Which Type of Steam Coil Are You Using?

There are two types of steam coils used in commercial and industrial applications - standard steam coils and steam distributing coils. The main difference between these steam coils is the design and construction – single-tube vs. dual-tube. For both steam coils and steam distributing coils, copper, cupro-nickel, carbon steel, and stainless steel tubes are available to match the temperature requirements and level of corrosion resistance needed.

Standard Steam Coils

Steam is a simple and economical heating choice, which is why steam coils are found in a wide variety of commercial and industrial HVAC systems. These single-tube coils operate at higher temperatures than other types of coils, so only 1 or 2 rows are usually required.

Steam moves from the boiler to the point of use and releases energy at a constant temperature when it condenses. As air moves through the fin contact area, it is heated by steam moving through the tubes. It then condenses and leaves the coil as a liquid. Standard steam coils are normally used in warmer climates where the air entering the system stays above freezing. In colder climates where frigid air can pass across a standard steam coil, the standard steam coil can freeze.

Steam Distributing Coils  

While standard steam coils have single-tube construction, steam distributing coils have dual-tube (tube-in-tube) construction. Steam distributing coils (sometimes referred to as “non-freeze” coils), contain a perforated inner tube that runs the length of the coil. As the steam turns to condensate travelling down the inner tube, the condensate is released through the perforations (holes) to the outer tube. Steam that doesn't turn into condensate is released through the end of the open inner tube to the outer tube. The outer tube has no return bends, so the condensate that is under pressure has nowhere to go but back down the outer tube toward the manifold where the steam originated. The steam in the inside tubes keeps the condensate in the outside tubes from freezing, even when air passes across the steam distributing coil at less than 32° F. Under extreme cold weather conditions, it is possible for even “non-freeze” steam distributing coils to freeze. 

Contact us today at 855-Coil-Now or sales@emergentcoils.com for help in selecting the best steam coils and steam distributing coils for your needs.