Single Short Main, do I have enough Venting

duffbuster243

let me just first thank this forum for the excellent information that It provides, I have been able to greatly up the efficiency of the steam boiler in my home with the information on this site.

I just want to confirm that my calculations are correct on my main venting. I have a small home with a single 35ft 2" main feeding 6 radiators that consume approximately 240sq/ft of steam.

According to my calculations from the vent capacity chart 2" pipe has .023 cf of air per linear foot giving a total of .805 cf of air through 35ft, is this correct? My main venting consists of 3x maid o mist #1's venting .341 each and 1 heat timer Varivalve straight pattern at its max setting which is listed to vent .660 cf (this is experimental and actually seems to work very well.) According to my calculations i'm venting 1.683 cf of air at 1oz, basically double what I seem to need.

nicholas bonham-carter

What is the timing on steam arrival to those vents from a hot boiler.
If you had a low pressure gauge, you could see from the backpressure whether your main venting was adequate or not.
Are all the rads getting steam at the same time?—NBC

duffbuster243

I have not actually timed how long it takes, I can tell that the main heats fast, I was just running the numbers to see if adding any additional main venting would be beneficial. I may some time soon time steam delivery to the end of the main open vs with vents to see if there would be any benefit. Steam delivery to all rads is not 100% balanced but that is by my own doing as some newer finished rooms are more insulated than other's I opted to slow down some rads and speed up the rads in the colder rooms.