hi all! i just purchased a bosch oven recently..and was noticing the temperature on preheating period..the oven temperature reaches the desired temperature and stays there for long periods and remains constant..however as i place any item into the oven for baking..the temperature drops by 20oC..does this happen for all ovens? is this how the temperature works? i understand everytime u open the oven door the temperature drops however mine just stays at minus 20oC of the preheated value..is this because the baked item is absorbing the heat as it bakes? O_O please advice PS : my oven heating setting is set on top and bottom heat element..without the turbofan on..