Do I need Main Vents?

SteaminTed

Hello! The folks on this site have made me smarter about my steam, so I'm going to take the liberty of asking a couple more questions.

Below is a picture taken looking up toward the ceiling above my Slant/Fin boiler. As you can see, the Main A leaves the boiler and quickly splits into three branches: B, C and D.

Branch B takes steam to eight radiators across three floors. Branch C takes steam to two radiators, both on the first floor. Branch D takes steam to four radiators, also spread across three different floors.

This system was installed (with an older boiler) probably around 1910-1920.

Here are my questions:

1. Is this distribution-per-pipe typical? The 8-rad burden on pipe B seems like a lot, compared to the others; but I'm a total amateur and steam is full of surprises.

2. I have hunted and hunted, but cannot find any air vents off the main or the three principal branches, or really anywhere at all at the basement level. I could be missing something, but all the air seems to have to leave the system via the radiator valves. (One branch has a cap that may once have been a vent.) Would it be wise, or economical, or prudent for some other reason, to have vents installed on the basement branches?

Thanks for any and all insights and advice.

ted

Fred

"A" is actually a riser, not a Main. Ideally the installer would have used both riser tappings out of the boiler to feed the Header (the horizontal pipe right above the boiler) and they would have used black iron pipe instead of copper.
The three mains, "B" , "C" and "D" should have each then dropped down into the header, individually. That way steam would have had a much more even distribution.
Having said that, and to answer your question, yes, each main, B,C and D should each have vents at the end of each main, after the last radiator Run-Out to allow air to be evacualed quickly. As it is, with no vents, a good portion of you heating cycle and fuel is spent pushing air out through those small radiator vents. No way to actually balance the radiators as it is.

JUGHNE

How well does this heat? Is it always quiet? What pressure does it run at? Do you have a return pipe from the end of each of the 3 steam mains.
Some pictures from each side showing all the piping you can include would help.

Jamie Hall

Many old systems from the era you are quoting were coal fired. They heated very slowly -- and therefore they didn't need main vents. New systems do, as the boiler comes up to temperature remarkably quickly. So... put some main vents on in convenient locations at or near the ends of the mains.

SteaminTed

JUGHNE, I would say...

• from cold start (after overnight, for example) radiators begin to feel warm after 20 minutes are putting out good heat by 45 minutes

• It is not always quiet. It's an old house, and there are horizontal runs between the risers and the radiators under some of the upper floors. The pitch of these pipes is unknown; one of the third-floor radiators was causing unbelievable water-hammer, but I closed the valve at the most likely offending radiator and now it's less of a problem. I suspect the pipe running back to the riser (steam.return combined) is poorly pitched. On the other hand, that room doesn't heat. Bummer.

• Return-wise, it's a mixed bag. Usually the farthest-flung mains have returns, but only one of the branches (C, with only two radiators) has returns for both.

Picture 1 is the farthest-reaching branch from MAIN B. It has a return (but no valve).

Picture 2 shows a branch coming off of MAIN B that does not have a return.

Picture 3 shows MAIN B running back to the boiler with the return line that goes back to the wet return.

Picture 4 shows anther branch from B, with a return.

Three more pics coming.

Phew! I hope these load in order!

t

SteaminTed

SteaminTed

Picture 5 shows both of the branches off of C; both have returns.

Pictures 6 and 7 shows branches off of D. Two have returns, and one does not.

SteaminTed

And as close as I can tell... it's running at half or three-quarters of a pound of pressure.

Jackmartin

Single pipe steam comes on at .5 and off at 2 psig. You are heating cold water each cycle it is costing you money you do not have to spend. Remember the old coal fired boiler never stopped making steam it was on constantly. As for the main vents now you are not firing with coal put them in. As for the,rad that will not heat and makes noise get a level and pitch the rad and the piping back towards the up comer you will then drain the rad of the offending water. You cannot bring a single pipe steam system to 0 psig and expect it to work correctly. The dead men sized and installed everything for the .5 to 2 psig rule. Who ever did the piping off your boiler should do one more job and then get a job selling shoes what a mess, I would love to see his journeyman’s license. In the interest of saving you money, put more insulation everywhere you can it will make your system run better —— I could state all the,reasons but better to get a copy of The Lost Art of Steam Heating read it at least five times you will know a great deal more and it is a really fun read. All the best Jack Canada

Jamie Hall

half to three quarter psi is fine. Nothing wrong with that. But as @Jackmartin said, do insulate everything that you can. It will help a lot. As to cycling on pressure... let's just say that that's a rather controversial topic. If your boiler usually runs most or all the way through a normal thermostat cycle without the pressuretrol cutting it off, though, you're fine. If it cycles off on pressure early in the cycle, that usually indicates you need more main venting. If it cycles off midway more or less through a thermostat cycle, it's probably that the boiler is bigger than it needs to be.

As I say, the topic of cycling a steam boiler -- whether by pressure, timer, thermostat or whatever -- is very complex, and a number of people have written here on the Wall about it. There really is no consensus of opinion, although there are a number of different theories and sometimes rather strong opinions as to the effect on efficiency of cycling (and on minimum pressures -- some of us run well into the negative pressure ranges with specialized equipment and report good success). The problem really is a lack of data, since there are too many variables to make good controlled comparisons to be able to say "this is the best way".

Fred

For those radiators that don't heat or where you hear hammer near the radiator, try raising the entire radiator up a half inch or so then re-pitch the radiator so that it also drains back towards the supply pipe. Often, over the years the horizontal pipe, under the floor will loose its pitch due to settling. Raising the entire radiator up will give that horizontal pipe some pitch again and allow the water to drain out of it. Anywhere along the mains, where you hear some hammer, examine that main in the area of the noise and see if the main has lost its pitch or if it is sagging in that area and holding water. Re-pitch the main or add some supports to the main to lift the sag out of it.

EBEBRATT-Ed

@SteaminTed , I would get someone knowledgeable with steam (if you can find someone in your area) and re pipe the boiler next summer. Adding vents and insulation will help.

PS did anyone notice in picture #5 the return line hung from the supply with the old split ring hangers? The old ones used 1/4" pipe or nipples instead of threaded rod. It's been years since I have seen one of those.

Also the installer didn't have much of a clue abut steam but he use d dieelectric nipples

SteaminTed

Thanks to everyone for the advice.

Not much I think I need to do this instant. I'll wrestle with the hammering radiator and try to get some pitch back into the run-out of the offending third-floor radiator, and then pitch the rad itself.

But when the heating season is over, I will definitely look for a Steam Man willing to come up to the Hudson Valley. It's not too far from Long Island and Queens, which seem to be a hive of Steam-Types.

Looking forward to it. Plus I'm a total steam junkie now, and my wife may not survive another one-hour discourse on "What I've learned today in You Got Steam Heat..."

Thanks again,
Ted