Need help with understanding two pipe steam dry return vent piping

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I am hoping someone can help me understand the 100 year old main vent piping next to the boiler. The system is two pipe steam where each radiator has its own thermostatic trap. The main steam lines return directly into the wet returns (no vents). There is a single main vent next to the boiler (B&J #397), and is piped into what I assume is a condensation tank of some kind? I have tried to reproduce in the attached diagram.

Any help is much appreciated. One of the guys who helped install the new boiler thought that all this piping could be removed. After reading much of this site, and some books, I know that can't be true.

JUGHNE

Are there any visible old brand names or labels?
Look on the rad inlet valves, rad trap covers and the "tank" in the basement.

Pictures of all this would really help.

New England SteamWorks

Agree w/ @JUGHNE , look for names, and send us pics.

Jamie Hall

Got to have pictures. Also, are there any traps to be found at the ends of the steam mains which connect over to the corresponding dry returns? There should be, or there should be evidence that they were there once.

In any event, you do have to keep the vent in question.

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Thanks everyone, some pics are attached.

There are no vents (and never were) on the ends of the steam mains, the mains go directly into the wet returns.

Almost all of the individual radiator traps are Barnes & Jones T120s.

The main vent trap (pictured) says Barnes & Jones No. 397.

The condensate tank (pictured) doesn't have any obvious names on it.

Jamie Hall

I didn't think there would be vents on the mains. I did think there would be crossover traps.

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there are crossover traps, I have found about 6. I can not see make or type.

Jamie Hall

Good. With crossover traps, you neither need nor want any vents on the mains. The whole idea is to do all the venting in a central location, since the dry returns have to be vented anyway.

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It's beginning to make sense to me. And I think that the condensate tank next to the boiler is actually an alternating receiver set up. I don't think that it's operational though.

nicholas bonham-carter

The Barnes and Jones steam trap will let the air out of the whole system, through the returns, but prevent water from coming out
The second picture is probably a reservoir tank to supply additional water to the boiler during periods of long steaming at higher pressure.
If it would be used with a new boiler, its height would have to be changed so that its horizontal midpoint would be at new boiler waterline height. If you keep the pressure down to a few ounces, then it will not be needed.—NBC

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I am running at as low as I can with the Pressuretrol. When the heating season ends, I'll add a Vaporstat so I am reliably at 0.5-1.5 psi.

I will leave the tank and piping in place, although I think it's all redundant at that low pressure.

I possibly should also replace the B&J vent when the season ends, it's got to be very old. I can't find a references to the 397 model, even on the Barnes & Jones website.

I haven't verified that the vent is working properly, but the radiators heat, so I am assuming it must be OK.

Jamie Hall

If it ain't broke...

If you do add a vapourstat -- which I recommend highly -- you may find that this was a vapour system. You should try running it at first at a cutin of about 4 ounces, and a cutout of around 12. You might be pleasantly surprised!

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I will try that low pressure setting. It was originally a coal fed boiler system, so hence the alternating receiver to manage pressure surges I think.

I noticed a significant improvement when I took the boiler install 5 psi down to the roughly 1.5 psi it is at now. I've also been changing out the radiator traps which are very old and in a few cases missing altogether. That has helped too.

I am still struggling with the radiator angle valves cos the new ones are about 1/4" shorter than the old throttle valves that are mostly broken, which makes replacement a pain.

Jamie Hall

Pity about the old valves. Even more I think it was vapour, and those old valves were almost certainly set to match the size of the radiator, thus placing very little -- if any -- strain on the traps. You may find -- almost certainly will find -- that running on very low pressure will speed heating up. You may also find that partially closing the new valves on the smaller radiators will even the speed to full heat across all the various radiators in the system.

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I wish there was a way to refurbish the old valves, but I have been unable to find any resources on that. They are works of art.

New England SteamWorks

zoom said:

I wish there was a way to refurbish the old valves, but I have been unable to find any resources on that. They are works of art.

If they are indeed works of art, it is very unkind of you to discuss them without sharing photos!

Jamie Hall

Are there any markings on those valves? And what, exactly, is wrong with them? Sometimes those valves can be taken apart (remarkably thoroughly! Keep track of the parts -- pictures are helpful) and cleaned up.

Jamie Hall

Are there any markings on those valves? And what, exactly, is wrong with them? Sometimes those valves can be taken apart (remarkably thoroughly! Keep track of the parts -- pictures are helpful) and cleaned up.

JUGHNE

How high is the center of the condensation tank above the existing water line, and could it have been the height of the old boiler water line. It looks too high to have been a receiver/accumulator tank even for the old boiler.

I believe it has some purpose for the venting system, but I do know that I don't know.

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The original boiler is gone, but the tank is approximately 40" above where the water line was. The tank is above the vent and was clearly purposefully placed several inches above the water line and indeed the boiler as a whole.

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Here's a couple of pics of the valves. A few of the valves are stuck closed. Almost all are non operational as a throttle. a couple spit water/steam.

Jamie Hall

The silvery valve is a Hoffman -- not sure about the other one. Both are eminently repairable. Both are designed with an internal throttle, which is adjustable and set to match the radiator to which it is attached when it is installed.

Don't scrap them! Spend the time and take them apart, if necessary, clean them up, replace the packing if needed (probably not) and reinstall them. They are far superior to anything you can buy today.

Let's see if I can attach the blurb on the Hoffman...

Sailah

> @zoom said:
> I am running at as low as I can with the Pressuretrol. When the heating season ends, I'll add a Vaporstat so I am reliably at 0.5-1.5 psi.
>
> I will leave the tank and piping in place, although I think it's all redundant at that low pressure.
>
> I possibly should also replace the B&J vent when the season ends, it's got to be very old. I can't find a references to the 397 model, even on the Barnes & Jones website.
>
> I haven't verified that the vent is working properly, but the radiators heat, so I am assuming it must be OK.

The 397 is the old Barnes & Jones condensator. They don't make parts for them anymore. You can replace with a modified F&T but only if it's not working.

T120 traps are easily repaired with cage units should they need it.

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The challenge with existing valves also is that they can't be removed from the steam feed pipe without cutting with a hacksaw to free up the thread.

But perhaps I can open them up without detaching them. If i can get at the insides maybe I can restore them.

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I think i will pull out the B&J 397 and replace with a new vent. I will cap off the piping to the old condensation tank.