In our lab we use a way of looking at DNA that involves putting a big flat metal box in a freezer at -70 degrees centigrade (this make the imaging techniques more sensitive). When we want to develop the image we have to warm the box (or cassette) up to room temperature, otherwise the metal hinges can crack – for that we use hair driers! We were very excited when we got some new ones last week!
We also use microwave ovens a lot for warming things up…. I always say that they are the most dangerous piece of equipment that we have because it is easy t heat things up and then have them boil over and hurt people.
Domestic fridges (4 degrees centigrade) and freezers (-20 degrees centigrade) are also common in labs, for storing chemicals and reagents that are sensitive to heat.