Single pipe vacuum idea

PMJ

> @izhadano said:
> PMJ
> I'm really not against the pumps. I'm recommending experiencing natural vacuum first. It is so simple and far more effective than most people think.
> =======================================
> I've started with naturally induced vacuum systems, - too much work to seal old piping. Plus some of it is hided inside walls - never know if your leak hunting is complete. You may see new leaks and never know exactly where they come from.
> From my experience, small vacuum pumps running 1-1.5 hr/day in 5-7 intervals is much more reasonable solution.

I'm just lucky I guess. 1926 piping and 50-60" H2O vacuum between firings. I tightened 8 or so radiator valves and the main shutoff valve that is it - not much effort. But you are right,the system is not getting tighter as it ages and I suppose an out of reach leak is in my future. Still, I've been running this way a lot of years now and I still think it is the right starting place for anyone. There is nothing to re-do to add a pump.

I guess I'm also a bit surprised that a small pump running 1.5 hours out of 24 can cover much of a leak.

I also don't think it is really sinking in how differently I am running with the cycles. I am trying to approximate the original design which was that the system always had steam in it. The rads always are a little warm. My calls for heat may go on for 2-3 hours now and I am still trying to lengthen them. The goal is to have the temperature just sit in the deadband of the tstat. The longer the call, the more even the heat - it really is true. Put some steam in, let natural vacuum take it where it is needed most, put more in. Spread it out, even it out. Valves and vents are fixed and can't adjust to changing outside conditions. Vacuum really does. I wouldn't have believed it until I experienced it myself.

I think @ChrisJ with his concept has the potential to do all this plus have the ability to slow some rads as needed on a schedule and zone as desired. I can't do this with a two pipe. It sounds really cool to me.

jumper

PMJ said:

jumper said:

My POV is that the problem with single pipe vacuum are the radiators. With two pipe radiators steam can go in at the top and air & condensate comes out the bottom. Then you can evacuate air to produce a vacuum anyplace in the system.

My point is that no evacuation is necessary. The air only needs a place to go - the biggest volume of it on first warmup if you don't let it back in. The vacuum happens when the steam collapses right where you want it - in the rads - so you don't need a pump. You will even get deeper natural vacuum in a one pipe system because the total system volume is smaller so a higher % is filled with steam when the collapse begins.

I read here that one pipe systems require atmospheric air to prevent vapor lock. Gas theory calculations indicate that naturally induced vacuum can only evacuate 20% of the air. Pumping out more air should lessen vapor lock?

And introducing steam higher up in radiator (two pipe type) enables steam to push air out. At least in my imagination.

PMJ

> @jumper said:
> I read here that one pipe systems require atmospheric air to prevent vapor lock. Gas theory calculations indicate that naturally induced vacuum can only evacuate 20% of the air. Pumping out more air should lessen vapor lock?
>
> And introducing steam higher up in radiator (two pipe type) enables steam to push air out. At least in my imagination.

I read that about vapor lock here too. It may be true - I can't say for sure it isn't. But then I also read about mystery problems in 2 pipe with vacuum and I have seen none of those. To me, vacuum means the entire system is still basically at one pressure - just lower than atmospheric. There are very small pressure differences between where the steam is condensing the fastest (the rads) and the mains which causes steam to continue to flow slowly toward the rads. I see no scenarios where gravity is not still in complete control of condensate flow.

I admit I may be wrong about one pipe as I have no first hand experience. In 2 pipe I am quite sure there are no issues.

ChrisJ

Single pipe with a small vacuum connection where the vent goes would have no problem either.

Vapor lock? Isn't that something that happens when gasoline boils and causes a fuel pump to loose it's prime?

AMservices

something you should know about evacuating air from a single pipe steam system. you don't want to have your vacuum pump pulling from a main air vent. you should only be evacuating from the air vents at the radiators.
You can't pull from the main vent holes because the steam will short cycle back to the pump before all the air is exhausted from the system.
The remaining air will be compressed into the radiator and you won't be doing much heating if air is trapped in the radiator. That's why it's so important to be removing the air directly from the radiator.
Then you control the air flow out of the system to balance the steam entering.
I say this because I noticed in your drawing at the top of the thread that you have a vacuum line connected to your main air vent. Dont do that.

Susantaylor

The idea was good, but I think this is a complicated task to do. The only problem is created balancing because of falls and leakage. I don’t have any idea how to solve this issue.

ChrisJ

@PMJ
I don't want to hijack the other thread.

But here's the deal with my system, and I'm sure it's not alone.

Some of my radiators need to barely heat on most days. Others heat quite a bit. A few, don't heat at all. I have TRVs on 5 out of 10 radiators, the 5 of course are the ones that are throttling back, on most days.

Some days......if it's windy, or it's night time, those radiators heat often heat a lot.

My bedroom has a large 19 section radiator in it which is the first one to get a TRV. I had a Gorton #4 on it while many others had 5's and 6s. The problem was I wanted more heat on windy days and less on very cold days. Cold days brought on really long cycles which meant that radiator was heating more and more. The TRV along with 2 CPH minimum nipped that in the butt.

All of my rooms stay within 1 degree or better of where I want them. The bedrooms stay cool, mid 60s. The kitchen stays high 60s and the livingroom, playroom and bathrooms stay in the low 70s. It's not all the same temperature, but it's completely intentional and it does this all winter long whether it's 40 or -10F out. The 5 TRVs + 4 areas being averaged by the thermostat makes for an amazingly balanced system that constantly biases it self to the environment. For example running the oven all day doesn't result in cold bedrooms and the kitchen radiators never get steam.

I see absolutely no way of achieving this, or anything even close to it by using checkvalves on all of the vents on a single pipe system. Unless, the radiators are properly matched to the spaces. Of course, that still won't allow you to have radiators not heat if the oven is going, or the room is warm from sun etc.

I see the system slowly getting into a fairly good vacuum and all radiators heating at near the same speeds, but with absolutely no control or bias.

Keep in mind, mine mainly has issues because the bedroom radiators are grossly oversized. I'm told this is from people sleeping with windows cracked and that it's very common in older houses. How are you going to tame such things? If you've got radiators that are a good 50% too big in all of the bedrooms vs the rest of the house, how are you going to keep those rooms comfortable?

Help me understand because I'm just not seeing it.

Eastman

"Six Kinds of Steam Heat" from 1941 discusses the issue of maintaining balance in one pipe vacuum systems with automagically fired boilers:

Look at the section called: ONE-PIPE INTERMITTENT VAPOR

https://heatinghelp.com/heating-museum/six-kinds-of-steam-heat/

In a nut shell, a valve of some sort was employed to reintroduce air periodically, thus restoring the systems ability to balance via cyclical venting. Hard vacuum developed by automatically fired, as opposed to coal fired, exacerbates the balance problem and necessitates the vacuum relief valve. This indicates to me, that more cycles would also be a benefit to the system, perhaps that would be more consistent with the behavior of a coal fire.

PMJ

@ChrisJ ,

This thing is fairly difficult to picture without actually experiencing it. It appears that I am one of the few who actually has. I have worked my way into it over many years now of observation. So if you will, bear with me some.

I am in complete agreement with you that to work well a system must from a cold start fill all radiators to a partial level close to what the demand requires, and all approximately at the same time - lets say +/- 2 minutes or so. A minimum level of reasonable balance is required. And this is in fact achieved this first time with valves in my case and valves + vents in yours. There isn't any way around this first step that I can see.

Having said that though, all my discussion about using vacuum has to do with what happens AFTER the initial fill. What I have found is that vacuum is absolutely magical at returning the entire system on each new burn back to the same level of fill that it was at the end of the previous one in all places. And it does so each time much more efficiently without all the air to remove. Large radiators DO NOT just get fuller and fuller cycling this way. They and all other radiators simply repeat to the same place over and over that you filled them to the first time. But after the first time it is not the valves and vents that primarily guide the steam, it is the vacuum. But the bias that you created with the first cycle remains throughout. The distant harder to fill radiator will get filled back to where it was too each and every time because I don't stop the burn until all the vacuum is gone. With the system closed up the only thing that can replace the vacuum in each radiator is steam. Also, this refilling happens much more quickly and effortlessly when the steam is filling a vacuum void and not having to push air out. Running this way the steam never stops moving from boiler to radiators unlike what it does open vented where the instant the burner shuts off the void being created in the rads begins filling immediately with air.

So my answer to you is that currently you balance/bias everything throttling steam with valves and air with vents each and every time your boiler runs. I am sure that you have done a very good job with that. But I am going to suggest to you that repeating to that place on all following cycles is more efficient and more reliable with vacuum than vents and valves. It allows for longer calls for heat with a smaller percentage fill which significantly reduces the temperature swing with yes, more cycles. With the simple oscillation back and forth burn to vacuum it is possible to maintain a very constant radiator condition that more closely matches the actual demand. It results in very even heat.

Now I know that nearly everyone has become quite accustomed to heat swings up and down through the dead band of the tstat on every cycle be it once an hour or less or more or whatever. I'm not going to tell anyone that it is not acceptable. I will just say that such swings were not possible with coal fired heat and don't have to be the case with intermittent fire either. Once experienced, a really long call for heat(hours) with the temperature hardly changing and radiators always warm is actually quite nice. As we know, with coal fired steam the call was endless.

Beyond this is the subject of changing demand conditions. Vacuum is better at adjusting for that too. I'll leave that to another time along with the specifics of how I control all this if you or anyone else is interested.

ChrisJ

I have an Ecosteam, I don't experience temperature swings.


I've also said many times in the past, intermittent fire is fine and the duty cycle of the boiler shouldn't be noticed.

The boiler is your pulsating DC supply and the cast iron radiators are your filtering capacitors.

Eastman

@ChrisJ
What did you think of the steam article^?

PMJ

ChrisJ said:

I have an Ecosteam, I don't experience temperature swings.

How long are your calls for heat? At a bare minimum your swings during each call are the deadband of the thermostat.

With Ecosteam your swing will definitely be less than with a standard control because there will be less overshoot. But the length of the call defines how even the heat is and therefore the rate of the swing.

ChrisJ

@Eastman interesting, but it would eliminate the benefit @PMJ is talking about.

@PMJ what's the deadband of a Honeywell Prestige set to 2 cph? Keeping in mind as far as I've seen they use temp change and time rather than just a dead band. My guess is 0.5 degrees is typical. At least that's what I remember with my VP 8000.

Then, how does it work averaging 4 sensors? Does that become an 1/8 of a degree overall?

Eastman

@ChrisJ
I think the idea is that the system would be under vacuum after a burn while the boiler is sitting there waiting for a new call for heat to come in, but when that call comes in, the discussed vacuum relief valve would briefly open to provide some air for balancing. This would happen every cycle, thus providing balancing control authority to the vents and TRVs, yet much of the time, the system might be in vacuum moving additional btus out of the boiler and up into the rads. Could be an interesting happy medium.

PMJ

@Eastman,

Regarding the article you referenced above article, I am going to take issue with the statement about the vacuum needing to be broken to assure even distribution in one pipe steam. As I know for fact, it is not necessary in two pipe steam, and though I can't test it I am not seeing the fundamental difference in one pipe. Somewhere I have seen Hoffman literature talking about using their vacuum vents with intermittent fire, and I don't remember anything about breaking vacuum.

I have stated that in two pipe vacuum, on each refire at the deepest point of the natural vacuum, steam refills the void left by the previous fill, less what is lost to reheat of pipes. With firings less than 20 minutes apart on a well insulated system I have found the reheat part is negligible and the rads nearly reach their previous fill level prior to the end negative pressure as measured at the boiler header. Hence my 3CPH target.

Now obviously this steam flow to the rads has occurred with no venting of air anywhere. I do believe the same thing would occur in a one pipe system allowed to sink into vacuum between firings. I think the steam would fill the void created by the previous fill the same way and in the same proportion everywhere, and then biased venting occurring once again after that as they system returned to atmospheric pressure to push out the small amount each cycle required to cover losses just as I do. Cycling this way, steam never stops moving forward to the rads. The pipes stay warmer reducing the reheat requirement each and every cycle.

If steam can keep moving into the rads from the mains when the boiler first goes off and vacuum is forming, it won't suddenly stop doing that just because you started a new burn and began putting new steam in at the boiler. The vacuum forms gradually and disappears gradually, with steam travelling forward the entire time though at a changing rate.

ChrisJ

For a fact from his extensive testing on one system.

PMJ

ChrisJ said:

For a fact from his extensive testing on one system.

@ChrisJ ,

Would it be OK if @Eastman spoke for himself? He appears interested in the subject of vacuum. So am I. Your comments always seem to end up defensive about your system as it is and making it quite clear there is no place for vacuum in it. Ok with me - really it is.

I am interested in talking about vacuum. By the title of this thread it would appear this is the right place. Maybe not. Please advise.

ChrisJ

> @PMJ said:
> For a fact from his extensive testing on one system.
>
> @ChrisJ ,
>
> Would it be OK if @Eastman spoke for himself? He appears interested in the subject of vacuum. So am I. Your comments always seem to end up defensive about your system as it is and making it quite clear there is no place for vacuum in it. Ok with me - really it is.
>
> I am interested in talking about vacuum. By the title of this thread it would appear this is the right place. Maybe not. Please advise.

Of course it's ok if he responds on this public thread, just as I did.

Though I do find it strange you're claiming that I've made it quite clear there's no place for vacuum in my system in a thread created by me about adding vacuum to my system.

You are quite correct my friend, this is a good place to discuss vacuum. That's why I asked you to. Please, by all means do so.

But also remember, not all systems behave the same and single pipe certainly doesn't behave like two pipe.

Eastman

Here's two Fuel Oil Journal articles on intermittently fired one-pipe:

https://heatinghelp.com/assets/documents/116.pdf
https://heatinghelp.com/assets/documents/121.pdf

These two are generally pro one-pipe vacuum.

Eastman

@PMJ
Do you think zoning with TRVs would work with one-pipe vacuum?

PMJ

ChrisJ said:

> @PMJ said:

> For a fact from his extensive testing on one system.

>

> @ChrisJ ,

>

> Would it be OK if @Eastman spoke for himself? He appears interested in the subject of vacuum. So am I. Your comments always seem to end up defensive about your system as it is and making it quite clear there is no place for vacuum in it. Ok with me - really it is.

>

> I am interested in talking about vacuum. By the title of this thread it would appear this is the right place. Maybe not. Please advise.



Of course it's ok if he responds on this public thread, just as I did.



Though I do find it strange you're claiming that I've made it quite clear there's no place for vacuum in my system in a thread created by me about adding vacuum to my system.

I find it strange to have to say it too @chrisJ.

Maybe it is just my ideas that can't possibly work. The ones coming from one of the very few here who has any actual experience running with natural vacuum. I'm not claiming to be right about everything. I'm learning as I go. But your rejection of a suggestion of mine is often so swift I wonder if you have even possibly read and considered what I wrote.

Anyway, I will continue on. I see @Eastman has just posted some more old articles. I will be reading with interest!

PMJ

Eastman said:

@PMJ
Do you think zoning with TRVs would work with one-pipe vacuum?

Well, though I have no experience personally with them I think they would. Installed at the vent of the rads right?

My basic position is that all balancing/biasing occurs only when the entire system is above atmospheric on initial cold start and any loss replacement venting at the end of each fire if you do frequent cycling as I do. During the vacuum filling/killing part of all refills the steam seeks to refill the system according to the already existing bias. That is the way it is in 2 pipe. So bottom line, I think all biasing occurs with the system over atmospheric anyway just like an open vented system. Any vents/TRV's or anything else that restricts the flow of exiting air would work.

Also, if you are only doing say 1CPH then all the existing vacuum will be killed each new cycle reheating pipes before any refilling of rads occurs. So to me the 1CPH vacuum one pipe system would bias just like an open vented one on every cycle. But it would pick up the benefit of continued steam flow to the rads and additional steam production after the boiler shut down each time.

Again, strictly speculation I admit. Do you have personal experience with it? If I am wrong I sure would like to clearly understand how one and two pipe are different on this one down to the specifics. Sounds like maybe you could help me with that.

ChrisJ

Everything else aside @PMJ how would TRVs on a single pipe system work if what you say holds true? Radiators with closed TRVs would continue to stay cold forever and those that heated fast would continue to do so and so on and so on.

Keep in mind, TRVs use a wax motor and are able to throttle the venting. They don't just do on and off. If it's true that the system will mimic its balance from the first start then the use if TRVs will be pointless. No?

PMJ

Eastman said:

@PMJ
Do you think zoning with TRVs would work with one-pipe vacuum?

Maybe I misread this. Do you mean TRV's on a main for a group of rads?

Eastman

No, you had it right the first time.

I don't have any personal experience with these systems. But it is interesting to read how they were intended to work. There seems to have been a good 100 years where a large variety of technologies and concepts were explored.

PMJ

ChrisJ said:

Everything else aside @PMJ how would TRVs on a single pipe system work if what you say holds true? Radiators with closed TRVs would continue to stay cold forever and those that heated fast would continue to do so and so on and so on.



Keep in mind, TRVs use a wax motor and are able to throttle the venting. They don't just do on and off. If it's true that the system will mimic its balance from the first start then the use if TRVs will be pointless. No?

I think it quite possible that you might find the original bias and repeating to it in vacuum to be preferable to TRV's - again speculation obviously. TRV's do seem more appropriate to fewer cycle fuller fill each time environments.

I think this takes us into the zone I am studying now which is changing conditions. Don't take what I have said too rigidly - like the first cold start bias is cast in stone and will never change. If somehow the system had been off a while and not a dead cold start but no steam left in the rads AND one room is still at temp and its TRV closed then no steam will enter that rad that burn. However, presumably down the road the temp will drop there and that TRV will open. On the very next cycle it will get steam because its TRV is now open. But it won't recover its position on one cycle. It will take time - perhaps too much.

Remember that with natural vacuum the entire system goes from deepest vacuum to above atmospheric and venting every burn of the boiler. It has to or because of the losses you will lose ground every cycle and not keep up. With natural vacuum you simply cannot stay in vacuum all the time. So changes in the venting will change the result - just not quickly. I really don't want any quick changes - just like the coal days. Steady is what I want.

Also, it is hard to appreciate what happens in vacuum with the burner off without experiencing it. During that phase which is a lot(most) of the time the steam will favor the colder areas more than warmer ones where your quick heat up rads are. This doesn't significantly change the bias, but it tends to even out rather than further exaggerate distortions.

PMJ

Eastman said:

No, you had it right the first time.

I don't have any personal experience with these systems. But it is interesting to read how they were intended to work. There seems to have been a good 100 years where a large variety of technologies and concepts were explored.

Exactly right. The disappointing part to me is how much has been lost. From a control standpoint today's standard is no better than forced air. Blast on high until the stat is satisfied then wait. Few have the more advanced controls like @chrisj does. Even the old mercury anticipator has gone away. I mean really? It does surprise me.

Dave in QCA

@chrisj Have you considered converting to 2-pipe with traps at the radiator? While it became the convention to feed 2-pipe radiators at the top, it is not required. Feeding at the bottom will work just fine. When combined to vacuum operation, with a pump or without, the inlet valve can effectively be used to control rooms at different temperatures as you desire.

Paul type systems, which you are designing with added features, work well to provide better balance, temperate season improvements, and reduction of piping losses. But, they do not work well to provided room-by-room control. Your plan to let air back into the system at the beginning of each cycle would probably provide room control abilities in your design. However, it seems to me to negate some or most of the advantages of operating on vacuum in the first place. Just my 2 cents....

ChrisJ

Dave in QCA said:

@chrisj Have you considered converting to 2-pipe with traps at the radiator? While it became the convention to feed 2-pipe radiators at the top, it is not required. Feeding at the bottom will work just fine. When combined to vacuum operation, with a pump or without, the inlet valve can effectively be used to control rooms at different temperatures as you desire.

Paul type systems, which you are designing with added features, work well to provide better balance, temperate season improvements, and reduction of piping losses. But, they do not work well to provided room-by-room control. Your plan to let air back into the system at the beginning of each cycle would probably provide room control abilities in your design. However, it seems to me to negate some or most of the advantages of operating on vacuum in the first place. Just my 2 cents....

Sure,
I'll have it all piped and installed by tonight.

jumper

Remember the device for converting one pipe steam radiator to two pipe (naturally) hot water? The supply distributes to all sections. Will it work with steam so that you can throttle supply while still having unrestricted condensate drainage?

You can also balance one pipe with louvered enclosures or simply covering part of the radiator for less output.

Eastman

@jumper
No that device does not allow one to throttle one-pipe steam.

However, this device apparently does:

"On August 14, 1903, John Collis of Des Moines, Iowa filed a patent for a one-pipe steam supply valve that could be throttled."

This was patent No. 763724

https://patentimages.storage.googleapis.com/6d/35/36/01f65f23c17401/US763724.pdf

Will someone please review this patent and explain how it was supposed to work? I couldn't follow it at all.

Gsmith

It appears to be a two chambered inlet valve for a two pipe steam system. Looks like a sort of plug valve where the upper part lets steam into the radiator and the lower part lets condensate get to the return pipe. Both chambers of the valve throttle by the same amount. The system also has an air vent on the top of the radiator. Wonder if any were actually built.

Eastman

Hmmm.....

It's not really a true one-pipe throttling mechanism then, isn't it?

ChrisJ

I also believe there have been many things patented that do not actually work.

I could be wrong, but I've seen quite a few that certainly seemed that way.

jumper

ChrisJ said:

I also believe there have been many things patented that do not actually work.



I could be wrong, but I've seen quite a few that certainly seemed that way.

I think it's called "Wilson" patent. On this site. A pipe leading to top of radiator to supply steam and then mechanism for draining condensate at bottom. Never see one because it requires a radiator with sections connected at top. So there's another example of patent that won't work for our purposes.

But on the other hand I have seen successful hookups of two pipe devices to one pipe. For example unit heaters connected to one pipe.

This thread is called single pipe vacuum. To me that implies no venting. If you want balance and control I think we have to look elsewhere than on steam pipes. The unit heaters have thermostats controlling the fan so there's your control.But single pipe radiators?

ChrisJ

@jumper all of my radiators are connected across the top.

Eastman

Haven't found the "Wilson" patent, yet.

But "Hubbard's radiator valve" is designed to modulate true one-pipe vapor systems.

https://heatinghelp.com/assets/documents/379.pdf

Essentially, a water column of sufficient length is created to use the weight of the condensate to overcome a vapor system's low operating pressure. This water column extended below the radiator.

jumper

I was certain I downloaded from here.

Eastman

It looks like Wilson's design would flood the radiator.