HYDRONICS FROM THE FIELD
The cold, hard truth about snowmelt systems: what they didn’t tell you in class
BY DAN FOLEY CONTRIBUTING WRITER W 64
ashington, D.C., is not exactly the Arctic Circle, but we have installed a surprising number of snowmelt systems over the years, everything
from walkways and front steps to a 28,000-sq.-ft. driveway and parking pad. I have approximately 40 systems installed over the past 20 years. We typically get three or four snowstorms a year and a
good ice storm every couple of years. Two years ago, we had the epic two- and three-foot dumps one week apart that practically shut down the city. While hardly a necessity, these systems do come in handy several times a year. Our clients choose snowmelt systems for several
reasons. Steep driveways are one. Another client had a heart condition that did not allow him to exert himself shoveling snow. We had a doctor that had to be able to get out of his driveway in any weather condition. Most often, we install it under driveways that would be difficult
and fix your snowmelt system that does not work. And bring your snow shovel!” Then you spend a couple of hours driving
20 miles an hour through blinding snow to fix the problem. If you are lucky, the equipment is installed in a garage or basement, out of the snow, where you can at least warm up and think straight. If not, you are outside, trying to remember where you installed the snow sensor or lying in the snow, digging down to the cover of manifold boxes or trying to figure out why the boiler is not lighting. Here is what I have learned from 20 years of
installing snowmelt. Insulate the slab. Response time is critical. When snow or ice covers the driveway, you want it gone as quickly as possible. You can debate Class I vs. Class II vs. Class III systems and response time with your client as his driveway resembles the Verizon Center hockey rink. Let me know if your conversation went any better than mine did. You want the energy of the system directed upward to
melt the snow. You do not want to spend the precious Btu heating crushed rock, gravel and earth below the slab, where it does no good. We always specify 2" extruded polystyrene insulation (Dow Blue and Styrofoam Pink are two products we use). Bubble wrap and reflective foil are a waste; use these products at your own peril. You need the R-Value of a good insulation product in this application. Short loops, large diameter. We typically use ¾" PEX at
9" centers on our driveways. We keep loop lengths at 300’. Ice cold glycol is difficult to pump. I use 5
Photo 1: This snowmelt innovation runs Multi-Cor PEX vertically down the steps and forms the bends such that the entire step is covered. Photo Credit: John Abularrage.
to plow or shovel; cobblestone, brushed aggregate, stamped concrete and limestone drives are among several that come to mind. Mostly, we install these for clients because they want
them and have the means to pay for them. No question, it is (for the most part) a luxury that the majority cannot afford. There are exceptions to this, such as commercial jobs, but most of our jobs fall into the luxury category. They are expensive to install and consume huge amounts of Btu. There is nothing “green” about a snowmelt system. Even on our largest residential projects, the snowmelt boiler or boilers dwarf those that heat the home. I have made every mistake you can make designing and
installing these systems and have learned from these mistakes. Hell hath no fury like a homeowner who just paid big bucks for a snowmelt system and finds that it doesn’t work when it finally snows. The conversation goes something like this: “Hey Dan, get your butt over here
/8 PEX
for applications that require 6" o.c. spacing but use shorter 250' loops. I only use ½" PEX on steps, where it is very difficult to get the larger PEX to bend tightly and keep the loops short, 200’ or less. These are just guidelines. Each job is different, so doing an accurate design is a requirement. I use three software programs: Wrightsoft Right-Suite Universal, Uponor ADS and LoopCAD. If you are uncomfortable using the software products available, all the tubing manufacturers will assist with design. To keep loop lengths short, we try to mount the
manifolds remotely as close to the driveway as possible. This minimizes the “wasted” tubing leaders to/from the drive. After experimenting with plastic irrigation boxes with mixed results, we have shifted to the concrete vaults used by utilities. Quazite is a good one that we have used for the last few years. Yes, they are heavy and more expensive than the plastic boxes, but they hold up better to the jobsite abuse they will see from the final grading, landscaping and maintenance. Steps are always a challenge. It is difficult to get the
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phc december 2011
www.phcnews.com
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