Main Venting Problem?

Brian_78

Hi everyone. I am still having a problem getting all of my radiators to heat up. I moved into my new home in July and am entering the first heating season and am slowly becoming me own steam professional. I have three mains in the home, and only one main vent. I've noticed over the past month that this main vent has stopped making its hissing noises and I'm wondering if it has failed. Anyhow the bigger issue, or from what I've read, is that each main is supposed to have its own main vent and they are supposed to be placed 6-8" above the main pipe and 15" before the last bend of the main. My three mains come together and then there is the vent directly above the last 90* bend. I don't believe this is correct?



Also, while I was following the mains looking for a place the original main vents may have been, I found a single thermostatic trap at the end of one of the steam mains. Its kinda of strange, the steam main connects to the beginning of the return main and in between is a single trap. Once I found this I realized that each of the other two mains also appeared to have had these traps at one point but someone has taken them out. Funny thing is that the main that still has this trap at the end heats up the best. Any ideas on what any of this means would be greatly appreciated. 



Thanks very much!  

Steamhead

Well, for one thing

it means you have a Vapor system.



This use of a radiator trap is called a "crossover trap". It routes the air from the steam main into the dry (overhead) return line. The air from the dry return is vented at one (usually) or several (sometimes) point(s) in the basement, usually near the boiler.



Often the vents were vacuum types, which worked great with coal but not so well with oil or gas.



You have two options here, one is to restore the crossover traps and the other is to use standard main vents.



Can you post some pictures?

DavidK_2

I can't help you with your problem,

It sounds like you may have a two pipe system. I skipped those sections.



I can recommend getting these books



[url=http://www.heatinghelp.com/products/Super-Deals/14/129/A-Steamy-Deal]http://www.heatinghelp.com/products/Super-Deals/14/129/A-Steamy-Deal



they are very useful when you become the steam pro in the house. They also give you a better understanding of how your system works - useful when talking to the pros (and the knuckleheads).



No affiliation, except the author supports this site, and I've found his writings useful and entertaining. My wife thinks I'm nuts (and she might be right) reading my "steam books" and talking to my "steam buddies", but the more I learn, the more interesting it becomes, and if it lets me do some things myself, saves me from hiring one knucklehead, and lets me communicate better with the pros, it is money well spent.



Now somebody else will come along and probably help.



Edit - see steamhead already came by - listen to what he says

Brian_78

main pics

Yes you are correct, it is a vapor system.



So if I leave the last remaining trap and also install main vents, am I potentially asking for trouble? I guess I'm kind of confused as to why anyone would take two of the three out and leave the last one in its place? Do you suppose that if i reinstall them my radiators on those mains would work better?



I've posted some pictures of the all my mains, the first is the one that still has the trap connected to it. I also posted a piture of my single main vent, which again I don't think is working because I no longer hear any air escaping from it. Does the installation of it look correct? Shouldn't there be at least three main vents for each of my three dry returns instead of just this master vent.   

Brian_78

I own two out of the three boks.

I have read "we got steam heat" and am just starting "the lost art," both are excellent.



Yes it is a two pipe vapor system. I replied to steamheads comments and attached some pictures...maybe it makes more sense now.

Paul Fredricks_3

Huh?

Correct me if I'm wrong Frank, but if the traps are missing and the pipes just capped off, how would the radiators heat at all?



And wouldn't traps be the best way to go to keep the steam out of the other returns?



just thinkin'

Jamie Hall

There's a good deal to be said

for restoring those two crossover traps -- they are ordinary radiator type traps.  Not that hard, since the opening for them are there.  If you do, those two mains should suddenly start to behave just as well as the one which is working!  Then go back and find the main main venting area, and vent the dickens out of it.  There are posts around here referring to "antler" or "menorrah" piping arrangements for multiple vents at a single point -- usually Gorton #2s.  You could try putting them all at the location of that master vent -- looks like you have plenty of room for them there -- if that is on a dry return.  Are you sure that that location is a main, and not actually a dry return?  From your description, sounds more like the latter to me.



Or as Steamhead says, just throw a Gorton #2 on each of the mains where the crossover traps used to be... probably would work just as well.

Brian_78

The steam mains terminate at the F&T traps

but there is also a crossover trap that runs a small pipe into the dry returns. Why this trap was originally installed I'm not certain. If the F&T traps are working fine I'm really confused as to what the need for these crossover traps.  But again, the main that has this original trap is working the best...but it is also the shortest main with the least radiators on it...coincidence or the beauty of the crossover trap??

Jamie Hall

Chances are

if you follow up those F&Ts, they go down into a wet return.  Which is dandy for condensate, but doesn't do much for the air.  The crossovers were to get the air into the dry returns and thence back to the main vents.  If the air can't get out, the steam can't get in...

Steamhead

Looks like

that one crossover trap is a Sarco.



Measure the length and diameter of your steam mains. That way we know how much air you need to vent. The dry return vent should definitely be bigger. Start with one Gorton #2 and add more if needed.



Also you mention F&T traps, but I didn't see them in the pics. Does this system have a return pump?

Brian_78

I feel like something is wrong...

The sytem does have a condensate return pump, but their is a problem, the motor is seized. I posted some questions about the importance of repairing it a few weeks ago and all the responses were telling me that the pump was probably never needed in the first place.



So now my system, as it stands today, has three steam mains which start at boiler (obviously) and terminate at an F&T trap. Actually four mains, but the fourth just stems out of the header and terminates 10 ft. later at its own F&T trap. The two F&T traps are then piped into the condensate return pump directly below them.



Then there are the three return lines. These start where the first radiators condensate drips down into them. All three of them run parrallel with the steam mains for the most part until the very end. They are joined together, then piped through the one main vent, and then piped down to the condensate return pump.



So try and picture this. I have a total of six pipes (seven counting the signle steam main with no radiators) that are piped into the condensate return pump, but only the three return lines are vented. Is this correct? The steam mains and returns lines are not connected in any way, except the last remaining crossover trap, until everything meets at the condensate ruten pump, which is not working. 

I'm stating to think that at some point, probably when the boiler was replaced in '96, someone changed the way the steam mains are vented, and am I'm not sure if this is correct. By reading the above responses and looking at the last remaining crossover trap it seems that the main vents should be at the end of the steam mains, not at the end of the return lines? But isn't it true that F&T traps are supposed to vent themselves? Anymore insight would be appreciated.

Charlie from wmass

Well a deep subject here.

The traps do not vent themselves. They allow air to pass through and condensate to pass through but stop the steam from passing. As stated the traps need to be put back in and the condensate pump needs to function or the system needs to be piped without the pump in the system. Without seeing it in person it is hard to say which is the best way for your system. The books do a better job of explaining the details of the function of the parts then I have the space or typing skills to do here.

Jamie Hall

Vapour systems

very often -- if not always -- were piped in just the way you describe: steam mains, and each steam main paralleled by a dry return.  The end of the steam main was connected to the parallel dry return with the crossover trap, which allowed the air to go back to the main vent(s) located very near the boiler.  Depending on the exact vapour system, it was important that that be the only vent on the system (no vents on radiators or steam mains), as on excess pressure (someone let the coal fire get out of hand!) the system was designed so that that vent would close, pressurize the returns, and force the water back into the boiler.  With reliable (?) vapourstats, that is not so much of a problem now -- but why mess with success?



The ends of the steam mains and the ends of the dry returns were also commonly (but not always) separately dripped into a wet return.  This picked up the condensate and happily let it flow back into the boiler under gravity.  Sometimes the wet return didn't exist, and the condensate ran along with the air in the dry returns and dropped to the boiler at the boiler; this sounds more like your arrangement.



In any case, if the boiler pressure is low enough the condensate should be able to get back into the boiler without the assistance of a pump at all.  That depends very much, though, on the distance from the boiler water line to the dry returns or the F&T traps and the boiler pressure.  Without knowing exactly what those dimensions are, one can't state what the maximum boiler pressure should be -- but there is no harm to running it as low as you can get it to go.



This help any?

chgosteam

hopefully this will help

Brian, First lets look at how your system is set up to work.  You have a two-pipe vapor system.  At one timeit probably had a boiler return trap or something like that to get the condensate back in the boiler and vent the air.  It probably failed and was replaced with a condensate pump.  A condensate pump vents air through its open pipe vent.  There should be an open 3/4" pipe that comes of the pump box.  This is the air vent for the whole system many times.  After all, what can vent faster than an open pipe.  There was no worry for steam to get there because everything is trapped.  You no longer have a "wet" return, it is the outlet side of the pump after the check valve.  So there was a clear path for the air to get out.  Without the crossover traps you are missing those mains were just venting their air through the radiators to the dry return, which also vented back to the condensate pump open pipe "vent".  Those mains might have taken longer but should have still worked.  Your pump is now seized and I am sure it is full of water now.  Being full of water you have now lost your main air vent since there is now a water seal in the condensate pump box.  This is also why that one main probably gets hot since it has its own air vent.   What you need to do is get that pump fixed or replaced.  Then either install new thermostatic traps in those two locations to help vent the mains ( the originals probably passed steam which showed up at the cond. pump), or some good main line steam vents either will work fine.

Brian_78

Thanks you Jamie and chgosteam

your responses are very helpful. I'm having another pro over to the house tomorow and hopefully he can help make the decicion to either elimnate the condensate pump or repair it.



I measured the distance between the center or the water level site glass to the lowest f&t trap and got pretty close to exactly 28". So, to my understanding and mathmatical skills, this is telling me that the maximum pressure the boiler can run at is 1psi. Only one problem though, my boiler is equipped with a pressurtrol and the lowest cut out setting available is 1.5psi. I guess I might be in the market for a vapostat, that is if I deciede to elimnate the condensate pump. However this might be the better option since a new motor for the pump is something like $750.  

Steamhead

At the moment

it looks like the air is being vented thru a condensate tank that probably isn't needed. But were that not the case, the air would vent thru the radiators if the crossover trap (or main vent) were missing. Of course that would mess up the system's balance.

chgosteam

be careful

Brian,

Don't be fooled.  The fact that all your steam mains are trapped means that you don't have an "A" dimension.  You have a "B" dimension.  You now will need a good 60" to return water to the boiler by gravity.  Steam traps pass air and condensate but not steam so you won't have that left over pressure to aid in pushing the condensate back in the boiler.  You need the pump, no matter what you run the pressure at.  I would still set it low like you have it and vaporstat is a great idea to run it at the pressure it was designed.  But for now, replace the pump and add the crossover traps and I am sure it will work great.