Snow Melt System Size and Performance
For our examples below, we’ll assume a standard-sized, 600ft2 driveway with a residential snowmelt system with a 150 BTU/ft2/hr heat output. This means a total hourly output of 90,000 BTUs.
For our “cold-start” pick-up load — the output required to heat the surface initially when the system fires up — we’ll assume 9.15 BTU/ft2/hr, for each degree we’re raising the surface temperature.
We will also assume a starting driveway surface temperature of 20°F, which should be brought up to 32°F, and a start-up time of 1 hour.
This means that 110 BTUs are needed for each ft2 of driveway surface to get the surface to the temperature at which snow will not accumulate.
With our 600ft2 driveway, this translates to a pickup load of 66,000 BTUs.
These are challenging assumptions to make because the pick-up load varies depending on the slab’s temperature at the start of the snowfall and how quickly you want the system to respond. Still, the chosen value should work for the purposes of an Order of Magnitude Estimate.