Ok, I have some serious concerns about venting.

[tinbender722]

Bluegiller,

Is this a torpedo type heater? I have been running a 150,000 btu one in a 6'x'4'x6' self built oven for a year with no problem. It will get to 520 degrees.
I also have a factory made 8'x8'x15' oven with a 1,000,000 btu propane burner. The oven needs to be vented to work right. Cut a 8" - 10" diameter hole at the top in the side of the oven and vent to outside. Or, change over to electric and send me a picture of your burner and the price - I am ready to build another oven and may be real interested in buying the burner.

Leo

[bluegiller]

Well after talking to pickle he pointed out that perhaps the propane bottle was frosting up, then the propane would not burn as efficent.
After another test run last night with the top door cracked a 1/4 inch for venting, the bottle did fost over and the temputure in the oven droped a lot when this happened. It came up to 275 pretty fast and then when the frost hit the propane tank it drop almost 75 degrees. (210)

I hop you don't mind tin man but I going to give you a call at the shop and try to figure out the proper venting system.

Here is a couple pics of the oven again. (I have a 2 foot extension tube now on the end of the heater.)

[jjucius]

My oven is 3' x 5' x 7' and i'm using a 375,000 btu heater i have a 40 pound tank but i am getting atleast 1 100 pound tank soon. on a heater that size you should use 1 or 2 tanks so the pressure keeps up. i have to put in anouther vent because mine heats up to 400 in 5 minutes 10 minutes it went up to 530 right now if i open the door half way it will sit at 410 i have the heater ducted in to the back and a 8 inch vent with a stove damper on top towards the front. i have no problem with powder blowing off but i need to put some type of deflector in the oven because it gets too hot where the heat comes in and tends to burn the powder if parts are hanging close to it. i will try to get some pics up soon.
Joe