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[almostplumb]

Just a light question, probably for slimjim, the P&M consultant
The Optimizer specs say the firebox (or firepot) size is 28' x 30" x 30" or 11 cu ft.
Isn't a cu ft = 12 x 12 x 12 cu in or 1728 cu in? 
28 x 30 x 30 = 25,200 and 25,200 / 1728 = 14.6 cu ft
Are the dimensions nominal and the volume precise or vice versa?
Or are these Canadian inches?

[slimjim]

Great question! Remember the top of the firebox is round, I think that is where the difference is and the math on that is way above my comprehension, my wife had me up until the wee hours sitting by the fire pit that I made for her last year and then she woke me up early with her snoring so I'm a bit fuzzy this morning.

[Jwood]

Could it be 11 cu ft is the usable fire box volume, you don't fill it to the top, right?

[slimjim]

Another good point!

[Big Wood]

Yes the top of the fir box is rounded and the air injection is in the top of the fire box so that would take out of the square footage. Most of my customers only fill the fire box half way or a little more hope this helps

[almostplumb]

That all seems to be part of it.
Assuming the rounded top is circular and given the 28" width, half the area of a radius 14" length 30 cylinder is 9236 cu in
The remaining box (30-14) * 28 * 30 = 13440 cu in
(13440 + 9236) / 1728 yields 13.12 cu in, so the other factors must come into play
I only pondered this because some of the competitors use the 'my box is bigger than your box' line
Would like to thank everyone's input on this forum.  We've pretty much decided on the 250.
Just need to sell the town home so we can move back into the country home.

[slimjim]

WOW do I feel upstaged, I guess i should not have slept through those math classes.

[mlappin]

That all seems to be part of it.
Assuming the rounded top is circular and given the 28" width, half the area of a radius 14" length 30 cylinder is 9236 cu in
The remaining box (30-14) * 28 * 30 = 13440 cu in
(13440 + 9236) / 1728 yields 13.12 cu in, so the other factors must come into play
I only pondered this because some of the competitors use the 'my box is bigger than your box' line
Would like to thank everyone's input on this forum.  We've pretty much decided on the 250.
Just need to sell the town home so we can move back into the country home.

They probably figure it's 11 usable cu. ft. It can be done on about any stove, but unless the top of the door is flush with the top of the firebox, you're not going to cram the top full.

Do those figures include the firebrick in the bottom, or is the height given from metal to metal?

[almostplumb]

You're right mlappin.  P&M is probably being honest about usable volume.  You wonder it the other
who use firebox volume as a sales pitch do it honestly.  Allowing for the air intake, firebrick, etc.
the 11 cu ft is the usable volume.