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How do stove manufacturers calculate cubic feet?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by kingston73, Oct 3, 2011.

  1. kingston73 Member

    joined: Feb 10, 2011
    117 posts
    SE MA
    It doesn't really matter much, I'm not going to take my brand new stove back because of it, but I'm wondering how cubic feet is measured? Is it the total box dimensions, without the firebrick? Unless I'm not converting things correctly, I measured my firebox and it's 17.5 inches wide, 13 inches deep (a little more, maybe another 1/4 inch or so) and about 7.5 inches to the top of the firebricks on the side. My stove supposedly has a 1.8 cubic ft firebox, but using my measurements I only get about a 1 cube ft space? Is this pretty common among manufacturers?

    Related question: this is my first stove that's used firebricks. Do I generally want to limit the height of the wood to below the firebrick level? In other words, I don't want to stack the wood above the highest point of the bricks?
    kingston73, Oct 3, 2011
    #1

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  2. rdust Minister of Fire

    joined: Feb 9, 2009
    3,345 posts
    Michigan
    This has come up many times, there doesn't appear to be a standardized method of measuring. Some manufactures seem to get it close while others are way off. Best thing to do is take the tape measure with you and decide for yourself what amount of the firebox is usable for you.

    Highbeam started this thread about it last year. http://www.hearth.com/econtent/index.php/forums/viewthread/57153/P0/

    With my Endeavor I used to load almost up to the burn tubes, I tried to leave a little room for the secondary combustion to take place.
    rdust, Oct 3, 2011
    #2

  3. begreen Super Moderator

    joined: Nov 18, 2005
    36,118 posts
    South Puget Sound, WA
    Good question. The accuracy varies from company to company and their marketing depts. It should be the firebox width x depth time x height with the bricks in. Height varying with the stove design, but lets say 2" below the burn tubes for sake of discussion. The Archguard 1600 is listed at 1.7 cu ft, but being generous, I come up with about 1.3 cu ft usable space (18x13.5x9) . Does that match what you are seeing?

    If it's any consolation, our T6 is supposed to be 3 cu ft, but usable is closer to 2.3 cu ft. Where is the missing cu ftg? I suspect marketing is measuring to the glass and right up to the baffle box. Done that way it is easily 3 cu ft.
    begreen, Oct 3, 2011
    #3

  4. remkel Minister of Fire

    joined: Jan 21, 2010
    1,433 posts
    Southwest NH
    L X H X W last time I checked :)
    remkel, Oct 3, 2011
    #4

  5. WES999 Minister of Fire

    joined: Jan 12, 2008
    758 posts
    Mass north of Boston
    I guess it is a bit like measuring cords of wood, there are dictionary cords and there are fictionary cords. ;-)

    My stove is supposed to be 1.4 cf but is closer to 1 cf if you actually measure.
    WES999, Oct 3, 2011
    #5

  6. BrotherBart He Who Moderates

    joined: Nov 18, 2005
    21,949 posts
    Northern Virginia
    In slight defense of the manufacturers, they don't say it is where you can stack wood. They say it is the size of the firebox. :roll:

    Which is what the EPA uses in Method 28 to define firebox size. Pretty much from the top of the door opening down and front to back to the glass. That is the firebox. Don't say nothin about what is reasonable for stacking a load in it.

    The cubic inch displacement of your car engine isn't measured with all of the pistons at top dead center. I am gonna love the teeing off on that one. :lol:
    BrotherBart, Oct 3, 2011
    #6

  7. raybonz Minister of Fire

    joined: Feb 5, 2008
    5,982 posts
    Carver, MA.
    Personally I think they fill the firebox with water then pour that water into 1 cu. ft. jugs then count the jugs LOL.. Generally they tend to be a bit generous in their stated capacity..

    Ray
    raybonz, Oct 3, 2011
    #7

  8. SolarAndWood Minister of Fire

    joined: Feb 3, 2008
    6,714 posts
    Syracuse NY
    I bet they do the Autocad equivalent.
    SolarAndWood, Oct 3, 2011
    #8

  9. raybonz Minister of Fire

    joined: Feb 5, 2008
    5,982 posts
    Carver, MA.
    Yup I think you're correct! This is why we get those inflated values...

    Ray
    raybonz, Oct 3, 2011
    #9

  10. ddddddden Minister of Fire

    joined: Oct 20, 2009
    1,169 posts
    Central Va
    Yeah, spec of 2.2 vs 1.8 actual measured for me. This comes up often. We should just make a wiki listing all current models and let folks enter their measured L x W x H. It would be very handy for folks looking to burn a certain length of split too.
    ddddddden, Oct 3, 2011
    #10

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