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Steam heat questions

Kate Clark | Posted in General Questions on

I purchased a home in Millinocket Maine and wish to have the most efficient heat possible. Currently there are steam radiators. I have a fan of Rinnai hot tankless hot water heaters and read they make “boilers”. Would they work for “steam heat”. Being a non-techinical person , I don’t know and don’t know what questions to ask.

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  1. David Meiland | | #1

    If you don't get help here, see if you can post at a lot of steam guys hang out there.

    Millinocket reminds me of this, a staple of my childhood

  2. Frank R | | #2

    Rinniai tankless water heaters cannot make steam heat. They make domestic hot water, not boiler water or steam. Rinniai does make hot water boilers, but there is no such thing as a condensing steam boiler. You might be able to convert your steam system to hot water, but it may be very costly especially if you have a one pipe steam system. Even if you do convert to hot water, a condensing boiler may not do you much good. A condensing boiler works at high efficiencies only when it has cold water coming back to the boiler. But to get the output out of the radiators you may need higher water temperatures. First things first. Do you have a one pipe or two pipe hot water system? Has the house had significant changes to add insulation from when it was first built?

  3. Kate Clark | | #3

    Thank you for the information and the YouTube link. I will check on the one or two pipe question. the house is insulated and for the moment is not being heated .
    With sincere appreciation.

  4. Dan Kolbert | | #4

    Bert & I were more coastal, Dave, lobstahs, fahg hohns, etc. - Millinocket is smack dab in the middle of the state - in the shadow of Mt. Katahdin.

    Kate - you really need to find a local heating contractor - all else is pretty useless if you don't have someone willing to do the work. I'm in Portland, don't know the scene up there. I'd check with the local building inspector.

  5. David Meiland | | #5

    Yeah, Dan, but they mention Millinocket. Didn't your parents have that when you were a kid?

  6. Kate Clark | | #6

    Dan, I think you are correct about looking for a local heating contractor. It is, however, wise to be able to ask some questions which show that I am not a complete dunce. Perhaps, I'll come back and see what the opinion is about the advice I get when spring comes.
    The famous quote from Bert and I for those of us who go to the Katahdin area, "Millinocket? well, ya can't get there from here."
    Gentlemen, my thanks.

  7. David Meiland | | #7

    Kate, I think you will be well-received on heatinghelp if you take some clear photos of your boiler, controls, piping, valves, etc., and post them. It is always good to be informed about what you have, what the upgrade potential is, and how to get there. You might also be able to get refs for someone in the area.

  8. Frank R | | #8

    Heating help is a great site. I have read the book "lost art of steam heating" front to back several times over. It is my steam "bible". If your local contractor has not read the book run away. Most contractors do not understand a thing about steam heat. Even being a mechanical engineer and a owner of a one pie steam system, i had a very difficult time getting a contractor to install a new boiler correctly.

    In order to tell if you have one or two pipe system. Look at your radiators. Is there one or two pipes entering the radiator? Given that your house is insulated but not super insulated your money may be better spent greening your steam system than replacing it.

  9. Frank R | | #9

    By the way, i would offer to look at your system, but the closest i have gotten to your town is Oxford Maine.

  10. Kate Clark | | #10

    You all are being so helpful. Thank you.

  11. Frank R | | #11


    To figure out if you have one or two pipe system just look at all of your radiators. If you see one pipe coming into the radiators you have a one pipe system. If you have two, it's two pipe. one question, What is the real reason you are looking to change to hot water? If it's energy efficentcy, the big expense of a hot water conversion is not worth it (unless money is not a issue). You may be much better off trying to make the system you have as energy effecient as possible. Don't get me wrong, a hot water system has many great advantages, but for little cost, steam can be made resonably effecient. That way your $$ can be put to better use. Just a thought.

  12. Kate Clark | | #12

    Good thoughts. I will ponder all the suggestions.

  13. Jenny Belman | | #13

    Look for local outlets/companies making heaters in your area and ask them about your requirements. They will customize it according to your needs. For any problem also, you can easily consult them.

  14. Expert Member
    Dana Dorsett | | #14

    If the house's air tightness, windows, and insulation have been upgraded, the steam radiators are grossly oversized for the actual heat load (and were probably oversized for the house when it was an uninsulated building with single pane windows and only mouse-nests for attic insulation.) It's sometimes possible to convert 2-pipe steam to a pumped hydronic system suitable for condensing boilers, but it's not within typical DIY design or implementation skill sets to get there, and the labor costs of having competent pros do it may be a bit daunting.

    Frank has it right- a good steam designer can probably get the efficiency of the system up to the ~75% range (up from 50-55% for many older mostly neglected steam systems) with cost-effective tweaks.

    Fuel types & cosst also loom large in the cost-effectiveness analysis. Natural gas is pretty cheap, but propane & oil aren't. In Millinocket heating with wood or wood-pellets is usually MUCH cheaper than heating with oil or propane at current prices. If the place is pretty tight and well insulated there may even be a ductless-heat-pump solution that would be cheaper than a full-on conversion to water heating using the same expensive fuels, and about as cheap to run as a natural gas boiler.

  15. Kate Clark | | #15

    Everyone has been very helpful. There are some caveats to the project, which now that so many have weighed in, should be mentioned. The house was built in 1916 and I am the second owner (family). I am not having the windows replaced contrary to what the local guys say. Also, this is not going to be my main, no pun intended, domicile for the moment. Now, what is a "ductless-heat-pump solution."

  16. Kevin Dickson, MSME | | #16

    A few comments from the owner of a steam heat system:

    1. If it is a natural gas steam boiler, good. If not, convert from oil to gas if possible.
    2. If you retain the single pane windows, retaining the steam heat is the easiest way to provide comfort-- the radiators will be at 200 deg. F and they are right under those COLD windows, a good combination for comfort if not low utility bills.
    3. Most steam systems can run at 80% efficiency when tuned up.
    4. If the home hasn't been heated for years, it may be because the steam system was "knuckleheaded" - see -
    5. It can be surprisingly inexpensive to tune up and de-knucklehead a steam system.

  17. Kate Clark | | #17

    You all are wonderful . A "knucklehead " who would have thought. Thanks!

  18. Expert Member
    Dana Dorsett | | #18

    If you're sticking with the original single-pane windows, it's VERY cost effective to add tight exterior low-E storm windows (Harvey makes the tightest storms in the industry, but the better class Larsen low-E storms available through box-stores are pretty air tight too.) While steam radiators under the windows mitigates wintertime frost/condensation on single pane windows, it does so by nearly doubling the heat loss out those U1.0 windows (!). A tight low E exterior storm brings the window down to U0.35 or better, cutting the window losses by about 2/3, and makes it comparable to a code-min replacement window (for a heluva-lot less money than replacement windows.) It's well worth paying for the hard-coat low-E glass, which REDUCES rather than increases the payback period on a new storm window. An exterior storm window also protects the original antiques from weather/water damage, the glazing putty from cracking from moisture cycling, and low-E storm even protects the sash paint from sun fade.

    I challenge the notion that you can really hit 80% system efficiency in an old steam system, unless you can rip apart walls and insulate both the distribution and return lines. You can maybe hit the very low 80s for raw combustion efficiency, but the jacket losses and distribution losses are HUGE, and at typical oversizing the standby losses still kill you in the end. While it's well worth optimizing it with the appropriate tweaks, 80% as-used efficiency is "only in your dreams". Most older steam systems will overheat the basement via standby loss, and in a typical air-leaky uninsulated 1916 basement that's a huge hit in "as used" performance.

    But the cost of replacing the system is huge, and it sounds as if there may be a lot of low-hanging fruit on the weatherization front that would be money better spent. (Tightening and storming over the antique single-panes is just for starters.)

    Ductless heat pumps are sometimes called mini-splits are air-source heat pumps that distribute the heat via refrigerant lines to an interior "head" or "cassette", that has a refrigerant-to-air heat exchanger coil for heating the rooms where the heads are mounted. It's essentially point-source heating (like parlor-woodstoves, but without the intense radiated heat), but it is much more efficient than ducted heat pumps for several technical reasons (we can go into that if you like, but with single pane windows it's unlikely to be a satisfactory solution.) The best you're going to do with a clear glass storm window with single-pane double-hungs is about U0.5-0.6, which is still WAY better than the original windows alone, but still much lossier than hard-coat low-E glazed storms.

  19. Kate Clark | | #19

    I appreciate your taking the time to be so thorough with your thoughts and concerns.
    Many thanks

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