Small main air vents for steam boiler??

pils

Hi folks, I just bought a 1875 house with one-pipe steam heating - my first. The system is running ok but it seems to be taking long for the rads to warm up. after reading one of Dan Holohan's book, I checked the main air valves. I have four separate runs going to 2-3 rads each and each run has its own main vent. One was leaking so I ordered a Hoffman 75 only to realize that it is much larger than the existing vents. Are the vents too small? They seem to be the same size as the ones on the rads themselves. The photo show them with the hoffman 75 next to it as a reference. Any advice would be greatly appreciated. Best,

BobC

The original vents are much to small. how long are the mains and what size is the pipe?

Bob

Steamhead

Depending on how long your mains are and what pipe size, the Hoffman #75 might be a good choice. But the existing vents have smaller pipe connections. A Gorton #D has about the same capacity as the 75 and is available in smaller threads. Post the info on your mains and we'll let you know for sure.

pils

alright so a rough measurements: OD ~ 1 3/4 inch and > 140 ft of horizontal pipe in the basement. Let me know if you need more info! Thank you

Steamhead

That would be 1-1/2" pipe, it's measured by inside diameter. How much pipe does each of those four vents vent?

pils

Ok with a 1-1/2, there is around 40-50 ft for each of the four vents. What I noticed when I put the heat back on after monkey around a bit was that most of the air was being pushed out of the rad vents and nearly (or nothing) out of the mains.

Steamhead

By my calculations each of those mains contains roughly 0.81 cubic feet of air to vent. This is slightly above the capacity of a Gorton #1 or #D which will vent .0330 cubic foot per minute at 1 ounce or 0.540 at 2 ounces. We want the mains to vent quickly so we size vents at these low pressures.

But the issue in your case is getting those old rusty reducing bushings out to use larger-size vents. Sometimes this goes well, other times it doesn't. I like to err on the side of caution during the winter

So in your case, I'd replace each of those old vents with Gorton D vents having 1/8" vertical connections. It's hard to tell if the existing vents are 1/8" pipe thread (inside diameter) or 1/4", if the latter a brass 1/4"x1/8" bushing can be used to reduce the opening. This will certainly make the system vent much more quickly, and if they do the job of balancing the system you may not need to do any more.

Come to think of it, we may have a box full of these at the shop from when we bought some of @JStar 's inventory. I'll check tomorrow.

nicholas bonham-carter

You are burning extra fuel to expel the air out of those little vents, which may not work anyway. The complication is the small size of the tapping into which they are screwed. The bushings, which reduce the port diameter must be removed, to expose the larger diameter. You could now wait until spring and then remove the bushings, so you have a larger tapping into which you can put a bigmouth vent, or you can now put in the largest vent which will fit in the smaller hole. Later, you can remove the bushing, and substitute the bigmouthvent, and hang the smaller vent on the Christmas tree, with some polishing.
Main venting is so important in reducing the burn times, as the boiler begins to steam. The longer the time for steam to arrive, and begin its job of heating the rads, the more fuel is burned. The cost of these main vents is an investment in fuel economy, and not an expense, like wasted fuel.--NBC

Fred

@Steamhead , a 1/8" or 1/4" inch opening will still vent faster than a Gorton#1, Can't he just remove those vents, add a short nipple and then use a 1/2" or 3/4"coupling with a bushing in it to mount on the nipple and then mount a Gorton #1 or #2 or a Barnes and Jones Vari-vent into the top of the coupling? That would eliminate having to deal with those old bushings and it looks like he has plenty of headroom.

Steamhead

I've found that that configuration can cause water to accumulate in the bushed coupling as the steam rushes up into it. The steam is moving so fast that the water can't drain back. This can cause banging which will shorten the life of the vent.

New England SteamWorks

Ideally that should all be redone with new 90s, antlers, and Big Mouths. Will save a lot of fuel. Where are you located? Perhaps one of us is near by and can help.

pils

I confirmed that the current main valves have 1/8 threads (same size as those on the rads themselves). I would love to find someone to get the valves properly sized. The bushings didn't seem to budge and I didnt want to push it in the middle of winter. I am thinking of getting 4 Gorton Ds as a short term measure to get through this winter. Are the Gorton D (as suggested above) the best short-term solution for 1/8 threading for my mains??

I am located in Western Mass - Amherst. If any one knows reputable steam heat specialist in my area please let me know. The system has been serviced for many years by a company that also sells oil so fuel efficiency may not be in their best interest....

Steamhead

I'd call @Charlie from wmass first. You can't go wrong with him. Go here:

https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating

And we have over a dozen Gorton #D vents with 1/8" straight connection, in their original packaging. Let me know if you need any.

@RI_SteamWorks - yes, I know it would be ideal to repipe all that, but we can't see all the complications that would be involved.

Fred

@Dave0176 may be in that area. He would be excellent i he covers Amhurst??

Fred

Hatterasguy said:

Dave is in NJ, not MA.

Sorry, I know someone here is in Mass. I think @Jamie Hall has an excellent Pro, who is that?

Jamie Hall

Fred said:

Hatterasguy said:

Dave is in NJ, not MA.

Sorry, I know someone here is in Mass. I think @Jamie Hall has an excellent Pro, who is that?

For steam you can't go wrong with @Charlie from wmass , as @Steamhead said.

pils

@Steamhead, how much for 4 gorton ds?

Steamhead

I'll send you a PM. We don't discuss pricing here.

nicholas bonham-carter

Try and get a good low pressure gauge on your system, so you can see how many ounces of back-pressure are shown during the venting phase.
See if you can measure the difference in time to steam arrival at the vent ports with the vents removed, and with them in place. Make sure you establish the header is filling first before timing.
The Gorton D's will certainly be better than the inoperative vents you now have, but I suspect the system will get steam more quickly to the rads with proper main vents, such as Bigmouths on 3/4 inch tapping, which I realize will involve the chore of removing the bushings.
If you find any rads heating up well in advance of the others, get some Hoffman 40's to throttle them down.--NBC