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New steam heating retrofit method

izhadanoizhadano Member Posts: 79

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 1880th 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.


  • izhadanoizhadano Member Posts: 79

    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.


    Igor Zhadanovsky, PhD

    Applied Engineering Consulting




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

    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{"issue_id":284133,"page":28,"publication_id":"8211"}

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

    NYSERDA (1994) “Energy savings in one-pipe steam heating systems”.  Retrieved from

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

    Retrieved from

    PARR (2011) “Steam System Balancing and Tuning for Multifamily Residential Buildings”. Retrieved from

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

    SIRA (2019) ”DIE-CAST ALUMINIUM RADIATORS” Retrieved from



  • Jamie HallJamie Hall Member Posts: 12,947
    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...
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • JUGHNEJUGHNE Member Posts: 6,971
    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.
  • dopey27177dopey27177 Member Posts: 306
    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.

  • PMJPMJ Member Posts: 950
    @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.
    1926 1000EDR Mouat 2 pipe vapor system,1957 Bryant Boiler 463,000 BTU input, Natural vacuum operation with single solenoid vent, Custom PLC control
  • izhadanoizhadano Member Posts: 79

    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.     




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