Is there benefit in splitting up main vents?

HarryL

As mentioned in another thread, I have 40 feet of 2" main and just finished installed two Gorton #2s. To expedite getting the Gorton's installed, I replaced the nipple and VentRite #35, located at the boiler end of the dry return, with my new Gortons. I then removed an ancient vent that was on a 1/4" elbow at the end of the main and capped it off. I am planning on eventually moving the Gortons to this location when I can get the bushing out. This will probably be next spring in case things go badly applying the extra persuasion that appears to be needed.

Should I pop off one of the Gortons near the boiler and move it to the 1/4" elbow at the end of the main? I know 1/4" isn't enough for two Gortons but the venting capacity does seem to be enough for one. With the Gorton antler off, it takes about 3:45 to get steam to end of the main. It is then another 2-3 minutes to get it down 25 feet of 1" dry return to the Gortons. My thinking is if I move one Gorton to the end of the main it will shut off first and enable the steam to start pushing up to the radiators 2-3 minutes sooner. The downside seems to be that the dry run will continue to vent through the remaining Gorton #2, but more slowly, and so I may not really see steam to the radiators sooner.

The diagram shows the Gortons today and what I am thinking of doing.

KC_Jones

Personally I would just leave it alone for now. You are basically splitting hairs. In addition you aren't talking about adding venting just moving it. Moving one of them to the proposed location wouldn't really speed anything up because you haven't added capacity. In addition once the steam hit is it closes and stays closed. If you are talking about adding another vent at that location that is a different story altogether. The steam goes to path of least resistance and those Gorton's have so much capacity 1 of them will almost certainly have more capacity than the attached radiation. Even with the fastest Gorton rad vent you need 4 of them to equal 1 #2 main vent. I doubt if you have that much capacity in your radiator vents. Just my opinion.

BobC

I think some of it is convenience but that location might be a better place because by the time the vents are hot that main is full of steam. If you have them at the end of the main they will probably close a bit to soon. It may cost a little more fuel but maybe you get better system performance.

Bob

HarryL

@kc_jones - Thanks! Kind of what I suspected.
@Hatterasguy - for me it is convenience. I think the better location is at the end of the main, past the last riser. If the vents are hot and closing, then steam must be at all of the risers ready to start heading to the radiators. (At least that is what I recall from Dan's books. I lent mine to someone a few years back and don't recall where it went. )

KC_Jones

Hatterasguy said:

KC, this begs another question that has been bothering me.........

Why are the main vents typically at the end of the dry return instead of at the end of the main?

If they were at the end of the main, the dry return would go unvented and steam would go to the radiation that much faster.

Must be a reason..............??

The way my system was set up by some old dead man my vents are at the end of the main and the dry return isn't actually vented. I don't have any condensate return issues or anything and steam is definitely getting into the dry return (ouch). I have contemplated adding them, but on my system in my house I am not seeing any obvious reason to do it. I have a vent antler and the end of the main and that is working nicely in my house. It's one of those things every house is a bit different.

PMJ

In a two pipe system where does the air go that gets pushed out of the rads by the steam into the dry return if it is not vented?

KC_Jones

This was just mentioned in another thread. In that situation the dry return gets vented according to how much radiation it attached. Steamhead mentioned this, but even he said it's trial and error. Here is a link to that thread.
http://forum.heatinghelp.com/discussion/comment/1352326#Comment_1352326

Mark N

It is covered in the LAOSH. In a one pipe system there is no reason vent the returns. The main vents should be placed after the takeoff for the last rad. Two pipe has different requirements. The rads are vented into the returns, therefore the returns need to be vented.

PMJ

KC_Jones said:

This was just mentioned in another thread. In that situation the dry return gets vented according to how much radiation it attached. Steamhead mentioned this, but even he said it's trial and error. Here is a link to that thread.
http://forum.heatinghelp.com/discussion/comment/1352326#Comment_1352326

I read the thread. I'm not following why in two pipe there ever is a reason you wouldn't just want the dry return at atmospheric pressure(as in a wide open pipe) when the burner is on. I mean why is it complicated at all or have anything to do with how much radiation is attached? If the dry return is not open to the atmosphere when steam is pushing air into it out of the rads then there is pressure in there - if even only ounces - that resists steam flow into the rads. Whatever it is it would require an equal amount more at the boiler to overcome it.

Mark N

If all the steam traps work and no steam makes it into the return, it would most likely be fine. Some systems used a rad in the return piping to condense any steam that made it that far.

PMJ

Mark N said:

If all the steam traps work and no steam makes it into the return, it would most likely be fine. Some systems used a rad in the return piping to condense any steam that made it that far.

Agreed Mark. I was assuming that all traps are in working order. But along that line of thought - since rads were supposed to be sized to heat the rooms on the coldest days with maybe even windows open then basically they never need to be full and the traps never really needed. I know my rads never fill up completely. For 90% of the heating season rads 1/2 to maybe 3/4 full easily gets it done for me. I suppose on the rare occasions when we hit 20+ below with wind a trap or two might actually close.

Mark N

My 1-pipe system behaves much like yours. During the coldest weather last winter, which was around zero, I would say the rads heated about 2/3rds of the way. My air vents on the rads never close, they may get slightly warm.