Trane vapor system with combination one pipe heating risers and two pipe radiators

spiro

I am trying to understand my steam heating system and fine tune it. I believe it is called a Trane vapor system? I have an old oil fired steam boiler that has a combination of one pipe risers (but no one pipe radiators) and two pipe radiators. I recently changed all the steam traps, air vents and main vents and installed a vapor stat. I am running the boiler with a cut out pressure of 1.7 psi and a cut in of 1.0 psi. There is an old Trane No. 2 direct return trap along with two old check valves and I'm not sure if they are working properly.

1) I would like to be able to run the system with as low a pressure as possible but I can't seem to get it working properly at lower pressures because the system needs to be at least 0.8 psi to get steam to the furthest apartment on the top floor of this 6 story building. At what pressure range should I aim to be at if all the issues are worked out for this type of system and how do I get there?

2) Also, I noticed that it takes approx. 14 minutes to get steam to the furthest two pipe radiator (living room) but it takes 22 minutes to get steam to the same studio apartment in the one pipe risers (bathroom & Kitchen). Does that make sense?

3) I noticed that all the one pipe risers and the two pipe risers are connected to the same steam main in the cellar and only the two pipe return pipe riser is connected to the condensate return pipe main in the cellar. There are two branches of the steam main and both drop into the wet return at the ends right after the main vents. There are two condensate return pipes from the two pipe radiators and they are dry returns that come together at a T and drop to the wet return at the boiler. There is another main vent at the top of this T. Is this the correct way and best way to pipe a combination one pipe and two pipe system?

4) Is this system called a Trane vapor system and if so how can I get literature on it? There were a link that I found but the link were no longer available: heatinghelpcom/files/articles/1392/26.pdf

5) How can I check to see if the Trane No. 2 direct return trap is working properly? The site glass is always dry.

nicholas bonham-carter

Do I understand that you have some 2-pipe radiators, and some 1-pipe radiators?
Maybe a layout drawing of the piping would help us understand what you are dealing with. There should be some literature in the archives onsite explaining the Trane system.
The times you quoted for steam arrival seem long, so some sort of venting problem is indicated. See if there are any crossover traps which have failed. These will probably be close to the Trane return trap.
You should be able to heat the building on less than a half psi.--NBC

NewwaySteam

I am curious, can you show pictures of your system?

vaporvac

Where to begin? I'm not sure where you looked, but the Heating Museum section on this site has quite a few references to the Trane system which I've linked to below. There is one that shows the return traps. I have an Air Eliminator and can just hear the air being expelled.
Do you have a vacuum system? Could you post some pics of a typical rad of both type, as well as their valves? Pics of the boiler, its specs and near boiler piping from a distance would also help.
what was wrong with your traps that you replaced them...and with what did you replace them?

Your pressure is WAY too high. These systems need ounces of pressure. What pressure does your system actually reach? Does the Tstat shut down the boiler or the Vstat?
How did you determine your main venting? Judging from your times you need more. Please give us the length and size of your mains and we can help figure out if you need more.
Do you know your rad's EDR and how that compares to your boiler's sq ft of steam rating?

Your site glass must be clogged. Someone may be able to guide you in cleaning it. Either that, or you boiler is over-filled which can make the sight glass appear empty. I can't help with the one-pipe issue, but this is a start.

https://heatinghelp.com/heating-museum/trane-vacuum-system-a-perfected-heating-system/

https://heatinghelp.com/heating-museum/trane-heating-specialties-for-vapor-and-vacuum-systems/

https://heatinghelp.com/heating-museum/trane-products/

https://heatinghelp.com/heating-museum/atmospheric-pressure-or-so-called-vapor-systems/

https://heatinghelp.com/heating-museum/data-for-heating-engineers-and-architects-for-the-design-of-vapor-heating-systems/

spiro

First off...thank you all for replying to me so quickly. I took some photos to help explain things better.

spiro

In Continuation. Those 3 main vents in the photos are Hoffman No. 75. Additional photos showing Trane No. 2 direct return trap and vaporstat are attached. Also photos showing the venting of the one pipe risers in the bathroom and kitchen and the two pipe steam riser at the radiator in the living room at one of 4 apartments on the 6th floor (top floor) of the building. This venting is the same for all 4 apartments on the 6th floor. The one pipe vents are vari-valve from Heat Timer and the 2 pipe steam riser vents are maid-o-mist "C". The boiler is shutdown properly by either the vaporstat when the pressure is reached or the heat timer depending on outside temperature and the heat sensor setting.

1) In reading the historical literature that was sent to me by vaporvac (thank you!), I wonder if I should change the main vents to vents that have vacuum checks in them? If so which vents do you recommend?

2) Also, I still can't find any literature on combination 1 pipe and 2 pipe Trane Vapor Systems. Can this hybrid run at very low pressures and what vents should I be using at the top of the 1 pipe riser in the kitchen and the bathroom?

3) Should I get rid of the venting at the top of the 2 pipe steam risers? I added those vents to speed things up but I may have made things worse by introducing air during condensation when I really should be maintaining a vacuum?

4) I don't see any cross over vents. Don't even know what they are or what they are suppose to do?

5) Good news is I fixed the site glass and the valves and the direct return trap seems to be working properly.

vaporvac

Does your system go into a vacuum when off? Has all the air expired prior? Have you checked to see how long it takes from a cold start (or warm) to get heat to the end of the mains? Can you do that and get back to us?

Fred

@vaporvac , no the Hoffman 75's are not vacuum vents. They open to the atmosphere shortly after the boiler shuts down. I use them on my 1 pipe system. It takes 2 of them to equal a Gorton #2. Hoffman did make a vacuum vent, I think it was a #76, can't remember for sure but definitely not the 75.

vaporvac

It must be the # 76. i just noticed that recommendation in another post. I only have the one huge vent, so I don't pay it any mind. I'll erase that post so as not to confuse the issue!

KC_Jones

I am thinking we need a point of clarification from the OP. I am guessing this is a 2 pipe system, but the OP keeps mentioning 1 pipe. To the OP are you saying you have radiators that only have 1 pipe connected to them? What makes it a 1 pipe or 2 pipe system is how many pipes are connected to the radiators, has nothing to do with vents or anything else. Just want to make sure we are all using correct terminology, because I haven't seen anything in the pictures to indicate 1 pipe anything yet.

spiro

There are no one pipe radiators...only 2 pipe radiators with kitchen and bath one pipe risers (shown in photos). I'm not sure what the correct term is for these pipes in the kitchen and bath (maybe a standpipe??)...my boiler guy said they are what makes the system a hybrid because they behave like one pipe radiators.

vaporvac

Are there NO radiators in the kitchen and bath, just these pipes? I can't really make out the piping in the rad you owed.... what happens after the trap? I do have one rad that enter at the to and exits and the bottom of the same side, but with two separate pipes and of course, no vents.

SteamedInWharton

I'm not a true steam head but I think I see the problem:

• one pipe radiators vent air through a vent which closes when it heats up
  
• two pipe radiators vent air through the second pipe which has a thermostatic trap that closes when it heats up to keep steam out of the dry returns (except on certain vapor systems where there are no traps since the radiators quickly condense the available steam)
  

Are there any vents on the "standpipe" radiators themselves, not on the risers (which I see in the picture) but the actual radiators?

If I'm reading your posts and interpreting your pictures correctly, both pipes on the radiators are connected to the same riser. Is the last picture in your next-to-last post one of the kitchen or bath radiators?

What I think is happening is steam rises (it's lighter than air) and it will first try to come up the lower pipe (until the thermostatic trap closes) possibly venting out the top pipe and via the riser vents. A little bit of steam might get through before the trap mechanism heats up and closes. However those riser vents are going to close pretty quickly once the steam gets there leaving no place for the radiator to go.

My alternative theory is the steam quickly rises, shuts the riser vents and tries to fill the radiators via the top pipe and push the air out the bottom pipe, except the thermostatic trap is about to close since you have a riser full of steam.

I wouldn't be surprised is a little of both is happening.

Hence the only way to force steam into the radiators is to run at a very high pressure using the pressure to force steam into the radiator against the opposing air pressure.

Fred

I think that trap is failed closed and someone decided to put vents on the pipe to allow the air to escape from the radiator. I'm betting if you fix the trap(s) you won't need the vents and could return this system to a vacuum system.

spiro

The steam traps are all new and working properly.

So I'm thinking I should change the three main cents to a vent with a vacuum check such as the Hoffman #76. Remove the vents at the top of the steam risers before the two pipe radiators.

The only question that remains is what type of venting do I need at the top of the one pipe standpipes in the kitchen and baths?

KC_Jones

spiro said:

The only question that remains is what type of venting do I need at the top of the one pipe standpipes in the kitchen and baths?

Are you sure you need the vents? Where do those pipes go? Are you 100% positive that isn't an express main going to feed the radiators on the upper floors? If they are feeding any radiators they shouldn't have vents. Changing to a vacuum vent, but leaving those vents on the riser pipes is an exercise in futility. Those vents make it impossible to have vacuum. If this indeed was originally a vacuum system those would have been vacuum vents also...if they are even supposed to be there.

vaporvac

Let's see if perhaps one of the vacuum pros pipes up before you go changing things. This systems seems to have had enough odd things done to it. @KCJones, I'm pretty sure this was a vacuum system originally judging by the apparatus in the basement ie. direct return trap, but these system only need ONE central venting place. I'm still waiting for the answers to my questions on the two prior posts to determine what venting he really needs on the mains as well as figure out what's going on with the rads, etc. Otherwise, it's just ad-hoc changes that further complicate thinsgs. why did you replacr the trapcs initially, how did you determine they had failed, what did you replace them with? They can fail out of the box, btw.

jumper

My friend designed and installed vacuum steam heating in multi-residential in Toronto in the fifties. He tried variations to determine what was most inexpensive for him.They were overhead distribution with two connections to terminals without vents. (Except one building where there was one connection but still no radiator vents) Sometimes condensate returned through separate piping and sometimes through supply (down riser?) My point is that it's possible to connect two pipe radiator to single pipe. Steam goes where it can and condensate goes down. So long that you get air out.

spiro

I've attached a sketch hoping to explain things a bit better. The steam traps that I installed are all MEPCO 1E traps. The reason I changed them is because the old ones where ancient and they had no label on them so I couldn't figure out what they were so servicing them would have been impossible. There are no radiators in the kitchen and baths...just those 2" diameter "standpipes" that I believe behave like one pipe radiators (without the radiators). These standpipes are connected to the steam main as shown on the sketch. P.S. I removed the maid-o-mist vents that were at the top of the steam risers today (removed from the attached sketch) and installed one Hoffman 76 (shown on the sketch) at the end of the dry returns. Both of these changes made no difference.

nicholas bonham-carter

I don't see how the boiler supply piping is connected to the rest of the supply mains. Your drawing appears to show it as gong into the Trane vent. Go over your system again, and see exactly how the steam (and air) travels up to the radiators.
This looks the same as a Dunham system:
As steam rises, the air is pushed out through the supply mains, radiators, traps, returns, crossover traps, main vent (Trane), and out to the atmosphere. The radiator traps will close when steam has arrived in the radiators. All the air will escape through the main Trane vent, and if it does not escape, the steam cannot get into the radiators. Usually, there are secondary traps between the returns and the main vent (crossover traps), and if these have failed, the air is still unable to escape, even with new radiator traps.
I would make the system work as a non-vacuum first, and then vacuumize it, by replacing any more vents in the system with Hoffman 76's. The bathroom and kitchen risers will need vents at the top of each.--NBC

spiro

So I spent the better part of the day today figuring out all the pipe sizes and connection points and then sketching the system as detailed and accurate as possible. Check out the attached sketch...I'm actually proud of the results. Lol. I hope this helps answer everyone's questions and hopefully you can help me with my questions:

Any ideas why it takes so long to get the furthest radiators hot and why I need so much pressure to do so? What's wrong with it and what do I have to do to get it running as it was originally intended to run almost 100 years ago?

Thanks for all your help!!!

KC_Jones

It's not that the boiler pressure is needed to push the air out, it's that the air can't get out fast enough causing the pressure. The pressure control on the boiler is a safety or limit, the system pressure is really set by boiler size and venting. You need more venting for sure, probably a ton more venting on a system that large. If I am interpreting your drawing correctly all the air is trying to escape through 3 Hoffman #76 & #75 vents? That wouldn't be enough venting on my 1500 sq ft house let alone an apartment building like you have. I would suggest you need to figure out how much venting you need and add it accordingly. To determine that you need to determine how much air needs to be expelled and on 2 pipe systems that is a lot of air. Also I am pretty sure those vents at the ends of the mains shouldn't be there. Generally on 2 pipe all the venting is at the end of the dry returns, but perhaps someone with more knowledge can comment on that.

nicholas bonham-carter

The Hoffman 75 above the dirt pocket looks like it will never be a route for air to take to escape, as it is water sealed.
Presumably, air should be exiting the Trane vent, but is not, due to some obstruction. The next step should be getting that to flow freely. There may be some sort of check valve or disc in the top which is stuck.--NBC

steamfitter

Some food for thought:
1. Much venting is needed for a large system. Main vents sometimes need a manifold with multiple vents. Risers have to vented at top, but before the radiator valve on the top floor. But that's generally for a 2 pipe gravity system and may not care for your hybrid.
2. In a vacuum system, all vents must be vacuum vents! Regular vents will not allow a vacuum to form.
3. I didn't see crossover traps near the boiler on your drawing. They act as main vents in a vacuum system.
4. Wet returns are usually clogged and prevent condensate from properly returning to the boiler. That can be a major problem because condensate can back up far enough to void the main vents. Sludge clogged condensate lines (wet returns) are a usual suspect.
5. In Holohan's "Greening Steam" book, there is a nifty way of using aquastat controls in the near boiler piping to simulate what the "dead men" did years ago with vapor/vacuum systems. I'm not sure if it would work in such a large system, but you may want to ask the other pros here about it.
Good Luck!

Steamhead

On the usual Trane Vapor system as installed during the mid to late 1920s, there was a vent at the end of each steam main and a single vent on the dry return at the boiler. The latter vented the air coming back from the radiators. Trane generally did not use crossover traps the way other vendors like Dunham and Hoffman did.

The riser pipes in the kitchens and bathrooms served as radiators for those areas. Setting them up as one-pipe makes sense- where would you put the return connection?

To size the steam main vents, measure the length and diameter of each steam main and post the results here. I'm almost certain the Hoffmans are too small, but let's see the measurements and we'll know for sure.

nicholas bonham-carter

Do the "open pipe test": let the system cool down, turn off the boiler with the switch, and remove the Hoffman 75 closest to the Trane vent.
Turn on the boiler, and as it makes steam initially, check for air escaping from the vent tapping. When steam appears at the tapping, be ready to switch the boiler off.
This may result in everything heating up more quickly, and if it does, then the solution is a manifold of Gorton#2 main vents at that location.
Later on, you could experiment with conversion to vacuum operation by using a horizontal check valve under all the main vents, including the ones at the top of the risers. Converting to vacuum may speed up the steam arrival times quite a bit, but you may need to repack some valves to keep the air out!--NBC

spiro

There are two steam mains. Both are 2-1/2" diameter. The one supplying the A and B lines is approx 30 ft long and the other one supplying the C and D lines is approx 90 ft long up to the main vents. The 4" steam pipe from the boiler to the T where those 2-1/2" steam mains start is approx 9 ft long.

Are there vacuum vents that vent more than the Hoffman No 76?

spiro

So I tried the "open pipe test" by removing the Hoffman #76 There was air escaping from the vent tapping but there was never any steam coming out of the vent tapping. I believe that's a good sign since the vent tapping is connected to the dry return and the steam traps should prevent steam from entering the dry return? The steam pressure and the time required to get the steam to the furthest radiators did not change by removing the Hoffman #76 from the dry return. I still believe I should change the two Hoffman #75 main vents to Hoffman #76 vents since they have vacuum checks? The only thing I am still unsure about is how the one pipe kitchen and bath risers with the air vents at the top that are connected to the steam mains might prevent this system from creating a vacuum. Does anybody know?

Fred

The only thing I am still unsure about is how the one pipe kitchen and bath risers with the air vents at the top that are connected to the steam mains might prevent this system from creating a vacuum. Does anybody know?

You won't be able to hold vacuum in that system after the boiler shuts down, with those pipes being vented unless you can find some vacuum vents. What are those pipes connected to above? Anything? Do they return anywhere?

KC_Jones

If there was no difference in time I would have to guess you have other issues somewhere in the piping. There should have been a DRAMATIC difference in the time to get steam to the rads. Have you posted your location yet? We might be able to recommend a good steam expert in your area to put some eyes on what you have. Sometimes there is only so much that can be done over the net. To hold a vacuum in the system everything has to be closed up when the boiler shuts down. The vents on those vertical pipes don't have vacuum checks so it won't hold vacuum. I think you need to relax about the vacuum, I don't see vacuum fixing any of the problems you are seeing. You can't even run at the pressure required for a vapor/vacuum system yet. You need to be running in ounces not pounds to even think about attempting vacuum.

spiro

Those pipes are not connected to anything above the air vents. They are capped above the 6th floor ceiling. I can't seem to find any vents on the market with vacuum checks other than the Hoffman #76 for these pipes. Problem is I would need 9 of them and the Hoffman #76 are very expensive.

This building is located in Brooklyn NY. If you can recommend someone locally who can help me with this that would be appreciated.

Thanks.

nicholas bonham-carter

A check valve mounted horizontally in front of a regular vent could hold a vacuum.
I would not worry about sub-atmospheric operation until you have the system running well in conventional mode.--NBC

spiro

I think I know what's causing my problem. In reading some more of Dan's book "the Lost Art of Steam Heating" I learned that the horizontal run-out needs to be sized accordingly and to have a certain pitch. In my case, the risers are not dripped. I'm estimating the EDR of the 60 ft. tall 2" risers (since there are no radiators attached to it) to be approximately 50 (please let me know if that is about right). These risers have a 3/4" horizontal run of just under 8ft long with less than 1/2" per foot of pitch. According to the book a 1" horizontal run (3/4" pipe data is not listed) is sized for a maximum EDR of 28. Could this be why my one pipe risers take 10 minutes longer to heat up than the two pipe radiators? If so, what's a practical way to fix this? Could I insulate the riser at every floor (say 6ft of every 10ft) to reduce the EDR of the riser?

SteamedInWharton

Now that I have a better idea of the system, I'd think your best bet would be to install some extreme venting (like 3 gorton #2's) at the top of each of those risers in the attic or in the top floor apartment.

A back of the envelope calculation suggests that 8 ft of riser in an apartment is about 5 EDR, which is about half the EDR my bathrooms have. Are the risers making a difference?

I wonder if the risers were added to the system later? I'd think having vented one-pipe risers on what had been a two-pipe vacuum system would prevent forming and maintaining vacuum.

Fred

In reality, trying to fill a 60 ft. , 2" pipe radiator AND return condensate through a 3/4" supply just isn't going to work. You probably have 50 to 55 EDR on that 2" pipe and it should have an 1-1/4 supply pipe. Are the feeds off of the mains to those 2" pipe rads bushed down? If so, can you remove the bushings and replace that 3/4" pipe with an 1 1/4" pipe? After that, you probably can put vacuum vents or a check valve before the conventional vent(as has been suggested) on those pipe rads to maintain a vacuum in the system. Low pressure (in the ounces) is key.

nicholas bonham-carter

Can you remove the vent on one of the risers, and as steam is rising, listen for any breathing sounds which would indicate standing water in the horizontal, interfering with the air removal?
Otherwise, i think you will be ok with a gorton #2 at the riser top.
As i said before, a check valve between the vent, and the tapping will enable vacuum operation, when that time comes.--NBC

spiro

There is definately a gurgling sound coming from the base of the 2" riser where it connects to the horizontal run. I can hear it through the pipe in the cellar and I also heard more of a sputtering sound through the air vent at the top of the riser when I had installed a gorton #2 at the top of the riser. PS the gorton #2 had no affect on getting the steam up faster. There is no bushing at the connection to the steam main. It seems like the pipes where always like this since the system was first installed in the 1920s. Changing these pipes from 3/4" to 1-1/4" will be extremely costly. Do you think insulating the riser as mentioned earlier would fix this problem. Has anyone ever insulated risers for this purpose or any other?

Fred

That gurgling is water that cant return to the boiler until the boiler shuts down. Probably because that 3/4" pipe simply can't handle both the steam and the condensate at the same time or the pressure is too high to allow the water to return, until the boiler shuts down. That 2" riser is intended to heat that space right? Insulating it will virtually eliminate its ability to radiate and heat. Do you have any way of adding a drip leg at the botton of that 2" riser and tying that into the wet return? I'm assumming that pipe is intended to heat a space on each of three floors, right?
It's not going to be free to fix this situation if two or three floors need that riser to heat a poarticular area. If only one floor needed heat, in that area, I'd suggest taking that 2" riser out and installing a 25 EDR radiator but I suspect that's not the case.

nicholas bonham-carter

Can you jack up the riser, in case the horizontal is pitched wrong?
might be worth a try at least, before trying to drip it.--NBC

Fred

nicholas bonham-carter said:

Can you jack up the riser, in case the horizontal is pitched wrong?
might be worth a try at least, before trying to drip it.--NBC

He says he's got 1/2" per foot slope on the horizontal. That's 4" over the 8 ft. horizontal. That can't be the problem.

Steamhead

I agree. Drip those risers and they will work much better.