Steam Basics Part 1: Understanding Steam and Steam Heat Exchangers

Chad Edmondson (JMP) and Norman Hall (RLD)

Steam heating systems are a bit of a mystery for many engineers and contractors. Much of the “old school” knowledge on steam heat exchangers retired years ago. With the limited number of new steam systems being installed today, this subject is rarely covered with any detail. But even though there are few “new” heating steam systems installed, there are existing steam heating systems that the engineer is called on to renovate or the contractor is called on to troubleshoot.

Most healthcare facilities and some industrial facilities use steam for humidification, sterilizing instruments, and possibly steam heat exchangers. Many older educational K-12 and university facilities may have one or two pipe steam systems. Many large cities have central steam distribution systems to downtown office buildings.

We'll explore the basics of steam and steam heat exchangers in the upcoming weeks. This series will cover many subjects including:

  • Why are most steam-to-water heat exchangers in building services provided with low-pressure steam rather than medium or higher pressure?
  • Why do I need a vacuum breaker and where should it be located?
  • What size steam pipe should enter the heat exchanger?
  • Why is the rule of thumb 14” for the drop leg to the steam trap from the Heat Exchanger Shell?
  • Condensate pipe sizing and flash steam
  • Is there a difference between steam strainers and condensate strainers?
  • Types and sizing of traps
  • Lift vs. gravity returns out of heat exchangers used for domestic water and hydronic heating
  • Temperature of condensate and condensate return units
  • Condensate pumps discharge piping
  • Saving energy with vent condensers
  • Flash steam and flash tanks

Stay tuned!