Vents too small on main steam lines(??) & vents STEAMING

RDC_BostonHomeowner

I hope someone can help give me advice regarding steaming air vents.



I am a homeowner with a one-pipe steam system with two steam main lines, each with two air vents that may be too small for my pipes and that may not be working properly:   One vent on one line can vent steam continuously for several (e.g., longer than 13 minutes today).    I think I need new and possibly larger vents, but I’m not sure of what size/kind would be best and how/where to have them installed.    



Below is a fair amount of background info (and a few pictures) that may help you come up with a diagnosis and possible solutions.   Sorry if I’ve included too much!



Model of boiler: Utica PEG 262CIDE (see photo #1 & #2, which show 2 U-shaped risers & near-boiler piping in the rear).



Ratings & data about boiler: A.G.A. Input Btu/Hr & Damper: 262,500; Net I=B=R Steam Rating: 159,000 Btu/hr, 663 Sq. feet; Annual Fuel Utilization Efficiency (AFUE) is 81.0.



I have a one-pipe steam system in my 1926, 8 room house (3 floors plus basement), which I have owned since 1989.   In 2003, I replaced the original boiler (probably used originally for coal that was converted to natural gas at some  point).There are two separate main steam lines coming from the boiler.  Also, a hot water line was added at the time of installation to heat a previously unheated sunroom.     It seems that the plumber (young) who ordered and installed the boiler did not really know what he was doing because he used some copper pipe for the U-shaped risers (rather than steel) and  we have had trouble heating the sun room (from the hot water line) without making the rest of the house (heated with steam)

too hot.   



I also later noticed that the manufacturer’s specs for this boiler recommend 3” pipe for the steam mains, whereas we have 2.5” (plus the 2” copper the plumber put in in 2003 to connect the new Utica boiler to existing steel steam mains).   I don’t think there is an ”equalizer” (since the two steam lines are separate?) or a Hartfood loop.  



I have replaced about 3 radiator vents since I bought the house, and only one since 2003. All radiators get warm or hot, but not evenly or in a balanced way (although this doesn’t bother us too much). 



I am interested in solving my “steaming vents” problem cost-effectively as my income is modest and I probably will sell the house sometime in the next 3-7

years.   



The North Main line consists of the following piping (starting at the boiler): 5.4 feet of 2” diameter copper pipe connected to 21.7 feet of 2.5” diameter steel connected to 20.2 feet of 1.25” diameter steel pipe connected to 10 feet of 1.25” copper pipe before returning to the boiler.    There are 2 air vents in total on this north main:  the first is about 24.85’ from the boiler and sits directly on an elbow for the 2.5” steel pipe (distance from connection hole on pipe to ceiling is 5.875”) (see photo #3); the second sits on the second of two elbows connecting the 1.25” steel pipe (distance from connection hole on pipe to ceiling is 11.375”) shortly before it drops down to return condensate to the boiler (this vent is about 47.3’ from boiler where steam exits) (see photos #4 & #5 in which I also try to show the connection point to the pipe).  



The South Main line consists of the following piping (starting at the boiler): 5.625 feet of 2” diameter copper pipe connected to 20.67 feet of 2.5” diameter steel connected to 19 feet of 1.25” diameter steel pipe connected to 2 feet of 1.25” copper pipe before returning to the boiler.    There are 2 air vents in total on this south main:  the first is about 24.625’ from the boiler and sits directly on an elbow for the 2.5” steel pipe (distance from connection on pipe to ceiling is 5.375”) (see photo #6;  the second sits directly on the second of two elbows (the second elbow is actually a T) connecting the 1.25” steel pipe (distance from connection on pipe to ceiling is 9.375” although this spot is fairly close to 2” wide spot in the ceiling that offers more clearance ) shortly before it drops down to return condensate to the boiler (this vent is about 41.8 feet from the boiler where the steam comes out).    See photos #7 & #8 of this second vent, which seems to be built off of a T pipe with some kind of insert/fitting that holds the 1/8” vent.  



All vents are “Dole No. 1933 Air Valves.”  In NONE of the location is the base of the vent elevated above the pipe it sits on (and is not on an “antler” to help protect it from water and debris).   I’m no expert on vents, but I wonder if these are RADIATOR vents rather than main steam vents because of the small diameter of their connecting base (with threads for screwing into pipe).    The first vent the North Steam Main and both vents on the South Main have an estimated diameter of only 0.4” at the outer edge of the threads (** could this be a so-called 1/8” connection because the diameter and size look identical to that of a Maid-O’-Mist 1/8” angle radiator vent valve);  the second vent on the North Steam main looks slightly bigger, about 0.54” in diameter at the outer edge of the threads and with slightly bigger threads.    The first north vent vents STEAM (rather than just air; I can see the steam in the air and on a mirror) for quite a while (several minutes – this morning it vented steam continuously for at least 13 minutes) after the boiler comes on.  The first vent on the south main line vents some steam, but for not nearly as long as the first vent on the north main.   



The second vents (near the boiler) on both lines do not seem to work.  I recall seeing one of these vent once, but that was at least a year ago.  The vents on one or perhaps  two radiators off the south main can vent steam for longer than I think they should (this morning one of them vented steam continuously for at least 13 minutes).  



Again, I’m sorry if I’ve provided more info than necessary.  



Here are my more specific questions:



1.       Given my current boiler and piping as described above, would it ever be effective (and cost-effective) for me to simply replace all four vents on the steam mains,  even if they are “undersized” and if I had to do so a few times over the next 3-7 years before I sell the house?     If so, what specific  vents would you recommend I use that would provide the maximum venting capacity?   Do you think they would shut off after the air was vented so that steam (and heat) would not be lost?  Is this a replacement I could attempt on my own (I’ve only changed radiator vents before), or should I call a pro?  



a.   Would it be sensible to put more than one vent with 1/8” fittings (e.g., Gorton D) on an antler arrangement that comes fits into the existing  tappings?  If so, what specific vents (and how many) would you recommend and how would you  recommend creating the antler?  



2.      I read another online suggestion (to someone with a  similar problem) who suggested that it might help to up a Heat Timer Varivalve on the radiator that comes of farthest down each main and open this Varivalve all the way (to help vent the air in the system).   Is that a sensible solution?       



3.  I’m guessing that the most effective solution would be to put at least one larger vent that is designed for mains on each main pipe, probably on some kind of antler arrangement to reduce the chances of condensate and crud larger clogging the vents.   If so, where would be the best place to do this and how?



a.  Must new/larger connection holes be made in the steam pipes (is that a time-consuming, expensive process that would create a long payback for the project?) or can the existing hole in each main pipe be used, perhaps with a fitting that allows it to connect to vent with a larger connection. If so, can you tell from the picture what kind of fitting(s)  and arrangement would be a good solution?  



b. If If there is not sufficient space between the steam main and the ceiling at the locations of the of the first vents ( see above: only 5.875” on the north pipe and 5.375” on the south pipe), is it  respectively)?     If not (or if it’s better),  is it OK to put this vent and venting arrangement at the sites of the second vents on the steam mains (1.25” diameter steel at that point) where the clearance to the ceiling is greater (11.375” on the north pipe and 9.375” on the second).           



c.      What brand(s) and model(s) of vents (and how many) would you recommend for this?  



d.  What suggestions do you have for constructing an “antler” or some other venting arrangement that  would protect the vents from condensate and crud?   What materials do you recommend for constructing and connecting the antler and vent?



4.  Any other suggestions or tips? 



Thank you so much for reading this and for offering any advice or help you might have (even if it is just one answer to one my many questions!).  

MTC

Wow, this is a lot...

but I'll try to get at least a start.



Your near-boiler piping is all wrong. If you're going to get into it and actually try to fix this system, it will cost you some money. What you probably need (w/o looking up the specs of that boiler) is two 2" risers to a 3" header at least 24" above water line. These should join together first, then have 2 take-offs from the header after those risers join, to go up to the two mains. After these takeoffs, there should be an equilizer down to the return line, which should be connected with a hartford loop using a short nipple. Your risers should be 2.5" and continue to the old steel pipe, replacing all the 2" copper that was hacked in there. ALL of the above must be steel, not copper. The returns being done in copper is fine.



Now to your questions:

1. Ideally you need about .75 CFM of venting on each main, I like to base it on 1oz. pressure. For this I'd like to see 1 Gorton #2, or 2-3 Gorton #1s. The #2s are large, so space might not allow for that in your case, you may need to do a couple #1s. The good news is that a 1/8" tapping can handle up to 1.2CFM, so you can theoretically get away with your existing tappings. The trick will be to be able to assemble an antler on one w/o stressing the fitting and breaking it off... you'll want to provide some auxiliary support to handle the weight of the antler/vents. I'm not sure where all those vents are exactly in the system, but you want the primary venting to be right after the last riser. I'd get all the venting in that location if possible, and just leave the existing old vents (as long as they're not leaking) in place on the ones at the end of the returns, or take them out and plug the holes. You don't need to vent the returns.



2. Do the above and see how you do. Venting mains fast and radiators slow is the preferred method, try it first, then think about possibly increasing radiator venting if necessary, but this is never ideal.



3. See above, I think I at least started to address all of these questions there. Ideally, you'd be working with a 1/2" or 3/4" tapping or fitting. See if there's a Tee somewhere with a plug in it, this can be an easy way to achieve this. If not, I'd rather tap out the holes larger (call a pro for this) than use the existing tappings, but if you really need to save money, you can probably get by with the smaller tappings.



Vents will do best when not placed right at the elbow turning down to the return, as some of yours are. This encourages water to slam up into the vent and destroys them. Ideally they're back at least 15" from this turbulent point, and up at least 6" above the main. If it were me, I'd probably take out the finished ceiling in the location closest to just after the last riser, to get the needed height to get the vents up at least 6" above the main. Then choose your vents by CFM rating and size accordingly from there.



Also, get as much of your steam piping insulated as possible. This is always worth it.



Once you get your main venting and insulation in order, crank the pressure down to .5 cut in and 1 on the differential wheel, if not already done, and see how things go. Then its time to deal with the radiator vents, as necessary. All of the above stuff will change the way the radiators heat, so don't do them until last, things will change on you. Hopefully for the better.

RDC_BostonHomeowner

? re: Possible locations for main steam vents

Many thanks to MTC for reading my long post and for  the helpful advice!



I hadn’t thought of the possibility of removing part of the existing ceiling in the area after the last riser on each main line.     That makes a lot of sense if these are the best locations.   



The first vents are shortly after the last risers, about 2 feet before where the pipe changes from 2.5” steel to 1.25” steel, and, as I mentioned before, sit directly on an elbow. 

 

I have a couple of follow-up questions:



1.       When you advise to get the vent up  “at least 6” above the main,” I assume you mean that the very BOTTOM of the vent (where threads are to screw into the hole) are 6” above the main, right?



2. Can the antler simply be a straight piece of pipe that is perpendicular to the main, or should it have an elbow in it, which would reduce the chance of getting water in it but might also make the antler a little more fragile (especially if we try to use the 1/8” hole rather than tap a new one)? 



3.     I’m confused about why it is preferable NOT try to put new main vents on the dry returns closer to the boiler rather than shortly after the last risers to the radiators. 

I read the following in another post (http://www.heatinghelp.com/forum-thread/142697/wet-steam-from-vents-of-a-single-pipe-system ), where Rod said: “If your system has main vents they should be located on the steam main either right after the last radiator (away from the boiler)  or on the the Dry Return pipe just before it drops down to floor level. (See attached drawing). ‘  I also re-posted Rod’s diagram that shows these “alternate” locations for main vents.     If these alternate locations are more accessible for me and possibly allow for easier tapping/installation, should I use them, or is it much better (and why) to try use the locations shortly after the last radiator risers (where I would need to remove part of the ceiling)?    



Here is a little more info in case it is useful: The riser pipes leading to the radiators are also 1.25” steel.  I also noticed that, unfortunately, the 2.5” mains have no tappings or unused pipes branching off of them AFTER the last radiator riser (although there ARE unused & capped radiator riser pipes in other locations:  the north main line has such a capped pipe after the first two and before the last two radiator risers; the south main line has a capped radiator riser pipe after the first four and before the last three radiator risers).  



Thanks MTC and to anyone else who can help!





 

MTC

For antlers,

I'd like to see a 6" nipple up to an elbow pointing uphill (so that if condensation gets in there, it flows back down and out of the antlers) to a series of nipples and tees. Make the nipples long enough that you can change out vents individually w/o having to take the whole system apart. Put the last vent in a Tee, with a plug in the end of it. This allows you to easy expand for another vent if necessary, or pull the plug to clean out the antlers if needed.



It sounds like the first vents are in ideal locations, other than being into the side of an elbow (on a straight pipe is preferable, but this is still not too bad of a location). The reason for putting them there rather than at the end of the returns is simply efficiency. Think like you're steam and you want to heat the radiators. The vents allow air out of the system, and steam to replace it, until the pipes up to the vents are all full of steam. Now, why do you want steam in your return lines way after the radiators?



It doesn't hurt anything, per se. But it does make the system work harder and costs you more money to run it.



That said, the ease of putting them at the ends of the returns has its perks, and is one of the reasons why its often done that way. You just have to weigh out what's most important.



I wouldn't use the ports that aren't after the last risers... you could theoretically do some calculations and put some venting at each of those locations, and then more after the last risers, and keep balance, but it would be harder to pull off, probably cost more, and probably give you less system balance.



If you use the 2nd location vents, you'll want to add about .3CFM to your target. This still puts you at about 1 Gorton #2, or 3 Gorton #1s. You'll just be maxing them out to hit the target I base my calcs on. If that tapping is 1/2", which is what it kind of looks like in the picture, a Gorton #2 will screw right into it, which is convenient. I'd still put a 6" nipple in there, then a coupling, and then the vent. This will take about 14" probably.

Rod

Main Vent Location

Hi- Your main vents will work fine in either position. The benefit of placing the main vents right after the last radiator lateral is that since there is no reason for thesteam to have to continue past that point and having them there willclose the main vents slightly sooner. However, keeping this in perspective, a very high percentage of steam systems have their main vents at the (“Alternate Position”) end of the dry return just before it drops down to the floor level to the Wet Return. Either position is fine. Just pick the location that works best for you.



To operate properly, main vents have to be mounted on the vertical plane.

The whole idea of the “6 inches above the main” is to put some distance between the vents and the end of the steam main as “slugs” of condensate travel down the steam main at a fairly high speed (30 MPH) so you don't want theseramming into your vents. (Again I must put this into perspective-you'll see a lot of main vents mounted directly on the dry return pipe- it's just good practice to use added piping to protect your vents)



If over head clearance is a problem, using a low antler (see attached drawing) will work just as well. The main concern is that the vents should be positioned so that any water reaching them will drain away. You will notice in the drawing that the antler is positioned so the it is parallel to the slope of the steam main and water will drain away. Also to get to the vents, water traveling down the steam main would have to turn 180 degrees. (Water would rather travel in straight line!) While you don't have to use an pipe union in the antler, using one makes it much easier to install and remove for maintenance.  Also note the the vent is mounted on a plugged pipe tee. This allows you to easily add another tee and a vent if you feel the need to increase your venting.

 - Rod

RDC_BostonHomeowner

Thank you! + alternative(s) to Gorton #2?

Thank you so much, Rod and MTC!



If space/clearance gets to be an issue for a Gorton #2, are there other, high capacity vents that you would recommend?    



Also, is there a relatively easy way for a layman homeowner like me to calculate how much venting I need in each steam main?   



Thank you **very much** again.   I feel lucky that this website exists and that you participate to help out.



Bob

MTC

Venting

Cu Ft of air per linear foot of pipe:

1.25" .01

1.5" .014

2" .023

2.5" .03

3" ..053



You probably won't need anything more than that.



The Gorton 2s are big, the #1 is a good bit smaller, so could be an option for you. You could also try the Hoffman 75 at .5CFM at 1oz.



If you decide to use your return vents, you could probably sneak a low profile antler and a gorton #2 on there. Or do a little higher profile with a few #1s. As mentioned, there's nothing wrong with putting them here, just less efficient. If it was my place, I'd probably tap out the existing ones after the last risers to 1/2" and do a low profile antler to a #2 or 2-3 #1s. If you need to make an opening in the ceiling for this, its not that hard (and kind of fun). Its all about your priorities though. If you're not going to be insulating carefully and maintaining low pressure and all of that to reduce operating costs, it might not be worth the effort to follow my suggestions. I'm all about maximizing efficiency though, so my perspective might be a little different. I am all for paying more/working harder now, to save long term.

RDC_BostonHomeowner

thank you! + vent "clearance" question

Thanks, MTC, for this information.  With yours and Rod's help,  I feel much more confident about what I want the plumber to do.



One last (I think!) question: How much clearance should there be between the top of a vent (such as Gorton #2) and the ceiling?    



Grateful Bob