Sorry CARS, but a dry run won't work. Even if you put eggs in the bator, each hatch is a little different. The reason a dry run won't work is because you won't have the mass that the eggs will give you. The eggs holds the heat better than air. So when you open an empty bator the temps dives, but with eggs in it, it won't drop as fast and will regain the loss quicker. Sounds cruel but you will lose chicks from time to time. Even those of us that have hatched thousands of eggs still lose our share. Do we like that, HECK no. But that is a fact of life.
Last fall we all was pulling for one of our young ones that was hatching some eggs. Made the bator and did everything right, just didn't work out. Since then a new bator has been made, don't know if it has been tested yet. But we will all know when horse777 hatches a batch of chicks.