Making electric kiln

Hi, So i'm making electric kiln and i use this as my guide and several other YT videos. Size of space in kiln is W 200mmxH 200mmxL 400mm. For heating i am using a special heating lamps that are used in plastic blowing machines rated at 400VAC 2500W. I meassured the current and it gives me 12Amps on 380VAC (so 4560W) with two lights on. So the problem is i use Ytong ZP10 insulating bricks and it heats up to 500°C in under 2 minutes. As i need temperature 1100°C i left it fol half hour and it heated only to 900°C and it gave away a lot of steam from bricks(they had them outside the store). Question is why is taking so long and why i dont reach the temperature in that period of time?

Thank you for your help!

edit: Lamp looks like this one but is rated 400V 2500W

Submitted January 30, 2016 at 07:09PM by kemc55 http://ift.tt/1JP1mYS