Vacuum system?

service_fitter502

so I probably don’t have to say this but I will anyways, I have little experience with fixing steam heating systems. I was sent on a call to a boiler the company I put in a few years ago. Complaint was that it hasn’t worked right since we put it in. They have a pressure tell maintaining 2psi. The header is all knuckleheaded together among other things. I guess my main question does having the Webster vent trap and other contraption next to it mean it is meant to be a vacuum system and vacuum system only? Excuse me if any of my terminology is incorrect. I am very green when it comes to residential steam. I really want to want to be the guy that straightens this system out for these people. Any response is greatly appreciated. I also apologize for posting so many pictures, the flue is right in the way of the Webster components and I just wanted to you guys to be able to see all the piping in efforts to get the best answers as possible.

service_fitter502

pressuretrol* not pressure tell

EdTheHeaterMan

This is what you need to do. https://www.heatinghelp.com/systems-help-center/the-25-steps-in-the-repair-of-a-vacuum-steam-system/

Or you can do more research before you even try to do anything. If you don't have the experience to get this right, then you need to find one of the folks on this site that know what you need to do. I am not that guy. I'm the hot water boiler guy and the oil burner guy. You need one of the steam guys. Where are you located? One of the steam guys may be close to you.

Jamie Hall

Well, yes. It does lokk as though it had been a Webster system — but it has also most likely been … um… modified?

Someone else will probably shriek, so I will first — the near boiler piping is not good. It may work — steam is remarkably forgiving — but it ain't right and should be redone the way the boiler manufacturer (and us) want. It will work a lot better.

In the meantime, the Webster — and similar systems — could and did drop into a vacuum at times, but that isn't the most important characteristic. They are called vapour steam systems, and were meant to work on very small pressure differences between the steam main supply lines and the returns, and 2 psig is about 4 times the maximum which they will run reliably on. If you have an ordinary pressuretrol, though, that can't be doen, and so they should have a vapourstat instead, set to a cutout of 8 OUNCES per square inch, with a 4 OUNCE differential. That's an easy right off the bat fix.

Then for your next project — actually two. Get a copy of The Lost Art of Steam Heating (Amazon or the store on this web site) and study it and learn how vapour steam systems in general are supposed to work. Then, taking that knowledge with you go through the entire system and familiarise yourself with all the piping and other devices, particularly the inlet valves on the radiators and any traps and vents — and then figure out what they were supposed to do, what they might be doing now — and what is missing or otherwise "modified". Take your time.

mattmia2

it is a warren webster vapor system. 2 psi will cause havoc. it needs a vaporstat set at about 8oz/in^2 and correct near boiler piping and if possible to have boiler return trap and the vent plumbed in properly. those are those rectangular boxes behind the boiler. hopefully theymatched the boiler to the connected edr or undersozed it a bot or controlling the pressure will be tough.

109A_5

@EdTheHeaterMan I say you are the control electrical an helpful image guy too.

@service_fitter502 Even if it was a Vacuum system how does the air get out ? My guess it it would be considered a Vapor system. Many systems can develop vacuum, they just don't retain it very well.

If the air can't get out the steam is not going to move very far. This valve seems closed.

service_fitter502

thank you Ed, I’m in Louisville ky, and Jamie I ordered the original and the companion yesterday. They should arrive on Friday. I’ve got my materials to make the header right on will call ready for pick up. I quick fools search of the model number and I was able to find the manual on it and it explicitly says how to do it.
I found some literature here on heatinghelp.com the Dunham vapor system from way back in the day. I noticed though that in the original piping schematic of that type of system, there was not an equalizer line.. why would that be the case? Also I know it might be difficult for you to say for sure with out seeing the system for yourself, is that the same type of system that would have a Webster air trap set up on it? Also do you know what that device to the right of it is by chance? I really appreciate you guys taking the time to reply to me.

heres how the header is going to end up when I’m done.

109A_5

Notice the check valve at the top.

From:

https://heatinghelp.com/systems-help-center/webster-systems-of-steam-heating/

https://heatinghelp.com/assets/documents/85.pdf

mattmia2

i believe the other device is a boiler return trap. its job is to let some steam in to the return to equalize the supply and return to allow the condensate to return to the boiler if the differential between the supply and return gets too great. that is why it is important that the only vent be at the vent by the boiler, so that steam can go directly to that vent and close it instead of traveling throughout the returns causing various problems with venting of radiators and banging.

mattmia2

dunham busch isn't the same as warren webster although pretty much all vapor systems work by controlling the amount of steam entering a radiator through a metering valve with a controlled, very low pressure.

service_fitter502

@109A_5 that is how I found it lol. I didn’t think it looked right. So would that just vent to atmosphere? Given that I’m green and it being a threaded connection I was hesitant to leave it open then leaving in case it was supposed to tie into some where.

@mattmia2 thank you for the input.

@EdTheHeaterMan and @Jamie Hall I’m new to the forums and didnt know how to tag you when I wrote my previous response.

service_fitter502

@mattmia2 good to know about that needing to be the only vent! Somebody at some point added a Hoffman at the end of the main before it slopes down into the return. So I’ll add that to my list as well. Is there any literature you could direct me to that is Warren Webster specific?

109A_5

" Complaint was that it hasn’t worked right since we put it in. "

That seems kind of vague to me. I'd try to get more details about this complaint. It may give you better troubleshooting direction.

mattmia2

here are 2 warren webster catalogs, there are some diagrams although they aren't the full design guide:

https://heatinghelp.com/systems-help-center/webster-systems-of-steam-heating/

https://archive.org/details/Sweets1938Sec2622WarrenWebsterAndCo

the catalog during wwii has some steel and iron substitutions of things that would normally be brass

there is some mention of webster systems in tlaosh but it doesn't seem to quite be the systems i have seen people post here.

mattmia2

the outlet of the vent should have a main vent on it.

mattmia2

if you keep the pressure controlled with a vaporstat, the return trap and single vent are less important.

109A_5

The thing is when that system was installed it probably was coal fired which has different characteristics than gas fired. There appears to be specialized components missing that can't be easily be replaced and the ones that still exist, their functional integrity is unknown. I'm sure the present performance can be improved, however it may never work as well as it did when new.

Is the Hoffman vent a vacuum vent ?

One nice thing about maintaining a vacuum from cycle to cycle is with each cycle you are not burning fuel to push air (as much air) out of the system so that steam can get to the radiators.

mattmia2

it looks like it is a type r system. it could go in to vacuum with a check valve on the vent outlet but it wasn't like some other warren webster systems that used a mechanical or educator vacuum pump and smaller returns so it needs vacuum to vent properly.

it looks like the parts are there at the boiler,

the boiler return trap:

and the vent:

can we see what is at the radiators?

EBEBRATT-Ed

Fix the header and make sure the Hartford loop is right. You need a vaporstat to keep the pressure low in addition to the pressure control you have and they should be on seperate tappings and brass pigtails. a 0-5 psi gauge would be nice.

If you don't have tapping's you could put a tee below the safety valve or drill and tap the header.

Post a few radiator pics and we will see what else needs doing. Louisville , KY your probably the only one doing steam. Make sure the mains are pitched.

look for cross over traps in the basement. The air all has to come out through the vent trap.

109A_5

@EBEBRATT-Ed makes a good point " The air all has to come out through the vent trap. " the existing Hoffman vent may help vent the steam main, but how does the air in the radiators get let out of the system so the radiators can fill with steam ?

As @mattmia2 mentioned " the outlet of the vent should have a main vent on it. " This may make a huge improvement.

These may help, not inexpensive.

76, 1/2" x 3/4" Straight Main Steam Vacuum Valve
Brand: Hoffman

https://www.supplyhouse.com/Hoffman-401432-76-1-2-x-3-4-Straight-Main-Steam-Vacuum-Valve-11742000-p

Hoffman's opinion;

If it was my system and I had to unwillingly abandon vacuum I would put a Barnes & Jones Big Mouth on top of that Webster vent trap for maximum venting. I would remove the valve or use a full port ball valve, probably won't see much steam.

A few folks on this site are enjoying the benefits of natural vacuum.

109A_5

Looks like something was there, it got removed, the valve was then closed, the vent and/or check valve was never replaced so the valve just remained closed trapping the air causing very poor system performance.

If you think about it every radiator in the system has to vent through this point with a closed valve. How well can the system work ?

The 2 PSI was probably needed to compress the air enough to get some steam into the radiators, not very efficient. just to give you a comparison, my house heats just fine at less than 0.072 PSI or 2 inches of Water Column.

109A_5

Sounds like your intent is to rebuild the near boiler piping. I'd wash off the production oil from at least the inside of the new piping. May save you a bunch of time Skimming the boiler later on.

Jamie Hall

With oil or gas fired steam systems, holding a vacuum is not as important as it was with coal. There should be a main vent where you have that closed valve, but it needed be a Hoffman 76 — they are quite expensive. A Hoffman 75 may do, but I'd be inclined to use one or two (on an "antler") Gorton #2 vents there.

The vent added at the end of the main is OK… sort of… if you use a vapourstat to control the pressure. I wasn't meant to be there… but crossover traps most surely are.

I would suggest that you tackle the near boiler piping and install a vapourstat first, then using the knowledge you will get from the books go around and see what else got messed up..

Steamhead

https://forum.heatinghelp.com/discussion/comment/1905774#Comment_1905774

That vent is so slow as to be almost unusable in a system like this.

This naturally-induced vacuum technique worked great in the Coal Era, but not so well on oil or gas. The problem is that often you get vacuum before all the air is out, which can cause the remaining air to expand and block steam circulation. I tried it once, never again.

The vent to use on that Vent Trap is the Gorton #2, which is at least four times faster than that Hoffman:

https://www.supplyhouse.com/Gorton-G2-Gorton-No-2-Straight-Air-Eliminator-3524000-p

And get rid of that red-handled valve.

What model boiler is that?

EBEBRATT-Ed

The general rule is a NATURALLY induced vacuum system will not work with oil or gas automatic firing.

A vacuum system with a pump is a different issue.

109A_5

Well I think @PMJ with his Mouat system proved vacuum works very well. Although his system is not a Warren Webster Vapor system.

It seems to me if there is less air to push out with each cycle the more efficient the system will be. If the air is not let back in you simply don't have to push it out again (burning fuel to do so). So the vent rate is not terribly important. The trick is keeping the vacuum also no excessive pressure differential between the supply and return.

If you can't maintain the system's integrity as far as keeping the vacuum in you have to go with ample venting. Presently it appears this system has neither, maintained vacuum or ample venting.

109A_5

The thing is, if you don't figure out why the valve was put on the vent trap (possibly condensate and/or steam loss) and deal with that issue you are probably never going to make that customer happy.

I would imagine their fuel bills are high and the comfort level is low.

PMJ

The "general" rule that natural vacuum won't work with intermittent fire at least in the case of Mouat piping is completely false. Been doing it 20 years plus and it is a big improvement in comfort and certainly more efficient not less. When you don't let the air back in there is shockingly little venting to do and it makes little difference where that one vent is.

EdTheHeaterMan

@service_fitter502 Asked: “I found some literature here on HeatingHelp.com about the Dunham vapor system from way back in the day. I noticed, though, that in the original piping schematic of that type of system, there was not an equalizer line. Why would that be the case?”

All I can say about that is that the original boiler may have been installed prior to the recommendation by manufacturers to use Hartford Loops and equalizer lines instead of check valves that might fail from time to time. That piping arrangement has no moving parts and was instrumental in reducing the number of boiler explosions that happened regularly back when that original system was installed.

The original boiler may also have had five times the water volume that your current boiler has.

Jamie Hall

Two thoughts here, since we seem to have wandered off from the character of vapour steam systems to thoughts about vacuum systems — which are not the same thing at all.

Coal fired steam heating systems were encouraged to drop into a vacuum. Hence the existence of vacuum vents. But we need to ask why. it was not to avoid "pushing air out on every cycle" because they didn't cycle. The advantage was that they could and did continue to heat with a low temperature banked fire. This allowed a thermostat (or homeowner…) to maintain a comfort level in the space simply by controlling the draught over the fire. Since they could run under sub-atmospheric pressure, the radiator output would be varied since condensation occurs at a lower temperature at lower pressures. As a little noticed aside, later vapour systems (with vents rather than open returns) could also run at higher internal absolute pressures and hence higher outputs, provided the differential pressure between the mains and returns stayed within design limits (there is no magic reason for a supply pressure of, say, 0.4 psig, by the way. The correct control parameter is that differential pressure — unfortunately our modern widgets are all psig controlled, not differential controlled…)

Hence all later vapour systems had some sort of contraption of varying complexity which controlled that differential pressure (the Hoffman Differential Loop is the simplest one I've seen; some of them are truly wonders of complexity!) Again, on coal systems, some of them also had a device to control the draught in response to differential pressure — usually in tandem with the thermostat control

Now there is no theoretical reason why a similar operating strategy couldn't be implemented with oil or gas firing; the key is modulation, and both oil and gas firing can be modulated over a wide range with little difficulty, and with little loss in efficiency (if any at all). There are several tradeoffs, however. One of the more significant has little to do with thermodynamics but a lot to do with aesthetics: oil burners are most easily modulated by pulse modulation; that is, the burner is on for a certain time, and off for a certain time; the modulation from full power is simply the ratio of on time to total cycle time. Provided the off time of the cycle is short enough that the boiler never goes below a simmer (and this is an argument for systems which can hold a vacuum) there is almost no hit to efficiency; the most common limitation on this is the post-purge and pre-purge delays needed for clean operation. Gas firing can be modulated the same way or, if the burner design is meant for it by limiting the gas pressure to the burner (air flow must be limited at the same time, of course)(this, for you automotive geeks, is how a carburetted engine varies its power output, by the way, except the control is on air flow rather than fuel flow)(fuel injection engines and diesels are technically pulse modulated, by the way).

Is the complexity worth the effort? Maybe. Maybe not. One needs to balance personal preferences, control complexity, maintenance and repair, and efficiency — and everyone will come up with different responses.

Again to look briefly in closing at the automotive world — a current generation gas engine is significantly more efficient than one from, say, the mid 60s (though not as much as one might be led to believe), but maintenance and repair costs and complexity are vastly different.

EBEBRATT-Ed

That is the problem oil and gas in a steam boiler are not modulated.

@PMJ

Which is why I stated "General Rule" I didn't say it can't be done as you infer.

It is just not going to be done often as vacuum vents are difficult to obtain and are expensive and most people don't have the time or $$$ to fool with it.. They are going to install normal vents and have a system that is more commonplace.

PMJ

I must point out that on/off is a form of modulation. The suggestion here is now and always has been that the modulation needs to be gradual for successful natural vacuum operation, which of course is the only way a coal fire can be changed. From years of actual experience with it I can tell you the rate of fire change does not need to be gradual. The change in vacuum level will be very gradual especially on the build side, however, even with on/off fire. In the Mouat system there is no special device to control pressure differential between supply and return. In natural vacuum it controls itself, regardless of the state of the fire, and the supply side pressure will always be higher than the return side. This is decidedly unlike an open vented system where air at atmospheric pressure is allowed into the return immediately upon end of fire every cycle, quickly making the return the highest pressure in the system. In that environment the vacuum being formed by the condensing steam in the radiators is filled with air from the rooms, not more of the already produced steam in the mains. Repeated cycle after cycle this is not a small difference in net results. I have run this system both ways. It isn't close. My lone vent is an electric solenoid valve and not expensive or hard to come by.

Jamie Hall

A bit of meditation on @PMJ 's comment — with which I largely agree. One of the things which is so easy to overlook is that "steam heat" isn't just one simple sort of thing. And the various classes and subclasses of steam heat — though they all make use of the properties of steam/water vapour — have really remarkably different characteristics. Not only are the devices different — sometimes remarkably so — but the underlying physics is different as well. Thus generalisations are at best risky, and can be actually quite misleading. Makes it much more interesting!

mattmia2

https://forum.heatinghelp.com/discussion/comment/1905834#Comment_1905834

most likely the 2 psi pressuretrol was causing steam to blow through various things and in to the returns and out that vent so instead of fixing the system, someone ut a valve in place of the vent or check valve or open tapping.

109A_5

https://forum.heatinghelp.com/discussion/comment/1905865#Comment_1905865

If the boiler is well matched to the radiation there would never be 2 PSI until the closed valve was put on top of the Vent Trap, now with radiation venting absent the load is significantly reduced causing pressure.

And sure if some radiators have bad traps steam may have been getting to the Vent Trap.

@service_fitter502 has work to do.

service_fitter502

@Jamie Hall again I apologize for my incorrect use of terminology. I believe what I meant to title the post was “ vapor system” not vacuum. I now understand the advantages of it being a vacuum system when it was coal fired and that it’s not really needed any more. In my continued search for information on the Webster system and reading my LAOSH books that arrived tonight I stumbled across a couple different piping diagrams for the system and am starting to understand it a little bit more. But there a few things that still don’t make full sense and the lack of literature on the Webster system is making it even more difficult. I see on the diagram where it specifies “no pressure wet return.” But doesn’t show the rest of the system piping. Then I found a video on you tube that I was able to screenshot a different diagram from and it shows it coming from a “Webster drip trap.” In my particular case thee drip trap is apparently MIA. What exactly does this missing component do? And would there be any work around with out? It is located to the far left towards the top on the first picture.

Steamhead

The Drip Trap is there because the return from the end of the main where the trap is, runs through the Boiler Return Trap. With this "non-pressurized return" there is no leftover steam pressure downstream of the trap to help get the water back to the boiler (called the 'B' Dimension, because the returning water can stack up in the vertical drip line more without the leftover pressure), so the Return Trap takes care of that. This is the same situation as the returns from the radiators, which also have traps, and route their condensate through the dry return. In the diagram the water from the dry return comes down from the Vent Trap.

Check your return line where it comes off the main. Follow it from that point to the boiler. If it bypasses the Return Trap, it's a "pressurized return" ('A' dimension) which does have leftover steam pressure in it, so a trap is not used.

Jamie Hall

Terminology will l get you every time! That Webster drip trap is what we would usually regard as a crossover trap. Quickly what happens is that the trap allows air in the main to escape into the dry return, where it goes back to the vent at the boiler. But you don't want steam in the return, so when steam makes it to the end of the main, it closes. In the Webster system (but not in most other vapour systems) it also prevents steam pressure in the main from appearing in the drip and thus in the wet return. Not really needed — an ordinary crossover trap will do, so not to worry.— the workaround is to place a crossover trap at that location so the air can get into the dry return, and to keep the drip — which is just a fancy name for a pipe which drops to the wet return! — to allow the condensate in the main (note which way the main is pitched) to get to the wet return and hence back to the boiler. There are several ways this could be piped, depending on the piping arrangement near that location; if you could provide a photo of the end of the main and the dry return at that location I might be able to come up with an arrangement.

Steamhead

Actually, @Jamie Hall , the drip trap in that diagram is a F&T (float and thermostatic) trap. You have to enlarge the image to see it. It's probably a #0026, which had an air line connection after the thermostatic element that was routed up to the dry return. So the returning water and air were split within the F&T trap rather than afterward, as we do with a more modern trap.

109A_5

Hopefully you can now see with that closed valve on top of the Vent Trap air can't leave the system, so steam can't get to the radiators properly. Correcting this issue may be the single most important thing you can do.

service_fitter502

@109A_5 yes thank you I do see how that is supposed to be now!