Primarily for use in vapor heating systems......

heatseeker1

I have two questions.
Question #1: Can someone explain the difference between steam heating and vapor heating systems? Are they one in the same?
Question #2: Dan's book "We Got Steam Heat" states that a crossover trap is necessary in a two-pipe system because it keeps the steam that's in the main from crossing over into the horizontal return pipes that are above the boiler's waterline. I have two-pipe steam, but I don't have a F&T trap anywhere along the dry return. How can that be? Don't I need one? Please help me understand. Thanks.

Jamie Hall

Vapour systems are a subset of steam heating systems, the major difference being that they are designed from the beginning to operate at very low pressure. They often have a variety of rather interesting means to control steam flow to the radiators, such as orifices or variable throttling valves, and to keep steam out of the dry returns -- although many depended on perfectly ordinary traps for the radiators.

Many, but not all, vapour systems use crossover traps rather than vents on the mains -- despite the enthusiasm in some quarters for main venting! In the early days, massive main venting wasn't needed, of course -- a coal fire builds very slowly, and remarkably little venting was actually needed. Since the dry returns must be vented anyway, it made sense to use a crossover trap (which is just an ordinary trap -- not an F&T trap -- piped between the steam main and the dry return). Many vapour systems also used any one of several approaches to keep the steam pressure from becoming excessive in the event the fire got carried away. Most of these depend on having all the venting right at the boiler, where the dry returns drop and become wet returns. If you have such an animal, the rule still applies: all of your venting must be at the boiler, as designed, with crossover traps provided to vent the steam mains into the dry returns.

JUGHNE

Do you have dry returns hanging from the ceiling or wet returns laying on or under the floor? Or a mix of both?

heatseeker1

I have both. I have a dry return line which brings the condensate back from the radiators and it runs high along the basement wall but then goes into a horizontal drop-down which connects into the wet return along the basement floor. That external wet return line runs back to the Hartford loop.

From Jamie's description of what constitutes a vapour system, I definitely don't have that. Mine is straight forward; 2-pipe steam. I have a main steam vent on the end of the main and I have a #2 Gorton on the dry return near enough to the horizontal junction which connects the supply and the return. Both of these lines drop to the floor and meet at the bottom which leads into the wet return. Do I need a F&T trap where that Gorton now exist?

JUGHNE

Your radiators drain condensate and pass air thru the rad traps, that goes into a dry return which must have air vents to vent the rads.
Your steam main should slope down away from the boiler, draining any condensate formed as the steam cools on its way. This condensate must drain back thru the wet return thru it's drip connection. It must also be vented at its end before that drop down into the wet return to get the steam there quickly, otherwise all air must pass thru rad traps....slow heating.

Now if both the dry returns and steam main drop down into the wet return, then there is no steam connection between. The water seal of the wet return is backed up into the vertical drop pipes prevents air or steam from passing thru. The depth of the seal must be deep enough that steam pressure cannot push the water out. (Think of your sink drains, they have a water trap that keeps sewer gas out of your house).

So both dry returns and steam mains must have air vents before they drop down into the water seal of the wet return. And they each must have their individual drop to be isolated from each other.

As long as your "horizontal junction" of the 2 pipes is under water then they are isolated.

heatseeker1

Jughne,
The horizontal connection is at the bottom (see pics) so I guess I'm ok. Is that what you mean when you say "as long as the horizontal junction is under water," as in under water-line of boiler? Thanks for being patient with me.
The pipe closer to the forefront of the "topview" pic is the supply and the pipe recessed to the rear of it is the dry return. The "bottomview" pic shows the horizontal connection at the floor.

Steamhead

Looks good. And yes, that is a "vapor" system. Have you found any names on any of the original radiator valves, traps or any devices in the piping near the boiler?

Based on what I've seen and read so far, I'll go out on a limb and guess it's a Trane.

JUGHNE

So where are your vents for those pipes? Picture would be good.

Also is your basement floor one level......that wet return copper pipe stays at that elevation up to the boiler? No drastic up and down like steps or such?

heatseeker1

The vents for those pipes are way up top in the shadows of the "TOPVIEW" picture. One Gorton #2 is on the main sitting inside the 90 degree elbow, (which I saw on Youtube is the worse place it could be), and the Gorton #2 vent for the dry return is also tucked up in that maze of pipework in the shadows of that pic entitled "TOPVIEW." My garage is so dark, I'd need a flood-light to get a good picture to show you. But I could try.

After dropping down the garage wall in the vertical, the next 9 feet of my wet return runs parallel along the bottom of the garage wall and then hangs 2 quick 90 degree turns into the inside of the basement (still at floor level) where the next 9 feet runs back to the boiler in a "pitched downward" fashion until it reaches the Hartford.

The issue I am having with my wet return is that at the end of the heating cycle, it is hammering and vibrating like it's going to pop! Why is that?

Jamie Hall

heatseeker1 said:

The issue I am having with my wet return is that at the end of the heating cycle, it is hammering and vibrating like it's going to pop! Why is that?

Almost sounds as though steam is getting into it. What is the elevation of the Hartford loop relative to the boiler water level near the end of the cycle?

And what pressure are you running? If this really is a Trane vapour -- and @Steamhead is usually right! -- you should not be over about 12 ounces. But, if you don't have a vapourstat, you can't get down that far. So...

heatseeker1

It's running at around 1lb of pressure. My Hartford, I'm told was piped at less than optimal height. The vertical run of the Hartford bends into the boiler at or above the water line. Can you see that from the pics? Is that the less than optimal portion or is something at the floor too high off the floor?

BobC

The Hartford should be tied in 2" below the water line. If you raise the water level in the boiler 1-1/2 to 2" does the problem go away?

Bob

vaporvac

That seems unnecessarily high. It should be 2" BELOW the water line; your appears to be exactly AT the water line. It doesn't look like a difficult fix, however.

heatseeker1

What determines whether a system is vapor or not? Is it determined by the manufacturer, make and model of the boiler or is it the way a contractor mixes and matches the components of the system? For example can you change a standard steam boiler to a vapor system merely by changing out the pressuretrol (with the differential wheel (1 to 5) and the scale from .05 to .9, in exchange for a vaporstat? I don't have a Trane.

vaporvac

How do you know it's not a Trane? Can we see pics of the boiler from further back and maybe a rad with an original valve/handle?
Vapor just refers to very low pressure steam ie vapor. I've only ever heard it used in regards to two-pipe as they run very well at low pressures and it seems almost all two-pipe systems were vapor. Many manufacturers did "vapour", Some, such as Trane, also combined the vapor with vacuum. A vaporstat is a must-have for some of these systems. Do you have rad traps? Could we see a pic?

heatseeker1

So, if I raise the water level about 1.5 inches above the waterline, that won't stress the system? I'll try it and see what happens at the end of the cycle.

What would fixing the Hartford entail?

BobC

I would not leave the water level that high permanently, this is just a test to see if the water level changes things.

bob

vaporvac

Is there a union upstream of your hartford loop?

heatseeker1

These are pics of my rads and a very old picture of my Dunkirk boiler before the near-piping was re-installed.

Jamie Hall

If the Hartford loop is at the static water line, it will be above it when the boiler is steaming. If that happens steam will get into the wet return -- particularly at the end of the cycle when the pressure in the boiler rises, which backs water out of the boiler or, in your case with a too high Hartford, keeps condensate from returning (which has the same effect of lowering the water level in the boiler).

That steam will usually cause some hammering in the wet return. Try @BobC 's suggestion and see if it helps -- but that isn't a permanent fix. @vaporvac is right -- the Hartford should be 2 inches below the water line, and above the lowest LWCO level on your boiler.

Fred

If you were to leave the water level high enough to cover that Hartford loop., it likely wouldn't leave enough room in the boiler, above the boiler block to produce enough steam. Water would boil up near the risers. Have the Hartford loop dropped and your water hammer in the return will go away. Dropping the Hartford loop would entail some minor pipe changes in the area above and below the Hartford loop to move it down so that it is a couple inches below the water line. A few nipples and couplings/nipples. Not a huge job.

heatseeker1

Actually I misspoke. That is an angle of my boiler after it was re-piped.

heatseeker1

Quite insightful information about the height of the Hartford and its effect on steam entering into the wet return. I bet that's exactly what's happening!

heatseeker1

Fred, thanks for the description regarding the Hartford loop reconstruction project. Now the tough part is finding someone to do the job right. Any takers?

vaporvac

Anyone recognize those recessed rads or the traps? Btw, those are some awesome tile floors!

heatseeker1

Vaporvac, can you see a union upstream of the Hartford in the above picture?

Steamhead

heatseeker1 said:

Actually I misspoke. That is an angle of my boiler after it was re-piped.

That's the AFTER pic?

It's still wrong. They reduced the size of the steam pipe leaving the boiler from 2-1/2" to 2", which the manual says specifically not to do. So you're still getting wet steam.

Where are you located?

heatseeker1

I am located in Philadelphia.

vaporvac

heatseeker1 said:

Vaporvac, can you see a union upstream of the Hartford in the above picture?

I totally missed that pic! That means you have very easy piping to change. If your up for it come spring( or a longish break in the weather), I'm sure the kind folks here could help you do it yourself, if you like. You'd probably just disconnect at the upper and lower unions and swap out a few fittings and away you go.

Fred

The boiler will likely need a skim after the piping is changed. Hopefully you have a skim port somewhere on the boiler?

heatseeker1

Thanks Vaporvac. From the size wrenches that were used when these fittings were installed, I would think it takes the strength of 10 men to undo them, but..........if you say it's a DIY, I'll take it into consideration in the Spring and get the Heatinghelp.coms experts to guide me through it! Thanks for the encouragement!

Jamie Hall

I stand corrected by the Master of Steam.

vaporvac

I considered using a Giffordloop on my own system, but didn't need to in the end. I think its usefulness is well-proven, but if the height of the Hartford isn't causing the banging at the end of cycle, what do you think is, @Hatterasguy ? I hope the OP's experiment will help.

BobC

Interested article about two pipe systems using orifices -

http://docs.google.com/viewer?a=v&pid=sites&srcid=ZW5lcmd5c2F2aW5nc2NpZW5jZS5jb218d3d3fGd4OjcwMTgxNmJlOTA2MjU0NjM

Bob

vaporvac

Was that man a genius or what? i'd love to read the other articles he refers to as "upcoming".

BobC

Here are some other articles from that source -

http://www.energysavingscience.com/articles/henrysarticles

Bob

JUGHNE

I used Henry's theory on a 2PSI system.

Also on a vapor system whose trap guts were all removed.
The Napier Formula chart was used. Thanks to FIZZ here on the wall. That chart goes from 1-32 OZ and from 1 EDR up to 200 EDR. Henry's chart is 2 PSI only. But the theory is still the same. Limit the steam input to 80% of rad EDR and traps are not needed.

However for a 2 pipe system whose steam main is vented solely by the traps thru the radiator inlet valve, (which in now a small orifice...1/4" or less) there may be slow air elimination for the steam main. I was fortunate enough to be able to add Gorton #2's on the mains at the boiler room drip.

If the original inlet valves were of the adjustable orifice type that problem would have existed previously. But back to the slow coal simmer burn venting was not an issue then. With rapid steam cycles today it seems this would be a problem for an all original orifice valve systems?

Comparing the price of a 3/4" orifice to steam trap elements we seen only a fraction of the cost for the orifice system. And they just about never wear out. I have removed some orifices that were 60 years old and showed wear and tear....but they ran at 5PSI for their entire life.

Jamie Hall

I hesitate to get into this again -- I may not know what I'm talking about, after all -- but @JUGHNE does have a point with the comment on venting, if all of the steam main venting is done through the orifices. However, in at least some vapour type systems -- and possibly in other higher pressure two pipe systems -- the mains are vented quite handily (in my judgement, anyway) with the use of crossover traps. They have an astonishingly high venting capacity, after all.

On the longevity of components. Perhaps I have merely been exceptionally fortunate, but of all the traps on the system I care for only one has failed in the eighty years since they were installed -- fortunately, open. It isn't a problem, though, as a Hoffman Equipped system in original or near original condition also has radiator valves which are adjusted to limit the steam to the radiator (and which were properly adjusted by the men who installed the system, I might add!). One might ask why have them at all, then -- but I expect that it has to do with the manner in which the system operates to limit the differential pressure between the steam mains and the returns.

Steamhead

heatseeker1 said:

I am located in Philadelphia.

That you, Carol?

Gordo

@heatseeker1: What is the condition of water in the boiler - is it generating "wet steam"?

One way to tell that, is there is great fluctuation in the water level in the sightglass or also there is a lot of "carry over" of water from the top of the sightglass fitting. Is there dirt floating on top of the waterline in the sightglass?

You may have to thoroughly clean your system as your type of boiler is exquisitely sensitive to contaminates. It is amazing just how little it takes to cause problems in this type of boiler.

Dirty water will trump even good piping.

Larger main vents cause the steam to circulate more quickly bringing back oils that were resting in your pipes. Also, re-pitching pipes awakens sleeping sludge and it too winds up the the boiler.

Next, try turning the pressure lower. Try for no more than 12 oz/in2. The system will likely short cycle, however.

Make sure all of your heating units are working fully to absorb the boiler's steam so pressure stays as low as possible for as long as possible during the on cycle.

The Hoffman 17a and other traps should also be rebuilt as they have likely failed partly closed.

PMJ

Jamie Hall said:

I hesitate to get into this again -- I may not know what I'm talking about, after all -- but @JUGHNE does have a point with the comment on venting, if all of the steam main venting is done through the orifices. However, in at least some vapour type systems -- and possibly in other higher pressure two pipe systems -- the mains are vented quite handily (in my judgement, anyway) with the use of crossover traps. They have an astonishingly high venting capacity, after all.

On the longevity of components. Perhaps I have merely been exceptionally fortunate, but of all the traps on the system I care for only one has failed in the eighty years since they were installed -- fortunately, open. It isn't a problem, though, as a Hoffman Equipped system in original or near original condition also has radiator valves which are adjusted to limit the steam to the radiator (and which were properly adjusted by the men who installed the system, I might add!). One might ask why have them at all, then -- but I expect that it has to do with the manner in which the system operates to limit the differential pressure between the steam mains and the returns.

This is again where it appears the dead men where way ahead of us. Mouat traps (and there were others) had no moving parts and were 2 speed. They have a high venting rate until there is actual condensate in the rad and then only an orifice. Nothing to fail. Of course on top of that the rads were never full either - so a close off type trap that are on most 2 pipe systems today weren't even needed. So now the standard system we replaced the coal boiler with has both trap and venting requirements and issues on every cycle! This is progress? Unfortunately it is also why steam systems are being taken out of beautiful 1910's and 20's homes all around me as we write this. Forced hot air furnaces are going in the attics with the air conditioning units with the pretty white PVC flues sticking out the side.

Two pipe systems will run very nicely at pressures too low to even use for control. Spreading out the runs in more cycles allows radiators to fill more gradually. And the very slight natural vacuum in the dry return if closed from the atmosphere on the off cycle will continue to pull steam from the main into the rads very nicely and evenly - actually more to the rads where steam is condensing the fastest. Almost no venting is needed running this way.