Water Heater Boiler Build?

[brant2000]

So, at work they just replaced a 125 gallon, gas fired water heater. I was able to grab the old one before it got hauled off for scrap and plan to use it to replace a smaller storage tank I have. There's nothing wrong with the tank, it was just causing rusty looking water (may be caused by the tank or may be from steel pipes upstream). Looking at it's design, however, got me thinking about the possibility to use it as a boiler. I believe it is constructed as shown in the image below, with the burner being installed in a ~6" diameter tube near the bottom. What I was thinking is that I could construct a downdraft fire box that would then connect to this tube. Obviously one of the biggest concerns is not having the ability to easily access the fire/flue tubes for cleaning. (perhaps these can be accessed from below, but it wasn't apparent.)

 

[GENECOP]

Some kind of a rocket stove L shaped chamber attached to the 6" inlet......definately worth a try. You would have to find some way to clean the Fire Tubes....any way to cut the top open? Then make the rocket connection removable, brush from the top, empty at bottom......post some photos if you go for it.....

 

[brant2000]

So, I've been thinking a little more about this and may eventually give it a go. Still trying to figure out what's the best and easiest way to accomplish what I'm trying to do, either a downdraft or rocket design. I think I'm leaning towards the downdraft, but am really trying to fully understand the airflow paths. For any of you who have experience in building/tinkering with these designs, what are your thoughts on using a stainless secondary air tube directly beneath the nozzle? I realize that temps in this area are extremely high, but the air supply will certainly cool the tube.

 

[GENECOP]

Richard C Hill, University of Maine.....you really should read his paper on wood burning and design, google it...most designs I have seen that involved stainless , the people that did not use stainless, eventually ripped the chamber apart and did.....so yea, SS is the way to go....

 

[tom in maine]

(broken link removed to http://www.hotandcold.tv/woodfiredfurnace.pdf)