Is 1-minute main line venting really possible?

greengiant

Is 1 minute venting really possible.

Hi

I originally put this onto the end of another thread I had going but was worried no one would see it so here is the start of a new thread. Sorry if you're seeing this twice.



I've been fooling around with venting on my system. It used to take 12 minutes for steam to get to the end of one of my lines. I've now got it down to 5 minutes. I added 3 Gorton D's to the end of the main and turned down the Vent Rite 1's on all of the radiators. I can't get the steam to move quicker than five minutes. I even took out a fitting, opening a 1 inch hole near the end of the line. It still took the steam five minutes to get there despite the gaping hole. Is venting a main in 1 minute really possible? I had been thinking of ordering some Gorton 2's to install because I know they have huge orifices but if a 1" hole makes no difference why would adding Gorton's?

Rod

Main Vent Timing.

Hi- How well are your steam mains and risers/'header insulated? Is the timing from a cold start or a warm start?

The warm start timing (time between heating cycles) is the one you need to be concerned about.  You have to keep in mind that the steam is condensing inside a cold main and until the piping heats up, steam won't be moving along all that quickly..  This is where good insulation makes a huge difference as you lose less heat between cycles and therefore not as much steam is used to reheat the steam mains when the burner starts producing steam again. I was amazed at how much noticeable difference it made when I insulated my near boiler piping.

- Rod

greengiant

Hi Rod

Thanks for the reply. My timing was done on a warm start. The insulation is not so great. The previous owner of the house insulated the 2" diameter mains with 1/2" thick fiberglass pipe insulation meant for 11/2" pipes. This means that the insulation only goes part way around the pipe and some of the pipe all the way down the main is exposed. I recently applied new insulation to the near-bloiler piping (1" thick fiberglass). I plan to continue the job as I get the money. Have you ever heard of mains actually vented in 1 minute?

Rod

Insulation

Hi- I just read your other thread.. If the steam main you are concerned about it the one that is mostly counterflow, you have to keep in mind that being counterflow,  initially the large volume  of  cold counterflowing condensate will slow up the heating of the steam main even further..

  The 1/2 inch insulation you now have is really next to useless. (See the attached graph by David Nadle)  1 inch is the minimum thickness you need.  Insulation gives you the best return for the money so I'd keep advancing that even a little at a time. It pays to shop around as insulation prices vary a lot!!  One of the "Wallies","Crash",  did a great series of posts on insulation.  Search the Wall for past posts using the worlds "Crash " and "insulation" and that should lead you to them.

- Rod

crash2009

Its gotta be possible

If the main was short enough and the vent hole was large enough.  Do we really need to vent the mains in 1 minute?  Whats the rush?  All I have ever read around here is vent them in "a minute"  not nescesarily "1 minute"  One ounce or one cubic foot per minute would be more realistic.

My mains are 75 feet long each, and I have 2 of them.  I am vented three times more than I need to be.  9 cf of vents venting 3 cf of air.  On a good day like today when it's cold and the boiler runs a lot, it still takes 3 minutes to vent those 3 cubic feet.  Other days it takes a little longer.  The only way I can get closer to 1 minute is by building a bigger antler, maybe one inch or one and a quarter.

Abracadabra

not with improperly insulated mains

no way you are going to vent a main in 1 minute with improperly insulated pipes.







The fastest it will ever vent is the time it takes with the main vent removed.