I was laid up from surgery complications for a few months and used my time to research and build an incubator. While I've been around farming all of my life this is our first flock and first time to incubate eggs. We incubated 4 dozen eggs of mixed breeds (cheap eggs) they started hatching a few hours before day 20. 28 eggs hatched during the 24 eggs before getting to day 21. Presently starting day 22 the other 20 eggs have not done anything. I'm not sure if I have enough posts to post picture of my incubator for reference. Here is a brief description of what I've built: Plywood box insulated with 2" styraoam walls covered with FRP board for easy cleaning. Lower chamber has a heat sink of 6 gallons of water in two tubs, rocks, 3 100 watt halogen bulbs, there is a computer fan to push air into this chamber and finally all of this is covered by an aluminum plate with a 1" air circulation space on the outside. Above this are two double cake pans that have water added in during lockdown to raise the humidity. Finally the egg chamber with egg turner, 2 computer fans on the lid to keep air circulating and temp distribution. When I set it up it ran for a couple of weeks before adding eggs. I put some water balloons in and measured temp with a human mercury thermometer. With my thermostat at 100.3, I got a consistent reading 99.5. Considering hatching was happening before day 20 and seems to have finished right at day 21. Does this mean that my temp was a little to high? Also the only hygrometer is a cheap analog on the end of an outdoor thermometer. When I added water on day 18, I was getting a reading of 50-55.
I might add that loud chirping can be heard from some of the I unhatched eggs. I'm thinking that I may need to try lowering the temp by a small amount and find a way to raise the humidity by placing sponges in the cake pans with water to increase surface area.
If you have chirping they have at least internally pipped so I would give them a bit longer to see what happens. You could have uneven heating inside the bator. I have one unit that reads slightly different temps in different areas of the bator. The eggs that haven't hatched yet, do you know if they were all from maybe one side or the other, or perhaps along the outside? Did you candle throughout to make sure all were fully developed before going into lockdown? I like to hatch at at least 65% humidity, you may want to add a wet sponge to bump it up if you are only getting about 55%.
Heating inside could be uneven, even with a fan which would make eggs develop at different rates. In my old bator almost all my hatches took place on day 19/20 because I usually got it to settle on the warm side. Bought a Hovabator this year and it's rock steady. I run right at 100F and my hatches are perfect at day 20/21. I wouldn't change temps unless they were hatching earlier than day 19 personally. You can test your hygrometer with the salt test and that will tell you if it's off.
As soon as I posted the last post, I thought of sponges and have placed some in there. We will see what happens. With these I'm presently registering 70%. While I probably have some temperature differences I tried to design the bator to minimize this. Air flows up from the bottom on the outside and out through a vent in the center with two computer fans centered on thirds pushing air back down. We started with 56 eggs then down to 48 for ones that didn't develop. When I candled at lockdown the airspace looked like diagrams that I've seen and was uniform from egg to egg.
That's a good sign. As long as the air cells are showing proper growth, numbers are irrelevant. I had an old forced air lg I used for 2 1/2 years. Even with the fan I had uneven temps. Directly under the heating element was at least a degree higher than the center and the outside. I always rotated my eggs in the incubator so they weren't in the same area for the duration of incubation.
Thanks for the replies. Since putting sponges in, we do have some more eggs starting to hatch. I'll put sponges down in the cake pans next time.
