Snow Melt control sequence

Hvacman

Folks,

I am working on an existing snow melt system that is copper tube in a 16'x90' driveway. Currently they turn on the system in the fall and turn it off in the spring with the only change in supply water temparature coming when the maintenance person manually turns it up if the weather will be warm for a few days. The slab has frozen once due to a "helpful" resident messing with the aquastat, thanks to the glycol it did not burst.

I am looking for control suggestions, hopefully a packaged system that includes a slab sensor that can be installed in an existing concrete slab. The fluid is heated via a shell and tube HX with steam, I will axe the existing pneumatic controls so the new controller should offer either a 0-10v or 4-20ma output signal to drive the steam valve. I'm also interested in calculating for the manager potential payback of the system, are there any online calculators available?

Thanks in advance for the assist.