I made an electric furnace that consume ~18 kW (3 phase) of power. I want to know how much energy is lost when its used to heat only air. The only sensing tool available as of now are thermocouple installed inside and amperemeter. It took approximately 250s to reach 500°C from 25°C. It's not fully sealed so there are some holes for air to go in and out.
Cant seem to make up my mind to decide which factor I should consider for the heat loss.
To add, it's an electric furnace and has temperature limit set to certain degree (500°C in my case, can be changed). At that point the contactor will start turn on and off to keep temperature constant. All I know is that it consume constant 27.3 A when its powered. That's where I got 18 kW from.