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Hello Everyone,

As the title says, this post will be about my furnace.

The furnace shell is an old 40 gallon water heater tank that I cut up. Inside of that there are 2 1 in layers of ceramic wool 2300F. Finally the flame face is made from 3200F castable refractory cement. There is a 2 in burner tube inserted tangent to the circle. The exhaust port is 4 in which I think is slightly too big so I just close it off a bit with a fire brick when in use. The refractory is also coated with HT-100 to help with getting and staying at temp. I do notice a little bit of difference when heating up.

[Furnace assembly]

Like I said, the burner is two inches in diameter and is only inserted into the furnace body about an inch. Any further and you will just melt the steel... On the burner, I drilled and welded a 1\4 in steel pipe nipple so that I could attach a 1\4 ball valve for quick safety shutoff and a 1\4 needle valve for fine control of the burner flame. The air source is a bouncy house blower connected with an old shop vac hose. Airflow is then controlled with a 2 in gate valve. I find that with my particular setup, no more than half of the gate valve should be opened up otherwise you will blow the combustion higher in furnace. If this happens you are almost guaranteed to have problems with your ingot.

For fuel I am using propane. I have used "waste oil" burners with diesel fuel and they do work well but for my current setup propane seems a better fit. The 1\4 inlet does not have an orfice, it just dumps propane.

[Burner assembly]


For the lid, I used the same 3200F castable refractory cement. I cut the top off of a 5 gallon bucket and used that as the form. It is about 2 inches thick. There is no rebar or any reinforcement in the lid. The lid prior had some rebar in it that ended up melting.... Where the lid meets the furnace there is a bit of a lip to help reduce excess heat escaping.

[close up of lid]



A bit of a warning when trying to light the furnace. Dumping full air and propane into a confined space and trying to light it, the potential for the propane to flash and or explode is quite high. So please be safe.

Unfortunately the images are no longer displaying... What are the inside dimensions more or less?

Sorry about that, I will try to get some new pictures up. I would say the inside dimensions are about 8x13 in.

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