DIY Incubator Question

[TheBajan]

Good morning!
We have a small flock of 8 hens and a rooster. They were two years old in March and as winter came to a close we were surprised to find that they still are not laying much. Two of our lazy hens stay on the roost till about 11am! The solution of course was to comb the internet researching how to build an incubator. Fast forward a couple of weeks and our incubator is done. I've collected eggs from my lazy birds and also gathered some from a neighbor who has his own flock.
The problem I am having is that my temperature varies by about 3 1/2 degrees from the top tier to the bottom tier. This is a forced air incubator that pushes the hot air down and has a return at the bottom to draw the return air back up. I'm not too savvy on thermodynamics but I think that if this test hatch doesn't work out well, I'll rebuild it [upside-down].
I've set the eggs due to the fact that some of them have been collected over the course of this past week and I couldn't wait longer. I distributed them strategically through the incubator to study the hatch rate in the various corners and levels. Anyone out there with suggestions to even out the heat distribution? I added a UTH just above the return air vent hoping to increase the heat in the lower tier but I don't see a difference. I'm out of ideas.

Note that the temp you see in the picture is because I had just set the eggs and it was still warming up. I have it set at 100 degrees +/- one.

 

[TheBajan]

Good morning!
We have a small flock of 8 hens and a rooster. They were two years old in March and as winter came to a close we were surprised to find that they still are not laying much. Two of our lazy hens stay on the roost till about 11am! The solution of course was to comb the internet researching how to build an incubator. Fast forward a couple of weeks and our incubator is done. I've collected eggs from my lazy birds and also gathered some from a neighbor who has his own flock.
The problem I am having is that my temperature varies by about 3 1/2 degrees from the top tier to the bottom tier. This is a forced air incubator that pushes the hot air down and has a return at the bottom to draw the return air back up. I'm not too savvy on thermodynamics but I think that if this test hatch doesn't work out well, I'll rebuild it [upside-down].
I've set the eggs due to the fact that some of them have been collected over the course of this past week and I couldn't wait longer. I distributed them strategically through the incubator to study the hatch rate in the various corners and levels. Anyone out there with suggestions to even out the heat distribution? I added a UTH just above the return air vent hoping to increase the heat in the lower tier but I don't see a difference. I'm out of ideas.

Note that the temp you see in the picture is because I had just set the eggs and it was still warming up. I have it set at 100 degrees +/- one.

View attachment 2135538

I wanted to update this to say that my husband found a solution. He built a simple diffuser that we slid under the egg turner on the lowest level. That seems to have taken the temp difference down to just one degree. The adventure begins!

 

[Shamo Hybrid]

Oh, wow..... that looks pretty darn cool for a homemade! Can I have it after you're done using it? Thanks!

 

[TheBajan]

Oh, wow..... that looks pretty darn cool for a homemade! Can I have it after you're done using it? Thanks!

Thanks! It was fun to build and I'm so excited to see how this goes!

 

[Katie386]

Wow definitely post your hatch results! That’s pretty cool

 

[TheBajan]

thought I'd update to say that today is day seven and we candled the eggs. There were 36 eggs spread out.
One egg had air bubbles so we tossed it.
Eleven eggs could clearly see veins.
24 eggs were too difficult for this novice to tell.

I'm going to candle again in 3 days and see what we have. The good news is that we seem to be maintaining temp on all three levels of the incubator. My humidity is still something I'm confused about. I keep seeing all ranges of conflicting advice regarding what my humidity should be. I've heard as low as 30% to as high at 60% before lock-down. It's been stead between 55%-60%. I would really welcome opinions from long time hatchers.
Thanks!

 

[Shamo Hybrid]

thought I'd update to say that today is day seven and we candled the eggs. There were 36 eggs spread out.
One egg had air bubbles so we tossed it.
Eleven eggs could clearly see veins.
24 eggs were too difficult for this novice to tell.

I'm going to candle again in 3 days and see what we have. The good news is that we seem to be maintaining temp on all three levels of the incubator. My humidity is still something I'm confused about. I keep seeing all ranges of conflicting advice regarding what my humidity should be. I've heard as low as 30% to as high at 60% before lock-down. It's been stead between 55%-60%. I would really welcome opinions from long time hatchers.
Thanks!

I've been successful with a 40% humidity throughout the whole process, from beginning to lockdown.... no problem. All eggs hatched minus 1 that pipped, zipped, dip baby dip, but couldn't make it out of it's shell and died.

 

[TheBajan]

Day 10 update:
Out of 36 eggs we have-
15 viable
2 quitters
1 bad egg
18 that were never fertile to begin with
This batch testing the incubator is fairly uniform throughout. There are five viable on the lowest level, four on the center, and six on the top. One of the quitters was on the bottom and the other was on the top. So, if I dismiss the eggs that where never fertile to begin with, as well as the one bad egg (it had lots of air bubbles but not viable at all either), I have a potential success rate of 15 out of 17.
On day 14 I will recheck the size of the air cells and adjust humidity as needed.

 

[TheBajan]

Day 14 update:

14 viable
3 quitters

So far so good. We did have a late quitter between day 10 and day 14. I marked the air sacs and they all look like they are progressing well. Interesting to me is that two of them appear to be smaller air sacs in comparison to the rest but still larger than at day 7. We built the hatching boxes that we will use during lock-down and I pulled out one of the egg turners today to test the fit of the hatching box. It fits perfectly but I discovered a problem. With the hatching boxes in place, four of my vent holes will be covered up so we will have to plug those and create vent holes in new locations. An oversight in my designing but easily fixed. I'll update again in four days when we go into lock-down. Crossing my fingers all the rest make it to hatch!

Here's a pic of the hatching box in place. We used plexiglass on the front so we have a full view of the chicks as they hatch. It's starting to get exciting!

 

[TheBajan]

I wanted to come back with a final update on my DIY incubator experimental hatch. I tested this incubator for hot/cold spots by distributing 36 eggs throughout. Of those, half were infertile, 1 was a bad egg, and 2 were early quitters. 14 eggs went into lock-down and 13 eggs hatched. I am pretty happy with the results. I don't really factor the infertile into the equation because, well, they were infertile. Since this was not a test of my roosters fertility rate, that info is not relevant to me. So, apart from that, my hatch rate was 76.47% and I'm pretty happy with that for a first time. What would I do different? Next time I will make it with four tiers for incubation only and continue to use this one for lock-down only. During lock-down I found it difficult to get the humidity up high enough with just the water and sponges in the bottom. I ended up placing two bowls of water on top of the upper, unused tier and that worked. I did find that the slight temp difference between the top and the bottom (about 1 1/2 degree) seemed to have no bearing on mortality but it did play into how early some of the eggs hatched vs the ones that hatched later. With that said, none of them hatched out of bounds regarding time frame and none of them hatched with any malformations. While I feel like this was a successful test of the incubator, I admit I never felt completely confident about my various thermostats accuracy. In the future, I will obtain and calibrate new thermostats so that I can go forward with more confidence about the readings.