I love to cook roasts in the oven at 200 degrees for at least 6 hours to ensure I have a tender piece of meat.  I add the potatoes, onions and carrots after about 2 hours.  I put about an inch of water in the glass pan and cover with aluminum foil.

So, what kept happening was the condensation rose and ran down the outside of the pan and then dripped onto the bottom of the oven.

To solve that problem, I made a well by running my fingers along the inside of the entire pan edge.  That way, the aluminum was down about a quarter inch or so and made the condensation drip back into the pan.

My smoke detector is very close to my oven and the least bit of smoke would set it off.  The drippings dirtied my oven and set off my alarm.