How long must I wait before using a meat oven to cook dairy food?
If you want to cook the food uncovered, you should wait 24 hours between the two. Otherwise the oven may be ‘burnt out’ by putting it on the highest setting for about 25 minutes. If the food is covered well, it may be used right after the meat. if the racks are dirty, a piece of tin foil should be placed where the pan is being placed.
Concerning covered foods, see Shulchan Aruch, Yoreh De’ah 108:1; Ksav Sofer 54; Igros Moshe Yoreh De’ah 3:10; concerning dry foods, see Igros Moshe Yoreh De’ah 1:40 (and 1:59, concerning baking a challah) based on Pischei Teshuvah 92:6.