt snow or ice. Features like this create critical efficiencies and save loads of energy.
With the right technology in place, the interface sends a signal to the BAS to turn off the snow melting system. Once the outdoor air temperature increases above the CWCO temperature setpoint, the interface will communicate to the BAS to turn on the snow melting system and resume its operation.
Of course, if conditions are too warm for the formation of snow or ice, the systems will use the opposite logic (WWSD) and tells the BAS to deactivate the system.
What types of alert functions are available to building managers?
Ideally, a snow and ice sensor interface will use error codes to signal the BAS controller if there are operational problems with the sensors.
This would allow the BAS to have feedback on the system and determine if any action needs to be taken.
Can contractors use the BACnet Sensor Interface with any snowmelt application controlled by BAS controllers?
Here, too—a versatile snow and ice sensor interface should be compatible with any snowmelt system application. After all, BAS controllers use BACnet MS/TP protocol for communication. The technology should be capable across many types of installations, such as snowmelt applications with a simple dedicated boiler, or more complex multi-boiler plants with multiple zones and mixing valves. And, the right technology should be BTL certified, providing the confidence of seamless integration.
Why is it important to control the slab temperature?
Controlling slab temperature is crucial to have an efficient snowmelt system. If the slab temperature is too low, the snow will not melt off. If the temperature is too high, the slab could be damaged and will waste a lot of energy.
Information = power
So, if you’re faced with the need to install—or retrofit—a commercial snowmelt system, and BAS is in the cards, you’re now equipped with new information and ready to reenter winter warfare. But this time, better prepared.
Cleber Alves is product manager for tekmar.