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coal furnace burning out in back

Luna1979 Member Posts: 2
We have a harman dual burner forced air furnace that burns out in the back (or front sometimes). The local dealer says to have a flat even layer of coal in the chamber. How should i be distributing the coal to have a better burning furnace?


  • Jamie Hall
    Jamie Hall Member Posts: 23,635
    I wonder

    how many folks here are old enough to actually have stoked a coal furnace?

    The main "secret" is to make sure that the coal is burning evenly -- all across the grate.  The procedure isn't that hard, but is a bit of a nuisance.

    Shake the grate to get the ashes down.

    Rake through the burning layer to distribute evenly over the grate, and ensure that there are no clinkers hiding.

    Add a thin layer of coal evenly over the entire grate..  Even in a very large power boiler the burning coal layer should be no more than a couple of inches thick!  Otherwise you can get uneven draught and hot or cold spots.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Mac_7
    Mac_7 Member Posts: 14
    Is the ash shaken down?

    We've been burning coal during the coldest weeks of every winter since the late 80s as a supplement to our oil fired boiler.  When that's happened to us, it's usually because when the ash is shaken down, the ash doesn't evenly fall into the bin, leaving a thick layer on the grate near the front or back edge (or both). 

    This occurs especially after a few weeks, when there may be more clinkers that don't fall through the grates when the ash is shaken.  This, because it seems to burn a little cooler near the firebrick.  Then when you add more coal, there's less to burn in these areas, since it's sitting on the top of ash, so it burns out sooner than that in the middle.

    I've used a long thin piece of steel with a notch cut near the end to reach underneath and through the grate to loosen the ash and cause it to fall through into the bin when this starts to occur.  Otherwise, I have to let it burn out and clean it, then restart it again, which is a pain in the ars.

    That's been our experience, with a coal stove insert, and a free standing Vermont Castings stove.
  • icesailor
    icesailor Member Posts: 7,265
    Upside down rakes:

    You mean the rake with properly spaced tines that fit between the slots in the grate that you rake from underneath to make the old ash and clinkers fall into the ash grate?

    Dirty nasty stuff. Ash and dust everywhere in the house. Wife did a careful cost analysis of before the coal stove, and when we had it. No savings after paying for the coal. House overheated when it was running and the bedrooms were cold.

    Get that POS OUT of here!!. I don't argue with her.
  • billtwocase
    billtwocase Member Posts: 2,385
    sounds like

    you are banking the coal. It needs to be even, and tended too frequently. It is not a set it and forget it process. It is also a dirty means of heating. Hung up my coal shovel years back