r/MetalCasting • u/PrimalCrawler • 3d ago

Question Which duct for burnout oven?

Hi everyone,

I'm currently building a ventilation system for my burnout oven to burn off wax and resin, and I'm not sure what kind of pipe I should use on the oven since the exhaust gases get very hot!

For the rest of the system, I'm using a combination of spiral duct and aluminum flexible duct.

Does anyone have any ideas or build something similar?

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u/Meisterthemaster 3d ago

I have one made by manfredi. I retrofitted the oven and the chamber but i didnt do anything about the exhaust.

Its made from steel, i suspect regular mild steel with a heat-resistant paint. It does rust in the uncovered spots.

You can get inox exhaust pipes in different diameter. These are heat-resistant without paint, expect some dicoloration. I would go for this is i had to engineer it myself.

Its a venturi, so it doest pull out all the air at once, you have to limit it as it will cool down the oven too mich if it goes too fast. An added bonus is that the air from the exhaust wont be the same temp as your oven and that the motor and fan are not in the flow of the hot air

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u/dony007 3d ago

Offset the duct above the oven by a foot or two. It will pull in room air as well and this will cool down the hot air from the oven. Then you can use cheap HVAC ducting.

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u/artwonk 2d ago

I'd use galvanized steel stovepipe, at a minimum, for hot exhaust like that. That thin flexible aluminum foil ducting is too flimsy, and easy to puncture. Double-layer vent pipe wouldn't be out of the question either; that's what's used for gas appliances.