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Is Smith G8 still the best option?

steve_173 Member Posts: 140
It has been a few months since I first starting researching my boiler replacement. Is the Smith G8 still the best (only factory) wet base gas option for residential steam?


  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688

    with all the publicity we've given this type of boiler, it's a wonder no one else has put one on the market......


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  • steve_173
    steve_173 Member Posts: 140

    Thanks for the quick response. I think they don't market it because the public is uneducated and so are the gas companies. I've had to convince everyone involved at each step of the way to go along with 2 G8s in 1/3 / 2/3 sq ft steam configuration.

    Any tips on the header layout for such a setup? I'm concerned the plumber will screw something up. I currently have a coal converted to oil boiler. It has two 4" risers that each feed about half the house without a single header connecting the risers together.

    I think the new system will need a header linking the two boilers and then feeding into the two halves of the house. Any layout tips?

    I've also had a heck of a time with a chimny liner due to the way my chimney was built. I'm hoping they can get an 8" oval in there and that it will be adequate for ~375 MBH including the hot water heater.

    Speaking of hot water heaters...any thoughts on tank versus on demand? Indirect is a good option, but will make the project even more complex. I'm also concerned about pump failures and maintenance down the road.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    To see the proper header/Hartford Loop layout

    for this setup, check out pages 66-67 of Dan's book "The Lost Art of Steam Heating". It shows three boilers, each with its own header and Hartford Loop, feeding into a common header that then feeds the steam mains.

    I'd make your common header at least 4-inch, and your boiler headers 3-inch. This will insure nice, dry steam.

    An indirect is pretty easy to hook up to a G-8. You could probably run it straight off the smaller boiler. Here's a link to a thread showing the hookup for a hot-water loop to a G-8- the indirect would hook up the same way.



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  • steve_173
    steve_173 Member Posts: 140

    I don't have a copy of Dan's book. My local plumbing house didn't know what I was talking about last time I inquired. I might buy it but haven't yet. Would ceiling height be an issue, i.e., does the common header have to be higher than the individual headers? I'm using a 3 and 5 section so each one only has a single riser.

    Is there any advantage to the common header being larger than 4-inch? Any disadvantage? Same for the individual headers?

    I've read that the indirect can be an issue because there is limited feed pressure for the pump to the indirect tank. The setup also seems to cost much more than an old fashioned tank. It isn't that clear how fast this pays back if at all.

    Any tips to be sure my system is well flushed before the returns are hooked to the new boilers? My plumber was not to happy when I suggested piping the returns to a drain and running the boilers as an open loop until the condensate runs clear.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    Time to buy the book

    you'll be better informed than many people who ought to be.

    On the G-8, Smith gives a minimum header size of 2-inch. Going larger slows the steam's velocity, allowing any water to drop to the bottom of the header and drain back to the boiler. It also lets the steam expand a bit before heading into the mains.

    The common header should be at least 4-inch because that's the size of the mains. Larger pipe and fittings are more expensive but I'd use them if I could, for the same reason. Of course the common header should have a drip at the end just like the boiler headers do, draining into the wet return before the Hartford Loops on the boilers.

    The right indirect will work fine with the G-8. The SuperStor, from Heat Transfer Products, has the best heat exchanger for use with a steam boiler that I've seen. As long as the pump is placed near the bottom of the boiler, pumping away from the boiler and toward the tank, there will be enough static head to keep it from cavitating. Indirects do cost more than ordinary water heaters, but last a lot longer in most cases.

    The "no-return flush" you describe is a good way to get a lot of dirt out of the system. I think your plumber needs to read "Lost Art".

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  • steve_173
    steve_173 Member Posts: 140

    Follow-up question on the superstor. Which line do you like, the Ultra? It looks like the 105 MBH smaller boiler can only do a 30 gallon tank (180 degree @ 102MBH, 200 @ 117MBH). I was planning on a 50 gallon water heater. Does one usually size down when using a indirect? Or do I need the 45/60 gal superstor and then hook that into the larger boiler. Will the 2/3 size boiler be strained maintaining the house and hot water?

    What effect on sq ft of steam and efficiency does the indirect have?

    The 30 gal costs about double a high recovery 50 gallon gas heater. How much extra do you think the pump and extra install tends to run. It would have to be very efficient for any reasonable payback.
  • Tim_64
    Tim_64 Member Posts: 76

    I'm interested in this dialog regarding the indirect, I'm just about to pull the trigger on one.
  • Works

  • steve_173
    steve_173 Member Posts: 140

    Can you give some more detail? What equipment and setup did you use? How does the sizing compare to an ordinary hot water heater?
  • vaporvac
    vaporvac Member Posts: 1,520
    Update Please!

    Hello,I've been reading through your old posts and am wondering how it all went for you with the configuration you described. i'm considering doing the same but with and equal split. Why did you choose the 1/3-2/3 way? Did you look into the Slantfin Intrepid? I'm in a similar situation, basically leading a plumber whose done some steam work.. The big companies locally weren't interested in trying awet based boiler so I'm on my own. You can respond to your old post as I'm sure others would be interested in your results I'd really like to know exactly what you did. Not sure if I'll add the HW at this time, but would like to know if that's worked for you or was it very difficult to install. Thanks in advance.


    I sent this as a personal email as I wasn't sure if you'd get it otherwise. Sorry for the duplication.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
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