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Coal fired domestic steam boilers

In looking for a wood-fired steam boiler to replace my 30 yo OIL fired hot water, I was shocked to find that COAL fired steam boilers for domestic use are still being sold in VT & NH. I've been told by salesmen that COAL generates more BTUs, is cheaper than OIL, and can be put in boiler via hopper, just like wood pellets. So what's the downside?


  • STEVEusaPASTEVEusaPA Posts: 2,820Member
    the environment, and the messy labor on your end.

    And now for the opposing opinion....
  • leonzleonz Posts: 322Member
    Hello and good Morning TMcGroy,

    Everything has an opportunity cost; meaning; what "you" are willing to give up to obtain something else of value.

    The only "real down" side is a higher initial purchase price causing the final installed price to be greater.

    You can purchase a smaller coal stoker boiler and add a buffer tank to increase its volume of deliverable hot water for hot water heating and making domestic hot water directly from the domestic hot water coil in the steam or hydronic boiler.

    A lot of folks that own coal stokers use the domestic hot water coil in them for making and using hot water the year round to eliminate the need for a hot water heater or only requiring a smaller hot water heater when the coal stoker is not used for heating in the off season from May to October annually.

    1. you can purchase hand fired wood and coal boilers that will have an H stamp so they can be used to make steam.

    2. you can purchase coal stokers that will have an H stamp that will be tested and rated for making steam.

    3. Anthracite Coal makes more BTU per ton than seasoned firewood or wood pellets.

    a. coal stoker boilers are very efficient and anthracite coal burners and sled and underfed coal stokers used to burn Sub Anthracite Coal and Sub Bituminous Coal burn with little to no smoke.

    4. wood pellets used in a scenario with a home or business that is poorly insulated will use more than double the amount in firewood tonnage that seasoned cordwood would require.

    5. burning seasoned firewood that is dried over a long period or firewood that is kiln dried cordwood will create unusable smoke that is fuel in particulate form that is lost up the chimney and causes asthma.

    6. Unless seasoned dry firewood is burned in boilers like the Switzer or Garn hot water boilers with three pass smoke tubes and ceramic lined fireboxes and induced draft fire combustion systems the result is fuel gas created by burning seasoned cordwood is wasted.

    7. The fuel gas particulates created as a result of combustion are lost up the stack and the potential energy it could and would can create is lost and unrecoverable.

    8. batch burning seasoned firewood in the Switzer and Garn hybrid wood boilers is more efficient as small amounts of seasoned firewood are burned in a controlled manner and the 3 pass smoke tubes remove as much fuel gas energy as they can within limits.
    a. The Switzer Hybrid boilers are pressurized hydronic boilers that create less smoke due to the induced draft combustion system.
    a1. the Switzer boilers are pressure tested for hydronic service.
    Gary Switzer and his son inlaw install every boiler they make.

    9. The Garn hot water boilers are open to atmosphere boilers that are simply open to water tanks with a 3 pass fire tube system like the Switzer Hybrid Boilers.
    a. The Garn boilers and other open to air wood and coal boilers require that the water in the boiler be tested and treated annually.

    10. wood boilers are referred to as forest eaters as they spend a large amount of time idling after the high limit is reached and smoke quite a bit. They could be massivly improved but the builders of these things has no desire to improve them by creating better fire boxes with a three pass smoke tube system and increasing their water volume. Their use of stainless steel is a selling point in some models using corrugated steel stainless sheeting to create the rectangular fireboxes to increase the available square area in the firebox to absorb heat from the fire.

    I gave up on firewood after 33 years of burning it and I am using a coal stoker boiler for heating my home with 3/4" fin tube baseboard(which I hate) and for making domestic hot water during the heating season from October to May.

    If you want to examine coal burning more you can register at the coal pail forum(its free to join and learn more about coal burning with coal stokers and hand fed coal and wood boilers.

    I hope that you expand further on what your needs are so I can answer your inquiry better to provide more relevant information.

  • mikeg2015mikeg2015 Posts: 761Member
    Best setup or coal or biomass boiler is where you take advantage of it’s modulation. Ideally it’s a vapor vacuum system so when the fire goes down, the system goes into vacuum and the load continues to match the boiler output but simple operates at a lower temperature. At 190F output is 180BTU/EDR. Its down to 140 @ 170F or just over half the output at 215F. IN reality it’s probably close to 50% as convective heat transfer drops so radiator output is less linear than is typically published, but depends on the configuration of the radiator. Taller radiators probably overperform a little vs. short wide radiators.
  • mikeg2015mikeg2015 Posts: 761Member
    ... downside to either is all of the ash, and as mentioned, not the greatest thing for the environment. Small residential boilers lack fine particulate filtration (Think giant Dyson vacuum cleaner) and limestone scrubbers to remove sulphur compounds. Even then, it’s still has issues with heavy metals in the ash and and flue gasses and higher CO2 output than natural gas.
  • TMcGroyTMcGroy Posts: 15Member

    Your response was awesome! It's going to take me several readings to understand it all, but I appreciate the information.

    My 2 main concerns with any boiler fuel is 1) getting the most BTUs for the least amount of money and 2) the environmental damage. Stoking and cleaning are minor considerations. Having already experienced bone-chilling temperatures in my first fall in VT, I'm prepared to put in whatever amount of work is required to keep warm.

    After living comfortably in Denver for 20 years with the original coal fired (converted to natural gas in the 60s) LPS boiler installed in 1938, without an auto-fill or LW cutoff, I found monitoring & maintaining one's heat source a necessity I enjoyed. I'm not a "set it and forget it" kind of person. I've been called a luddite, which I don't find insulting.

    Ultimately, I want to restore radiators to a huge brick building, built in 1874, removing the dropped ceilings. There are two rooms; each roughly 30 x 30 X 16 (ceiling), with 4 (4' x 8') single pane double hung windows (that are staying as long as I own the bldg), currently unheated. Until I find a Dead Man's protege to pipe that system, I'll settle for two stoves.

    What do you recommend?

  • Robert_25Robert_25 Posts: 177Member
    The downside of a coal fired unit is definitely the handling of the coal itself, and the ashes. If that doesn't bother you, read on.

    I would forget hand firing. If you really want to power a steam system with a coal boiler, get a stoker boiler that is setup for that purpose. A stoker can be adjusted to provide an output that is well matched to the radiation, and the fire ramps up slower than oil or gas.

    The environmental aspects of coal tend to be generalized, despite the large differences in the different types of coal. Most of the comments above are applicable to Bituminous coal, which is not what you would likely be using in your area. Anthracite has emissions comparable to oil, and the ash can be treated as clean fill according to the EPA. Check and see if there are any anthracite dealers in your area.

    Another good resource for anthracite in general, and coal fired steamboilers is the forum over at
  • GrallertGrallert Posts: 305Member
    After burning coal for a year or so in an old coal parlor stove call a Heatrola not great but nice, the biggest down side for me was the toxic ash. Can't be used in the garden or compost. I now burn wood in a Weso coal wood stove. Ash goes right in the compost or on the snow over the garden.
  • ChrisJChrisJ Posts: 9,626Member
    The whole "X fuel produces more btu's" is a load of B.S.

    It doesn't matter how many btu\h you get from a specific amount of fuel. The only time it matters is when you're engineering a system or trying to compare fuel prices because then you need to know the quantity of fuel you're going to use.

    A 100,000 btu/h boiler burning it's intended fuel produces 100,000 btu/h regardless of if it's burning coal, oil, nat gas, propane etc.

    The downside of coal is having to handle it, have it delivered, the dust, ash etc. I don't know if there's a downside vs wood.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • TMcGroyTMcGroy Posts: 15Member
    What size propane/wood/coal stove is required to heat a room 28' x 32' with 16' (sixteen ft) ceiling, four (4) 4' x 8' single pane windows, double brick exterior walls, lath & plaster interior (no insulation). Picture attached.

  • mikeg2015mikeg2015 Posts: 761Member
    TMcGroy said:

    What size propane/wood/coal stove is required to heat a room 28' x 32' with 16' (sixteen ft) ceiling, four (4) 4' x 8' single pane windows, double brick exterior walls, lath & plaster interior (no insulation). Picture attached.


    What's the outdoor design temperature? Climate, location (temp it hits 1% of the time most years)... not the rare 0.01% evnery other year temp.

    Are the windows and sill plate sealed descent from air leaks?

    Honestly, the smallest boiler you can find should heat that room, the the high ceiling will challenge any system. You'll want a fan to push hot air back down.
  • mikeg2015mikeg2015 Posts: 761Member
    As for coal... i still have bits of coal and coal dust on top my my rafters and white residue from ash in my basement walls in the boiler room. There hasn't been coal in there in probably 70 years. They likely added a oil burner to it, in the 40's then a gas burner in probably the 60's, then switched it out for the boiler I have now i theorize. Point being, it's messy. And coal takes up a ton of space in a large home to meet it's heating needs.
  • TMcGroyTMcGroy Posts: 15Member
    EPA has approved the use of anthracite coal ash as substitute for portland cement in concrete. That's what I'm going to use it for. The more generated, the better.
  • SteamCoffeeSteamCoffee Posts: 75Member
  • TMcGroyTMcGroy Posts: 15Member
    What does Axeman-Anderson answer?
  • SteamCoffeeSteamCoffee Posts: 75Member
    AA boilers are great, efficient and by their design, minimal dust. I looked into this extensively a few years back but Anthracite is next to impossible to get for me. If I had access, I’d do it in a heart beat, inc. DHW. is a great resource..
  • TMcGroyTMcGroy Posts: 15Member
    Thanks for the recommendation.
    I went to AA's website & got a call back pronto. I was emailed some specs same day. I'm really impressed with their customer service. Keystoker is 6 weeks behind on delivery of their hand or hopper filled stoves. I may be on the crest of a new wave of coal. Anthracite is easy to get in VT/NH.
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