Adding main vents

smoothdeity

Hey all

My 1 pipe steam system has slowly been getting louder over time. There's a lot of hissing, along with some sputtering and spitting. While investigating possible causes, I discovered that there don't seem to be any main vents downstairs.

I haven't confirmed this since the piping goes behind drywall in places, but it appears there's one big main in a loop. At the far end of the basement on this main I found a plug. Is it possible/advisable to convert this to a main vent? Picture attached.

BobC

How close to the end of the main is that plug? Vents are usually put at or close to the end of a main.

It's possible the pigtail below your pressuretrol has become blocked, that could allow the boiler to run at higher pressure and that could make your radiator vents sing louder. Do you know whn that pigtail was checked and cleaned last?

Bob

smoothdeity

I did a little more poking around—turns out the main is not a loop. It looks like there's a return pipe angling down into the wall just before the drywall, right past that plug. I found another plug on the other main that was kind of hidden by some acoustic tile.

Both plugs are towards the ends of the mains. I can't get a good look at the second plug without some acoustic tile acrobatics, but it appears to be the same kind of plug as the one pictured above. I'm assuming a main vent should go where each of those plugs are?

@BobC What's the pigtail—is that the low pressure cutoff valve, or something else? I checked the pressure and it's set to 1.5 psi, and the gauge shows 1.5 psi as well.

BobC

Those plug locations sound like they will work, getting those plugs out is likely to be a chore if they have been there for a long time.

A pigtail is the curly pipe that connects the pressuretrol to the boiler.

Bob

smoothdeity

Gotcha. Do you have any recommendations on how to get the plugs out? I assume I'm going to need a lot of leverage, but are there tools that would help?

Also, any recommendations on which vents to use, and how to get them on there? Are there vents that go into that size hole, or is there some sort of piece that steps that hole down to the vent size?

Fred

crap off that putty as much as possible and try to wrench thhe plug off. Doesn't look like any corrosion there so it might come off pretty easily. You want to buy a Bushing to take you down from that opening size to a 1/2" or 3/4"opening. Bushings are sold almost everywhere. Be sure to use a 45* elbow so that your vent is vertical when mounted.

smoothdeity

What vent do you recommend? Looking through other threads I see a lot of recommendations for Gorton #1 or Gorton #2, but I don't totally understand when to use what. My current understanding is that faster is better (which would mean Gorton #2), but my understanding isn't that great

And I assume I should use some teflon tape on the bushing as well as the vent itself?

Fred

If you have at least 7" of headroom, the Gorton #2 is the fastest main vent. A good rule of thumb is the equalivant of one Gorton #2 per 20 ft. of 2" Main. If you don't have that much headroom, you can use Gorton #1's but it takes about 3.5 Gorton 1's to equal the venting capacity of a Gorton #2. The other option is Hoffman #75 if you have about 5.5" of headroom. It takes about 2 Hoffman 75's to equal the Gorton #2 but the Hoffman's open faster at the end of a heating cycle so they are ready to work for the next cycle where the Gorton's may not be fully open. Most noticable during really cold weather where the heating cycles are longer and the off cycles shorter.
I use Hoffmans but I would say the majority on this site use gortons. You can use a combination of Gortons and Hoffmans on an antler to give you better between-cycle opening performance.

smoothdeity

Thanks so much, @Fred and @BobC !

I'll see if I can get some main vents on and report back.