Incubator vent sizing

[JDGreene]

I'm making an incubator from a Coleman Xtreme 60 quart cooler and don't know what size vent(s) to put in it. It will have a light bulb and fan. I've never incubated or made an incubator but feel pretty confident other than this.

Any ideal what size?
Do I need more than one vent?

 

[ChickenCanoe]

Likely you'll need many more than one depending on size and fan placement.
If it is too many, you can cover them with tape.
Early in incubation, the embryo needs very little oxygen but the last 3/4 of incubation they start needing much more oxygen.
As a guide, little giant incubators have about 8 holes, top and bottom just a little smaller than a pencil.
Old Sportsmen incubators have three 2 inch holes across the back of the bottom and top with dampers that can be opened and closed.

 

[JDGreene]

Thank you for replying. That does help somewhat. I haven't started incubating yet but will in a few days.

Lets say the little giant (18"x15"x3.5") has eight 1/4" vent holes. That is 0.39 square inches of vent to roughly 0.56 cubic feet of incubator.
= 0.7 square inch of vent per cubic feet of volume.

Is this the right incubator? Are you saying it has 6 vent holes?
A sportsman (30"x15"x31") has six 2" vent holes. That is 18.85 square inches of vent to roughly 8.07 cubic feet of incubator.
= 2.3 square inch of vent per cubic feet of volume.

I have two 3/4" pvc pipe vents right now. That gives me 0.88 square inches per 2 cubic feet (60 quarts) of volume or 0.44 square inch of vent per cubic feet of volume so sounds like I don't have enough ventilation.

If i use two 1" vents, then I would have 0.79 square inch of vent per cubic feet of volume.

I know every incubator is different, but does this sound like a reasonably way to calcualte vent size to be in the ball park?

 

[JDGreene]

This is what I'm dealing with.





I'm thinking change the 2 vents to 1" and add another 1" vent. That will give me 1.18 square inch of vent per cubic foot of incubator. Surely that is enough. They could be capped off with pvc caps or drill a hole in the cap to make the vent smaller.

There are ice trays in the bottom that I can pour water through the vent into the trays to adjust the humidity. I will run my thermostat wire through the vent above the eggs.

 

[ChickenCanoe]

That looks good. You are on the right track. Yes, the GQF Sportsman is the type I have. I think mine are much older though. It is the same size cabinet. I have 2 with the turner racks like that one and another one is just a hatcher, same size cabinet but with 6 stationary shelves for hatcher trays. I just measured and the 6 vent holes are 1 1/8 inches - 3 across the top of the back and 3 at the bottom.
I think the idea is that due to thermal stratification (hot air rises), some holes need to be high to exhaust carbon dioxide and some need to be low to bring in oxygen

 

[JDGreene]

Thank you for measuring. That changes the calculation in post #3. Looks like they are pretty close to the same if you figure it up that way. At least now one can get in the ball park with vent sizing.

Lets say the little giant (18"x15"x3.5") has eight 1/4" vent holes. That is 0.39 square inches of vent to roughly 0.56 cubic feet of incubator.
= 0.70 square inch of vent per cubic feet of volume.

A sportsman (30"x15"x31") has six 1.125" vent holes. That is 5.96 square inches of vent to roughly 8.07 cubic feet of incubator.
= 0.74 square inch of vent per cubic feet of volume.