Around what time do eggs start putting off their own heat?

[thebulg]

We are on day 8 of incubating. Diy still air incubator in an old roaster. Every night from 3am to 630am when i wake up, we get a 2-3 degree temperature drop. It's been incredibly steady. So from about midnight to 3am, i let the incubator hold at 102 on top of the eggs, 99 behind, because i know the temps will drop.

Last night they didn't! At all! Weather is the same as its been. The eggs held steady at 99 behind them and got up to 103 on top. Could the eggs be giving off their own heat? Also, in a still air incubator, a few hours at 103 isn't guaranteed death, right?

 

[Egghead_Jr]

A few hours is fine. What you have to keep in mind is air temp is not the temp inside the egg. As the air fluctuates in temperature the egg stays very steady. You may be experiencing the low temps at night due to insufficient insulation of your incubator or fluctuating room temperatures. Solar heating is a big one so avoid incubating near windows and try to find the most stable temp in your home. The other thing to keep in mind is incubators fluctuate temp as it turns on- warms up, turns off- cools down. A reading at any given time will never be the same. By finding the high and the low of the swing you can average for an accurate reading. The more eggs or stones or water bottles you put in the incubator the tighter the temperature swing will be. Like my forced air will swing 3 degrees without eggs, 2.5 degrees with less than 12, 2 degrees with 18 and 1.7 degrees or less once I get over two dozen. My high reading is about 30 seconds after the heater turns off (still emitting heat) and low is same time after heater turns on (takes a bit to warm up element).

At what point do eggs emit their own heat? Not really sure. It may be gradual but any real difference I don't see until late in hatch, past 14 days. And any difference it makes depends on how many eggs you have set. When doing two dozen or more eggs at a time I need to adjust temp down around 18 days. A small batch doesn't have the mass to effect incubator temp.

 

[thebulg]

This is super helpful! Thank you! I only have 3 eggs in there (i put in a handful of eggs and was counting on this being trial and major error, but instead it has been an incredible surprising success. These 3 were the only fertile ones and they appear to be very very healthy), so it likely is not the eggs that made the difference last night. I could add rocks to hold the temperature more steady? Would it also raise the temps as the day goes on, or would it make it more steady and even the entire day?

From about 7am (after i adjust from the little drop) until 3am, i haven't had more than a 2° difference and it has been very gradual. The incubator is in the corner of our bathroom and doesn't get any direct light, but it warms up as the day warms up, which i figure is consistent with what would happen outside under a hen. behind the eggs always reads 98-99, front of eggs 101-102, and sometimes it hits 103 right before i go in and turn. I did finally read somehwere that 103° on top of the eggs isn't the kind of temp that kills them, it's internal temperature. So at 103 on top and 99 behind, i would have to assume the internal temp is somewhere in the middle and that is REALLY encouraging.

I candled yesterday and i didn't want to candle today, so it's reassuring that i shouldn't need to check and should assume everything is fine.

 

[Egghead_Jr]

Large stones, more eggs or capped water bottle will all add thermal mass. Thermal mass is by itself inert, it doesn't do anything as in it wont raise temp. What it does do is hold temperature. By holding temperature you make the air temp in incubator more stable. As for eggs internal temp your looking for 99.5F. A range of 99 to 100 is perfect but obviously 99,5 is best. Your right in thinking the top of egg and bottom of egg is a high and low and it's the average that the inside of egg temp will be. People usually can't measure the temp under the egg so rule of thumb for still air incubators is 101.5F at top of egg and in doing that your ensuring the inside is right temp. That number is based on eggs being upright in turner. If on side then that's a smaller space and 100.5-101 F is more likely a better number.

The deal is there are so many variables, once in realm of homemade incubators even more so. But something as simple as the thermometer is a massive variable. We all aren't using the exact one. Most people don't even calibrate them. So your most important tool in incubating is suddenly suspect. I use an oral thermometer. Cheap and the most accurate device you'll find anywhere near the price point. I've read of $30 dollar Brinsea thermometers being off. Honestly, unless you purchase a $100 lab thermometer just stick with what you have or use an oral thermometer from medicine cabinet or purchase one for $6 at wally world. When using a thermometer keep notes. See what day the birds hatch. If they all hatch a day early the thermometer is reading lower than actual temp, a day late the thermometer is high. Measure temp in the same place all the time. By the end of a hatch you know what temp and where to measure it for your incubator with that thermometer. An off reading thermometer isn't useless it's merely unique, where you measure temp is unique and if you average temp or any other little thing is unique. Do it all the same all the time and adjust what temp your going for by how the hatch was. That dials you in. If birds are piping day 19 and hatching day 20 you'd do everything the same and lower temp by 0.5-1.0 F the next hatch. Of course it's important you measure day 21 correctly. If you set on a Sunday then day 21 is on a Sunday.

 

[thebulg]

Large stones, more eggs or capped water bottle will all add thermal mass. Thermal mass is by itself inert, it doesn't do anything as in it wont raise temp. What it does do is hold temperature. By holding temperature you make the air temp in incubator more stable. As for eggs internal temp your looking for 99.5F. A range of 99 to 100 is perfect but obviously 99,5 is best. Your right in thinking the top of egg and bottom of egg is a high and low and it's the average that the inside of egg temp will be. People usually can't measure the temp under the egg so rule of thumb for still air incubators is 101.5F at top of egg and in doing that your ensuring the inside is right temp. That number is based on eggs being upright in turner. If on side then that's a smaller space and 100.5-101 F is more likely a better number. 

The deal is there are so many variables, once in realm of homemade incubators even more so. But something as simple as the thermometer is a massive variable. We all aren't using the exact one. Most people don't even calibrate them. So your most important tool in incubating is suddenly suspect. I use an oral thermometer. Cheap and the most accurate device you'll find anywhere near the price point. I've read of $30 dollar Brinsea thermometers being off. Honestly, unless you purchase a $100 lab thermometer just stick with what you have or use an oral thermometer from medicine cabinet or purchase one for $6 at wally world. When using a thermometer keep notes. See what day the birds hatch. If they all hatch a day early the thermometer is reading lower than actual temp, a day late the thermometer is high. Measure temp in the same place all the time. By the end of a hatch you know what temp and where to measure it for your incubator with that thermometer. An off reading thermometer isn't useless it's merely unique, where you measure temp is unique and if you average temp or any other little thing is unique. Do it all the same all the time and adjust what temp your going for by how the hatch was. That dials you in. If birds are piping day 19 and hatching day 20 you'd do everything the same and lower temp by 0.5-1.0 F the next hatch. Of course it's important you measure day 21 correctly. If you set on a Sunday then day 21 is on a Sunday. 

This is sincerely some of the most helpful advice in one spot that i have seen. A trial and error approach with guidelines to correct the unique set up we have. Thank you.

 

[Egghead_Jr]

Everyone does things a bit different. I'm not one to purchase the most expensive thing and put my faith in that. Trial and error really is the simplest method. I like simple and using notes or writing on masking tape fixed to incubator my calibrations. With the oral thermometer I have it's spot on. I've a forced air unit so just stick it down the vent hole and turn it on. It automatically stores the high temp reading then I pace around the incubator waiting for the light to turn on to know the heater kicked in and start to turn on and off the thermometer (digital medical show highest reading) until I find the low. Average the two. It's been spot on for the three years I've been doing it this way. Some hatch day 20, most day 21 and few late early day 22 if I kept an average temp at 95.5 F. This $6 unit has proven time and time again to be spot on accurate. I keep a cigar humidor combo unit in the incubator as quick temp reference and humidity gauge. If that ever read different than 97 F then I know the temp is off. LOL. Yeah, had early hatch the first year I used only that and being so early was not a good hatch rate. Knew to try 98F next round then got the oral and have not looked back. Was unnerving to see the 97F on cigar unit the first time I used the oral but it proved true.

Temp is the singular most important thing for a good hatch. Turning the second and humidity third I think. You got to do some horrible things with humidity to destroy a hatch. Biggest mistake is to have higher humidity during first 18 days of incubation. The drier is much better than too moist. If you ever get a hygrometer preform a salt test on it to calibrate. Easy to do and takes all guess work out. Again, any cheap hygrometer will do if you salt test it for calibration. As for RH, I like 30% for incubating and 70% for hatch.

Salt test-

Milk or juice cap filled with salt, add drops of water until saturated. I pour off any standing water.

Put cap and hygrometer into a sealed container and leave on kitchen table. I like quart zip seal bags and provide small pillow of air when sealing.

Wait 4 hours or more and take your reading. Subtract your reading from 75 and that's your calibration #. Write it on masking tape and stick to incubator.

Ex: Your reading is 84%, 75-84= -9. You'll always subtract 9 from readings for true RH.

Simple right?

I'm trapped waiting for birch sap to be syrup. Have all sorts of time this morning, just run out every 30 minutes to add more concentrate to boil. Got another hour or so....lawd, it took 8 days to boil on 2x3 pan just to get to this stage. So ready to be done with it!