Yet another Main Vent Sizing Question

BD Brannan

We have recently moved into a 90 year old home with steam heat. I've learned a lot from reading Dan's books and visiting the Wall (it's addictive), and I have been tweaking the system step by step, new vents, pitching rads, etc. But the amount of hissing and wheezing, especially upstairs, suggests that our main vents may be inadequate. I think they may be partly clogged, too.

Anyway, the house has two 2-1/2 inch diameter steam mains, one is 65 feet long, the other is 55 feet long. Currently there is one pretty suspect looking Hoffman 75 on the end of each main. If I could get suggestions on the correct main vent sizes it would be much appreciated. If they are the right size then I'll go ahead and try cleaning them, but I figured I would see if I needed to do any additional work first.

Then - I can move on to the next opportunity for improvement.

Thanks,

bd

Mad Dog

Steamhead has all the charts...but I would start with

atleast 2 Gorton #2s on each main. The faster the air gets out the better. Mad Dog

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

jesse the great

main vent size

you have roughly 2.5 cubic ft. of air in in those lines
a hoffman 75 removes 1.4 cubic ft. per min at 2oz of pressure. so basicly they are sized right but it will take 2 mins to get all the air out. or you could go with mad dogs ad vice and get the air out in like 45 secs

Steamhead

Mad Dog nailed it

a Gorton #2 on each should get those mains full of steam in a super hurry.

www.gorton-valves.com

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

BD Brannan

Thanks Guys!

I can't wait to get this taken care of. Quick question though, Mad Dog sez 2 Gorton #2's each and Steamhead sez 1 #2. Any risk of noise or weirdness by going with two each? The mains are all happily and continuously pitched down from the boiler to the drip riser, so from what I have learned it may not be a big deal.

Thanks,

bd

Steamhead

I don't think it's possible to over-vent those mains

two per main can't hurt. If you want, try one per main and see if they vent quickly, then add more if needed. I have a system with mains similar to yours running great with one per main.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

BD Brannan

Thanks, Steamhead. I kind of thought that was the case but wanted to be certain.

Thanks again,

bd