Heating Things Up
Snow-melting and deicing systems are clearing a path to easier snow and ice control.
Fifteen percent of all accidental deaths are related to slip-and-fall incidents. This number, which may surprise you, is second only to motor vehicle accidents. In fact, each year, more than a million people seek hospital treatment for slip-and-fall accidents. Of those million, 300,000 will suffer debilitating injuries and 12,000 will die. Moreover, many of these slip-and-fall accidents could easily have been avoided through simple proactive measures. In particular, in the wintertime, hazardous snow and ice conditions have been identified as a major cause of slip and falls.
These numbers emphasize the importance of effective snow and ice removal. Maintaining safe public facilities and residential areas—anyplace people walk—serves to protect them, reducing liability and bringing potentially perilous icy winter conditions under control. Additionally, snow and ice can cause damage to buildings and walkways, as well as cost thousands to remediate, and businesses can be held liable for a dangerous accumulation of ice and snow if they do not take adequate precautions to clear it. That’s why they turn to you and your arsenal of solutions.
Snow-free and safe
The good news is that effective safeguards to prevent hazardous conditions are available through a variety of products and sophisticated systems now on the market. Snow melting and roof and gutter deicing systems have become a staple for keeping walkways and pathways clear and for alleviating the effects of ice dams, which can form dangerous icicles and can cause water ingress into buildings. These snow-melting and deicing systems can now be found in a variety of places, such as outdoor malls, parking lots, driveways, ski resorts, loading ramps and even car washes.
Concrete and asphalt driveways and walkways are a common surface for snow-melting systems. Concrete offers many advantages over asphalt, including greater durability, longer service life and less maintenance. But in the winter, when temperatures fall and the snow starts, concrete and asphalt surfaces have equal maintenance needs: both require frequent shoveling and deicing.
With snow-melting systems in place, concrete and other exterior flatwork surfaces stay maintenance-free and safe year-round. These in-slab, snow-melting systems prevent slip-and-fall accidents and eliminate plowing and shoveling. Moreover, they prevent potential damage to the concrete and asphalt that can sometimes be caused by snow-removal equipment and potentially corrosive deicing chemicals. Though contractors usually install these systems in new slabs before laying concrete or asphalt, you can also retrofit a heating cable into an existing slab by cutting channels, inserting the heating cables into the channels and then resurfacing the slab.
Installing snow-melting systems
Generally, hydronic and electric are the two most common types of snow-melting systems used in exterior slabs. Both provide a heating element, which is embedded in the slab, and sensors to detect outdoor air temperatures and moisture. Both also require an available power source and a controller to tie the heating element, sensors and power source together.
In a hydronic system, the heating element consists of closed-loop tubing made of a flexible polymer (usually a cross-linked polyethylene) or a synthetic rubber that circulates a mixture of hot water and propylene glycol (antifreeze), much like the mixture used in a car radiator. The fluid is warmed to temperatures of 140°F to 180°F to provide sufficient heat for snow melting. The tubing ranges in diameter from ½ to ¾ inch and is flexible enough to bend into different layout patterns. It’s also designed to have a long service life. The tubing resists chemicals and corrosion and does not become soft at high operating temperatures or brittle at low outdoor temperatures.
The successful operation of a hydronic heating system depends on proper tube spacing and layout. Because the hot water will give off heat as it travels through the slab, manufacturers usually recommend laying the tubes in a spiral or serpentine pattern to help distribute the heat evenly. Tube spacing depends on several factors including the snow melting rate desired, the amount of insulation used under the slab, and the expected rate of heat loss. A typical spacing for an exterior slab on grade is 6 inches on center, which conveniently corresponds with the 6-inch grid pattern of welded wire reinforcing. However, you may need to use closer spacings in some applications.
Instead of hot water, electric systems use heating cables to prevent the accumulation of snow. A self-regulating heating cable utilizes a cross-linked, conductive polymer core that is extruded between two copper bus wires, forming a parallel circuit. The polymer core automatically adjusts power output at every point along its length in response to pavement temperature. A mineral-insulated heating cable is comprised of a heating conductor that is surrounded by magnesium oxide insulation, a solid copper sheath and a high-density polyethylene jacket. The high-density polyethylene jacket protects the copper sheath from the corrosive environment that exists in most snow melting applications.
Installation of an electric snow melting system is similar to that of a floor warming system. The selection of a grid or serpentine system depends greatly on the shape, size, and various installation conditions. Pre-sized snow melting mats, with heating cables spaced on a grid, are ideal for square and rectangular areas, while stand-alone heating cables are preferred for irregular areas.
The cost to operate a hydronic or electric snow melting system is can be as little as several hundred dollars each winter, depending on the size of the unit and the area it is covering. Considering the cost of labor and equipment for traditional snow removal, plowing services and chemicals—in conjunction with the liability associated with slip-and-fall accidents—snow-melting systems provide reliable protection at a comparatively low cost, particularly in areas where there is heavy snowfall.
But hazards don’t just exist on the ground. One easily overlooked area of potentially serious hazard is rooftops, where ice dams can form. Ice dams develop on a roof when melting snow and ice refreeze on a cold roof edge and prevent water from draining properly into a gutter. Improperly draining water may not only cause serious property damage, but can also contribute to slip hazards for pedestrians.
Administrative buildings, warehouses, storage facilities and production buildings can all benefit from roof and gutter deicing systems. Roof and gutter deicing systems enable melt-water to run freely down a drain path to the gutter, then to the downspout. These systems, which usually consist of a self-regulating heating cable, are relatively simple to install, with no retrofitting or alteration of existing structures necessary.
Roof and gutter deicing systems typically include a heating cable, roof clips, downspout hanger kit, snow controller and a power distribution panel. Heating cable runs along a roof edge, inside of gutters and drops down the inside of downspouts providing a drainage path for melt water to leave the roof. For roofs with heavy snow loads or with extreme roof pitches, snow guards should be installed to prevent avalanching. Most systems are also self-regulating and will automatically cut down on its power output and save energy when the roof is dry.
Famed marketplace and institution Faneuil Hall in Boston is a beneficiary of such a system, where roof and gutter heating cables were used to successfully prevent snow and ice buildup from falling onto an entrance reserved for the handicapped. The Sears Tower in Chicago has also implemented a deicing system with equal success.
Factors to consider when choosing a system
There are a few considerations to keep in mind when choosing a snow melting or deicing system. With a variety of different products on the market, consider your needs and match those needs with a product that matches in performance.
Space availability is also an issue. Power distribution for an electric system requires less space than what is required for a hydronic system. For a hydronic system, there must be space for a water heater or boiler, circulating pump and manifold.
Another factor to consider concerns retrofitting. If you want to install a snow-melting system in an existing concrete slab, it’s simpler to retrofit an electric cable since it has a smaller diameter. The concrete can be grooved and the cables merely laid in the grooves. However, more extensive concrete removal is required for hydronic snow melting systems.
Finally, maintaining your equipment is essential. You should periodically inspect and test snow-melting and roof and gutter deicing systems to ensure that they are working properly. Hydronic systems typically require more maintenance, as they have a boiler, pump and fluid levels which need to be inspected on a regular basis.
Snowy winter days can be a lot easier with the right planning and precautions. It is the responsibility of facility managers, property managers, and building owners in cold-weather states to safeguard their public spaces against accidents; and it’s your job to help them do it.
Brian Stoops is marketing manager for Tyco Thermal Controls, a global heating solutions provider with operations in 48 countries.
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