I just completed a 180 egg, staggered, 3 week, 60 egg per set, incubation/hatch in my 1502 and 1550 setup. Of the 170 fertile eggs, I successfully hatched 158 chicks. As far as temp and humidity settings go, I watched it like a hawk for the first week. Humidity in the 1502 with a full water tray stayed right around 40 to 45. After the first week, I just let the thing do its job. I made sure the water tray was full which resulted in adding water about every other day.
Once I moved the first 60 eggs to the hatcher on incubation day 18, I added 1 wick and kept the water tray full again. Per my cheepo weather station I bought to monitor temp/humid in the hatcher (bought the hatcher used and wasn't sure about whether or not the humidity was reading right), temp was always about 99 degrees and humidity hovered around the 65 to 70 percent mark. Again, all i did was make sure the water tray was full.
I achieved a 92.9% hatch rate just by turning the machines on and making sure they had water. It was THAT easy!!!! I never had to mess with temperature settings at all. BTW this was my first attempt at hatching eggs of any kind EVER!
If I had auto waterers for the 2 units, Im convinced they would have been 100% hands off.
Guess my point is, Im not real sure you have to sweat ANY of the small stuff with these units. Fill the water tray, turn 'em on, verify initial temp and humidity and let 'em rip! I was hesitant to spend the money required for these units but dang Im glad I did. I will take that kind of hatch rate all day long!.
Ron