Single pipe vacuum idea

ChrisJ

I don't know, think it'll work?
I came up with it this morning.

The drawing is far from perfect and ignore the fact it's apparently a counter flow system.
The valves by the solenoids are used to throttle the vacuum flow if necessary for balancing, aside from the thermostat system.

The PLC would control everything based on thermostats and time. When the boiler is off all solenoids are closed except the one to atmosphere. The PLC fires the boiler up when it determines enough rooms want heat. Once steaming it closes the atmosphere solenoid and opens the solenoid to the main vent vacuum line. Once that line starts getting hot the solenoid closes and allows the rooms to receive vacuum.

Canucker

Would you need all the solenoids and vac lines if it was a single temp system? Could trv's be used for each room? Once you're under vacuum and filled the system with steam, I'd imagine the system would self balance, as the colder rooms would condense more and draw more steam. At least that's been my experience with the closed vacuum systems I work with that have multiple condenser temps. I believe @PMJ has experienced this too

ChrisJ

Canucker said:

Would you need all the solenoids and vac lines if it was a single temp system? Could trv's be used for each room? Once you're under vacuum and filled the system with steam, I'd imagine the system would self balance, as the colder rooms would condense more and draw more steam. At least that's been my experience with the closed vacuum systems I work with that have multiple condenser temps. I believe @PMJ has experienced this too

PMJ's system is a two pipe.
Single pipe systems are said to constantly have problems with balancing when in a vacuum. Another issue is radiator sizing. I know my own system has two radiators that are grossly oversized for the spaces.

The main point of this system is to speed up venting and make it controllable, each room being it's own zone.

I also feel there may be a way to have a solenoid that can open to atmosphere for a short time to stop a radiator from heating once the boiler is running.


Could this pull the entire system below atmosphere to lower the temperatures as well? I don't know, I think it'd be risky regarding balancing. Especially in homes where radiators are no longer appropriate for the space.

TRV's won't work on a single pipe vacuum system.

Canucker

Are the balancing problems because there are small leaks in the rads? I could see that making it difficult.

ChrisJ

Canucker said:

Are the balancing problems because there are small leaks in the rads? I could see that making it difficult.

No idea, I've never tried it my self.
I already know I'll have severe balancing issues just from sizing.

Rumor on the streets is draining can also be an issue on single pipe systems.

PMJ

I like it a lot @ChrisJ .

I also think there are lots of possibilities short of actual mechanical vacuum. Regardless of that, the starting place is the lines to a central place with control solenoid valves. Consider doing the extra to plumb the lines to each rad with valves such that you could switch back and forth easily between testing your new approach and your standard venting.

Please go for this.

ratio

How/will you keep steam out of the vacuum system?

ChrisJ

> @ratio said:
> How/will you keep steam out of the vacuum system?

I explained that in how the system functions

Pumpguy

Look into a Paul system. They are one pipe systems piped very similar to yours. On the outlet of each rad is a "Paul Valve" that closes when the rad fills with steam.

ChrisJ

Pumpguy said:

Look into a Paul system. They are one pipe systems piped very similar to yours. On the outlet of each rad is a "Paul Valve" that closes when the rad fills with steam.

I've seen very little on it, but from what I gather the Paul system still won't help with radiators that are sized wrong. Also, where does one get "Paul valves" these days?

PMJ

@ChrisJ , the central solenoid approach once installed would allow a level of control well beyond what I have in my 2 pipe. You basically turn down/off some rooms on a schedule for instance - you just need a PLC with a real time clock. In the same way you could limit how full oversized rads ever got. I think it would be incredible actually.

Gordy

Since this is a fix for over sized rads. Why not get right sized rads instead of complicating simplicity?

ChrisJ

Gordy said:

Since this is a fix for over sized rads. Why not get right sized rads instead of complicating simplicity?

Where did you see "this is a fix for oversized rads".
This is an improvement for a lot of things, not to mention tampering with 80-100 year old radiators is asking for problems. Especially when all of them use the special nipples for assembly like mine.

However, back to,
Where did you see "this is a fix for oversized rads"??

This turns a single pipe system into a completely zoned system as well as forces it to vent much faster than normally possible.

Gordy

I guess I miss spoke. However when I see "Zone" in heating season usually it pertains to the ability to have cooler rooms than desired whole house setpoint. Say bedrooms, or in bigger homes unused rooms set to a much lower unoccupied temp.

You can achieve lower, or higher desired setpoints in rooms through sizing emitters according to the heat loss of a room. All the while using the same supply temp the other rooms have.

With zoning comes unintended consequences back at the boiler room more specifically the boiler, and its ability to handle the smaller zone loads efficiently. It also adds more hardware, and controls to a simple system. Is the lesser loads a problem for a steam boiler sized to the edr?

forgive my steam ignorance. I'm only trying to understand why one would want to complicate it.

Is the return in efficiency worth the extra cost to do as you propose? Why not just use trvs? Is this a bandaid to a poorly designed, or leaky system?

ChrisJ

I'm not so sure I can forgive your "steam ignorance". I mean, you're responding to a steam thread in the steam section.

AMservices

Your over complicating things. You only need 1 solenoid valve on the common vacuum line manifold. You would use the ball valves at the radiator to balance the airflow out of the system. As long as the vacuum line manifold is able to drain condensate back into the system, there is no problem with steam entering the vacuum lines.

ChrisJ

AMservices said:

Your over complicating things. You only need 1 solenoid valve on the common vacuum line manifold. You would use the ball valves at the radiator to balance the airflow out of the system. As long as the vacuum line manifold is able to drain condensate back into the system, there is no problem with steam entering the vacuum lines.

The hard and expensive part is running the copper tubing.
Once it's there, why not add solenoids for each room so you can zone them all separately? Could also adjust timing to whatever each room wants.

In theory...........perfection.

AMservices

You'd end up short cycling you boil a very quickly. If you have 10 radiators in only 2 of them are calling for heat. But then what happens when one of them satisfies and the other one is still calling?
The solenoid valve with close on the vacuum line, but because there's no way to close the steam Supply, you will overheat the other room

ChrisJ

That would all be handled by the PLC. It wouldn't fire the boiler unless enough rooms need heat.

PMJ

> @ChrisJ said:
> Your over complicating things. You only need 1 solenoid valve on the common vacuum line manifold. You would use the ball valves at the radiator to balance the airflow out of the system. As long as the vacuum line manifold is able to drain condensate back into the system, there is no problem with steam entering the vacuum lines.
>
>
> The hard and expensive part is running the copper tubing.
> Once it's there, why not add solenoids for each room so you can zone them all separately? Could also adjust timing to whatever each room wants.
>
> In theory...........perfection.

You are right here @ChrisJ. The individual valves give you options. You are going for the ability to respond automatically without manual valves. I wouldn't worry a bit about reducing EDR at some times and boiler size as you know. You just cycle an appropriate on vs off percentage for the EDR you have open (which the PLC obviously knows how much it is at any time because it closed the valves.

Please consider the even cycle approach. If you don't need as much steam you just run a lower percentage on time vs off. You can not do this running to a pressure stop no matter how low. Put the required amount of steam out there in short even burns with natural vacuum during the longer waits in between. I promise it will work wonders.

steamedchicago

ChrisJ said:

I've seen very little on it, but from what I gather the Paul system still won't help with radiators that are sized wrong. Also, where does one get "Paul valves" these days?

A supply house. Hoffman number 3, part number 401419.

AMservices

ChrisJ said:

That would all be handled by the PLC. It wouldn't fire the boiler unless enough rooms need heat.

If I was to try and zone a single pipe steam system with vacuum lines, I would have separate manifolds for the zones, Grouping radiators together that way and thermostat controlling them.
Probably use a simple taco zone valve relay.
That's just me.

Dave in QCA

In addition to the Paul system, Dunham offered a similar system. You have to go to the a Dunham handbook to see the details of the system. I have spent a little time looking on here for it, but can't find it. I have original publications of several of the various Dunham handbooks that were published through the years.
https://heatinghelp.com/assets/documents/Dunham-air-line-service-valve0001.pdf

Chris, in overall comment to your proposed design, I think it will work with a few provisions.
1. Adding zoning is only beneficial if zoning control is actually needed. If a single control is adequate, adding zoning control may not add a benefit, and in many cases can add problems. Those may be from the added complexity and from the increase in the total amount of devices and equipment that may fail over time. In some cases, excessing zoning will cause zones to fight with each other.
2. If you're going to run vacuum, which I think you should. You need a Hoffman "Paul" vent in addition to the 180F thermostatic control of the solenoid. The reason is the obvious fact that in a vacuum the steam (vapor) may well be cooler than 180F depending on the amount of vacuum. The vent is designed to operate over a range of vacuum or pressure and so it will close whenever it encounters vapor, regardless of the temperature.

I would suggest that you spend some time studying both Paul and Dunham sub-atmospheric systems. There are benefits that go beyond "getting the last little bit of heat out of a coal bed". I say this because Dunham was very specific about the systems being applied to Oil and Gas fired boilers as well as coal.

Keep on working on this Chris. Its interesting to see what others come up with.

AMservices

When I started working with @izhadano I asked if he considered using the Paul's vent on his vacuum lines. He told me they were expensive and almost all of them failed in his testing.
A Paul's vent is a small steam trap that can't be repaired, only replaced.
To get around using steam traps it takes creativity. With a vacuum pump doing the work, it must be protected, so it just needs to run long enough to have the radiators filled before the steam gets to close to the pumps high limit. How the air is balanced as it's exhausted and how good your vacuum line piping is will make or break everything. Quite literally.
I do agree that a vapor vacuum system can achieve balance without zoning and adding more components with controls adds points of failure.
The simplicity and Elegance of a vapor vacuum steam system is a thing of beauty.
But I do love thinking of making steam systems more appealing to the forced hot water guys and home owners that can't see past the burner.
Plus, I'm a control freak, so I'm dreaming of a fully modulating steam boiler with sealed combustion, that would be adjusting the firing rate to ride between 4 and 8 ounces. using a vacuum pump to exhaust the air out through zoned vacuum lines.
That would give steam guys another good weapon in the fight to keep steam alive.

But again, simplicity is reliability that turns into longevity and overall efficiency in any properly maintained steam system.

PMJ

Just some thoughts for consideration with this:

Much of the discussion here so far is about the concern of steam getting past the radiator into the vent lines and then possibly to a pump. I really recommend experiencing natural vacuum first and then adding mechanical later if you still want it. When only natural, the deepest part of the vacuum occurs in the rads and not in the dry return. With a pump, the deepest part of the vacuum is at the pump, which will end up trying to pull steam out of the rads and into those vent lines. This does not occur in natural vacuum - the only way to get steam into those lines is with pressure above atmospheric and overfilling the rads. As has been observed many times, a rad full enough to close a vent(or a trap) has much more steam in it than is required for the conditions and is overshooting the room. The overshoot may be small and not of any real consequence, but certainly it is not desirable and might as well be avoided anyway.

This brings me to cycling again. Somehow the advent of on/off fire control brought with it hurry up air removal and hurry up rad filling. Then, conventional systems allow all the vented air right back in and one has to do it all over again every cycle.There was no hurry up of any kind when these systems were designed. Putting steam into the system in much smaller amounts evenly spaced (but a total amount that is enough to heat) easily solves the over filling issue while firing, and then the natural vacuum in between automatically keeps the steam in the rads when the fire is off. The combination of both of these things will dramatically reduce the possibility of steam getting into the vent lines - and also produce a dramatic improvement in how even the heat is. Try it, and then see if you even want the expense and trouble of a pump and all those devices to protect it from steam. I don't think the solenoid valves themselves in the boiler room need any protection while you get your program developed.

jumper

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.

PMJ

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.

AMservices

@ pmj
I haven't experienced the problem of over heating with the vacuum pumps I've installed.
As soon as the thermostat satisfies, the boiler and the pump shut off and then the natural vacuum takes place. Then the steam finds its way to where it's needed the most. Just because I can boil water faster with a pump doesn't mean I have to over heat.
Don't knock it until you try it

izhadano

ChrisJ
I don't know, think it'll work?
I came up with it this morning.
=====================================
Hi ChristiJ,
sorry for late comments.
I did tested similar idea with Paul/check valves combo. Worked with naturally introduced vacuum. Will surely work with vacuum pump and solenoid valves. For some time. Till one of bi-metal switch/solenoid valve/Paul valve/etc. fail - the vapor will fill vacuum part of the system and you'll get maintenance call. You're lucky if there are less then 20-30 bi-metal switches/solenoid valves/Paul valves/etc. in a system to check. What about hundreds? in apartment building with limited access?
Steam heating reliability and longevity is based on system simplicity, let's keep it this way. It's a reason why only one solenoid valve is used in the retrofits we did with Ed@AMservices. We may use more in bigger systems, though, for zoning. And no steam traps, ever ...
Ball valve/TRV on vacuum line from radiator is the simplest method for the local temperature control. Modular Bi-metal aluminum radiators is another option
Our retrofitted system starts in vacuum, but may eventually run at positive pressure to prevent air leakage into the system under vacuum, - almost unavoidable in old piping.
Thanks,
Igor

PMJ

> @AMservices said:
> @ pmj
> I haven't experienced the problem of over heating with the vacuum pumps I've installed.
> As soon as the thermostat satisfies, the boiler and the pump shut off and then the natural vacuum takes place. Then the steam finds its way to where it's needed the most. Just because I can boil water faster with a pump doesn't mean I have to over heat.
> Don't knock it until you try it.

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.

izhadano

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.

DanHolohan

I've seen Igor's work and I'm a believer.

ChrisJ

DanHolohan said:

I've seen Igor's work and I'm a believer.

You're always welcome to stop by Dan.

DanHolohan

Thanks, Chris!

ChrisJ

DanHolohan said:

Thanks, Chris!

It would be nice to have someone else to back up my comments about a single pipe system, perfectly balanced running as low as 0.25" (0.15 oz) at times.

So far I've only got Bradford White that has seen it since I put the Magnehelic on it. I don't think Mark S has been by since then.

DanHolohan

I hope you never have to get that boiler UP those stairs.

AMservices

@ChrisJ
Have you ever calculated the pressure drop through your system?
The larger the pipe with very few elbows, the lower the pressure you need to fill the system. Having a perfectly sized boiler, you have your perfection with a single pipe air vented system.

ChrisJ

DanHolohan said:

I hope you never have to get that boiler UP those stairs.

Same way I got the old one up them. With an 8lb sledge hammer and a steel wedge.

ChrisJ

AMservices said:

@ChrisJ
Have you ever calculated the pressure drop through your system?
The larger the pipe with very few elbows, the lower the pressure you need to fill the system. Having a perfectly sized boiler, you have your perfection with a single pipe air vented system.

Yes, though I don't know how accurate it came out.




I need to update that drawing, the main bedroom had the vent on the elbow eliminated and a G5 put on the TRV. I found this worked better when running 2 cycles per hour.

AMservices

I'd say if the pressure drop to your last radiator is 0.0055, the numbers don't lie. Who can argue with that? I got your back.

AMservices

Correction, furthest radiator pressure drop 0.006 7.
Had to correct myself, I'm sure you probably noticed