I am really confused. I have been hatching eggs in a styrofoam incubator for a few years with mixed results. I have had much improved results with an older 1588 that has a thermostat and fan. The temperature stays around 100. I was tired of hand turning so I cut some holes out of the bottom of a cheap egg carton and was just propping the incubator to turn the eggs. It worked great with some cheap eggs and I had a near 100% hatch. Now I have some more expensive eggs and it was all great till about 8 days in and then I started experiencing temp Spikes when the heat kicked on in the house. One day one of the thermometers was showing 105 degrees. This has been getting worse for the last five days.I even stopped tilting the incubator but it made no difference. I checked the switches on the thermostat and they were set right but I went ahead and reset them just to be sure. I put the lid back on and within a couple hours the temperature was back up to 102. I was just going to switch them to the little giant and I decided to take the eggs out of the egg cartons and lay them flat.Much to my surprise the temperature stayed around 100 degrees. I then decided to heat the house to 80 degrees and see if they spiked up. Again the incubator is keeping constant temp close to 100 degrees.Did the egg carton somehow hold heat inside the eggs? The carton was just like many on this board have used in the past. The top was removed and the bottom cut out. Now what, should I put them in the Little giant for a couple days and lower the temperature down or just take my chances now that the problem seems be corrected. I am somewhat venting but would appreciate advice.I checked the eggs and yes they are moving around.