New steam heating retrofit method

izhadano

Dear steam heating practitioners and believers:

After years of tinkering with steam heating I’m still fascinated by its simplicity, resilience, reliability, and electricity-independence (if the gas boiler is equipped with a millivolt control). Well-designed and maintained steam heating systems can provide superior comfort and efficiency. The opposite is also true, and this is why steam-heated buildings often have open windows during the winter. This is wasteful.  

The complaint I usually hear about steam heating is that it offers uneven heat distribution. This is usually because it’s very tricky to move the air out of all the parts of a steam system quickly and easily. Balancing steam distribution is an art many heating professionals have either never learned, or forgotten. Air vents (NYSERDA 1994, PARR 2011), orifices (Oland C.B., 2001) and Temperature Regulating Valve (TRV) (Bobker M., 1995) are not a panacea for this inborn, air-venting flaw.  As Albert Einstein said, “We can't solve problems by using the same kind of thinking we used when we created them.”

So, some new thinking:

Until 1900, vacuum was basically ignored in steam heating. But then came a great advance as some systems began to take advantage of vacuum. This greatly improved system efficiency and comfort. Instead of slowly pushing air through multiple vents from the system with steam at 2-psi pressure, low temperature vapor could now pull steam from boiler into radiators. It did this evenly by using 5-7-psi vacuum that moves steam at speeds of up to 160 mph.

In addition, naturally induced vacuum continued to extract extra heat from the boiler long after the burner fire burned down. To appreciate how easier is steam heating system operation under vacuum, try to breathe in/out into manometer/vacuum meter. You can barely get 1.5-2 psi by pushing air out against atmospheric pressure, but effortlessly make 10-12”Hg (5-6 psi) vacuum when breathe in.  Nature is an ingenious engineer, worth to be copied.    

Today’s vacuum systems are “pseudo” vacuum ones because we separate the vacuum part of the system from the positive pressure of the steam at the inlet of each radiator. This requires steam traps, however, and steam traps present an ongoing maintenance problem. Steam traps on radiators last only 10 years at best, and are often ignored when they fail because of the expense and annoyance of having to repair them. The result is unbalanced, noisy, and very expensive systems.

There is a solution, nevertheless.

I’m one a few people who has seen vapor and condensate flow through transparent plastic piping (Holohan D., 2015). It turned out that vacuum system can self-balance quickly and evenly according system design. This has inspired a new “no steam-traps” type of vacuum system.

I verified the concept in my house (7 years study results) and had it implemented by A&Mservies in a retrofit of 1880^th steam system. This technology is now approved for low risk financing. I invite you to use it on your next retrofit project. The benefits are:

• Payout from energy savings
• If ROI is 4-5 years,   20% of energy savings are passed to owner
• No upfront cost (the only limitation - minimum project cost $250K, but steam retrofit can be combined with other energy efficiency improvements).

Sorry, have to continue my story in next post because of length limits.

izhadano

Let’s compare my system with the realities of converting from steam- to hot-water heating.

Converting to hot water heating may seem like the best practice today, but the rationales of this are still questioned on The Wall (2016 discussion).  As an example, successful project on 179 Henry str., NYC required fuel change, boilers replacement, drilling the 12 concrete deck floors, running and enclosing the new piping and the heating elements, and saved 33% of heating cost. The lessons learned were summarized as follows: “Over the years, many of us in the New York City multifamily energy efficiency world have talked about how cool it would be to convert steam-heated buildings to hydronic heating. The problem is not one of will but one of money. Changing the boiler is not the big deal—it’s the heating distribution system that is the challenge. … Plenty of these conversions have been done in the last 20 years in buildings that were gut rehabs. These jobs did not always get the best boilers, or insulation in the walls, but they did get a more efficient heating distribution. The real challenge was to convert a building with steam heat, with tenants in place (Rieber D. 2012, p.32).

Without any contempt to great planning and implementation of the 179 Henry Street project, I’d like you to now consider the advantages of converting the same building into new vacuum heating system:

• Old boilers, piping and radiators can be salvaged/upgraded/fixed after leak test, steam traps are either left in place or removed.
• The only new equipment are vacuum pumps (two, - one as backup), vacuum pump steam/condensate separator and few sensors and controllers.
• The only new piping is vacuum line on second-to-last floor ceiling, connecting return lines to vacuum pump (located either in the basement, or on the roof, or designated room on top floor).
• Plumbing and radiators may be upgraded later when building will go into gut rehab.
• Estimated fuel savings - 30-35% according to 100 years old data on steam heating conversions into vacuum heating (Holohan D., 2004).

            My estimations on material cost and labor cost reduction – 45-70% depends on particular project, in addition to drastically cutting off tenant’s disturbance, work time, system corrosion and negligible water loss (and treatment) in upgraded system.

In many steam heated buildings, boiler replacement is long overdue because insignificant or no savings is expected (Shapiro I., 2010).  But when boiler replacement is combined with system conversion into vacuum heating, 25-35% of fuel savings can be achieved (along with hefty new boiler incentives in many states).

If you have project similar to 179 Henry Str. on your plate or aware of one in neighborhood, please, let me know – I’ll be happy to discuss it. Two pipe (or an old style vacuum heating system) in low footprint building would be easiest to deal with. Probably, energy gains for old style vacuum heating system will be less, but steam traps and vacuum pump maintenance headache would be resolved.

I’m in Massachusetts (near Boston), but looking for projects in other states as well.

Sincerely,

Igor Zhadanovsky, PhD

Applied Engineering Consulting

 

 

References

Bobker M., & Kinsler E.R. (1995) “Balancing apartment building heating with thermostatic radiator valves”, Retrieved from

https://www.armstronginternational.com/sites/default/files/resources/documents/balancingapartmentbuildingheatingwiththermostaticradiatorvalves9-95.pdf

Holohan D., (2004) “The lost art of Steam Heating” p.251

Holohan D., (2015) “A new look at vacuum heating”, P&M magazine, Retrieved from http://digital.bnpmedia.com/publication/?i=284133#{"issue_id":284133,"page":28,"publication_id":"8211"}

NGRID (2014) “Technical Assistance Study. Vacuum Steam Heating” Downloadable from

https://drive.google.com/open?id=0B-5hKw5FhaA4am1Eb2VyaUNwR3c 

NYSERDA (1994) “Energy savings in one-pipe steam heating systems”.  Retrieved from http://www.osti.gov/scitech/biblio/10191625

Oland C. B. (2001) “Review of Orifice Plate Steam Traps” ORNL report

Retrieved from https://www.energy.gov/sites/prod/files/2014/05/f15/orificetraps.pdf

PARR (2011) “Steam System Balancing and Tuning for Multifamily Residential Buildings”. Retrieved from https://www.energy.gov/sites/prod/files/2013/11/f5/steam_system_balancing_tuning_multifamily_residential.pdf

Shapiro I., (2010) “Water & Energy Use in Steam-Heated Buildings”,  Retrieved from

https://www.taitem.com/wp-content/uploads/SteamBoilerReplacements.pdf

SIRA (2019) ”DIE-CAST ALUMINIUM RADIATORS” Retrieved from http://www.siraindustrie.com/en-gb/radiators/die-cast-aluminum-radiators/primavera/

 

 

Jamie Hall

I'm always fascinated when someone tells me that steam traps only last 10 years... or whatever. The ones connected to Cedric have lasted 90 years so far, without failures, and counting (so has the #76 main vent, backed up for the last 15 years by a Gorton #2)... of course, that's helped by the carefully set orificed (Hoffman) valves on each radiator, and the Differential Loop, but... gee whiz, folks. Cedric isn't unique...

JUGHNE

I was certain that the 55 year old traps in a school house would have been toast. They were original as evidenced by having to cut open book cases to access them. Surely it was time to change out. It was to be a summer job so all were changed at once.

What I found was orifices installed in most of the supply valve unions. Hoffman valves, but not orifice controlled. Only the orifice in the outlet union. Perhaps most of the trap elements I changed were OK, but the time involved to test and check was not available because of inaccessibility during the heating season with school on.

Jamie, I am guessing that your traps never see steam like most of mine never did.
So perhaps an active busy working trap might have a less than 10 year life expectancy.

dopey27177

It is amazing that some one finally figured out that steam traps are needed on steam vacuum system.

Where have you been before.

During the 1920s and thirties many of these vacuum systems used special radiator valves and orifices to supply only enough steam the provide the edr needed for the radiator.

On the outlet of the radiator special fittings that had no moving parts were used to trap water and release air.

Many of these systems are on the north shore of Long Island and New England.

Interestingly enough they do not need maintenance unless some one tinkers with them and breaks a part.

Jake

PMJ

@izhadano ,

As a long time vacuum steam operator I can vouch for what you say here from actual experience. Vacuum provides much more even heat far more efficiently with fewer moving parts than the air breathing dragons these systems have been allowed to become. Intermittent fire somehow caused the loss of much of steam heat's subtle but very important assets. It really didn't have to be this way as you explain here far better than I can.

This site is filled with seemingly endless discussions on how to remove the same air over and over again every single time the boiler fires, all while trying to keep everything balanced under constantly changing conditions. Many here have tweaked their way to results that really are in fact quite good. But I agree with you that vacuum does do a much better job with all this. The idea that maybe all this air just shouldn't be let back in every cycle is all too quickly dismissed.

I guess @DanHolohan summed the situation up best with this from his 2015 article that you just referenced above:

"So why aren’t people rushing to his
door and begging him to help them save
fuel, get rid of the annoying noises and
most of the troublesome, labor-intensive
elements of a typical steam system?
My guess is most people are making
the same mistake I made. They think
they know it all and they don’t want to
shut up and listen, but I wish they would. "


Please keep going with your excellent work. There really are some of us out here who are very impressed.

izhadano

Hello, PMJ and dopey27177. 

Thanks for kind words, pleased to hear from experts.

 

Hello, Jamie Hall.  

 Steam trap market is estimated at USD 3.34 billion in 2017 and is projected to grow to reach USD 4.11 billion by 2022. Stable business, good to be in, isn't it? As JUGHNE suggested, may be the 90 years old steam traps you care of are protected by Hoffman radiator valves/orifices and never see the steam.  Perhaps, you’re very lucky fella not experiencing problem with steam traps. unlike many others guys around.

 

I have to clarify  the difference between steam trap roles in two-pipe steam system and vacuum system (may be incorrect on technicalities, though). In both systems steam traps serves to prevent steam entering into return line, but consequences of failure are quite diverse.

In steam two-pipe system “shut open” steam trap failure creates steam short path through this particular line to system air vents. Result is no heat to upper floors tenants and complains. Steam trap “shut close” failure locks the air in particular radiator and reduce heating in one room. Steam trap replacement is an easy fix and resolve the problem in both cases. Complains and costly heating bills are often ignored, nevertheless.

In vacuum heating system “shut open” steam trap failure opens pass for steam into vacuum lines.  Steam hammers and destroys delicate bellows/bi-metal disks of the nearby steam traps first, hunts the rest and breaks efficient system operation. Imagine such failure of one out of 6600 steam traps in Empire State Building ... Would not be surprised if steam traps checked/replaced there every other year.  “Shut close” failure is a blessing, compared to “shut open”, it reduces heat delivery into single radiator and easy to fix.

 

The purpose of the post, however, is not discussion of steam traps but rather finding a project/demo for new steam retrofit technology. Hope the rationales and benefits are explicit enough. Questions/suggestions are very welcome.     

Thanks,

Igor

 

ariccio

dopey27177 said:

During the 1920s and thirties many of these vacuum systems used special radiator valves and orifices to supply only enough steam the provide the edr needed for the radiator. On the outlet of the radiator special fittings that had no moving parts were used to trap water and release air. 

This sounds like much more than the usual setup for an orifice plate. It sounds a bit like the "dynamic" traps I've heard about that use some kind of fancy topology to only let water through by way of thermodynamics. Can you say more about this? It sounds like you're saying they work for the kind of low pressure vacuum steam systems that are still in use.

I tried looking into this last year for my apartment building - where management and maintenance deny the concept that steam traps need routine replacement (of course) - it sounds like a perfect solution, but I couldn't get anybody I emailed to respond.

mattmia2

You really just need the orifice plate and to control the pressure of the system to under 8oz or so. The amount of steam that passes through a hole is dependent on pressure so you need to keep the pressure low.

The return fitting can be a steam trap or just a plain elbow(or a trap with the guts removed). If the trap is working or failed open you can leave it in place. If the trap is failed closed then you have to remove the guts. The regulation happens between the orifice plate and the boiler pressure. The return just needs to let air and condensed water out.

You do need to have working steam traps and vents on the mains and returns.(or the mains dripped to the returns below the water line and working vents on the mains)

EBEBRATT-Ed

@ariccio

If you have traps, they need to be maintained. As others have said orifices can be used if you can run with low steam pressure but if they were not installed originally, it would be a time-consuming process to install them.

Many large building do a trap maintenance program every three years or so. The time it takes to test traps can quickly exceed the cost of replacement trap innards & labor. I am talking about induatrial plants , hospitals etc. Commercial buildings and residential the traps can last longer IF the system is run correctly and maintained but that is a huge IF. Since they are generally neglected they don't last.

It unfortunate that management in your building does not understand this.

Neglecting traps wastes more $$$ in fuel, ruined feed pumps and boiler damage than fixing the traps.

ariccio

Oh yeah, no question the office plates can work very well. The original reason I was poking around Mr. Zhadanovsky's thread here though is that the engineer in my gut feels like an orifice plate leaves efficiency on the table, and I'm never truly comfortable with tradeoffs like that!

In my gut, an orifice plate feels like a well tuned single barrel carburetor. Simple, reliable, boring, but with all the downsides of open loop control. A theoretical perfect steam trap feels a lot more like a more modern EFI system, only letting the exact amount of steam necessary through the radiator. The engineer in my gut always asks the obvious questions about tradeoffs inherent in any complex system, but is cranky and stubborn about answers.

I came across this thread because yeah, it does seem an awful lot like a retrofit to Mr. Zhadanovsky's system is a lot closer to the ideal than just chucking orifice plates in a poorly balanced and maintained system.

I may run for the board of this building at some point when I'm sufficiently fed up with stupid things to take on yet another responsibility, and honestly, have been giving a lot of thought to a system like his! It's helpful for me to figure out what gives the best chances for a system to work seamlessly.

Many people I deal with in my personal and professional life really do not feel comfortable being the first they know of to try something different. Many times I've seen people give up the new thing at the very first issue that surprises them. Then, they swear off it forever.

If it can be done correctly the first time - sufficiently idiot-proofed to deal with things like poor maintenance, while still achieving maximum possible efficiency - it's got a much better chance of convincing others down the line of it's value.

The fact that I struggle to find good info about a very very specific question (how/do dynamic orifice traps work in low pressure steam vacuum systems as opposed to non-vacuum systems?) just so happens to also slot in nicely here!

AMservices

@ariccioyou want to regulate the flow of steam entering the radiator, not restrict the flow of air and Condensate exiting the radiator. 
A packless orifice supply valve makes balancing a 2 pipe steam system simple. 
By throttling the supply you can deliver just enough steam that the the radiator condenses all the steam before the last section heats. 
Steam trap never closes because steam never reaches the trap element. Therefore no steam can make it to the dry return. 
A steam trap to me, should be looked at more like an insurance policy, in the event someone changes the adjustments to the supply valve, the pressuretrol malfunctions, for whatever reason, the heating cycle is excessively long, ect...
 Adding a vacuum pump does decrease pickup losses by lowering the pressure, water boils faster and fills the system faster. 
After the system is filled, the vac pump turns off and a natural vacuum forms due to the condensing steam. 
At the end of the heat cycle, the burner turns off, a Solenoid valve isolates the vacuum, Preventing air from being pulled back in, the steam condenses, but more importantly, condenses faster in radiators that are in colder areas of the building. Any steam being produced thanks the the natural vacuum lowering the pressure, will be drawn towards the coldest spots in the system, making a naturally balanced heating system, without a ton of thermostatic controls. 

Jamie Hall

"The fact that I struggle to find good info about a very very specific question (how/do dynamic orifice traps work in low pressure steam vacuum systems as opposed to non-vacuum systems?) just so happens to also slot in nicely here!"

Ok, let's get rid of one thing here. Orifices do not sacrifice efficiency. What they do do is limit the volume of flow at a given pressure differential between the feed side and the downstream side. If the orifice diameter is correct for the pressure differential, just enough steam will enter the radiator to condense fully in the radiator, leaving only condensate to pass. If the pressure differential is less, the steam flow will be less, of course, and the heat output somewhat reduced. If it's greater, not all the steam will condense and you will get steam in the returns.

Now. You mention vacuum vs. non-vacuum systems. This is where things get interesting. First off here, if you are talking about vacuum assisted returns, but with "normal" supply pressures, the pressure differential up there is thrown way off and, without traps, the system will work poorly if at all. There are a few ways to create such systems, but the most obvious -- and most efficient -- is to have some of the condensing, at least, taking place at relatively low temperatures. This can, of course, be arranged in various ways, such as preheating the feed for domestic hot water. In power boilers it is done by air or water cooled condensers, and the efficiency loss there is more than offset by the power gain across the turbine or engine.

However, if you are talking about systems where the entire system is operating at less than atmospheric pressure, the system will work and work well, but the pressure differential between the supply side and the radiator side must be less. Why? Because at the lower radiator pressure the radiator condensing capability is reduced dues to the lower boiling point, and thus less steam can be allowed to enter the radiator. Many times when people talk about operating a residential or other heating system in a vacuum, they are dealing with a system which operates at sub atmospheric pressure at a low firing rate at the boiler. This was actually quite common in the days of coal fired boilers, and it worked well -- many vapour systems were equipped with vents which closed against a vacuum, and thus when the firing rate dropped the system as a whole would drop into a vacuum -- in principle extracting more heat from the low (or dying) fire..

The problem with running any vacuum assisted or sub-atmospheric system is, of course, the same as running low pressures in any heat exchange system which depends on evaporation and condensation cycles to transfer heat: elimination of non-condensable gas in the system and keeping it out. In a normal low pressure heating system, this is done by means of the vents. No problem. In sub-atmospheric systems, using a vacuum pump, water vapour must be kept out of the pump (or the water loss accepted) -- which means a low temperature condenser or that the system is vacuum tight.

PMJ

AMservices said:

@ariccioyou want to regulate the flow of steam entering the radiator, not restrict the flow of air and Condensate exiting the radiator. 
A packless orifice supply valve makes balancing a 2 pipe steam system simple. 
By throttling the supply you can deliver just enough steam that the the radiator condenses all the steam before the last section heats. 
Steam trap never closes because steam never reaches the trap element. Therefore no steam can make it to the dry return. 
A steam trap to me, should be looked at more like an insurance policy, in the event someone changes the adjustments to the supply valve, the pressuretrol malfunctions, for whatever reason, the heating cycle is excessively long, ect...
 Adding a vacuum pump does decrease pickup losses by lowering the pressure, water boils faster and fills the system faster. 
After the system is filled, the vac pump turns off and a natural vacuum forms due to the condensing steam. 
At the end of the heat cycle, the burner turns off, a Solenoid valve isolates the vacuum, Preventing air from being pulled back in, the steam condenses, but more importantly, condenses faster in radiators that are in colder areas of the building. Any steam being produced thanks the the natural vacuum lowering the pressure, will be drawn towards the coldest spots in the system, making a naturally balanced heating system, without a ton of thermostatic controls. 

Exactly so. And please note, none of this automatic balancing happens in open vented systems. When the burner turns off in an open vented system air rushes in to fill the void created by the collapsing steam and instantly stops the flow everywhere. This is no small difference in overall performance.

jumper

Interestingly enough they do not need maintenance unless some one tinkers with them and breaks a part.
Jake

That's one reason pumps are to be avoided for steam heating. Sooner or later somebody fixing something fixes it good.

There are other reasons as well.

AMservices

jumper said:

Interestingly enough they do not need maintenance unless some one tinkers with them and breaks a part. Jake

That's one reason pumps are to be avoided for steam heating. Sooner or later somebody fixing something fixes it good. There are other reasons as well.

Fortunately, the vacuum pumps we can use on retrofits today are far better, smaller, requires next to no service, and the manufacturer of @izhadano vacuum pump (who I have also talked to https://airtechusa.com/products-solutions/products/hp-dry-piston/ ) estimates a 30 year life expectancy based on calculated run time, annually.