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boiler replacement advice

After this heating season is done I plan to replace old steam boiler. The current boiler is a 30 year old HB Smith(g210-s-5) rated for 120 mbh gross output. The boiler is leaking between the sections. My bills have actually not been that high(about $325 for a very cold January). I did a survey of my radiators and came out with 261.83 feet EDR. I have a finished basement so I can't get a look at the mains but I would estimate that there is aprox 40 feet of uninsulated 2" main. If I go with a 1.5 pickup factor I come out with a gross output of 94,258.8. The 2 boilers that I came up with are the slant-fin gxha 120 which has a gross output of 97mbh or the peerless 63-03 which has a gross output of 98mbh. The HB Smith gs-118 also has a gross output of 98 mbh but my supplier is unable to get the residential Smith steam boilers. The Slant-fin brochure mentions a "speed skimmer". Is there any benefit to this? From the diagrams it seems to be slightly higher then the bottom of the water glass. The other issue that I have to deal with is very limited space. I will take measurements again tomorrow but I seem to remember having 70" front to back and 36" right to left.Any advice or suggestions would be greatly appreciated.


  • BobC
    BobC Member Posts: 5,317
    A 1.3 pickup factor might be fine.

    I believe using a pickup factor of 1.3 should be fine in your case because I'm assuming the basement is not an unheated space in your case. Also i believe the Net IBR on the name plate implies a 1.3 pickup factor, if you choose a boiler by matching the EDR I think you'll be fine.  Make sure you know what your main vents capacity is and see if it should be increased because the new boiler is likely to make steam faster than the old one did.

    Also install a boiler that the local installers are familiar with and have parts in stock if you need them down the road. Insulate all the near boiler piping you can reach on the new boiler.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
    STEAM DOCTOR Member Posts: 1,522

    The basement is fully heated. If I use a 1.33 pickup factor I come out with 83mbh which would allow me to drop down in boiler size to the slant fin gxh 105. This would also give me some more room to work with because of the external draft hood.
    STEAM DOCTOR Member Posts: 1,522

    The gxh-105 is no longer available as a steam boiler. At one point it was and the slantfin website still lists it as a water or steam boiler. It is actually listed in two places one as only water and one as steam or water
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