Ventilation is the key not humidity!

Lets say I built an incubator.(Incubator A) An I put enough vent holes so that the air in the incubator replaced its self every hour. After trial an error I figure out that I have to run my humidity at 40% to get a good hatch rate.

Now lets say I built two more almost identical.

Incubator B: I put in enough vent holes to let the air replace its self every two hours.

Incubator C: I put in enough vent holes to let the air replace its self every 30 minutes.


Now I set all three up side by side at a humidity of 40%.

Three weeks later incubator A starts hatching but B an C has almost none hatch. Why?

Opening eggs from incubator B you would see very wet drowned chicks.
Opening eggs from incubator C you would find chicks dried out an stuck.

Whats going on here?

When cold air enters the incubator an starts to warm up it starts pulling moisture from anywhere it can find it. Humidity trays an eggs. Everyone knows that bigger humidity trays means less moisture loss from the eggs.

In incubator B the air replaces its self ever 2 hours. As it does it as to absorb X amount of moisture from the eggs.

In incubator A the air is replace every hour. The same X amount of moisture is absorbed each time. So you have twice as much evaporation over 3 weeks as incubator B.

Incubator C replaces the air every 30 minutes. It has twice as much evaporation as incubator A an 4 times as much as incubator B.


I could run the humidity up to something like 60% in incubator C an I may get good hatch rates. But I'm not fixing the problem I'm compensating for it.

I could also drop the humidity in incubator B to 25% but again I'm not fixing the problem I'm compensating for it.

If you have to run really high humidity to get good hatches your ventilation is to good.

If you have to run really low humidity then you need more ventilation.

Yes outside humidity has an effect on it but not as much as ventilation.

That's why no one can agree on the right humidity. Everyone has different ventilation levels. Even with manufactured incubators the difference between having one plug out or two is doubling the ventilation level.

I don't know what to say,..but WOW! Makes sense! Good work!

Hmmmm very intersting

So how do you figure the math on how quick air is replaced? These three you say the air changes at 30 min, 1 hour and 2 hour, what is the math formula to figure the exchange rate?

I am going to watch this thread very closely. I am on my first hatch on my new Dickeys incubator. I have had the two vent holes in the back wide open the whole time. I have had to cover the humidity pan about 3/4 of the way to keep the humidity at 45%. When I put the eggs in the hatching tray at the bottom, I have been misting them 3 times a day. This is what Mr. Dickey told me to do. When the hatch is complete I will post what hatch rate I got. I think I agree the more ventilation the better. I guess I will find out.

Goes to show that there is no "magic" that makes incubators work.

Everybody has to learn what works best for the incubator they have and what works best for the season. Even have to figure out what's best down to the room or part of the room they have their bator set. What works for one may not work for another, and what works in the spring might not work in the fall.

That's along the lines I've been thinking of as to why some people have to keep the humidity much higher in their forced air than a still air. My guess is the moving air and increase in ventilation bringing in low humidity air is drying the chicks out faster even though the humidity gauge says there is the same moisture.

Quote:
Right on!

I don't know a simple way to figure how many times a day the air is replaced. What I do know is every time I build an incubator it has a set humidity it wont's to run at. Usually 30% to 50%. If I just let it run at that an adjust the ventilation till I get the evaporation rate where I wont it, it gets more controllable an more predictable.

I still believe the last 3 days you should add moisture an not adjust ventilation. Pushing humidity up by sacrificing ventilation is not a good idea.

Depends how much ventilation you have. If you already have plenty blocking a vent or 2 to increase humidity 5-10% can work. If you have minimum ventilation it's a very bad idea.