[7up]

The furnace is built with fire bricks so copper can be melted down and cast,but when the lid is closed the flame goes out.

[tickle]

You need an in draft to keep the fire going. When you close the lid, you cut off the oxygen supply that keeps the fire going. In other words you need 'dampers'.
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[tickle]

7, you don't need a blower, just a good up draft, or side draft. It has to be the kind of draft you can control, like a damper in a fireplace insert. Go take a look at one in a store where they sell them.

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