Preventing a Snowy Driveway
Welcome to another freezing winter in the US Northeast. In some places it’ll be so cold your spit will freeze before it hits the ground. It’s the sort of cold that would give you frostbite on your spleen. We’re located about a mile south of Freezing to Death, for those who’re curious. There are only a few traditional ways to fight this: sweat and tears, sweat and tears with a snow blower, or just have some lifted four wheel monstrosity. There is however, a modern way to fight the cold: heating systems.
Some Basic Concepts
When it snows, the snow will only actually become a problem if the ground itself is cold or can be chilled by the snow. The first couple hours of snowfall may melt as soon as it hits the ground and produce no significant challenges. This is the major weakness of snow: it requires something to be cold.
Snow will almost always build up first in grassy and wood covered areas. Dirt, wood, and grass are quick and easily chilled to support the snow. Pavement however, essentially rock, things made of denser, heavier elements is not so fast to change temperature. Road surfaces retain a lot of thermal energy. It takes significant effort to warm or chill one of these surfaces.
The easy solution would be to spray down the driveway with hot water, melt off the snow, and drive way. Unfortunately, the laws of physics pose some challenges. Although water is incredibly efficient at carrying energy, the water we put down will eventually turn to ice. We can combat this with chemicals, but then we’re going to kill every blade of grass and flower in the spring. Ice melting chemicals are awful for plantlife.
An Outdoor Heated Floor
Water and other heating technologies however, are still the answer. Heated floors have been a thing for years. We run piping or heating elements other certain types of flooring and instantly provide a warm, cozy surface. This sort of technology is often most effective with stone and ceramic flooring, which will readily absorb and distribute the heat.
What is a driveway but a big, rough, stone floor?
In principal, fighting off a snowy driveway is as easy as warming up the interior of your home. There are however, a few caveats to bear in mind. First and foremost is the insane amount of energy it’ll take to heat the driveway. A household or small business furnace might be rated up to 100,000 BTU. Melting a driveway is more often closer to 250,000 BTU. We also have to consider how to make such a system hold up. Outdoor plumbing is known to have issues with the cold and heating elements might not take so well to water.
Water Based Snow Melting
In a water-based ice melting system the set up is straight forward in principal. A series of tubes are run under the parking surface in a grid that will efficiently and evenly heat ground above it. Typically insulation is placed under the piping to prevent heat from being wasted heating the ground below.
The first major challenge is that the water in the piping doesn’t get a chance to freeze. There are two big mitigations available. First, use PEX piping. Copper pipe will burst readily, but as PEX is a more flexible, plastic material, it can take some of the pressure caused by freezing. Second, these driveway heating systems may use antifreeze and similar chemicals to prevent the pipes from being frozen immediately (though they can still burst at cold enough temperatures). In the event of extreme cold, it may be necessary to drain the heating loop or run the system continuously.
The second major challenge is generating enough heat. The driveway heating system will typically have its own, special furnace. These heating systems will be massive, big enough to make the building’s main furnace look tiny by comparison. In bigger installations that some businesses may use, the temperature needs to be gently raised. Raise the temperature too fast and thermal expansion can cause the driveway to deteriorate like pouring water into hot glass.
Lastly, there is that issue about the cost of fuel. Producing this much heat is expensive. Most businesses opt instead for hiring a plowing service because it’s cheaper than the cost of fuel involved in operating this type of system. These ice and snow melt installations are generally done in smaller facilities access is essential, typically for doctors, some emergency services, and hard to plow driveways.
The alternative to a water and furnace based system is to use electrical heating elements. These aren’t going to have issues with pipe bursting and fuel that a water-based system would have. They can be run on demand and shut off as soon as the ground is clear, regardless of the environmental temperature.
The installation for this type of heating system is nearly the same as for a water system. Insulation will be laid under the driveway, the heating elements will be placed in a grid, and electricians will have to wire everything together. The hardware costs may be greater for this type of system, you’re basically buying a gigantic square footage of heating elements and copper, neither of which are especially cheap.
This system has a few major weaknesses, depending on how it’s designed and installed. If the elements are daisy chained together, it’s possible that when one fails, every element after it will fail. There could be weight limits involved, given the ceramic elements will have limits on how much weight they can take. Lastly it’s essential that this system is completely water proofed from the start, and contains thorough protections against water entering the system later in its life.
The upside is that heating elements are electrical. It may be cheaper to operate this system, depending on local utility costs. With a big enough solar panel array, it could be possible to operate these at near no cost. Of course, solar panels don’t tend to work well when they’re covered in snow and they won’t run well under cloud cover either. That becomes a nearly moot point. The how water system however, could have its electrical components easily run on solar, battery, or generator power.
Are These Systems That Common?
It’s hard to tell just how common these de-icing systems are. There aren’t any ways to just recognize it when looking at a driveway or parking lot. That said, we’ve found that most major heating manufacturers offer these driveway heating systems. With the proper installation, these save you significant struggling in the winter, if you can afford them.
Categories: Heating Tech