Snow-Melt
Viega Radiant snow-melting systems are used outdoors to keep driveways and sidewalks free of snow and ice build up.
Depending on the level of system installed, it may completely eliminate the need to remove snow and ice from these
areas.
Entrances to public buildings and hospitals, parking lots, car washes, etc., using pex, keep the area above freezing to
prevent ice from forming and to melt snow as it hits the surface. It is important to note that snow-melt systems require a
much higher heat input from the hot water source to operate effectively. BTU requirements, water temperatures, tubing
density and water flow rates are all much higher than those required for all other types of radiant systems.
There are three basic levels of snow melting systems:
Type I systems, commonly referred to as residential systems, may allow some snow and ice build up during extreme
weather conditions. Type I systems generally use the minimum capacities, 80 to 125 BTU's per square foot.
Type II, or commercial systems, are used in high traffic sidewalks, building entrances, and steps. These areas are kept
free of snow and ice, yet may remain wet. Heat input capacities range from 120 to 250 BTU's per square foot.
Type lll, or industrial systems, are used when slabs must not only be free of snow and ice, but are preferably dry.
Common applications of Type lIl systems include hospital emergency entrances, toll booths, and shipping areas. Input
heat capacities may go as high as 450 BTU's per square foot.
The higher heat requirements of snow-melt systems usually require higher flow rates and 3/4" Viega Radiant PEX is
normally used. Tubing loops may also be spaced closer and be shorter in length than those used in heating systems.
How the system will be operated will effect how large a hot water source is required. If the system will be turned on
when the snow starts to fly, a large amount of heat must be transferred into the slab quickly to bring the slab up to
melting temperature. However, if the slab is maintained above the melting temperature, your hot water source will be
sized for a given snowfall rate. Local weather conditions will dictate heat load requirements.
To prevent potential stress-cracking of concrete, caution must be exercised when selecting the supply water
temperature for a snow melting system. The temptation is to use very hot water (over 130° F) to quickly bring a cold
slab up to melting temperatures. This practice is likely to produce stress-cracks in the slab. Limiting the supply water
temperature to no higher than 130° F, or selecting a system control that automatically monitors and limits supply water
temperature, minimizes the stresses placed on the concrete.
Insulation is an important consideration of a snow-melt system. A fully insulated under-slab will lessen the heat energy
expended warming the soil below. Insulation cost versus operating cost must be considered in the design phase. An
un-insulated slab results in a slower responding system and uses more energy. Ultimately, insulation cost may be offset
by reduced operating cost in a relatively short period. A design professional should be consulted before installing a
snow-melt system.