Monday, February 02, 2009
Heating a driveway melts winter shoveling
By Ann Robinson and Annie Schwemmer
Heating your driveway is one of the most popular outdoor heating applications with obvious advantages, especially in the midst of a Utah winter.
There are two basic choices for driveway heating — electric cable or hot water systems. You cannot add such a system to an existing concrete driveway without completely removing and replacing it. Snowmelt systems can be used with a variety of materials including concrete, asphalt or pavers, though concrete is usually the material of choice.
There are three main elements of a snowmelt system — the heating element, the controller and the activation device. The heating element can be either electric cables or piping/tubing that circulates hot water. The controller is a wall-mounted control box for electric systems or a boiler for hydronic (hot water) systems. Hydronic systems also require other parts like pumps and manifolds needed to operate the system. Both types use either manual or automatic activation devices.
Manual devices are simply on/off switches and are less effective because they may not always be started before the storm arrives.
Automatic sensors include aerial-mounted and pavement-mounted snow switches. These sensors activate the system when there is moisture present and when the temperature drops below 38 degrees. Since automatic systems run continuously at low levels, they respond more quickly to a storm than the all-on/all-off approach of the manual start systems.
When a new concrete driveway is installed, steel reinforcing bars are placed throughout the area to strengthen the concrete and to prevent cracking and settling in the new drive. The heating elements of the snowmelt system (cables or piping) are set on top of the wire mat prior to the concrete pour. It is possible for a homeowner to install this piping or cabling, though. In the words of one manufacturer, it requires an "ambitious" do-it-yourselfer. Connecting the heating element to the controller will most likely require the help of an electrician or plumber, depending on the type of system.
The controlling system must be installed in an area protected from the elements, often a basement or garage. The water-based system, including a boiler and manifold system, requires more room than an electric system and will need an area from 4 feet to 8 feet in diameter.
The cost of a snowmelt system ranges between $12 and $21 per square foot of area heated. Factors that affect the final cost include: whether or not you must remove an existing driveway; the price of concrete (which varies depending on the location of the project and market demand); the installation labor; what type of control system you select, and the size of the system required. Obviously, while you are at it, you can also heat sidewalks, ramps and exterior stairs if you want an entirely maintenance-free design. The cost of operating such a system is approximately $0.28 per 100 square feet per hour.
There are other options for outdoor heating that we will discuss next week
Remember that while pricey, the advantages of a snowmelt system extend beyond never having to shovel. Your home will reap additional benefits such as never again having anyone get stuck in your driveway, providing a much safer, slip-free situation, avoiding the use of environmentally damaging chemicals and adding value for resale. As always, we welcome your home architect design questions at firstname.lastname@example.org.