Ok, so my old oven was dreadful but instead of replacing it like for like, I splashed out on 2 single ovens (each with dual fan technology!) where you could bake at all levels of the oven. I was soooo excited. Put my thermometer in the oven and whacked it up to 180...temperature was bang on the thermostat. I then put 2 sandwich tins in there in the middle shelves with the thermometer next to it and the temperature was showing 20 degrees lower than the thermostat! I've tried turning the fan off, conventional baking, mix of both but it still does the same. Turn the heat on with an empty oven though and the temperature is perfect!
Does anyone else have this problem? Things are definitely taking longer to bake as well which is OK for some cakes but concerns me for light sponges in case they dry out. I am at the point where I'm considering taking them back and trying to find an alternative :-(
I did not read your post completely but........of course the temp dropped when you put some COLD new items in plus opening the door also allowed cold air in.
Ovens work by dropping and elevating the temp for *average* temp over the entire baking time. That's the normal :)
Complete y our baking and see how long it took. If it's not done in a normal time.