Single pipe vacuum balancing

ChrisJ

PMJ said:

@chrisj,

I'm sorry you seem to have taken my comment personally.

I merely agreed with you that moving air creates a friction loss. Way back when I started my work and listened to all that air going in and out it all the time it seemed really wasteful to me. It is, so I don't do it anymore.

I'm always happy to lick around the technical aspects of any of this with anyone interested on any thread. I'm not a one pipe expert. It is not my hypothesis. Keeping the air out is a very old idea.

I'm starting this thread to keep things in order.

@PMJ
Keeping the air out is a very old idea.
However, trying to balance improperly sized radiators in a steam system which cycles a lot is a very recent idea. And I would say it most certainly is your hypothesis that it's possible.

We're not lighting a coal fire and letting it simmer all day.

In my case, even if my bedroom radiators weren't grossly oversized I still keep my bedrooms 8 degrees cooler than the rest of the house. My TRVs and slow venting in such rooms allow this. The TRV's also help deal with solar gain etc.

I use TRVs in my kitchen to hold those radiators back, if not totally shut them off if the oven is going.

How can any of this happen with vacuum on a single pipe system?

PMJ

@chrisj,

Everyone always defaults to the idea that one pipe vacuum valves were only for coal fired systems and primarily a once end of day thing when the fire dies down.

I have attached a Hoffman document I am sure everyone has seen which talks about one pipe vacuum systems using their vacuum valve. It says it is also for oil and gas systems saying it will cut down the number of operations per day. Cycles anyone?

Beyond this look for posts of happy one-pipe vacuum system users on this site who obviously are running cycling systems. There aren't many. They get turned away here quickly.

So please, let's get started on the right foot. It is not my hypothesis. I know from first hand experience that natural vacuum in cycling two pipe is a wonderful improvement. From the literature is seems Hoffman thought it was in one-pipe too. They called it "Locking the door against the heat thief".

ChrisJ

PMJ said:

@chrisj,

Everyone always defaults to the idea that one pipe vacuum valves were only for coal fired systems and primarily a once end of day thing when the fire dies down.

I have attached a Hoffman document I am sure everyone has seen which talks about one pipe vacuum systems using their vacuum valve. It says it is also for oil and gas systems saying it will cut down the number of operations per day. Cycles anyone?

Beyond this look for posts of happy one-pipe vacuum system users on this site who obviously are running cycling systems. There aren't many. They get turned away here quickly.

So please, let's get started on the right foot. It is not my hypothesis. I know from first hand experience that natural vacuum in cycling two pipe is a wonderful improvement. From the literature is seems Hoffman thought it was in one-pipe too. They called it "Locking the door against the heat thief".

@PMJ

You basically answered with "My best friend's sister's boyfriend's brother's girlfriend heard from this guy who knows this kid who's going with the girl who saw it work"

I was hoping you would explain some ideas behind why it should work since you've brought it up so many times. If anyone else who has tried it cares to comment I'd love to hear.

I'm certainly not going to do a lot of work and modifications to my system based on rumors. Especially when I feel the idea is fundamentally flawed. This is why I was hoping you could go into some detail of why you think it will work.

acwagner

@ChrisJ Is your question if you were able to convert your single pipe system to a single pipe vacuum setup, would you still be able to "zone" certain rooms similar to a TRV setup?

ChrisJ

acwagner said:

@ChrisJ Is your question if you were able to convert your single pipe system to a single pipe vacuum setup, would you still be able to "zone" certain rooms similar to a TRV setup?

Yes.
As well as would slower vents still be able to "hold back" oversized radiators. I.E. can I balance rooms by vent speeds like I can now.

acwagner

I suppose it depends on how the system is modified.

If you modified all the vents on your system to have a low cracking pressure check valve in series with them (which the Hoffman #2 appears to be), then initial filling of radiators would operate the same in terms of "holding back" flow to radiators.

Once it goes to vacuum, then it will be governed by the lowest pressure in the system, which is a function of the heatloss of radiators to their respective rooms. From what @PMJ has been saying, this process is self governing in that it keeps the temperature uniform throughout the house.

I don't see how that setup would allow the "zoning" that the TRVs allow you to do, without using.....TRVs.

But, since TRVs need to be in conjunction with a vent, if you could modify the vent (including main vents) you could potentially get the benefits of the TRV plus vacuum.

I've considered trying this on my own system, but I couldn't find an inline low/zero cracking pressure check valve that I could add to a Gorton vent that was rated for steam temperatures. I think the lowest cracking pressures I saw was like 0.5 psi. Too high for our systems.

ChrisJ

acwagner said:

I suppose it depends on how the system is modified.

If you modified all the vents on your system to have a low cracking pressure check valve in series with them (which the Hoffman #2 appears to be), then initial filling of radiators would operate the same in terms of "holding back" flow to radiators.

Once it goes to vacuum, then it will be governed by the lowest pressure in the system, which is a function of the heatloss of radiators to their respective rooms. From what @PMJ has been saying, this process is self governing in that it keeps the temperature uniform throughout the house.

I don't see how that setup would allow the "zoning" that the TRVs allow you to do, without using.....TRVs.

But, since TRVs need to be in conjunction with a vent, if you could modify the vent (including main vents) you could potentially get the benefits of the TRV plus vacuum.

I've considered trying this on my own system, but I couldn't find an inline low/zero cracking pressure check valve that I could add to a Gorton vent that was rated for steam temperatures. I think the lowest cracking pressures I saw was like 0.5 psi. Too high for our systems.

How is it self governing?
Because the system is in a vacuum it stops following all of the other rules?

If you set the system up correctly, the check valves likely will never see steam.

PMJ

ChrisJ said:

acwagner said:

@ChrisJ Is your question if you were able to convert your single pipe system to a single pipe vacuum setup, would you still be able to "zone" certain rooms similar to a TRV setup?

Yes.
As well as would slower vents still be able to "hold back" oversized radiators. I.E. can I balance rooms by vent speeds like I can now.

My experience is that radiator fill level is determined in above atmospheric conditions only and therefore only by vents and valves. Atmospheric conditions occur in the initial fill and and the end of every subsequent refill when the small amount of air that leaks in each cycle must be removed. The portion of each refill that occurs in vacuum returns each rad to its previously filled level, it does not change it. Radiators which I valve down to run 1/2 full remain so cycle after cycle, even though the system stays in vacuum some 80+% of the time.

ChrisJ

PMJ said:

ChrisJ said:

acwagner said:

@ChrisJ Is your question if you were able to convert your single pipe system to a single pipe vacuum setup, would you still be able to "zone" certain rooms similar to a TRV setup?

Yes.
As well as would slower vents still be able to "hold back" oversized radiators. I.E. can I balance rooms by vent speeds like I can now.

My experience is that radiator fill level is determined in above atmospheric conditions only and therefore only by vents and valves. Atmospheric conditions occur in the initial fill and and the end of every subsequent refill when the small amount of air that leaks in each cycle must be removed. The portion of each refill that occurs in vacuum returns each rad to its previously filled level, it does not change it. Radiators which I valve down to run 1/2 full remain so cycle after cycle, even though the system stays in vacuum some 80+% of the time.

How does that make sense though?
I can see how friction losses could keep radiators different, but the greater the pressure difference, the easier it will overcome this and "drift". No?

How much of a pressure difference do you feel a 50% radiator has vs a 100% fill one during an off cycle?

KC_Jones

PMJ said:

Radiators which I valve down to run 1/2 full remain

We can't do this on 1 pipe, so we need an alternate control method. This is the point Chris is trying to make, you have control, the idea of vacuum on 1 pipe removes the control we do have.

Also the comment about keeping things even is exactly what Chris is trying not to do, like many of us. I also keep the bedrooms cooler with small vents on those rads.

You mistake our comments for being against vacuum, personally it sounds cool, but I am not going to put effort into something unless we can figure out the answers to all the questions.

PMJ

KC_Jones said:

PMJ said:

Radiators which I valve down to run 1/2 full remain

We can't do this on 1 pipe, so we need an alternate control method. This is the point Chris is trying to make, you have control, the idea of vacuum on 1 pipe removes the control we do have.

Also the comment about keeping things even is exactly what Chris is trying not to do, like many of us. I also keep the bedrooms cooler with small vents on those rads.

You mistake our comments for being against vacuum, personally it sounds cool, but I am not going to put effort into something unless we can figure out the answers to all the questions.

On one pipe the fill control method is the rad vent instead of the valve as you know.

I don't remember saying anything about even as in all the same. I'm saying I think things can return to the same place cycle after cycle, just as uneven from a fill standpoint as you make them like you do now.

acwagner

I don't see it violating any rules, but perhaps we're interpreting that statement differently. I see it as when it switches to vacuum the steam continues to flow from the boiler to the radiators proportionally to their demand. It doesn't become unbalance and suddenly send all the steam to the nearest radiator making that room unbearably hot compared to other rooms or some other arbitrary response. That's what I meant by self governing.

I'm not saying a vacuum setup can correct for oversized radiators in a room, or an oversized boiler, or stop temperature overshooting at the thermostat.

I agree that the check valve in theory shouldn't see the steam, but if a vent failed to close for whatever reason (say debris blocking it) then it would see steam. For a short term experiment that wouldn't be a problem. I'm not sure what would happen if just one vent/valve combo failed. I guess it would whistle when the boiler shut down and all the air rushed in from that one point?

PMJ

ChrisJ said:

PMJ said:

ChrisJ said:

acwagner said:

@ChrisJ Is your question if you were able to convert your single pipe system to a single pipe vacuum setup, would you still be able to "zone" certain rooms similar to a TRV setup?

Yes.
As well as would slower vents still be able to "hold back" oversized radiators. I.E. can I balance rooms by vent speeds like I can now.

My experience is that radiator fill level is determined in above atmospheric conditions only and therefore only by vents and valves. Atmospheric conditions occur in the initial fill and and the end of every subsequent refill when the small amount of air that leaks in each cycle must be removed. The portion of each refill that occurs in vacuum returns each rad to its previously filled level, it does not change it. Radiators which I valve down to run 1/2 full remain so cycle after cycle, even though the system stays in vacuum some 80+% of the time.

How does that make sense though?
I can see how friction losses could keep radiators different, but the greater the pressure difference, the easier it will overcome this and "drift". No?

How much of a pressure difference do you feel a 50% radiator has vs a 100% fill one during an off cycle?

Pressure differences throughout the system are tiny.

I have seen no evidence that a big radiator steals anything from a small one. All rads still condensing steam must get more steam from the main or they quickly become the lowest pressure spot in the system and the steam has no choice but to go there. All I have observed is a remarkable return to the previous fill level in all places whatever that was during the vacuum state. That previous level was determined the standard way - above atmospheric.

ChrisJ

PMJ said:

ChrisJ said:

PMJ said:

ChrisJ said:

acwagner said:

@ChrisJ Is your question if you were able to convert your single pipe system to a single pipe vacuum setup, would you still be able to "zone" certain rooms similar to a TRV setup?

Yes.
As well as would slower vents still be able to "hold back" oversized radiators. I.E. can I balance rooms by vent speeds like I can now.

My experience is that radiator fill level is determined in above atmospheric conditions only and therefore only by vents and valves. Atmospheric conditions occur in the initial fill and and the end of every subsequent refill when the small amount of air that leaks in each cycle must be removed. The portion of each refill that occurs in vacuum returns each rad to its previously filled level, it does not change it. Radiators which I valve down to run 1/2 full remain so cycle after cycle, even though the system stays in vacuum some 80+% of the time.

How does that make sense though?
I can see how friction losses could keep radiators different, but the greater the pressure difference, the easier it will overcome this and "drift". No?

How much of a pressure difference do you feel a 50% radiator has vs a 100% fill one during an off cycle?

Pressure differences throughout the system are tiny.

I have seen no evidence that a big radiator steals anything from a small one. All rads still condensing steam must get more steam from the main or they quickly become the lowest pressure spot in the system and the steam has no choice but to go there. All I have observed is a remarkable return to the previous fill level in all places whatever that was during the vacuum state. That previous level was determined the standard way - above atmospheric.

90% of the winter my front bedroom radiator is ice cold. The TRV is completely shut. Only on windy days will it heat, some of those days it heats a lot.

A rear large bedroom heats at night, but not during the day due to sun.

My kitchen radiators heat unless the oven is going, and sometimes one of two radiators doesn't heat due to sun.

My livingroom heats all of the time, though it's held back a lot unless there's a strong wind out of the North.


My single pipe steam system with 10 radiators in reality has 6 zones.

There are days my system literally shuts off half of it's radiation to maintain comfort.

Jamie Hall

At the risk of being somewhat simple minded...

Let's suppose that we decide to run a one pipe (or two pipe, for that matter) system at a vacuum. Either natural or imposed (pump, ejector, what have you). Let's not, for the moment, worry about removing all that bad air from cycle to cycle, but let's think about how the system actually operates once the air is removed.

What the interior of the system "sees" is one pressure -- let's say for argument 6 ounces per square inch gauge -- at the boiler. It "sees" another pressure at the outlet of any vents, whether at the radiator or on a main. In an atmospheric system, that would be 0 psi gauge. In a vacuum system, let's say for argument that we have a negative gauge pressure of - 24 ounces (3 inches of vacuum) gauge. In the atmospheric case, the driving pressure on the system is a total of 6 ounces per square inch. In the vacuum case, the driving pressure is 30 ounces per square inch.

It is the driving pressure in the system which will govern where steam goes and how fast it will get there. The system doesn't care two hoots and a loud yell what the air pressure is on the outside of the pipes.

Now what will change as a result of the absolute pressure inside the system is the temperature at which the steam will condense, and hence the BTUh output of the radiators.

Again, not to be too simple minded about it, on a two pipe system the easiest way to operate with the system in a vacuum is to replace the main vents with Hoffman 76s. Pricey, but they will hold a vacuum very nicely. Not sure about a one pipe system, but small diameter vacuum pipes instead of radiator vents would seem to be in order...

I might add -- throwing another monkey wrench here -- that while the temperature of the space into which a radiator is radiating will affect the rate at which it can condense steam, if the inlet valve is open the internal pressure of the radiator will be that of the steam main to which it is attached, with only very small differences dues to friction losses. Hence all radiators in a system, so long as the inlet valves are open, will see pressures within ounces of each other, regardless of how fast they are condensing (within "normal" limits of velocity, of course)

acwagner

I think single pipe would still have control using the vents/TRV if it had a check valve. We say "vacuum" but it's just less than atmospheric inside the system--there's still air in there. The next cycle the vents/TRV would operate the same, just that there is less overall air to be purged assuming the system is tight. This all assumes the check valve has a low cracking pressure, otherwise you're just building pressure to overcome the check valve, which seems kind of pointless. Probably defeats the purpose of setting up the vacuum in the first place.

ethicalpaul

acwagner said:

I've considered trying this on my own system, but I couldn't find an inline low/zero cracking pressure check valve that I could add to a Gorton vent that was rated for steam temperatures. I think the lowest cracking pressures I saw was like 0.5 psi. Too high for our systems.

I am in complete agreement with this. I too was interested in my one pipe system holding some vacuum and I even bought a couple of the lowest cracking pressure check valves that I could find, but they were not nearly low enough for me to even try to test.

PMJ

acwagner said:

I think single pipe would still have control using the vents/TRV if it had a check valve. We say "vacuum" but it's just less than atmospheric inside the system--there's still air in there. The next cycle the vents/TRV would operate the same, just that there is less overall air to be purged assuming the system is tight. This all assumes the check valve has a low cracking pressure, otherwise you're just building pressure to overcome the check valve, which seems kind of pointless. Probably defeats the purpose of setting up the vacuum in the first place.

With regard to the low cracking pressure - I have a cheap plastic water check valve setup on my system to relieve pressure should my solenoid fail to open. I have run a while with only that here and there. I'm not sure the cracking pressure but I think maybe .25psi which is way higher than any pressure I ever see normally.

Even running that way is more efficient that open vented. I think the major advantages to the partial vacuum are that steam stays traveling to the rads 100% of the time and that there is dramatically less time or effort lost removing air. The period of time that your system would have to go to 6oz to push a very small amount of air out would be very short. The benefits of the vacuum would still be there 80% of the time. That alone would not stop me from trying. How alike they all are with regards to cracking pressure might be more of an issue.

jumper

Plug all vents. Evacuate air at one strategic place. Two pipe type TRV s can control amount of steam entering a one pipe radiator. But will they allow condensate to drain? What happens when try to adjust one pipe radiator's heat output by messing with its valve?

PMJ

jumper said:

Plug all vents. Evacuate air at one strategic place. Two pipe type TRV s can control amount of steam entering a one pipe radiator. But will they allow condensate to drain? What happens when try to adjust one pipe radiator's heat output by messing with its valve?

I think air(and there is always some air) must have a way out of every radiator separate from where the steam comes in or they will never fill. This is why 2 pipe is so much easier - the air exit of all rads is already tied together so air can easily be removed in one place.

ChrisJ

With my idea of a brazed copper and brass system there would be no issues of air getting in.

PMJ

Jamie Hall said:

At the risk of being somewhat simple minded...

Let's suppose that we decide to run a one pipe (or two pipe, for that matter) system at a vacuum. Either natural or imposed (pump, ejector, what have you). Let's not, for the moment, worry about removing all that bad air from cycle to cycle, but let's think about how the system actually operates once the air is removed.

What the interior of the system "sees" is one pressure -- let's say for argument 6 ounces per square inch gauge -- at the boiler. It "sees" another pressure at the outlet of any vents, whether at the radiator or on a main. In an atmospheric system, that would be 0 psi gauge. In a vacuum system, let's say for argument that we have a negative gauge pressure of - 24 ounces (3 inches of vacuum) gauge. In the atmospheric case, the driving pressure on the system is a total of 6 ounces per square inch. In the vacuum case, the driving pressure is 30 ounces per square inch.

It is the driving pressure in the system which will govern where steam goes and how fast it will get there. The system doesn't care two hoots and a loud yell what the air pressure is on the outside of the pipes.

Now what will change as a result of the absolute pressure inside the system is the temperature at which the steam will condense, and hence the BTUh output of the radiators.

Again, not to be too simple minded about it, on a two pipe system the easiest way to operate with the system in a vacuum is to replace the main vents with Hoffman 76s. Pricey, but they will hold a vacuum very nicely. Not sure about a one pipe system, but small diameter vacuum pipes instead of radiator vents would seem to be in order...

I might add -- throwing another monkey wrench here -- that while the temperature of the space into which a radiator is radiating will affect the rate at which it can condense steam, if the inlet valve is open the internal pressure of the radiator will be that of the steam main to which it is attached, with only very small differences dues to friction losses. Hence all radiators in a system, so long as the inlet valves are open, will see pressures within ounces of each other, regardless of how fast they are condensing (within "normal" limits of velocity, of course)

I agree with this in principle. You find though running in natural vacuum that the pressure difference numbers are very small. The important thing is that steam moves from the boiler to mains to rads 100% of the call time. Open vented air enters rads immediately upon every boiler stop and time and effort is wasted removing next cycle.

You are also correct that the temperature outside the rad has a big impact on condensation rate. Also that all rads remain very close in pressure, regardless of the total condensation occurring in each.

ChrisJ

@PMJ

So,

How do I get my TRVs to work with it on a single pipe system? I've described how they currently work. That gives me far greater comfort and saves me more fuel than vacuum alone would.

Fizz

So, if you put vacuum vent(s) at end of return on one pipe system, would this cause vapor lock? Also, could it put boiler in vacuum causing low temp steam potential? What's worse case scenario?

PMJ

ChrisJ said:

@PMJ



So,



How do I get my TRVs to work with it on a single pipe system? I've described how they currently work. That gives me far greater comfort and saves me more fuel than vacuum alone would.

I think a zero pressure check valve inside the TRVs and they work fine except you dont process all the air. You describe a need for some pretty dramatic and abrupt changes - something few recommend for steam systems generally. Seems to me you have all you want or need.

So I am confused. You seem certain vacuum has nothing to offer you. I'm really not trying to convince you otherwise. So what is your interest in this thread?

ChrisJ

> @PMJ said:
> (Quote)
> I think a zero pressure check valve inside the TRVs and they work fine except you dont process all the air. You describe a need for some pretty dramatic and abrupt changes - something few recommend for steam systems generally. Seems to me you have all you want or need.
>
> So I am confused. You seem certain vacuum has nothing to offer you. I'm really not trying to convince you otherwise. So what is your interest in this thread?


My system adapts and conforms to conditions and it does it amazingly well. I can also do a 10 degree recovery with no issue, something else people say steam shouldn't do. Though, if a lot of TRVs are shut, it could build pressure and have the Ecosteam shut it down for 10 minutes at 8"WC. But that's never happened yet other than during a test.


My interest in this thread is to see what comes out of it. Let's see if anyone actually using single pipe vacuum chimes in.

The Paul system has interested me for years but I still don't believe simply adding check valves will work.


Basically, prove me wrong. Even without TRVs.
If you can change my mind I'll gladly climb aboard the vacuum train.

Right now I'm convinced vacuum will not work correctly on a single pipe system. I'm hoping to get some feedback from those who are running them.

PMJ

ChrisJ said:

> @PMJ said:

> (Quote)

> I think a zero pressure check valve inside the TRVs and they work fine except you dont process all the air. You describe a need for some pretty dramatic and abrupt changes - something few recommend for steam systems generally. Seems to me you have all you want or need.

>

> So I am confused. You seem certain vacuum has nothing to offer you. I'm really not trying to convince you otherwise. So what is your interest in this thread?





My system adapts and conforms to conditions and it does it amazingly well. I can also do a 10 degree recovery with no issue, something else people say steam shouldn't do. Though, if a lot of TRVs are shut, it could build pressure and have the Ecosteam shut it down for 10 minutes at 8"WC. But that's never happened yet other than during a test.





My interest in this thread is to see what comes out of it. Let's see if anyone actually using single pipe vacuum chimes in.



The Paul system has interested me for years but I still don't believe simply adding check valves will work.





Basically, prove me wrong. Even without TRVs.

If you can change my mind I'll gladly climb aboard the vacuum train.



Right now I'm convinced vacuum will not work correctly on a single pipe system. I'm hoping to get some feedback from those who are running them.

@chrisj,

Reading through your posts it seems rather clear that you receive my comments about the benefits of vacuum as an attack on your system. They surely are not meant as such. Vacuum has done wonders for me. I write for the very few who might be interested in resurrecting this old technology which I think actually very effective. It does not appear that you are one of those interested. That's really fine with me. Obviously you have plenty of company.

I have not just dreamed up this idea for vacuum in one pipe systems. Hoffman did that long ago and documented it I think rather clearly for cycling systems too. Perhaps they had it all wrong. I can't prove it one way or the other. Hoffman has a pretty good reputation in steam though and would be good enough for me to move forward if I had a one pipe system. Based on what I have found in two pipe there would be no question but that I would try. To each his own.

ChrisJ

PMJ said:

ChrisJ said:

> @PMJ said:

> (Quote)

> I think a zero pressure check valve inside the TRVs and they work fine except you dont process all the air. You describe a need for some pretty dramatic and abrupt changes - something few recommend for steam systems generally. Seems to me you have all you want or need.

>

> So I am confused. You seem certain vacuum has nothing to offer you. I'm really not trying to convince you otherwise. So what is your interest in this thread?





My system adapts and conforms to conditions and it does it amazingly well. I can also do a 10 degree recovery with no issue, something else people say steam shouldn't do. Though, if a lot of TRVs are shut, it could build pressure and have the Ecosteam shut it down for 10 minutes at 8"WC. But that's never happened yet other than during a test.





My interest in this thread is to see what comes out of it. Let's see if anyone actually using single pipe vacuum chimes in.



The Paul system has interested me for years but I still don't believe simply adding check valves will work.





Basically, prove me wrong. Even without TRVs.

If you can change my mind I'll gladly climb aboard the vacuum train.



Right now I'm convinced vacuum will not work correctly on a single pipe system. I'm hoping to get some feedback from those who are running them.

@chrisj,

Reading through your posts it seems rather clear that you receive my comments about the benefits of vacuum as an attack on your system. They surely are not meant as such. Vacuum has done wonders for me. I write for the very few who might be interested in resurrecting this old technology which I think actually very effective. It does not appear that you are one of those interested. That's really fine with me. Obviously you have plenty of company.

I have not just dreamed up this idea for vacuum in one pipe systems. Hoffman did that long ago and documented it I think rather clearly for cycling systems too. Perhaps they had it all wrong. I can't prove it one way or the other. Hoffman has a pretty good reputation in steam though and would be good enough for me to move forward if I had a one pipe system. Based on what I have found in two pipe there would be no question but that I would try. To each his own.

@PMJ
This would be an incorrect interpretation on your part. I have never felt you were attacking anything.

I feel your assumptions of how a single pipe system behaves may be incorrect and am looking for those who are running single pipe systems in vacuum to come forward and share their experiences.

You have said multiple times there are several people doing it successfully.

PMJ

You have said multiple times there are several people doing it successfully.

Not so - didn't say that. I know of at least one poster from several years back who loved his one pipe vacuum system looking for replacement Hoffman valves who was told one pipe vacuum doesn't work. Don't have it handy. Search the site.

My position that this is possible is based on Hoffman. Please read that. You keep assigning the whole thing to me.

acwagner

I believe this is the post that @PMJ is referring to:

https://forum.heatinghelp.com/discussion/66051/vacuum-vent-valves-for-steam-radiators#latest

ChrisJ

PMJ said:

You have said multiple times there are several people doing it successfully.

Not so - didn't say that. I know of at least one poster from several years back who loved his one pipe vacuum system looking for replacement Hoffman valves who was told one pipe vacuum doesn't work. Don't have it handy. Search the site.

My position that this is possible is based on Hoffman. Please read that. You keep assigning the whole thing to me.

PMJ said:

@chrisj,

Everyone always defaults to the idea that one pipe vacuum valves were only for coal fired systems and primarily a once end of day thing when the fire dies down.

I have attached a Hoffman document I am sure everyone has seen which talks about one pipe vacuum systems using their vacuum valve. It says it is also for oil and gas systems saying it will cut down the number of operations per day. Cycles anyone?

Beyond this look for posts of happy one-pipe vacuum system users on this site who obviously are running cycling systems. There aren't many. They get turned away here quickly.

So please, let's get started on the right foot. It is not my hypothesis. I know from first hand experience that natural vacuum in cycling two pipe is a wonderful improvement. From the literature is seems Hoffman thought it was in one-pipe too. They called it "Locking the door against the heat thief".

Maybe I misunderstood.

Gsmith

@ethicalpaul and @acwagner : I too have been interested in converting my one pipe steam system to vacuum if I can find a simple and reliable way to do it. You might look into Generant DiscValves which have a very low cracking pressure (they claim 1" water column which is about 0.036 psi or about 0.5 oz/sq. in. I've been thinking of trying them attached to a clear vinyl hose clampted to the outlet of a standard radiator valve so they don't see steam pressure (they claim 212 deg F as max operating temperature). I haven't priced the whole assembly but think it might be pretty pricey, but maybe in total on a par with running small diameter vacuum lines from each radiator to a central control area. Attached is a cut sheet from Generant (made in NJ)

ChrisJ

Gary Smith said:

@ethicalpaul and @acwagner : I too have been interested in converting my one pipe steam system to vacuum if I can find a simple and reliable way to do it. You might look into Generant DiscValves which have a very low cracking pressure (they claim 1" water column which is about 0.036 psi or about 0.5 oz/sq. in. I've been thinking of trying them attached to a clear vinyl hose clampted to the outlet of a standard radiator valve so they don't see steam pressure (they claim 212 deg F as max operating temperature). I haven't priced the whole assembly but think it might be pretty pricey, but maybe in total on a par with running small diameter vacuum lines from each radiator to a central control area. Attached is a cut sheet from Generant (made in NJ)

Have you been able to get a quote on those valves? I'm curious what they go for?

acwagner

@Gary Smith

Thanks! I saw that Generant check valve during my research as well, however I couldn't find a vendor. Any idea where they could be purchased?

Gsmith

No I have not taken the time yet, not sure if they can be bought from the factory or from a distributor, the website is not clear on that.

Gsmith

Their website indicates the company's phone number is: 973- 838-6500

acwagner

I also considered making my own. I came up with the attached assembly.

In theory it has a low cracking pressure (if using a teflon bearing) and all the materials are rated for temperatures above steam. However, I don't know how well it will seal and hold a vacuum.

I did make a test one. I found using a steel bearing and pressing it into the copper cap made a better connection. But I haven't gotten around to pressure testing it to see if it would hold a vacuum. Other house projects got in the way.

Gsmith

Interesting. I also remember dimly reading a post on this forum quite a while ago (some years ago) about someone using used rifle cartridges to make a homemade vacuum valve but I've lost the thread.

acwagner

Is this the thread you are thinking of?

https://forum.heatinghelp.com/discussion/163498/back-to-vacuum

The valve discussion is at the end. Sounds like the original poster made something similar to what was proposed.

PMJ

ChrisJ said:

PMJ said:

You have said multiple times there are several people doing it successfully.

Not so - didn't say that. I know of at least one poster from several years back who loved his one pipe vacuum system looking for replacement Hoffman valves who was told one pipe vacuum doesn't work. Don't have it handy. Search the site.

My position that this is possible is based on Hoffman. Please read that. You keep assigning the whole thing to me.

PMJ said:

@chrisj,

Everyone always defaults to the idea that one pipe vacuum valves were only for coal fired systems and primarily a once end of day thing when the fire dies down.

I have attached a Hoffman document I am sure everyone has seen which talks about one pipe vacuum systems using their vacuum valve. It says it is also for oil and gas systems saying it will cut down the number of operations per day. Cycles anyone?

Beyond this look for posts of happy one-pipe vacuum system users on this site who obviously are running cycling systems. There aren't many. They get turned away here quickly.

So please, let's get started on the right foot. It is not my hypothesis. I know from first hand experience that natural vacuum in cycling two pipe is a wonderful improvement. From the literature is seems Hoffman thought it was in one-pipe too. They called it "Locking the door against the heat thief".

Maybe I misunderstood.

My apologies Chris. I admit to a small embellishment there. I did say there aren't many did I not?

However, just to show it is not totally made up here is one:
https://forum.heatinghelp.com/discussion/66051/vacuum-vent-valves-for-steam-radiators

A long time ago, yes, but it my opinion this fellow has it exactly right. He lists the same things he likes about the vacuum I do and Hoffman describes. The reception shows why they're aren't many here and won't be.

ChrisJ

PMJ said:

ChrisJ said:

PMJ said:

You have said multiple times there are several people doing it successfully.

Not so - didn't say that. I know of at least one poster from several years back who loved his one pipe vacuum system looking for replacement Hoffman valves who was told one pipe vacuum doesn't work. Don't have it handy. Search the site.

My position that this is possible is based on Hoffman. Please read that. You keep assigning the whole thing to me.

PMJ said:

@chrisj,

Everyone always defaults to the idea that one pipe vacuum valves were only for coal fired systems and primarily a once end of day thing when the fire dies down.

I have attached a Hoffman document I am sure everyone has seen which talks about one pipe vacuum systems using their vacuum valve. It says it is also for oil and gas systems saying it will cut down the number of operations per day. Cycles anyone?

Beyond this look for posts of happy one-pipe vacuum system users on this site who obviously are running cycling systems. There aren't many. They get turned away here quickly.

So please, let's get started on the right foot. It is not my hypothesis. I know from first hand experience that natural vacuum in cycling two pipe is a wonderful improvement. From the literature is seems Hoffman thought it was in one-pipe too. They called it "Locking the door against the heat thief".

Maybe I misunderstood.

My apologies Chris. I admit to a small embellishment there. I did say there aren't many did I not?

However, just to show it is not totally made up here is one:
https://forum.heatinghelp.com/discussion/66051/vacuum-vent-valves-for-steam-radiators

A long time ago, yes, but it my opinion this fellow has it exactly right. He lists the same things he likes about the vacuum I do and Hoffman describes. The reception shows why they're aren't many here and won't be.

@PMJ
I do not see anyone being disrespectful in that thread.
@Steamhead Was giving what he believed to be sound advice.

I also do not see any indication that the OP's system had been running in a vacuum. It sounded like he was trying to restore it's vacuum operation and that the vents were likely all leaky.

The benefits he says sounds like he's quoting sales literature.