Discovered vacuum steam running on pressure

motordiscord628

so my suspicions were confirmed today, my new to me house has a converted vacuum steam system with “vapor vacuum” brand valves and pick ups. Several of the valves have been abused and leak (under pressure…) and several others are busted. I’ve got my Holohon bibles but wanted to know what people think. I need to repair these valves but I also can’t seem to find an air vent in the system! System is currently slow to heat up and some of the radiators with wrecked valves done even show heat at the supply line but I can’t find evidence of a shut off anywhere else. Pressure control is extremely rudimentary. Boiler is a peerless 63-05

I’m professionally familiar with vacuum distillation systems and honestly I’d love to restore the vacuum function if I can. I’m assuming I can just repack these valves but I’m also assuming rebuild kits don’t exist… help?

109A_5

Hello motordiscord628,

Well who knows how far the system had been modified for the worse. I would try to find an original system diagram and repair the valves if possible. If the system was capable of utilizing a natural vacuum it probably would heat faster than having to push the air out on every cycle. Some air vents were actually in the flue.

mattmia2

It is a vapor system so the boiler needs a vaporstat that will keep the pressure under about 8 oz/in^2 (1/2 psig). The stops on the valves probably should not all be at the max. If the pressure isn't correct or the valves aren't limited to the correct positions based on the size of the radiator, you will get steam in the returns and that will likely prevent some radiators from venting through the return and heating.

Show us some pictures of the boiler, there is probably a device unique to that vapor system that also contains the vent.

Mad Dog_2

Tunstall in Chicopee Massachusetts will make you anything you need to rebuild them. I'm salivating like Pavlov's dog...lucky guy...Mad Dog

clammy

Aside from a vaporstat which i have seen vapor vacume systems work without you will really need to check the main vents and see if they are vapor vacuum vents a hoffmann 67 is what is needed if not you will never form vacuum . I seen a few richardson operate fine w a standard pressuretrol abided the boilers where properly sized . One of the biggest challenges w a vacuum system is will it hold vacuum being a vacuum leak is much harder to locate then a steam leak . I wouldn t obsesses about the graduated supply valves a orifice can be installed if you getting steam passing to the return . Install a compound gauge and install a small ball valve on a extra tee off the safety valve piping i do this on systems that go into vacuum so i can break the vacuum to flush the boiler or perform water side work being if you try and drain or break the vacuum below the water line it sucks in air and stir up all the crap so its easier to install a ball valve and just open it to break the vacuum and then drain

Even though alot may disagree when a true 2 pipe vapor vacuum system operates and still can hold vacuum it is truely a thing of beauty ,the speed of transmission through the supply can only be beaten by a system w a vacuum pump or induced vacuum of course there's alot more details which is a determiner how well it will perform short of decades of knuckle heading and possible the expense of the proper main vents and possible traps if required and usually a vapor stat i will say if the boiler has a cycle guard low water cut off please replace w a non cycling low water cut off it shall be in your benefit . If after checking your existing connected edr and comparing to the boilers edr to ensure your boiler is not oversized . Generally a true vapor vacuum system the boiler size should be less then the connected edr ,this usually ensures that steam does not pass through the rad to the dry return in some cases a2 stage gas valve and a additional vaporstat can put those issues in line .

Wish you the best of luck bringing it back to its former operational glory and for any contractors who are not willing to entraintain or willing to attempt try finding some one w a good grip on these types of systems which there are not alot of out there and even further less who have a clue on wear to start except the stuff that changing out produces revenue and possible not postive results . Bringing any 2 pipe vapor vacuum system back from the pressurized version to its past proper operation is never a easy task and never a one step program theres a whole process to it and if it cant hold vacuum thats where to start . The best thing bout these system is aside from fast distrubution is that if holding vacuum that they rarely lose water and i mean rarely like adding zero for a whole heating season amazing systems to bad most a butcher up and after the run around from contractor most just settle for a pressurized version unfortunately

Peace and good luck clammy

Jamie Hall

I think it's a Hoffman 76 vent, Clammy… and they are still available, though pricey.

There is sort of a gotcha with vapour systems which can go into a vacuum which, I think, is little appreciated. The key to them is to keep the differential pressure between the steam mains and the dry returns to a very small value — never more than 8 ounces per square inch. But kindly note: that is the DIFFERENTIAL pressure between the mains and the returns, not the GAUGE pressure at the boiler. A quick study of the various gadgets used on these systems, such as the Hoffman Differential Loop, will illustrate this. They are controlling that differential, and they aren't affected by the gauge pressure at all. Now if the dry returns are open vented to the atmosphere — though open steam vents or just a straight pipe — there is no difference; the differential and the gauge pressures will be the same. But if you are using a vacuum vent they won't be necessarily.

None of this would make any difference if it weren't that these systems also calibrate the amount of steam going into the radiators based on that small differential pressure — not on the gauge pressure — and if the gauge pressure stays high, but the returns are in a vacuum, you will get steam in the returns and things won't work as well as you want them to.

The problem, of course, is that our modern pressure control gadgets (or, before you scream, perfectly sized boilers) are based on gauge pressure, not differential.

Systems which can drop into a vacuum are not vapour systems in the sense of being designed around a low differential — they may, in fact, run at astonishingly high differential pressures, even with a vacuum showing on the main — and must be designed that way; that is, as conventional two pipe systems — and the provision of traps and water seals and A and B dimension considerations, all of which rely on differential pressure, must take the vacuum and total differential into account for them to work properly. This is not to say that they can't also be vapour systems — they can, but only if the boiler firing rate is modulated so that the steam mains are also operating under a vacuum.

Fun fact: some high end coal boilers in the old forgotten age did do exactly that: the intake draught dampers were controlled by differential pressure, and the firing rate by a thermostat (sometimes a thermostat sensitive to how far off the temperature was from the setpoint, rather than just on or off — so you got more fire if the error was large…). Very close control. Downside? Part fire efficiency was horrible, and so were emissions…

motordiscord628

here are some more photos. I can’t for the life of me find a main vent which makes no sense at all… also not sure why that pressure gauge is so high, so small, or what it’s indicating unless they have this set up at a high pressure? I’m installing pressure gauges and a test manifold as soon as it all shows up…

EDIT: tested the high pressure relief valve manually any it was clear and vented. Vented pressure was not anything like 25psi. PA404A set to a differential of 1psi… maybe a busted gauge? Not on a pigtail. Still can’t find a damn vent. Broke out the infrared camera and didn’t see anything hidden….

Jamie Hall

I hope that gauge is busted. Probably is…

mattmia2

The main vent was probably at the boiler on some sort of specialty for that particular vapor system. Someone likely removed it when they replaced the boiler(or the previous boiler) and didn't put another vent on it.

What happens at the end of the mains? The mains either need to have vents or crossover traps in to the dry returns and need to have drips or traps to let condensate get to the returns.

The dry returns could have a vent on them, they could just be open or open in to a chimney or some systems have a radiator on the ceiling in the basement that condenses any steam that finds its way in to the returns and then vents.

If the air can't get out a lot of your system isn't going to heat.

delcrossv

Mepcollc.com makes regulating valves that will work with that , but you'll need to get the pressure way down.

https://www.mepcollc.com/product/swrf-b-regulator/

mattmia2

I missed the picture of the drip in the main at a corner. That is how the condensate gets back from the mains but I don't see a vent unless there is a finished ceiling or crawlspace it is buried in.

motordiscord628

I’ve crawled just about everything and haven’t found a single vent. I’ll draw it up after I’ve traced it. There HAS to be one.

so to clarify these photos, the red circled area is the condensate return from the radiators where an elbow looks freshly installed, likely with the new boiler in 2018. The pipe dope is different and they used tape. The blue arrows shows the steam condensate return from the header. This follows the floor of the basement, half an inch off the floor right against the wall, for at least 40 ft across 3 rooms. It’s 1-1/2” pipe and goes from warm to basically cool/room temp to the touch as it leaves the steam header.

Steamhead

@motordiscord628 et al, this is a Kriebel system. You can find it in chapter 15 of @DanHolohan 's "The Lost Art of Steam Heating".

"The Vapor Vacuum Heating Company" was the company the Kriebels set up to market their system. It was located in Philly.

The main vent on this system looks a bit like a beam-balance on one of those tall scales you see in a doctor's office. Look for a 3/4" or 1" pipe coming off the dry return near the boiler that doesn't look like it's coming back from a radiator. If you can't find it, some knucklehead probably took it out. In that case I'd install a Gorton #2.

The radiator return elbows have little check valves in then, called "bafflers". These kept any steam that might be in the dry returns from backing into a radiator when the steam valve was closed.

If you have to replace any original Kriebel radiator valves, use orificing ones like those MEPCO sells. The original valves were set up with orifices and you need to preserve this to keep the system in balance.

mattmia2

There should be a vent. There doesn't have to be if someone removed it. The air in the system will compress and allow some steam i to some of the emitters so it will sort of heat, using a lot of fule in the process of heating poorly.

The blue along the floor is a wet return. i wonder if that up side down tee at the drip in to the wet return was a vent at some point or if it connected to some other device that did the venting. Maybe there was a vacuum pump of some sort there.

If you add vents at the ends of the mains and somewhere in the dry returns (what you circled in red), it will work much better. You may need to then deal with controlling the pressure and setting the stops on the radiator valves. Ifit is building pressure the valves will leak more too.

mattmia2

the pressuretrol should at very least be set to the .5 setting and the wheel inside set to one.

Jamie Hall

A critical question on venting. What, if anything, connects the steam mains at or very near their ends to the corresponding dry returns (returns at overhead level, not floor level)?

We are sort of hard-wired today to assume that the steam mains had vents at their ends. Well… a lot of older systems, particularly vapour systems, didn't. Instead, there was a connection with a steam trap (or possibly simply a Kriebel elbow) connecting the two. This allowed air from the mains to pass into the returns and, together with air from the radiators, return to the boiler. At that location, all the dry returns would tie together above the water line, and then drop to the wet returns or the boiler. There would also have been a vent at that location — often in connection with some pressure differential control device — or in some systems just an open pipe to the atmosphere or into the stack.

Any dry returns must be vented. As i note just above, this may be just one location, near the boiler.

The blue arrows in your drawings are wet returns, handling condensate from various drips, and have nothing to do with venting or steam. There should never be steam in them, nor in the dry returns.

mattmia2

@Jamie Hall did some 2 pipe systems, especially those designed for coal, only have drips from the mains to the returns and vent the mains through the emitters and out the dry returns?

Steamhead

Found it! Kriebel book from 1910:

https://www.heatinghelp.com/systems-help-center/kriebel-system-of-vapor-vacuum-heating/

109A_5

I wonder if part of that main is counter flow, or does the part of the main to the right work its way around and goes back to the boiler, since there may be a bull head tee above the boiler (hard to see) if you use the wet return path as the orientation reference.

mattmia2

https://forum.heatinghelp.com/discussion/comment/1821674#Comment_1821674

So the controller is just a vacuum vent?

Steamhead

Pretty much. But that was in the Coal Era. Nowadays we just vent these with Gortons.

109A_5

Fun stuff !!!

ethicalpaul

those “guaranteed” fuel savings are pretty funny. It appears they found a way to make fossil fuel over 100% efficient.

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1821685#Comment_1821685

Actually, no. They were working with coal fired boilers (often hand fired) with dampers to control the heat. Lucky to get 40% efficiency on a good day…

ethicalpaul

I don't understand how a coal fire could only be 40% efficient. It's a heat source under a pot of water, just like my boiler today. How did 60% of the coal's hot combustion gases go past the pot of water where my boiler somehow captures 82% of gas's hot combustion gases?

Jamie Hall

A coal fire, well banked down, is pretty bad. Very incomplete combustion for one thing (in another application, the combustion was sufficiently incomplete for the resulting combustion gas to be used as "town gas" for lighting and even gas stoves! It was mostly carbon monoxide… it's a wonder we didn't all kill ourselves). Also the fire was sufficiently small that it did a poor job of heating the boiler metal — and the water. Imagine your pot of water on a gas stove with the burner turned way down.

Granted — if you opened the damper and carefully stoked the fire, you could get pretty good results in terms of efficiency. 70 or 80 percent is quite imaginable.

As an exercise in an absurd thought experiment — consider an ordinary candle set in the middle of the firebox of a three section boiler…

ethicalpaul

Thank you, I see what you are saying, but the efficiency is measured by how much of the produced heat goes into the appliance (I think). With steam I admit there is the additional issue of "is any steam being produced at all?".

I'm not sure if that plays into the efficiency calculations, but regardless of all that, I remain highly skeptical of the marketing of these vacuum systems. Even if there were proof of the ability of a vacuum system to pull otherwise lost heat out of a crappy coal fire, that benefit is no longer relevant.

But these old systems are very fun to see and think about!

mattmia2

The upshot here is there was at one time a device that they manufacturer called a "controller" that was an early vacuum main air vent in the dry return at the boiler that someone removed at some point. You should put a new main vent or main vacuum vent in the dry return near the boiler somewhere.

motordiscord628

@Steamhead this is awesome stuff. The nerd in me wants to transfer all of the working/repairable original valves to visible places and replace the busted ones with modern valves (unless anyone knows of spares!) My plan is to put in a Gorton #2 at that new elbow at the return. Given the pressures and temperatures involved I’m inclined to put in a service saddle so I don’t have to disturb the rest of that near piping. I’ll switch out the pressurtrol for a vaporstat (l408j1009 looks right) and put in a diagnostic manifold. Folks seem to be against the self testing low water cut off but not sure why. One thing though… isn’t a vaporstat just a low range pressure control with a deadband? The controls guy in me wonders why I wouldn’t just put in a 0.25% pressure sensor and a programmable process controller… he’ll why not put it on a PI or PID controller? Spending $350 for the microswitch vapor stat when I can build a more accurate, network connected version…

mattmia2

Note that the valves have different sized orifices built in to them so they have to be matched to the same size radiator. They have different size openings when they are fully open. Most vapor valves have a way to adjust their maximum opening, this system just uses different valves for different size emitters. There are new metering valves still available but they are pricey. You can also use a regular steam valve and an orifice plate (a metal disc that sits in the union and has a specific size hole punched in it)

The cyclegaurd isn't self testing, it just stops the boiler every short period of time to let the water level settle to see if the probe is still under water. This has the effect of stopping steam production every 20 minutes or so and will make it harder to balance the system.

You can control it with other low pressure controls. I'd keep the pressuretrol plumbed in and wired it in series with the other control so the boiler will shut down if something happens with the unlisted control.

Jamie Hall

A vapourstat is NOT just a low range pressuretrol. It has a completely different — much larger — pressure sensing diaphragm which provides the necessary forces to activate the switch at the low pressures.

The "deadband" on both a pressuretrol and a vapourstat is controlled by the spring tension set by the differential setting. In both there is a minimum deadband (the inherent deadband is on the order of a couple of ounces), but normally the differential setting is greater than that.

One could put in a very sensitive electronic pressure sensor and various electronics or a small computer to perform the same function. I wouldn't — for a very simple reason: simplicity and reliability. The microswitch versions of the pressuretrols and vapourstats — all you can buy new — are limited by the reliability of the microswitch, but that is in the tens to hundreds of thousands of cycles. The old mercury versions were limited by fatigue failure in the diaphragms, and if they were not abused they typically lasted for decades. I appreciate the urge of the modern control guy to digitize and computerize everything — but I don't share it.

109A_5

Hello motordiscord628,

I would get some functional gauges on the system to see what the actual pressure is. A vaporstat may be a total waste of money. I have a pressuretrol, just as a safety device, a vaporstat would be useless since my pressure never goes over 2" WC. Also I read complaints about system vacuum damaging the the newer versions of the vaporstat, just in case you ever want to restore the vacuum advantage to the system as it seems it probably was originally designed with.

You certainly can turn the whole thing into a process control like hobby, others on HH have and seem to enjoy it.

mattmia2

You need to get the vent back on the return before you'll know how it works, if it ever build pressure.

motordiscord628

Steamhead stick with gorton #2's on this or the big mouth? the system is all 1-1/2" pipe and smaller. I've been reading about the big mouth and they seem sturdier than the gorton? I may be over-thinking this. Kind of surprised I only need 1 at that elbow too. I don't see any harm in "over-venting" though?

109A_5

Some folks like the Gorton #1s, some like the Gorton #2s for various reasons. One thing I like about the Bigmouth is that it has a pipe thread on the outlet side so if you ever wanted the put a check valve (or some other gadget) there to hold the vacuum in the system you could. Also you can take it apart, but I have the tools to do that.

motordiscord628

https://forum.heatinghelp.com/discussion/comment/1822174#Comment_1822174

@109A_5 do the bigmouth's not hold vacuum?

109A_5

Most vents unless specifically identified as such do not hold a vacuum and let the air back in when they cool down. Vacuum vents are now rare, a Hoffman 76 is still available but expensive.

The Vapor-Vacuum Controller your system probably originally had didn't let the air back in, the little valve on the bottom was probably a check valve.

I think most folks have given up on vacuum, since vacuum leaks are hard to find, so some efficiency suffers.

mattmia2

If your radiator valves are leaking it won't form a vacuum anyhow. Trying to get it to go in to vacuum is a in a couple years after you have sorted out the more major problems problem.

motordiscord628

true, not shooting for vacuum asap is the right move. I like the idea of the bigmouth coupled with a vacuum check valve like I've used on vacuum pumps. I think I'll give that a go

ethicalpaul

https://forum.heatinghelp.com/discussion/comment/1822162#Comment_1822162

The Gorton #2 is plenty sturdy. The Big Mouth is freaky ridiculously sturdy being cast.

109A_5

Hello motordiscord628,

As far as vacuum is concerned the system needs to be air tight and the vacuum check valve needs to be able to crack open at about 1" WC or less IMO and/or you could automate the process with a mag valve to control the venting. Much to play with here if you want to.