What are all of these pipes? This is our new snow-melt system which will keep the plaza clear and easy to walk across even during the biggest snow storms. The heating element in a hydronic system is a closed-loop tubing that circulates a mixture of hot water and propylene glycol (antifreeze). The fluid is warmed to temperatures of 140 to 180 F to provide sufficient heat for snow melting. The tubing ranges in diameter from 1/2 to 3/4 inch and is flexible enough to bend into various layout patterns. Its also designed to have a long service life. The tubing resists chemicals and corrosion and does not become soft at high operating temperatures or brittle at low outdoor temperatures.