Vacuum System

joe amadio

I am a licenced plumber that does case research and investigative work for attorneys and insurance companies. A new case that I am working on involves what I am told to be is a closed vacuum steam system. The basis of this case involves damage to property caused by water. One side is arguing that a large puddle of water about three feet in diameter was seen emanating from under the radiator on and off for several days during operation. A plumber that was hired by the building is going to testify that a closed vacuum system is designed to completely avoid leaks and to minimize if not entirely negate the collection of moister and condensation.  He explains that steam enters the radiator via a feed pipe and is sucked through the radiator into the return pipe by the vacuum system. he also says that the steam trap on the return catches condensation and prevents leaks.He says that because the steam is being sucked through the pipes and radiator that it would not be able to escape the system even if there were a crack in the radiator.He says that even if the radiator was cracked that the amount of steam that would escape would only produce an ounce or two of condensation not nearly enough to produce a large puddle of water. Now I have worked on quite a few steam systems in my career but admittedly not that many vacuum systems. Without getting to technical I thought the steam trap is normally open until steam reaches it at which point it would close trapping the steam which would then turn to condensate. If this is the normal function of the system isn't it then possible for the condensate to leak from the system if there is a break in either the radiator, a nearby fitting, the steam trap itself or the return piping? Please advise because I have never heard of this plumbers explanations in my life.

Unknown

Vacuum Systems aren't Magic!

Joe - I don't mean to sound rude but you posted this question last night in Strictly Steam and Gerry Gill has already given you an answer. If you were making a list of ten people in the United States who know the most about old vacuum steam heating systems, Gerry Gill's name would be on that list. 

So what exactly is it that you are asking?

Vacuum removes some of the air in the radiator and creates a pressure differential that enhances the movement of steam into the radiator. That's it ! No magical whisking steam through the radiator without leaving a drop and out the return ( At least not if the trap is working )

That's why they call it a "Steam Trap" - it traps steam IN the radiator!

Since you are "a licenced plumber" I don't have to explain why steam systems need radiators and how radiators work and that they condense steam and that condensed steam is what we normally call "water." and that water`runs downhill in this case to the bottom of the radiator.  So if we found a puddle of water under the radiator we probably can make a pretty good guess as to where it came from.