Furnace struggling to melt copper, help needed.

Discussion in 'Furnaces and their construction' started by Conor, Feb 24, 2025.

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  1. Conor

    Conor Lead

    Hi all,
    I'm sure this is a really simple question to some, I am aware I don't understand some basic principles of air/fuel ratios and how it produces heat. I'm hoping someone can help me.
    I have a VEVOR propane furnace and every time I adjust the choke on the burner more than one hole, the thing starts to sputter and becomes unusable. My gas pressure usually between 10-15 PSI (but sputtering continues no matter what way I adjust the PSI). So this system is OK, and will melt tin bronze fine, so it obviously reaches bronze melting point easily enough. But today I had about a kilo of copper and after more than an hour, it still hadn't melted. So my thoughts are that it was struggling to reach a certain temperature. I increased the PSI up to 25 but still couldn't adjust air flow so I think I was just wasting fuel. Maybe if my furnace allowed me to increase air intake beyond a certain point, melts would be much quicker? Or maybe it doesn't work that way.

    Maybe my copper was alloyed with something else making it harder to melt, although I doubt it as it was scraps from the jewelry dept in art college and was told it was 100% copper.
     
    Conor, Feb 24, 2025
    #1
  2. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Some close up pictures of your burner might help. I'm a forced air burner user, so take the rest with a grain of salt.

    It might help to keep experimenting with making just small adjustments to the gas (and air intake if necessary) once you have it running stable/neutral. Within a certain range of gas pressures, you may not have to adjust the air intake (much?) to turn the heat up or down without changing the mixture significantly, since more/less gas flowing into the venturi should suck more/less air in with it. (I think. Again, I use a controllable blower)

    In theory, if you have the right mixture, more air and gas at the same ratio should heat things up faster. At least up to a point. Likewise, the wrong mixture may cool things off.

    I'm not sure what pressures yours is designed to run best at, you might be able to find a sweet spot if you keep playing around with it. Ideally you want to hit pretty close to neutral. The way I identify that is when the flames completely fill the furnace without really coming up through the vent hole in the lid more than just a little bit.

    Good luck,

    Jeff
     
    Tobho Mott, Feb 24, 2025
    #2
  3. DavidF

    DavidF Administrator Staff Member Banner Member

    You should add forced air to it, it'll do the trick. I use a hair dryer on low and I'm able to melt cast iron.
     
    DavidF, Feb 24, 2025
    #3
    HT1 likes this.
  4. HT1

    HT1 Gold Banner Member

    Which Vevor furnace do you have???
     
    HT1, Feb 24, 2025
    #4
  5. Petee716

    Petee716 Gold Banner Member

    Wondering if the propane tank is freezing.
     
    Petee716, Feb 24, 2025
    #5

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