I Purchased this #4250 last year for my daughter to use at her work/school. She already had a large incubator in the science lab, so it sat all winter at her house. The unit has an automatic turner w/fan and heater. Its an led readout. Easy to use.
I decided to use it this year to hatch 24 eggs from a previous supplier.
At day 20 a chick hatched. At day 21 another. Nothing since. Its now 24 days and I plugged the plug. I may give these eggs to my daughter to do a look and see what was what.
The #4250 seemed to work fine. Although I had to add water for humidity often to keep it around 50-60 percent. These eggs have a very hard shell. Black French Copper Marans.
I moved them out of the turner at day 18. Possibly the remaining eggs were not fertile?