With a single pipe parallel flow system

Fizz

when the return is a dry return of length, it seems like a lot of piping to be heated before steam reaches vent. As a newbie to the system, can one put the vent up the line on return as opposed to end?

ethicalpaul

The purpose isn't to get the steam to the vent, the purpose is to get the steam completely filling the main. People talk about getting the steam to the vent all the time because in a proper setup, the vent is at the end of the main.

If you move your vent to the beginning of the main, you will have accomplished the first thing, but left your main full of air that must be vented through the radiators.

But you're right about having to heat a lot of main pipe. So insulate it.

JUGHNE

Paul, I think he means to move the venting to the beginning of the return piping.
IMO, it seems, if practical to have them in the boiler room they will get attention in the event of leaks etc.

Once the steam gets to the last runout, the additional time to get to the end of dry return does not matter for venting time.

Yes then insulate the piping.

ethicalpaul

ahh thanks @JUGHNE

Fizz

So moving vent to front of return would be more efficient?

gfrbrookline

Your gain will be negligible and as @JUGHNE stated, better to have them in the boiler room so the can be monitored and serviced if needed.

Fred

I personally prefer them at the end of the Main, anywhere after the last radiator Run-out. Steam will take the path of least resistance and with good venting, that will be the first path. Why waste any time heating a Dry Return and pushing air out of it. Most vents can be monitored anywhere in a typical basement. Crawl Spaces, Not so much.

Jamie Hall

If the flavor of dry return about which we are speaking here is an extension of the steam main back to the boiler in a one pipe system, and pitched to drain that way, then overall the best place for the main vent is just after the last radiator runout. However, if you find it is better -- for any number of good reasons -- to put the vent back at the boiler, then you really must insulate that dry return.

In a two pipe system, the dry return absolutely must be vented, and better done at the boiler, as that is the way air gets out of the radiators. In such a system, there are two ways to vent the mains: you can put main vents at the ends of the steam mains or you can use crossover traps at the ends of the steam mains, going to the usually very handy dry return. Some vapour systems, to work properly, require crossover traps.

Fizz

Thanks guys! The return is insulated. The last run in main is to 2nd floor rad, which is after drop to dry return. The drop is about 6-8" to parallel run to boiler of about 33'. As noted in prior post the vent(Gorton#2) doesn't get steam til near end of cycle. Initially the vent was Gorton #1, then#2 with little or no improvement and ran system with open pipe with no difference.

neilc

"open pipe with no difference" ?
so why isn't the steam getting there?
is the main insulated all the way back to the boiler?
(steam collapsing before it can get there?)
Is steam going to "other" main(s), and not here, due to poor piping at boiler header?
picture of main connection(s) to header ?
Boiler too small?

Fizz

Main is insulated to boiler; steam goes to back main(same set-up) which is not insulated, has edr of 84 attached, while front has 134. Back main has MOM#1 for vent and is somewhat quicker than front. Boiler is WM SGO3, so plenty big. Hope pictures help.

Fred

I'm guessing a couple things here that may affect that Main:
1. Steam will take the path of least resistance. You may have the radiator vents on that slow main open so much that it is easier for the steam to go to radiators before it fills the main.
2. Hot will also go to cold. Having that one main insulated and the back one uninsulated may also be affecting where the steam wants to go.
Insulate that back Main and slow the radiator vents down to balance the entire system, not just one main.

Fizz

Here is venting for rads: back side-wall type 9sf gorton5, collumn 30sf MOM5, coll 24sf G5, iron tube21sf MOM4; front col42sf MOM5, col33sf GD, It 21sf Heat timer 1/2 setting and col38sf MOM6. I used table from Gerry Gill and Steve Pejak as guide.
As for insulating back side, it's difficult as piping is too close to wall.