I'm not looking to make steam just hot water. Check out this guys coil and where he would put it. I need to recoil my copper and put it at top where the heat exits. I've not used copper to catch heat before. Had in my mind that it might melt or break down from the heat over time. Guess with water moving through it, keeps in cool. So I can put it in the flame?
YouTube - Lynx Wood Gasifier Boiler Part 2


http://img98.imageshack.us/img98/799...2010002.th.jpg
This is where It's going to live. Testing it out. I like this stove. You can put your hand at the bottom of the barrel and it feels cold. About 3/4's the way up it becomes to hot to keep your hand on. At top water sizzles.

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My Dad gave me this old water heater tank. It was leaking at the element. Bet it has 20 - 30 pounds of calcium build up in it. Note the concave bottom. Going to clean it up and make it water tight. Then put it where the bowl is now. Might insulate it and cover it with another barrel.

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I'd put it in the flame too. Copper's melting point is pretty high (higher than other soft metals) @ 1984°F. That is a very hot flame. Like you said, you also have much cooler water running through the lines to cool it.

I guess you have installed an alternate exhaust chimney to allow smoke to move up the smoke stack.

Does that bowl get really hot?
It seems like putting that tank on top (where the bowl is now) will be like
a dead-end heat-pocket that's not going to be as hot as the heated air
and exhaust gases flowing up & out of the main Rocket stove chimney.

I believe your very much right on the dead end heat pocket. I also came up with the desire for a grill / hot plate and a oven. in the final build. Probably need two rockets one for grill and water and one for the oven. Here is my idea for the water. Do plan to keep the coil around the riser and have it feed the tank.

http://img688.imageshack.us/img688/5...terjpeg.th.jpg

I did a little rework on the copper of my current rocket. It's supplying all the hot water I need for my BBQ kitchen. I can bring up 500 gallon up four degrees in 3-4 hours. A 5 gallon bucket packed wood and paper well give me 10 degrees. I'm hoping this well improve with the final build having more mass to capture the heat.

So, I'm right? About it not getting very hot up at the top 'dead-end-heat-pocket'?

Looking at your 'double-rocket' drawing, I'm not sure that I'm understanding the layout correctly,
but it seems like the exhaust is down on the lower right side of the pic.?.

If that's the case, then hot gas has to travel around a lot of obstacles,
Before it can get to the real chimney..
Which seems like it's going to cut down the draft, and the obstacles are
going to absorb much of the heat from the exhaust gas..

For the main chimney to work correctly, it must have some really hot
exhaust gas coming into it.. I think you might have a problem getting
a good draft.. Unless, you feed in a LOT of fuel..
(Or, your main chimney is really tall).

It seems like a waste of fuel to be heating the cook-top whenever you
want to heat water..
If I was designing this for myself, I would likely want to build two separate Rockets,
one for cooking, and one for hot-water..
Two fuel ports with fuel-loading doors/air-blocks, to stop air input when they weren't in use.

Maybe have an upside-down 'Y' connection to the main chimney.?. :confused:

Think I'm causing confusion. The top of the riser is the hottest part of the rocket I think. The hot gases hitting the top of the bowl/ barrel cause the gases to cool and fall down the outside of the riser. I was thinking more the dead space would be interference with the chimney draw / flow.
Photos du Rocket

The GIMP drawing is just hot water only.