Vent Configuration

JohnLaPlante

With many thanks to Dave here and Gerry Gill through e-mail, I'm going to install 2 Gorton #2 vents on both my supply and return mains.  I have a plumber coming on Thursday to install them (vents will be here Tuesday from PEX Supply), but I need some help in the actual configuration of the vents.  I have attached a simple sketch of what my vents look like now (relative heights of the vents and the mains are pretty close).  I don't have that much room to play with above the mains (although I do like the idea posed in an earlier thread about cutting a hole through the floor for a display of the vents :), but if I move about 2 feet to either side of where the vents are now I would have more room to play.  Also, I can't really move down the pipe as there is asbestos insulation that I'd rather not disturb.



Any thoughts or recommendations??



Thanks, all. 

Roma

do you know if there is any difference in the venting?

I was wondering if you knew if there is any difference in the venting performance when you come off the pipe and split into 2 directions like a U shape off of a Tee as apposed to what they do on gwgillheatingandplumbing.com when they add them all one after another?

Dave in QCA

Probably OK

Either arrangement for putting on 2 vents should be OK.  In my venting update project, I had 3 mains to deal with.  I used and antler arrangement on 1 of them and the menorah arrangement on 2.  This was strictly because of clearance issues by the vents.



Regarding your return line vents, you do not need 2 Gorton #2 vents.  Over venting your return lines can create a situation of  venting your radiators too fast and can cause balance problems in your system.   I don't recall if you have told us what kind of traps you have on your radiators.  If you have Dunham, Trane, or the old style Hoffman, they vent very fast.  The new Hoffman 17c traps vent much slower.   (Just went back and read.  OH YES,  Mouat!)   Ignore what I have just said above, except, you do NOT need to have tons of venting on your returns.)



In my attempts to repair and balance my system, which took me about a year, I eventually came to the point of slowing down my return venting.  I am using a Varivalve set wide open, (because I had it on hand) and it vents the same as a Hoffman 75, which would have been a better choice, and my system has 1,200 EDR and is firing at 600,000 BTU.



My perspectives on venting the return lines slow are concurred with by noted authority, Dave Bunnell, who is working on an article on the subject.



The 2 Gortons on your return line may, or may not cause you problems.  If you go ahead and install them, you will find out.  If you have uneven heating of your radiators, you will know that the first adjustment to make is to reduce your return venting.  If you feel compelled to put in all new vents, since you already have them in hand, I strongly recommend that you not put in more than one Gorton on the return.  One of your old Hoffman, cleaned up and delimed, would be better.

Roma

i am so confused

I actually do have trane convector boxes in the walls which would have trane traps (they are actually barnes and jones replacements).  I already put the two gortons on each main.  I put the remainding hoffmans (two on each) on each of the returns.  They are all in a U shape or an antler configuration.  I did this after talking to steamhead (ALL STEAMED UP) and also looking on gwgillheatingandplumbing.com website which talks about maximizing venting.  They claim you can't overvent.  Now I am really confused.

Dave in QCA

Venting Mains

It is true, that you cannot over vent a steam supply main. 





However, in the process of balancing 2-pipe systems, some systems will perform better if the vents on the returns a bit restricted.  Many atmospheric steam/vapor systems have large case iron radiators that are slow to heat and the time that it takes to bring hundreds, make that thousands of pounds of cast iron up to temperature, reduces the venting needs.  It is a slow process. 



In one-pipe systems with cast iron radiators, over-aggressive radiator vents can cause those radiators nearest the boiler to become steam hogs, and they can suck in all of the steam and interfere with even steam distribution.  The same thing can happen in a two-pipe system, if the traps and venting are too fast.  



However, your system is differnet.  You do not have a ton (literally) of cast iron to heat up.  Your Trane convector boxes have heating elements that are constructed of copper tubes and steal or aluminum fins.  They heat up very fast when the steam arrives.  There is little air content too.  Therefor, when the steam starts to go out into your system, fast venting of the mains and the convector boxes is essential to making your Trane Convector box system work in a manner that is balanced, efficient, and provides you with the comfort that your fine system was designed produce.





And, most of all, if Steamhead gave you recommendations regarding your system, his opinions and advice are worth their wieght in gold, having been formed by years of experience and study.  Don't second guess his recommendations based on discussions of other systems that are different than yours. 





Did you recently do your venting updates?  I imagine that the system is working great!

JohnLaPlante

@Dave

Dave, thanks.  I know you mentioned re-using one of my Hoffman 75s in the return.  But in some off-line discussions with Gerry in Cleveland, he recommended that I put 2 Gorton #2s on my return as well as my supply.  Since I don't have radiator vents, I think Gerry recommends this much venting in the return to get the steam into the radiators...but I could be wrong. 



Thanks for responding...I always look forward to your advice!

Roma

Thanks for the clarification

Thanks for the clarification.  I wasn't second guessing steamhead.  I am just very confused.  I know some of my steam traps are bad as well.  So that is going to be my next step.  I replaced the elements about 8 or so years ago.  So I plan to not beat around the bush but just replace all 21 of them.  It will be a little costly though as they go for about $32 a piece.  My systems seems to be heating pretty good.  I actually have to shut the trane heat box convector doors in the room with the thermostat so that the rest of the house runs for a while.  Otherwise the heat pumps in that room and satisfies the thermostat.  I also have to cut away some of the ceiling to allow for the gorton #2's to be completely vertical.  I have been trying to find someone who's is an expert on these systems that services Yonkers, NY with no luck so far.  DAZED and CONFUSED and almost at wits end.

Rod

Vents

Either vent configuration will work fine. You can also "remote" your vents if it is more convenient. There is no harm moving them (reasonable) multiple feet away from the main if you can better height there. The important thing is to have good drainage back to the main so that any water that gets in the vent pipe will quickly drain back out. If you go a long distance away from the main you might want to use 3/4 inch pipe. I would also use a pipe union (as in Brad White's menorah /antler drawing) to attach the vents as this allows you to easy service /add and subtract vents.



Dave - When your talking about limiting the return main's venting, is this in regards to what Gerry Gill calls "Air Lock" ?   On a two pipe system, this is a situation that can occur where the steam entering the steam main "sees" the Return Vent and then rather than continue to the end of the steam main to the steam main's vent, it "short circuits" through the first couple of radiators to the Return Vent leaving ones farther up the main without steam.  Gerry Gill has a discussion on this in the following link:

http://www.gwgillplumbingandheating.com/webapp/GetPage?pid=608

gerry gill

Either way of installing the vents will work just fine,

provided that the moisture in the pipe can drain back to the vertical drip pipe...as for venting the return to fast, i don't generally see a problem there..especially with systems like Mouat who if the return pipe ended back in the boiler room would take a pipe into the chimney at a full 3/4 or 1 inch bore and vent the return mains with a full open pipe with a slight negative pull on the end of it..my opinion would be if the return pipe can't be vented well there is some other balance issue at play.

Rod

An Important Caveat!

Gerry Gill and Steamhead are top notch steam pros!  Any advice they give FAR OVERULES comments from people like myself who, compared to them, are rank amateurs in the area of steam heating!!

Dave in QCA

brochure on Trane concealed heaters

I am sure you have probably seen this brochure, but if not, I am passing it along.  It is in the Heating Help Library.  http://www.heatinghelp.com/files/articles/1271/219.pdf

Dave in QCA

Totally agree with Rod's Caveat!

Rod, agree completely with your deference to the Pros! 



Regarding my return venting comments and discussion.  I am familiar with Gerry Gill's airlock.  In fact, I was on the verge of proceeding with the installation of that setup, but decided to try a few other things before purchasing the materials to proceed.  That set up, by the way, I regard as ingenious, and I think it is probably the best solution of problematic uneven distribution in a 2-pipe system.



In my system, the returns were all piped together and essentially vented through an open pipe.  The smallest pipe size, as the piping converges is 1", so that was in effect that capacity of my return vent.   I began the whole project by replacing and repairing radiator traps.  Then added generous venting to the mains, 2 stations of 2 Gorton #2, and 1 station of 2 Hoffman 75s. The main venting improved, and steam got to the end of the main in about 2 minutes for all 3 mains.  I also added vents to the top of the risers in the locations that were slow to heat. Steam arrived at the rads all about the same time.  However, depending on where the rads were located, close to the boiler as opposed to end of the line, the heat was still uneven.  (perhaps being a bit picky, but was shooting for room temps within 1-2 degrees.)   What I did, as an experiment was to restrict the venting of the return main.  I had an extra varivalve on hand, ( used them for riser venting because they are easy to install with 1/8 threads.  Not real happy with their operation, but they do vent well!)  So, I put that verivalve, set wide open, (.66 cfm @ 1oz) in as the vent on the returns.  Now, when my boiler starts to make steam, I see 1 oz of pressure at the boiler.  As soon as the main vents close, the pressure rises to 2 oz., where it remains until the radiators become fully heated and the traps close, at which point the pressure will creep up (eventually) to the 8 oz cutout on the vapor stat.  Of course, in normal operation, it very rarely builds pressure greater than 2 oz. 

What all of this did, was even out the steam distribution in my system.  Granted, all systems are different, and the subtle idiosyncrasies of systems operating at atmospheric pressures can be a real challenge.  But, this is an actual case where slowing down the radiator venting, by adding a very slight restriction on the return line vent, proved to be a great help.



Had I to do it all over again, I think I would have gone the orifice route.  There are many advantages, even though it requires higher operating pressure, but still no more than 2 psi.



My apologies for taking this post off on a tangent, just trying to answer Rod's question.

JohnLaPlante

@Gerry - Thanks!

Gerry, thanks so much...I appreciate your contribution and help.  

Roma

I agree

I am an amatuer.  I am glad that there are guys like them that are willing to help us out.  I wish you guys lived near Yonkers, NY so you can fix my problem.

Roma

I agree

I am an amatuer.  I am glad that there are guys like them that are willing to help us out.  I wish you guys lived near Yonkers, NY so you can fix my problem.