>>>She said if it wasn’t flat it wouldn’t heat properly. Any comments? <<<
Only if you are using it on a glass flat top range (not recommended for larger canners)..
Makes no difference if you are using gas or regular electric range... Since it overhangs the element on the electric coil range, it would heat quite well since it would be in full contact.
Even if it did heat unevenly, just think - The internal temperature of the vessel has to be 240º F. at sea level with a pressure of 10#... T hat’s the whole interior of the vessel.... Since we are not browning meat, making pancakes or baking a cake, it matters not if it is hotter on one side or one spot or another... All that matters is if it can maintain enough heat to keep the pressure uniformly at the 10-11# (10# with weighted regulator and 11# with manual spring loaded valve)
Gee, when it gets too hot in the kitchen, I often do my canning on a kerosene stove outside... The canner overhangs this a couple of inches on each side, so the center is going to be hotter than the outside edges of the bottom... Never had any problems with it... (Except I get to scrub a bit of soot off the bottom when I am done)
“Makes no difference if you are using gas or regular electric range... “
That’s pretty much what I thought. I have a gas stove and didn’t think it should really affect the heat/pressure in the canner.