Adding steam main vents! Help!

grye

TL;dr: have a main vent on one side of the system, was told to add one on the other (front and back of the house). Do I have to match vents?

Hi all. I posted on here last season and diagnosed my issue of a terribly unbalanced system. Lack of main venting. My piping isn’t ideal to add a main vent where I need to, but it has to get done. The experts here told me with a T (again not ideal, should be further back from the return but it just can’t happen).

One pipe system, the boiler is in the middle of the house. The main that runs to the back of the house has a vent (pictured). I believe I’m supposed to add another vent to the main that runs to the front of the house. Do I have to match vents or anything?

Fred

The vent, in your picture is probably not nearly large enough to efficiently vent that main and probably needs to be replaced as well. To answer your question, the vents on each main need to have the capacity to effectively vent each main, based on the size and length of the main (the amount of air that needs to be removed from each main). The vents do not need to match. The goal is to have enough venting on each main to get steam to the end of each main at about the same time, so that the steam starts to travel to the radiator run-outs at about the same time.
If you can give us the length and diameter of each vent, we can probably tell you what size/quantity of vents to use. Also, provide the diameter of the tapping/fitting the vent is mounted to. There is a limit to the amount of air that can be vented out of that hole and adding vents beyond that capacity is a waste of money. I can't tell from your picture if that tapping is 1/4" or 1/2". It also looks like that tapping was drilled into the elbow and there is a lot of goop in that area, which may indicate that it leaked at some point and was sealed up with some kind of sealer. That may be a problem if/when you change that old vent out for a new and/or larger capacity vent. Are you sure that old vent still even works?

grye

The mains are each about 15 feet. (I think its the same main, if that makes sense. But 15 feet to the last run on each side).

I'm not sure what the tapping is to be honest. I saw the goop and was worried about that also. But the vent does work, i've heard it open/close. Is there a way to figure that out? And with that old leak that we're assuming they had, can I use the same tap with a new vent?

grye

I swear everytine I look at my system I find something new !!

This is a plug isn’t it? Meaning at one point there was a vent in this spot?

Jamie Hall

Does look like a plug. If you're lucky you can get it out. Looks like you have a really tight clearance to that wall there, though, so if it were mine to do I'd come out with a street elbow (which has the advantage that you can angle it slightly off level to drain), then some out with a nipple more or less parallel to the wall, then another (regular) elbow) and another short horizontal (slightly tilted again) and then your new vent in that location.

grye

Should I be concerned as to why somebody would remove it?

Is what you recommended easier/better than either having somebody drill and tap a new hole or add a sideways T instead of the elbow on the return?

gerry gill

Why didn't the 'expert' do the job? I would cut a tee into the drip and then pipe a main vent off the drip. Thats not a homeowner job and the tee would still need to be 28'' higher than the boiler water minimum.

Fred

grye said:

Should I be concerned as to why somebody would remove it?

Is what you recommended easier/better than either having somebody drill and tap a new hole or add a sideways T instead of the elbow on the return?

Using a Tee to replace that elbow is by far the best way to go if you can do it. I'm not sure you have the head room to change out the elbow for a Tee and get a vent on there too. I don't like drilling and tapping the side wall of a pipe. There just isn't enough metal in that sidewall to really get enough treads and support for a vent without the risk of a leak. Some of the pros can do it but it's hit or miss. If you have to drill and tap, fitting walls are a bit thicker.

Steamhead

That vent was probably removed because it got in the way when they added the wall. With the wall there you might not have enough room for a vent, so a new tapping might be needed on the other side of the pipe. Just make sure the tapping is up as high as you can get it, as mentioned earlier.

With only 15-foot mains, you could put Gorton #D vents in those tappings and they'd work great. We've done it.

grye

A Gorton D on the new added vent, what about the one in place?

Is it worth it to try to remove it and replace the vent? Or may I just be opening a can of worms (where as it it doesn't screw off clean, having to have somebody plug it, and then tap a new hole?)

Fred

If you know that vent is working, it may be ok to leave it as is, at least until you get the other one on. Then you can see how evenly steam moves down each main. Are those mains in a garage, by chance? Steam mains should always be insulated to help prevent the steam from condensing before it gets to the radiators. Especially if they are in garages or crawl spaces.

Steamhead

grye said:

A Gorton D on the new added vent, what about the one in place?

Is it worth it to try to remove it and replace the vent? Or may I just be opening a can of worms (where as it it doesn't screw off clean, having to have somebody plug it, and then tap a new hole?)

Shouldn't be a problem, but don'1 force it! And yes, assuming both mains are just 15 feet long, a D at each end.

grye

Fred said:

If you know that vent is working, it may be ok to leave it as is, at least until you get the other one on. Then you can see how evenly steam moves down each main. Are those mains in a garage, by chance? Steam mains should always be insulated to help prevent the steam from condensing before it gets to the radiators. Especially if they are in garages or crawl spaces.

One is in a very very cold garage. I understand i've been doing myself a disservice by not insulting them. The only reason I didn't (but will now) is because water lines run next to them, and we've had an issue with frozen pipes before. In my mind I was thinking the pipes were being heated by the steam main (which they were, i'm just paying a fortune for it).

Jamie Hall

The steam pipes in the garage must be insulated! You're really hurting yourself. If you have an issue with the water lines freezing, though, may I humbly suggest that you enclose both them and the steam lines together in a box, and insulate the box?

grye

Steamhead said:

grye said:

A Gorton D on the new added vent, what about the one in place?

Is it worth it to try to remove it and replace the vent? Or may I just be opening a can of worms (where as it it doesn't screw off clean, having to have somebody plug it, and then tap a new hole?)

Shouldn't be a problem, but don'1 force it! And yes, assuming both mains are just 15 feet long, a D at each end.

@Steamhead @Fred

Here's a stupid question (or maybe not...)

If I'm OK putting a Gorton D on the steam main.... Can I just put the D on the first radiator off the last run?

I understand it should be anywhere before that radiator, and that radiator will fill fastest, but it's a large radiator in the living room of an open concept anyway.

Is that an acceptable solution (worthy of saving me $500 to pipe it in before)?

Fred

@grye The issue with that is if that radiator is over vented, the steam may race across the top or bottom of that radiator and close it before steam has an opportunity to heat the entire radiator. Mains should be vented quickly (to get the bulk of the air out of the Mains), radiators vented slowly (to allow them to heat evenly).

Jamie Hall

But... you can put that main vent on the inlet to the last radiator. That's been done successfully in a pinch.

That way it's venting the riser and the main, but not the radiator, and the radiator is vented normally.