2 pipe radiator explanation - new to steam

Baynton

I just finished the book, "We Got Steam Heat",and  had a question about our particular 2 pipe radiators.  Background is: very large old house, 50% of radiators are getting hot and we're slowly debugging the system, but realize I need to know a lot more about the details.  The book describes 2 pipe radiators with a supply and return, simple enough, but also with a steam trap on the return and no air vent.  Ours have valves on both supply and return and an air vent in the appropriate spot for a 1 pipe radiator.  The return has an identical valve as the supply, it does not appear to be an elbow return trap.



My question is - I see how the air vent could still help quickly remove air from the system, but I don't see anything that would block steam from continuing to the return pipe, which the book indicates could cause blockages for other radiators (which seems to be happening, many stay cold).  Any thoughts on this design, or does it sound like someone replaced a trap with a valve without knowing what they were doing?



Many thanks and apologies for misused terms,

Baynton St

Charlie from wmass

How new do the valves look?

Do you have any pictures to share?

jpf321

dan described

a very special beast the other night .. a vented 2-pipe system. perhaps that's what you have. do you know when the house was built? and can you tell us where it's located (closest major metro area is fine)?



but more likely someone's been "hacking" the system. 

TomM

link?

Hey, jpf, where's the link for Dan's article.?  I can't find it.  Seems like the two pipe air vent system was popular in the philly area, as I am noticing that a lot of homes here have it.  It creates A LOT of confusion when discussing one pipe vs two pipe as there is not a lot of info on it, and everyone always wonders where who took out my traps, but they were not invented yet when the system was installed. 

jpf321

sorry it was during steam school ...

perhaps there is something in TLAOSH .. I'll have to look.

Jamie Hall

This one sounds like

one of the original efforts at two pipe systems -- they had a steam main, a dry return one or two sizes smaller, valves at both ends of the radiators, both ends fed at the bottom, and air vents on the radiators.  A slightly later variation had the "return" end of all the radiators dripped to a wet return, instead of a dry return.  You can tell by seeing where the returns go.



If it is the former type, they are a bear to balance, although thermostatic vents or at least variable vents will help.  They do work -- essentially steam does come to the radiator in both directions, and condensate wends its way back to the boiler mostly through the returns (depending on pitch).  They really are more like a one pipe system with twice as much pipe than a two pipe system, and one must think of them that way.

Maine Vent

Hi Baynton, similar system

I have 4, 2 pipe rads like these in the pics, and 5 1 pipe rads. my system heats very well and evenly. I have vari vents on all rads.  I have dan's EDR rad book and it shows these Crane Radiators and I think these are Crane???? 

Baynton

Pics and more info

Hi Folks - here is a link to several pictures of my radiator in question:



http://allshiv.imgur.com/radiators



The house actually is in Philadelphia (Germantown area), good guess.  We think it was built sometime around 1880, the rad in the picture was forged in Germantown and has a patent date stamped on of 1874.   There has been plenty of hacks on the house over the years, so no doubt the system is not balanced.  There are several 1 pipe rads in the house also, with 19 total, and a whole rats nest of pipes to supply them.



There is only 1 main line trap in the basement, and a few suspicious end caps where it looks like maybe there were additional, previously.  My guess is to replace and add in those spots.  Should I consider replacing the return valves with a trap?



Thanks

jpf321

2-pipe gravity return dripped to wet

dan has a picture of the system in TLAOSH on pg. 125 .. his picture shows a rad with a floor valve on each end of rad and a vent .. it looks like it came from an old text .. i'll see if i can find a more detailed "source" reference.

Jamie Hall

One and a half pipe

Maybe that's what they should be called?



Originally the system would have had no traps at all, for the simple reason that they weren't invented yet.  I wouldn't be a bit surprised if it had been hacked like mad over the years.  There is, however, no particular reason why you can't have plain vanilla one pipe radiators hooked into it, along with the two pipe.



If your water levels are OK, there should be no need for the trap in the basement.



It would be possible to replace the return valves with regular thermostatic traps, although it would be a big job.  If you did, it might be easier to get a decent balance on it, but I wouldn't bet on it.  My instinct would be to leave those alone, and pretend that it's a one pipe system with, as I say, a whole lot of extra pipe and hardware.  If you were to do that, you could treat it as one.  Balancing can be handled with vari-vents, or thermostatically controlled vents -- which you will need for the one pipe radiators anyway.



Do look around in the basement.  If this is one of the later types of this system, there may be a wet return there, and all the radiator outlets might have been piped directly to that wet return.  Those actually work pretty well -- but it is important that the wet return is wet.  If you have one, check your water level vs. the elevation of where any drips hit the wet return.  The drips have to be lower.

jpf321

source references

hubbard discusses 2-pipe with a valve on each end around PDF page 65 from this book: http://books.google.com/books?id=UmJGAAAAMAAJ&printsec=frontcover&dq=related:OCLC57514462#v=onepage&q=&f=false



baldwin discusses the various systems of piping schemes in the first chapter of this book (ed 3 http://books.google.com/books?id=Eks1AAAAMAAJ).. however, he refers to Figure 1 .. unfortunately there isn't any Figure 1 .. unless it's the missing have of the picture on PDF pg 29. (I just looked at other editions of the baldwin book .. in edition #5 .. you can see that there was was looks to be a fold-out of the systems on PDF pg25 .. probably Figure 1) (ed 5. http://books.google.com/books?id=QPsJAAAAIAAJ)  .. in ed 20, the right side of the drawing seems to be clearer than in ed. 3 http://books.google.com/books?id=kONIAAAAIAAJ PDF pg. 29 ... and there's no record of the drawing at all in ed. 11.



this book http://books.google.com/books?id=L2IJAAAAIAAJ shows 2-pipe vented rads and discusses problems that one man encountered .. PDF pg 66



if I come across anything, I'll let you know...it seems to be a very common way to do thing in the 1880's ... the reason they work is because the returns from each rad are dripped directly to a wet (sealed) return and therefore there is no exchange of steam through  returns.

TomM

2 pipe air vent

told you there were a ton of this style in Philly!

I wouldn't think about turning it into a true two pipe system if I were you.  You'd have to add a ton of traps (you said you got 19 rads) and I'm not sure if the one pipe rads would work if you put traps on the two pipe ones. 

I would make sure that all the valves were definitely open, since you have the original valves with the wood handles.  Most of mine don't close, but you never know. 

and make sure that you have enough boiler for all those rads.  sounds like a big house.   you never know what they were thinking when they converted it over from coal. 

also, at my place, i think all the suspicious end caps were once main vents that were removed. 

Charlie from wmass

I like the marble slab

I wanted a customer to do this but they thought it would not go with the radiator. If only I had this picture to show them then.

Baynton

wet returns

I'll have to bone up about wet vs dry returns, and then check out how it looks.  I do know that the returns, as they get closer to the boiler are newer (they're copper), so I expect that the pitch and elevation could have been changed along with the re-piping.   I'm now thinking of this system more like a 1 pipe - and I'll try and research how to debug cold pipes.  My header gets hot up to a point, then stops cold.  Radiators beyond that are out of luck.  I was assuming this was an air blockage, but I'm hearing maybe vents/traps on the main line might not help this system.



Thanks everyone for their thoughtful answers

Baynton

jpf321

main vents?

what type of main vents are installed now? I can't think of a reason why main vents would not assist with this system .. anytime you suspect a "clog" in a main steam line is probably due to a venting issue. if you raise the pressure, does the pipe heat further along? is so, then it's most definitely a venting issue. (and remember to turn your pressure back to 0.5/1psi)