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[mlappin]

From my experience with mine, 120 degrees does melt snow faster, especially if you don’t have any sensors to detects snow fall like mine, I just have a electro mechanical timer on the kitchen wall by the back door. Believe it’s a 6 hour timer.  If I wake up in the morning to quit a bit of snow I’ll turn the knob an exact number of turns to crank the temp up to around 110-120. If your on the ball and start it as the snow starts to fall 80 is plenty, if its a light fluffy snow 60 will work, ay 60 a wet heavy snow will cool the cement off enough between runs to where it doesn’t melt, in that case 80-100 degrees works better. On something like snow melt going a little overboard on insulation isn’t a horrible ideal.

i run primary/secondary loops in my basement, snow melt is dead last and it will pull very hard on start up especially if it’s been very cold for several days, the glycol will be the temp of the cement when first starting, if its been zero for awhile, the glycol will come in at zero. I also am using a Taco ΔT pump for the house loop as well.

[E Yoder]

Good info.

[silver star]

I did security at recoding artist John Mellencamp's home while it was under construction.  He fired  a contractor half way through and worried the clown would come and vandalize it.

There was what I now understand to be pex tube along his driveway, and throughout the construction.  No OWB, but whatever his heat source, his matching HUMMERS didnt have to slip and slide in the Winter.

[wreckit87]

I don't know what length they were, just getting ideas on how much I can stretch it. My guess is they're between 100-200'.

I put 1/2" in my sidewalk at home because I had a bunch of leftover tubing. 6" OC, my runs are about 175ft long (2 loops). I start mine cold, but it only takes about 10 minutes to get the return temps up to 100 degrees and then 3 hours to start melting. I put it on a 12 hour manual timer to spin a B&G NRF22 pump through a 3x8" 20 plate. I set a 100 degree supply temp right off the plate and run a 33% ethylene glycol mix. By Delta T goals, it's performing just fine that way but having done many other systems with 5/8" and a few 3/4", they definitely perform better in terms of speed. My apron at home is set up the same way but with 5/8" at 6" OC, ~250 ft loops on a 5x12" 40 plate. Also 100* setpoint, takes about 1/2 hour to get the return up there but starts melting in a little over an hour.

I have one system at a military development facility here about 4 years old, where I continue to do other work on their 75,000 sq ft building so I can see how it performs. That was 5/8" at 6" OC also, but an 8" slab and 4,000 sq ft in size. NO INSULATION per the engineer's demand, despite hours of arguing. Tubing is suspended in the center of the slab. It's fed by a Lochinvar Mod/Con and I set the temp at 75* to try it out, it's doing very well so far. There is a precip sensor telling it when to run, and I've never seen snow sit on it for more than an hour. Pair of Grundfos 26-150 pumps shove 33% ethylene through the loops. It moves heat very fast, but it runs almost constantly in the winter. A single snowflake will trigger the precip sensor. I'd hate to see the gas bill on that bugger.

That said, I'd never run an atmospheric system on anything that goes in a slab. Everything is always closed loop. Call me crazy, but I refuse to send a bunch of oxygenated fluid into an inaccessible space to gum up and destroy the system's efficiency over time. You know that black slimy shat that's in your strainers when you blow em down? Yeah, that same shat settles to the bottom of the slab tubing. I've torn apart many a slab that were full of that garbage because someone either didn't know any better or was too cheap to buy $200 worth of HX and expansion tank. It's cheap insurance my friends, please stop doing this