> Dr. Physics to the rescue!
>
> Yes, Heat rises. Physics 101.
Actually, heat doesn't rise. Warm air will rise, if there is cooler (more
dense) air available to displace it.
So, the air at the bottom is heated at the bottom by being in contact with
the heating element. The air above it has been cooled by being in contact
with the oven walls and top, so it "runs down" to replace the warmer air,
thereby bringing the cooler air in contact with the heating element and gets
warmed in turn. So, as Rush said, there is a convection cell setup as long
as the element is warmer than the top and sides of the oven. For an
ordinary kitchen oven, this is most of the time, as they're not especially
well insulated. Even when the element cools, there is still a weaker
convection cell, from the air at the sides being cooled by contact with the
walls. Unless cold air from the outside is admitted, the temp will stay
fairly even for a long time. And from what I've seen of kitchen ovens, the
element will be turned back on by the thermostat within a minute.
But again, we're only talking about curing powder coat here !!
Randall
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