I just purchased my first furnace, it is a USA Cast Masters 12kg Propane furnace with a 10kg crucible. I have done two melts so far and have made some copper ingots that have came out pretty good. The provided valve says 20 psi but has no gauge. I cranked it all the way up and left the air flow fairly low so it didn't sound to loud. I did it in my back yard in daylight and I wasn't able to see any flame coming out the top. As I understand when melting copper I should have a little flame coming out the top, but either I couldn't see it in the light or I couldn't get the right air/fuel ratio to see the flame. It took about 35mins before the copper started to melt and probably another 25mins to get half a crucible melted. I did see green flame for a little bit when added copper to the forge.
Is it better to have more or less space between the walls of the furnace and the crucible? Should I try a smaller crucible? Would using refractory cement over the kaowool hold in heat better?
I purchased a 30psi valve/gauge and next melt I think I will try at night.
Thanks!