HVAC piping encompasses many different fluids, pressures, and temperatures. This piping can be located above or below ground and route through the interior or exterior of a building. Typical space heat transfer is completed using an air-water coil designed to return the water at a defined temperature. HVAC piping delivers hot water, cooled water, refrigerant, condensate, steam, and gas to and from your HVAC components. Its effectiveness is largely influenced by the materials used to make it.