Is this my main vent?

KeithG

Hello, My wife and I just bought an older home in Westchester NY that has one pipe steam heat, we're new to steam heat (as well as home ownership) and Im in the proscess of insulating all the pipes in the basement and I think I located my main vent (pictured) which is not far from the boiler, about a few feet above and behind it. It says its a Hoffman No. 6, and its much bigger than the vents on my Radiators. So i'm almost sure this is my main vent. I also have another one that is identical to this that one in another part of the basement farther away from the boiler that I think is also another main vent, so i think I have 2. Would I be right in assuming that?



It seems very old and rusted and I want to replace it , but i'm not sure exactly what to replace it with. I was looking at a Groton No.1 main vent to replace it with. which i found at PEX supply here. <a href="http://www.pexsupply.com/Gorton-G14-Gorton-No-1-3-4-x-1-2-Air-Eliminator-Main-Vent-Valve-3522000-p ">http://www.pexsupply.com/Gorton-G14-Gorton-No-1-3-4-x-1-2-Air-Eliminator-Main-Vent-Valve-3522000-p </a> . would this be a good vent to replace those with? I'm finding it hard to find the right radiator vents for my system. There seem to be several choices and i'm just not sure which ones to go with. But right now i'm more concerned with replacing those main vents so my rads upstairs will heat up more evenly.

Jamie Hall

Probably is...

 but that one has been there for a while!  Main vents are sized on the basis of the amount of air they need to eliminate -- the length of the main and it's diameter.  That said, it's almost impossible to over vent a steam main.  Myself I'd be inclined to go with the Gorton #2.  It's more expensive, but it vents a lot faster.



However, if you give the diameter and length of the main, we might be able to say that yes the #1 will work just fine.

KeithG

Thanks

Thanks Jamie,



Please excuse my novice explanations, i'm still learning the terminology. I think you mean the threads on the main vent intself, the part that screws intop the pipe? That looks to be about 3/4 inch in diamater and the runs are about 5 feet away from the  boiler for the first vent and about 25 feet away for the second vent, both in the basement. I'm just concerned about getting the right vents to replace those main vents in the basement. So you think the Groton #2 would be better than the # 1?

Jamie Hall

Actually

I was referring to the pipe diameter of the mains themselves -- but you have at least given the length, and assuming that they are normal sized pipes a Gorton #1 will do just fine on the shorter -- 5' -- main.  I'd use a #2 on the longer one.



You may find that the threads on the vents are a different size from the existing threads on the mains, though.  And, given that the vent (at least in your picture) are right at the ends of the mains, you will do well to add a short length of pipe -- called a nipple -- of at least 6 inches to space them up from the main -- if you have the headroom to do that.  It will help protect them from water hammer, if you ever got any.  You can get nipples of the right size at any good plumbing store -- and for that matter many big box stores have them as well.  You can also get bushings there to change the thread size to what you need.



Be sure to use pipe dope or teflon tape on the threads to seal them!

KeithG

Another question,

regarding the nipple and the vent size. The  gronton #2 is 1/2 inch, would i get a 1/2 inch nipple to attach first to the brushin an then to the groton #2? im just a bit confused about the sizes.But is that about right? I apologize if i'm not understand correctly.

Jamie Hall

What you need to do...

taking that Gorton #2 as an example.



There is, already, a bushing showing in the picture.  Probably reduces the thread on the T down to half inch, from the look of it.  So you need a half inch diameter (pipe size -- the actual diameter is bigger) six inch long nipple which will thread into that bushing after you take the old vent out.  Then at the top of that, a half inch coupling (inside -- female -- thread at both ends).  That screws onto the top of the nipple, and the Gorton should screw right into the other end of it.



As I said, don't forget the dope or tape...

Steamhead

If that's like other Hoffman #6 vents I've seen

the threads are 3/8".



Since it may be difficult to remove that bushing without some serious tools, you can get a short 3/8" nipple and a 1/2"x3/8" reducing coupling. Screw the nipple into the bushing, screw the reducing coupling onto the nipple and screw the #2 vent into the reducing coupling.



The hole in the threaded portion of the vent is only 3/8", so this arrangement should work fine.



If the shorter main is only 5 feet long, you may not need a vent there. After installing the #2 on the long main, see if the steam takes longer to reach the end of the short main than it does to reach the end of the long main. If not, you don't need to upgrade that vent. You want the steam to reach the ends of both mains at about the same time.

Jamie Hall

Follow Steamhead's advice

not mine -- he's a lot better at this stuff than I could ever hope to be!

KeithG

thanks guys,

this is very helpfull advice. Here is a picture of the second vent thats about 25 feet from the boiler. as far as I can tell it is the same exact Hoffman #6 vent, its very old and isent venting proprely anymore. As far as I can tell it looks like it has a reducing coupling as well as a brushing and then the vent? would that be right? would I use the same parts to replace this one as with the first one? I know the Groton #1 and #2 are different thread sizes? Or would you recommend the # 2 for both of them? both these vents are in the basement.