An article in Habitat looks at some potential HVAC trouble spots in multifamily buildings, including issues related to steam heat.
Steam radiators often create loud banging noises that cause residents to complain. Habitat says the noise is caused by steam coming in contact with cooler water (condensate), creating a rapid expansion of the condensate water in the pipes. Older buildings typically have just one pipe shared by the steam and condensate. The downward slope of the pipe returns condensate back to the boiler for heating. But over time, pipes can sag or get bumped, causing the steam and the condensate to collide. Energy managers should check the pipes to see if they should be repositioned or replaced.
More modern two-pipe systems use steam traps to keep condensate and steam from meeting. But steam traps expand and release thousands of times in a heating season and will eventually fail. It’s up to the energy manager to monitor and replace steam traps.