Incubator temp swings.

[ZJchicks]

Just built my first forced air incubator. I am reviewing temp readouts between 97-102. It never goes below or above these temps. Is this ok? I'm using an analog thermostat. I am trying to incubate guinea egg

 

[lazy gardener]

What are you using for a thermometer? Does it read in tenth's of a degree? IMO, you've got too much swing going for safety. Especially if you don't get a breakdown to .1 degree. B/C that 97 could very well be 96.5 or lower, and that 102 could very well be 102.5 or even 103. Has that thermometer been calibrated with a good medical thermometer? Only after getting it calibrated, so you know it's accuracy will you be in position to know if those swings are going to be a deal breaker. Also, have you checked to see if you have warm or cold spots. Even with a fan, you are bound to. My styro bator, home made has quite a lot of variation, and I've had to spend up to a full day working with tin-foil baffles to direct the air flow to minimize the high/low spots. Also, how long have you been running it? You'll want at least a 24 hour run, after you've played with baffles, and you'll want to run it "full" to mimic a full load of eggs. Bators work best when there's a thermal mass to help regulate temps. I put in a couple of 16 oz. bottles of warm water, and let it run for 24 hours before committing to eggs. Then, finally, when you put those eggs in, you'll know that it's been running steady. Don't touch that thermostat once the eggs go in, (for the first 24 hours) unless it's to turn it DOWN!

 

[ZJchicks]

Wow! That's a lot to think about. My thermometer/hygrometer is from lowes for household use. It doesn't read tenths unfortunately. My bator is only about 14"x16" and I have a 40W incandescent hearing it and an analog lower water heater thermostat regulating the bulb and a 12w AC computer fan circulating air. These eggs came and I know guineas( especially mine) are not particularly motherly. So I figured I'd try my hand at building an incubator. This is a pretty crude setup but I figured it'd be worth a shot.

 

[Egghead_Jr]

That's not a bad temp swing really. When setting up to ensure my incubator is holding stable before placing eggs I put a container of water in it. Large enough bowl or tupperware that will mimic two dozen eggs in mass. This heat sink will stable out that temp swing. After 12 hours you can use an oral thermometer from your medicine cabinet to check the temp of water. No mater the temp swing it will stay a constant temp (will be average of your swings). An oral thermometer will be accurate and get you to 99.5 F to fine tune your incubator settings. If you are not setting a lot of eggs know that you can use capped water bottles for the thermal mass to steady the temp in incubator.

I use Oral thermometer to spot check my incubator. To calibrate the hygrometer you need to perform a salt test. Really easy to do and only takes 6 hours.

Fill a milk cap or similar size container with salt. Add drops of water until wet sand consistency not slurry.

Put cap and hygrometer in a zip seal bag, sandwich or quart size, ensuring some air in there making a pillow.

Wait 6 hours and note the hygrometer reading. Subtract that form 75. A salt environment is exactly 75%.

Write the calibrated amount on piece of tape and place on incubator to remind you how much to add or subtract from your hygrometer for a true reading.

ex. your hygrometer reads 82%. 75-82= -7. You'll always subtract 7 from your readings for true humidity.

 

[lazy gardener]

EH: I've never heard of the "cap of salt" calibration. I've always read (If I remember correctly) that it needs to be done with a large amount of salt in a measuring cup (I forget the amounts). Your very simple method may give me the motivation to try it out!

ZJ: I certainly hope I did not discourage you. I'm glad that some one else weighed in with a much more liberal philosophy re: what works and what won't! I wish you the best with your hatch.

 

[Egghead_Jr]

The amount of salt needed is dependent on the volume of the sealed environment. A small zip seal bag only requires a milk cap, juice cap amount of salt which is three times the amount of a beer, soda cap.

As it's the salt itself that is striving for 75% RH I'd fear that too much salt would have too much water in it when damp that it would make the air in a small sealed environment more humid than the salt.

 

[lazy gardener]

If it's all variable, and not measured to match the volume of air, I can't understand how anyone'd get an accurate calibration. Sounds like an exercise without defined parameters or results. Which is kind of why I've not bothered with it.

 

[WalnutHill]

If it's all variable, and not measured to match the volume of air, I can't understand how anyone'd get an accurate calibration. Sounds like an exercise without defined parameters or results. Which is kind of why I've not bothered with it.

Actually, it works. http://www.omega.com/temperature/z/pdf/z103.pdf

 

[lazy gardener]

So, would some one please help me wrap my mind around this concept: The salt/H2O slush does not have to be of a specific volume, and it creates a specific humidity in the enclosed container, which will correlate with the exact temperature according to the chart? Explain what's happening at the molecular level?

 

[WalnutHill]

A saturated salt solution has a specific humidity. When enclosed, the humidity in the enclosure will equalize to the humidity of the salt slurry. As there is no moving air, there is no additional humidity due to evaporation.

Any more specific I can't get, but it does work, as long as pure salt and pure water are used, and that the water is completely saturated with salt.