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Converting steam to hot water system?

i would make sure that your boiler is operating as efficiently as possible, before making any such conversion to hot water. you will probably need new piping and rads before you are through moving from steam to hot water.

get a copy of "the lost art of steam heating" from this site, and begin to examine all aspects of the sysytem. unfortunately you can't fire the boiler in the summer, but you can check settings such as pressure, venting etc.

is this 1-pipe or 2? when we put in a new boiler [1,050,000 BTU], and got our pressure down, and main line venting improved, our consumption seems to have dropped by 1/4 judging by past figures from the gas co.

however i would not immediately assume that your old boiler is unuseable simply because of its age. what make is it? also to be looked at would be the boiler control-thermostat or otherwise. a bad location can cause temperature overshoot which of course is wasteful.--nbc


  • JoshuaJoshua Posts: 4
    Converting steam to hot water system?

    I have a 1928 Tudor style house with a 50 year old low pressure steam boiler. My heating guy has maintained the system since 1990. My winter season heating bills are $4000 (in SE Wisconsin.) When I suggested replacing the boiler with an efficient steam boiler, he suggested greater savings would be achieved by converting to hot water heat. Replacing our radiators would be very expensive & messy, as those on the first floor are hidden in the plaster walls.
    I installed new windows on the 2nd & 3rd floors in 1999, and new storms on the first floor. I plan to get an energy analysis as well. My insulation is lousy, but may be difficult to improve, as I have flooring throughout my attic.
    Please offer opinions on getting a new steam boiler vs. converting to hot water boiler. Thanks.
  • Maybe....

    How about a Burnham Megasteam? I am not a steam expert by far, but I have heard good things about this product. Many others here will give you much better input.
  • brucebruce Posts: 222

    Check out the thread " Conservation vs. efficiency" for many views on achieving lower heating bills. The upshot seems to be Insulate, insulate, insulate and insulate again.

  • All the above suggestions are good. I was in a similar situation with my heating guy pushing to get me converted from steam to hot water. As Nicholas suggested above, you need to get Dan's books on steam heating. See "A Steamy Deal" on the bottom of this page. Start by reading "We got Steam Heat" and then read "The Lost Art of Steam Heating" - Easy reading, very informative and in an evening or two you'll have a whole new insight to steam heat. With just a little "fine tuning" most steam systems can be made a lot more economical. I was able to cut my seasonal fuel oil bill by 1/4 to 1/3 and am planning some further modifications by upgrading my thermostat system this summer.

    If you do change to hot water don't let anybody talk you into using/keeping the old radiators! Steam operates on less than 2 PSI and water at about 30 psi. The odds of springing a disastrous water leak reusing the old radiators is extremely high.

    - Rod

  • Jamie HallJamie Hall Posts: 6,437

    you really truly have to for some reason, don't do it. You will almost certainly have to replace most of the radiators, as they will leak. You will also have to repipe the whole thing.

    You not gain anything significant on fuel usage from a hot water system over a properly operating, modern steam boiler -- in fact, you may well lose.

    The Burnham Megasteam is good, but almost any good modern boiler will do the trick.

    Do get the book NBC suggested; one of the keys to steam is maintaining the system properly, but that isn't hard once you get the hang of it (in fact, in most cases it doesn't involve any work at all, once any problems are identified and fixed -- and you may wind up having to do nothing at all except replace the boiler).


    As I said before, just Don't Do It!

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

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • JoshuaJoshua Posts: 4

    Hi Guys,

    regarding the questions: My boiler is a U.S. Radiator Corp. (or something like that) circa 1960. Steve does the annual cleaning and service each summer. He fine-tuned the system to a lower pressure and preaches about proper balance, etc. He gently yells at my wife for not draining the sediment monthly. He has never pushed for replacing anything, but I am worried I'll have a breakdown in season and be stuck. (My low-water cut-out valve failed twice in 20 years; the last time it had to be drilled out.) When we renovated our kitchen in 1995, Steve installed hot water heat in the ceramic tile floor: great job. It runs off a 40 gallon dedicated water heater.

    In sum, I think my current boiler is properly maintained, but worry that it may fail, and hope that a new one is much more efficient.

    Thanks for all the tips.

  • M grallertM grallert Posts: 19

    I gotta say this regarding conversion from steam to water. I have done a number of steam to water conversion and in a number of cases including my own home I have used old steam rads. When I do a conversion I do repipe using pex and manifolds and modern radiator valves. It's perfectly ok to convert and if one is careful existing radiators are great. a simple pressure test is important.
  • Larry CLarry C Posts: 94
    Reusing steam radiators for hot water. How do you remove air?

    Reusing steam radiators for hot water. If the radiator sections are not connected across the top, how do you ensure the disolved air is removed?

    Larry C
  • M grallertM grallert Posts: 19

    Well of course the radiators would be of the type that can be used for either water or steam. So I simply plug the air vent and install a coin vent at the top. But one thing I think I will tryn at home just for grins is to install a steam only rad upside down, or also I thought it might be fun to drill and tap the tops of all the sections and build an air removel manifold. Crazy but maybe kinda cool.
  • But why spend all that time and money and effort

    when I can produce similar fuel savings by fixing the steam system? If you're competing against Gordon and me, you'll lose every time because we can get similar fuel savings for a lot less investment. We can offer a faster payback.


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  • RobKRobK Posts: 5
    Steam conversion

    Have you tried Danfoss valves? They can be installed in place of the shut off valve on each radiator. The temperature for each room can be preset at individual radiators. Use adjustable air vents on each radiator to fine tune the system if it is a one pipe system.Danfoss valves are integrated into the steam system.No other changes are nessary.
  • JoshuaJoshua Posts: 4


    My current system is gas-fired, and I'm pretty sure I have a 2 pipe system. Are there any residential gas-fired steam boilers that are energy-star certified? I looked at multiple sites and could find none. Everything is either oil fired, commercial sized or hot water. Any suggestions?
  • Best bets for now

    would be the Smith 8 series or Slant/Fin Intrepid series- these are wet-base boilers normally used on oil, that are also factory-certified with power gas burners. Not quite EnergyStar, but better thermal efficiency than the typical atmospheric gas boiler.

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  • Jamie HallJamie Hall Posts: 6,437

    If I may be so bold as to make a politically incorrect comment... the actual operating efficiency over a heating season of the two units Steamhead mentioned will probably be just as good, if not better, than an 'EnergyStar rated' unit -- provided both are set up by a competent technician. The efficiency of a boiler is much more closely tied to the guy who adjusts it than to a little label on the side...

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

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • JoshuaJoshua Posts: 4

    Does either of those units qualify for the $1500 IRS tax credit? I thought energy-star rating was required for that.
  • Jamie HallJamie Hall Posts: 6,437
    Probably not

    which is why I said my comment was politically incorrect. Don't get me wrong; I'm all for taking the taxmen for a long ride -- but not if it's not the best way to do something, or if it's going to cost me money in the long run. Unless a tax credit is really huge (and $1500 isn't, in this instance), I would never base a purchase or repair/replacement decision on the existence of a tax credit.

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

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Keep the steam

    A co-worker converted her one pipe steam to hot water. Two of tha radiators leaked. Fortuantely this was discovered during the install and not when they were away on vacation. The quote for a new steam boiler was $12K. Her install was $22K. If we say there is a 20% savings hot water vs steam (which I think is very high) and she spends $2,500 on gas, thatis a $500 annual savings. Sounds like a lot, but her ROI on the extra $10K is 20 years. Stay with the steam
  • RobKRobK Posts: 5
    Keep the steam

    Steam systems (gas or oil fired) will not qualify for energy star rebates. Remember, to make steam you have to heat water to 212 deg. F. This is a waste of energy. But If you can control the way the energy is used by modulating the zones it is sent to, you can save fuel. You have not stated what kind of boiler you have or the square footage of the area you are heating or the average degree day for the heating season.
  • Actually

    there are steam boilers that are EnergyStar labeled- the Burnham MegaSteam is one. Unfortunately there's no gas version, just oil. The Smith 8 series is EnergyStar also on oil, not sure if that holds true for the gas version

    The higher temperature of the steam translates to more heat delivered to the room per square foot of radiation. This offsets the higher boiler temperature.

    As far as we know, there has never been a scientific, apples-to-apples comparison of the relative efficiencies of transporting BTUs by steam as opposed to hot water. So any claims of one being more efficient are simply someone's opinion, not supported by fact.

    Keep the steam.

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  • ttekushanttekushan Posts: 901
    What steamhead said.

    How can you question someone who provides wonderful photos of how it should be done? The only thing I would add is to be sure the boiler is sized properly as described in "the lost art of steam heating." That book will pay for itself many times over.

    And another thing, you really have to do something about that insulation. As I've said ad nauseam, 100% of heat generated goes outdoors. We just want to get as much of it to hang around indoors for as long as practical.

    When you get Dan Holohan's books, read especially closely about two pipe vapor systems that utilize graduated hand valves or radiator inlet orifices. Most of these have the radiators sized to fill only about 80% or so. This is to prevent steam from entering the return system in lieu of thermostatic steam traps. Why do I mention this? You may have such a system and its been screwed up since the "new" 1960 boiler was installed. I've seen this time and again. If its a vapor system thats designed to operate with limited radiator steam inlets, then you should size the boiler for the net EDR being heated so you don't mistakenly oversize the boiler. You need a good steam guy to pull it off but you may have one on your hands if he understands system balance.

    The best part of understanding the restricted radiator inlet concept is that graduated radiator inlets in conjunction with a Vaporstat low pressure steam control illustrates the fundamental concept of effectively downsizing the radiators and heating system once insulation is added to the house. Its often assumed that you can't downsize a steam heating system without hacking sections out of radiators and that you are therefore stuck with a large boiler. IMO, this is BS.

    I learned how to downsize steam when encountering a steam boiler that was sized to the new heat loss of a newly insulated home. The boiler ran all the time and the rooms near the boiler were sweltering and the furthest rooms were cold. What to do? It was a two pipe system with hand valves and radiator covers so the valves were less likely to be tampered with. I started out by sharply increasing the main vent sizes. Starting with the valves in a closed position I opened each one about 1/2 turn, larger radiators more, smaller ones less so. I touched up the valve adjustments for good system balance, allowing the boiler to cycle off on a pressure of 8 oz in 30 minutes or so. *PRESTO- A downsized steam heating system!* Each radiator only heated about 2/3 the way across max. The insulated house turned out very comfortable and didn't overheat. I marked the valves with an instruction tag and an index line with paint. The owners didn't want to spring for inlet orifices since this worked so well. Apparently the heating bills plummeted from what I've heard.

    Don't use the hand valves on one pipe steam! You have to do this with very slow radiator vents.

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