"Gymmie Bob" wrote in message
...
You don't honestly believe that now do you?

Does it blow your oven door off very often or does it implode?


Don't be an idiot. Of course a temperature difference between the oven and
the kitchen doesn't develop a large difference in pressure to 'implode the
oven'. But a 20 ft tall house heated 50 to 60 F warmer than the outside
will generate enough of a pressure difference to cause air leakage if the
house isn't sealed up properly.

The difference in pressure created by a temperature difference is easily
calculated as the density of the fluid on one side (inside the house) times
the vertical distance, minus the density of the fluid on the other side (the
outside air) times the same vertical distance.

With an indoor temp of 70F and outdoor of 0F over a 20ft height would be
about 11 Pascals. Not the 50 that Nick mentioned in the test he described,
but enough to cause significant in-leakage at the ground floor. A 400F oven
that is 2 ft high in a 70F kitchen could generate a pressure difference of
only ~3 Pascals from the bottom of the oven.

Leave the damper open in a fireplace with no fire in the grate. In winter
time there will be a strong draft as this modest pressure difference forces
heated air from the room up the chimney.

Look up 'natural convection' or 'natural circulation'. It is caused by a
density difference that is brought on by a temperature difference, acting on
two columns of fluid. A layman explains it by saying 'hot air rises', but
that isn't quite true. 'Hot air' only rises if there is some 'cold air'
that can get underneath and push it up; and the fact that air changes
density with temperature and gravity acting on the two masses.

daestrom