Should this have a main vent

callen_03

Hey All,

I am new to steam heat. I recently replaced the steam vents on the radiators and reinsulated all our pipes. I am still hearing a good bit if hissing from our steam vents on our radiators. 

One thing I did notice when I was reinsulating is that there appears to be a cap on the end of a main line that I am wondering if it's supposed to have a vent on. I am wondering if you all would have some input and how I would go about putting in a vent because it seems like the cap is sized larger than a typical main vent. 

Waher

The reducer bushing beneath the close nipple the cap is threaded onto would have to be removed and replaced with a reducer bushing sized appropriately to thread a vent. Depending on if you have the clear height above the cross the bushing is screwed into you would want to add a nipple + a coupling to get a standoff distance above the main to protect the new vent from any potential water hammer/turbulence backsplash from being so close to the elbow leading to an elevation change.

What is the pipe below the cross fitting?

callen_03

The pipe below is a condensate pipe that leads back to the main drainage back to the furnace. 

Long Beach Ed

The value of venting that main depends on its length and what it serves. Right now that main vents through the radiator(s) which may or may not be sufficient.

Good luck getting that cap off. You certainly can put a vent there to vent that main, but it may be a lot of work and the benefit may not reward the work.

Steamhead

How long is that main, and what pipe size? Is it the only main in the building? If not, what are the lengths and diameters of the others? Do they have vents on them?

callen_03

The main is 30 feet long with a second main that offshoots from it about three feet back from the cap that then goes an additional 12 feet. There is a main vent at the end of the secondary main. The first main (the one with the cap) has a diameter of 2 inches for about 15 feet and then switches to 1 3/4 for the rest of the line. 

callen_03