I do not have 3 phases i only have 1 phase, so i might as well try to convert the oven to single phase, this is a dumb question but what would be the difference ?
No dumb questions, just dumb mistakes. You know that alternating current changes polarity 60 times per second. It doesn't just jump from positive to negative, but is a wave form. The standard 240 volt power in households consists of two of the three phases, or waves, of the current: To add the third phase, you either have to get (and get billed for) commercial three phase from the power company, (They usually won't do this unless you use a LOT of electricity. I run a little machine shop, and have three phase right across the street, but I can't get it at my usage levels), or the alternative, to make your own third phase with a rotary generator. These make a lot of noise but they work fine. The solid state three phase converters just fool motors into thinking they have the third phase, and you don't get the benefits like instant reversing, and they run on partial horsepower. I assume on a heating appliance they would be worthless.
It might be cheaper to convert to single phase heating elements if they are available.