No need to preheat the microwave if you are just using it for reheating purposes. You only need to preheat the microwave if you are doing convection cooking.
Read more: How to use a microwave oven effectively and safely
We have one model (EMS3087X) that comes with the convection function. When the appropriate temperature has been reached, the beep will sound twice and the temperature set will flash on the electronic LED screen to remind you to place the food into the microwave.
Discover our support for your Electrolux microwaves at Microwave Ovens Support page.
The convection oven cooking is different from microwave cooking because of the different heating functions available in the oven:
(i) Convection function which transfers heat via the hot air circulation assisted by a fan.
(ii) Heating functions via the heating element i.e. top heater, bottom heater and grill.
Microwave oven heats food by passing microwave radiation through it and this wave make the food cooked from within the outer surface and the cooking time is shorter as compared to the oven cooking method.