5 hours ago, Maison Rustique said:
It shouldn't be more than 10 minutes. Ours is only a couple of years old or so, but it started taking longer and longer to heat up, then just wouldn't ever reach the desired temp. Turned out that the bottom heating element was burned out and had to be replaced.
After reading about your burned out bottom element, I opened our oven doors. And again, this is a double wall oven....and there is NO bottom element in either oven! Just a single upper/broiler element in each oven. Now I wonder if that's the reason it takes so long to preheat??
BTW, i always use an oven thermometer...well ever since our oven in Mexico which had NO thermostat (this is common in even the 'better' ovens there).