2 pipe steam

segph

I have been out of an area where steam is used for many years. I worked on steam systems years ago ( 20 ) and have a few questions about a 2 pipe steam system.

Should their be steam vents on a 2 pipe system as on a 1 pipe system?

Can I put in a hot water system with a pump in place of the steam system and get the proper flow?

And in general, even on a 1 pipe system. What high effintacy boilers are a good choice?

Dave in QCA

2-Pipe Steam Systems

2-pipe steam systems, with a steam inlet valve, and an outlet with a trap, do not need and should not have a vent installed in them.  The venting takes place through the trap and the dry return piping.  There must be a point in that dry return piping where the air is allowed to escape, either through a main type vent in the dry return, a vent in a condensate receiver tank, or other device, such as a Dunham Air Eliminator.



Steam systems converted to hot-water are a huge gamble, usually never work right, and almost never return the expected savings.   The radiator for steam are calculated at 240 BTU / sq ft of surface.  Hot water radiators are calculated at 150-160 BTU / sq ft.  Thus, you may not have enough radiator to actually heat the space on the coldest day of the year.  Many radiators used on steam systems are not connected across the top, and will not work on hot water.





In a steam system, the near boiler piping is probably more important than the actual boiler itself.  The pros on here usually say that getting a boiler matched to the load and the physical constraints of the job is the most important.

Popular manufacturers of cast iron sectional boilers are Weil-McLain, Burnham, Slantfin, Peerless, Dunkirk.  For oil applications, the Burnham Megasteam is considered one of the best, for reliability and efficiency.



High Efficiency on steam is 81-86%.    Remember, that if you are comparing to the efficiency of a gas fired condensing hot water boiler that boasts of over 90% efficiency, this efficiency only occurs when the return water temp is cold.  This is typical in floor radiant systems, but probably not in most hydronic applications, and certainly not in a steam system converted to hot water.  Generally, when the return water gets above around 135 F, the efficiency starts to drop way off and falls down into the mid 80% range.



I cannot stress the importance of correct near boiler piping on steam.  It is amazing how many installers out there will make minor modifications, thinking that they don't make any difference, when in fact, they are critically important. 



A good business move on your part would be to really come up to speed on the intricacies of steam heat, because there are not a lot of good steam men/women out there.