But, the extra BTU's from higher wattage elements aid in curing heavier items.
That BTU clac. shows the number of watts\BTU's to heat "air".. But we are more interested in heating metal.
Think about it.. a Heat gun will get your oven to 400 if it's well insulated, but willl you be able to cure parts with it ??
If you put a 5 lb chicken in the oven and wait 10 min after the stat say's it reached 200 degress, would you eat it
? Now compair that to a 20lb Turkey.. it takes all day for the friggin thing to reach 200 in the center. Now do it again with frozen birds and look at the times.. Burnt in some areas and frozen in others..
You wouldn't need to many BTU's to cure , say a motorcycle fender as compaired to an engine block.
I would think it would be best to go with as many BTU's (Watts) as possible, uses a convection fan, (Convection oven can bake a cake in half the time as a regular oven) ramp your temps depending on the weight and type of metals you are cooking
and take lots of notes...
In the Powder coating hand book (I think it is the one in the sticky notes) there is a calculation for lbs/btu. I would look at that to be a more reliable method of determining BTU's need rather than the Home heating calc.
An advantage we have over the conveyor line industrial coating guys is that we can (and often have to) cure our parts one at a time.. therefore we can dial in the best time and temps for each item.. Or use the info to run the ovens as effeciantly as possible based on the weight, materials and btu's at hand.. Not just 500 degress for 30 min once around the conveyor
Bill
PS.. if someone is good with excell Id really like to see them make a spread sheet using the info from the BTU/weight section of that manual.