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[Scott7m]

yoder, why would i be losing a lot of heat? have you ever heated steel before?  what cools faster thicker or thinner steel?

you are losing lots of heat, the 3/8 firebox for ncb
tested 12-14% less efficient than the same stove 1/4 inch thick.

It is much harder to transfer heat into the water with thicker steel, besides that, it's
not the goal to store heat in the steel, you store your heat
in the water

[yoderheating]

 Yea, hot steel out in the yard doesn't do much to heat your home. You have to be able to transfer that heat into the water to do any good. Your furnace will be unable to capture as much heat as it produces and so it will escape out the chimney. I had a chart showing the efficiency of different thickness of mild steel and stainless steel but I don't know what I did with it. I do remember that it lost a lot the thicker it got. 

[Scott7m]

It's about transferring heat to the water, not storing it in steel.  I never realized folks seen
it that way.  An example would be would u rather hold your hand on the back of 2" piece of steel while ur buddy waves a torch over it or a 1/8 piece of steel, answer is neither, but your going to get burnt a lot faster with the thin metal lol

[rosewood]

jackel , good points..but dont forget that the water on the other side is still hot 165,not stone cold 65 deg water  my on cycle time is about 2-3 times longer then the average 400 gal owb.but i have 3 times thewater capacity at 1200+gals.with that said i dont see how im wasting heat.thicker material has more durability benefits. thick steel and large capacity of water has also resulted a really clean furnace,little to no smoke after a hour or less of burning . i am just giving my 2 cents based on my real world results and not by speculation or theory.

[Scott7m]

this isnt theory, but if an OWB would last equally as long with the same material, you would want the thinnest material you could possibly get!  Thats saying it would last equally.  look at radiators, everything is made really thin in them for maximum heat transfer, what your doing with your stove is no different, transferring heat through a metal into water...

[rosewood]

when you say radiators are you talking about cast iron rads,baseboard rads,or automotive?anybody thats been in a old house iron rads knows how long the steel holds temperature.thinner baseboard rads expell heat faster but require more flow of hot water thru them. a automotive rad is designed to expell heat . for friendly debate,i believe you said it was harder to transfer heat with thicker steel,to the water and not the goal to store heat in the steel. were do you thinkthe absorbed heat in the steel goes when its submerged in a tank of water? water doesen't absorb heat? thick stock is radiating heat in water after the fire stops. we all know how wood furnaces work ,when air flow stops entering firebox it locks heat in thats why smoke stops flowing from chimney , therefore any thing hot inside stays hot for extended periods of time.thicker stock stores more energy and can release it into water longer after the fire is off.thinner stock would release the same way but would run out stored energy quicker . what purpose does fire brick serve in wood  stoves?2 things..keeps fire from burnning thru thin wall stoves and stores heat energy then radiating out to room .mass holds energy ..thats theory.

[jackel440]

jackel , good points..but dont forget that the water on the other side is still hot 165,not stone cold 65 deg water  my on cycle time is about 2-3 times longer then the average 400 gal owb.but i have 3 times thewater capacity at 1200+gals.with that said i dont see how im wasting heat.thicker material has more durability benefits. thick steel and large capacity of water has also resulted a really clean furnace,little to no smoke after a hour or less of burning . i am just giving my 2 cents based on my real world results and not by speculation or theory.

That's what I love about this site! We all have our own ideas and theorys. :thumbup:We know what works for us and thats what we try and build.
I can see where you would have long burn times to heat sink the thicker steel to bring up your water temp.More efficient burn during wide open heat output then short on and off again cycles.
Maybe we are doing it all wrong.....Perhaps we need to use the 1/4" material for the burn chamber then use a 1" out jacket.Then super insulate it to hold the heat...That would quickly bring the temp up in the water and then the large mass of the thick tank walls to slowly give up its BTU s as it cools.
Dang I would hate to buy the steel for a tank out of 1" plate.Heck I would need Versa-Lift truck to move it.
http://www.versa-lift.com/
I use one at work all the time to set machines.Might have to pour concrete all around the poutside of my shop to hold it up.LOL!

[rosewood]

jackel your right on about theory  and ideas. as a fellow homebuilt  owner you can see real world results and tell people your info , accurate info first hand and not from a sales advertisement.

[yoderheating]

 Steel transfers heat at a set rate that is reduced the thicker it gets. At some point if you made it thick enough it would no longer transfer any heat. Any heat produced by your fire in excess of the transferring ability of the firebox to transfer is wasted energy. Using steel that is twice as thick would require either a fire that produces half as much energy or twice as much area for heat exchange.
 The firebox is a obstruction in the path of the energy. What if we take the thicker firebox theory to the extreme? If 1 inch is better that 1/4, would 10 inches be better than 1inch? What about 3ft, would it be even better?
 These theories have all been tested by furnace companies many many times and I can assure you none have come to the conclusion that thick fireboxes transfer heat better.
 I think Jackel has a good idea, a thick water jacket would be much more desirable because you would not be fighting the heat transfer issues but may gain some with respect to holding heat.