Building a super furnace

Project code name: Hefty Harriette - Part 1

With the advancements in the waste oil burners I need to make sure that the furnaces keep up. My previous furnace had a 10" diameter chamber and I'll step it up with this new furnace to a 12" chamber. I'll also use refractory capable of withstanding over 3,000 degrees. Hense I've accepted the mission of building a super furnace which I will call "Hefty Harriette." - Aug./10/2007

The hot water heater located

My well trained and professional eye can spot good junk from a quarter mile away... This is a photo of a hot water heater that I spotted from a distance. The heater is laying on it's side, highlighted by the red circle. I know that these heaters have a strong steel tank in the center and it'll make a fine furnace shell that I can weld components onto. That is a nice benefit over the usual sheetmetal shells.

Under the cover of darkness I mobilized my troops (me and a handtruck) and pulled off a successful rescue and recovery of this item. I'm sure the homeowners were unhappy to have to replace the water heater but I was quite pleased.

Dismantling the tank

In this photo I secured the heater and transported it into the Lab's underground work facility (the basement).

The heater torn open

The heaters are easy to take apart. Just unscrew any valves and such, then unscrew the lid piece and pry it off (it's glued to the insulating foam). Then slice the sheetmetal shell and unwrap it. The insulating foam surrounding the central tank can be easily scraped off with a chisel type of tool. In some cases the foam is sealed inside a plastic "bag" type membrane and it is simply slid off the tank in basically one piece.

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The cleaned tank

In less than an hour and a half I had the tank freed from it's casing and the work area cleaned up (or at least back normal). The chunks of foam are incredibly flammable, almost like it were a gasoline sponge. I wonder if they can be ground into some sort of fuel. All that work has rewarded me with a tank that is 18" in diameter and about 50" tall. The steel shell is only slightly thinner than a barbecue style propane tank. Good stuff!

Now I can begin the work that I personally enjoy most, the metal work. I must cut the ends off this tank, weld parts on and otherwise finagle this tank until it's right for the refractory stage.

The furnace body cut away

Here is a look at the tank after I made the first two cuts. The section cut loose is the furnace shell. As written on the tank it is 18" tall and the lid will be cut next 3-1/2" tall.

I can't remove this cutout section yet because there is a tube running down the center of the tank which is welded to the base and the top. So I have to cut this tube to remove the top section of the tank and free the furnace shell.

The central tank tube

Here you can see that central tube I was talking about. I think it's a "chimney" of some sort for hot air to rise through while heating the water inside.

In this photo the tube has been cut, the tank's top removed and the furnace shell area taken out. You may also notice a line 3-1/2 inches down from the cut end of the shell. This is where I'll cut the lid section off from.

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Cutting off the lid section

Here you can see the angle grinder with cutting disk slicing through the tank shell to remove the lid section.

The cuts were easy to make. I first went all around the tank with the grinder to "score" the line then made the final cut. This cut took about 3 minutes.

The cutting is complete

On the right is the cut furnace shell and lid section. I now need to weld a plate to the bottom of the shell as a base. On the left are the remains of the hot water heater tank. I was considering saving it for making a cupollette furnace but I didn't want to have the material taking up space until I got around to building it so I took it to the scrap yard for recycling.

I should have cutout and saved the central pipe. It's approximately 5" in diameter and long enough to have made about seven welded steel crucibles 6" tall.

The factory tank welds

I wanted to throw this photo in because the factory welds on this tank look amazingly neat. I guess they use a CNC welding robot.

On to part 2.


Copyright © 2007 by Lionel Oliver II All Rights Reserved.
This site was created Sept. 28, 2000