Which vent should I replace these Hoffman's with?

Kybeans403

I'll be starting the boiler replacement next week and I don't know enough about the proper vents to replace these puppies with. Any suggestions would be much appreciated. There are 4 on this particular system and all 4 are stuck open. I believe they are #75's...? There are no other leaking returns on this system and I am confident that these were the culprits causing too much fresh water to be fed.

Ironman

Big Mouth vents. They vent over twice as fast as that 75.

Paul48

If you measure the size and length of your mains, I'm sure a steam pro can tell you how much venting you need. Big Mouths are the best on the market, but, who knows, you may need more than 1.

Fred

Are there four mains, each with one Hoffman 75 on them? The Bigmouth vents a slightly over twice the rate of a 75 but, you should measure the length and diameter of each main to determine if one per main will suffice.

Kybeans403

Correct. There are Four (4) 2" mains off of the header. I will stop by tomorrow to measure properly.

Ironman

The vent really shouldn't be at the very end of that line like that. At the very least, see if you can get a couple 90's and long nipples between the vent and where it connects. The way it is now, a water hammer will damage it.

EBEBRATT-Ed

There are vent charts in the new LAOSH and maybe in the library on this site

@Ironman is correct. The vent should be on a tee 18" before the end of the main. If you cant re-pipe a couple of elbows and nipples between the vent and the main will help to prevent water hammer also raise the vent as high as possible

JUGHNE

I thought that a Gorton 2 vented over twice of a 75.
And also doesn't a Big Mouth vent twice of a Gorton 2??

BobC

@JUGHNE tour right, the BM vents at 1.8 X the Gorton #2 and about 4X the rate of the 75. The important thing for even heating is that steam begin to fill all the radiator risers at about the same time.

To do that you have to know the volume of each steam main and vent them proportionately. If you have a single main you just have to check the volume so you will know if one vent is enough,

Bob

Steamhead

Measure the length and diameter of each main and post it here. We can tell you what's needed.

Fred

@JUGHNE , you are sooo Right!

Kybeans403

Ok so here we are for mains/vents. Thank you in advance

#1 - 2" x 18 feet
#2 - 2" x 25 feet
#3 - 2" x 30 feet
#4 - 2" x 35 feet
#5 - 2" x 8 feet

All mains currently have the Hoffman's as posted earlier

Erin Holohan Haskell

EBEBRATT-Ed said:

There are vent charts in the new LAOSH and maybe in the library on this site

Here's the Balancing Steam Systems Using a Vent Capacity Chart: https://heatinghelp.com/systems-help-center/balancing-steam-systems-using-a-vent-capacity-chart

Danny Scully

#1) gorton C
#2) gorton C
#3) gorton D/1
#4) gorton 2
#5) gorton 5

nicholas bonham-carter

A low pressure gauge will also tell you what the back pressure or resistance of the escaping air in the mains, and you want it as low as possible for even distribution-2ounces.—NBC

Kybeans403

Was able to get 4 out of 5 vents installed in this manner.

No more leaks either. Replaced substantial amount of wet return pipes, but last one didn't show up for about an hour and a half after boiler was steaming

Koan

good work!