How Should Steam Coils Be Designed?

How Should Steam Coils Be Constructed?

Steam coils are the most hard to operate of all the coil kinds. They are, in essence, a byproduct of the system and controls that surround the coil. Steam coils simply will not work if they are not fitted correctly.

The goal of any steam coil is for steam to enter as steam and exit as condensate. In an ideal world, the BTU load on the coil converts steam to condensate just before it is ready to escape the coil. Condensate, on the other hand, frequently begins to form inside the tubes practically immediately under real-world conditions. You must find a mechanism to drain the condensate from the steam coil, especially when dealing with low-pressure systems.

Pitch of the steam coil within the coil casing: A skilled coil maker will internally pitch the steam coil within the coil casing to urge the condensate toward the outlet connection. Typically, this pitch is 1/8" every lineal foot of coil.

Coil Length: If you need steam to travel 144" and make many passes over the coil, your system will not function properly. Condensate forms too quickly and is unable to leave the coil. As a result, coils cannot be excessively lengthy. A better method is to split one large coil into two smaller coils that are fed from both sides.

Steam distribution coils sometimes require 1 1/8" diameter tubing. If the BTU load on a coil is really high, you will generate significantly more Lbs./hour of condensate. If the tube diameter is too tiny, the condensate that must be evacuated has nowhere to go.

Traps: Steam coil systems require traps. The traps should be of the "float & thermostatic" variety and should be installed 18" below the condensate connection on the steam coil. Without this, the condensate simply sits in the system with nowhere to go.

Vacuum Breakers: Vacuum Breakers are commonly used in coil systems to remove any extra condensate that may have accumulated within the coil.

Insulated Piping: A "Condensate" Heating coil designed as a steam coil does not exist. IT IS NOT WORKING. Unfortunately, because to the great lengths the steam must travel from the boiler to the coil, many times the steam enters the coil as condensate due to the pipes not being insulated.

Anything that causes condensate to accumulate in a coil is detrimental to both the steam coil and the system. You will receive a "water hammer" when the system is turned on and the incoming steam just blows against the condensate. Worse than the loud and unpleasant sound it makes is that it just ruins the steam coil. Water hammer was never intended for brazing. Also, the coils do not heat up adequately. Have you ever encountered a long coil and run your palm along its length only to discover that the coil's entering steam end is hot but the far end is cold? Most of the time, this indicates that condensate is laying in the coil, preventing steam from adequately traveling the length of the coil.

Designing and building steam coils requires a high level of knowledge. Vrcoolertech has a long history of resolving coil issues and constructing steam coils that work the first time. Send us an email (info@cstheatexchanger) for your next project And you'll be surprised!